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Intellectual disability v3.23 SCN8A Sarah Leigh Added comment: Comment on mode of pathogenicity: Based on report in PMID 31625145, reporting biallelic loss of function SCN8A variants in three cases in two families with severe developmental and epileptic encephalopathy. This differs from the previosly reported gain of function monoallelic variants (PMID 24194747;22365152).
Intellectual disability v3.23 SCN8A Sarah Leigh Mode of pathogenicity for gene: SCN8A was changed from to Other
Intellectual disability v3.22 SCN8A Sarah Leigh Added comment: Comment on mode of inheritance: Based on report in PMID 31625145, reporting biallelic loss of function SCN8A variants in three cases in two families with severe developmental and epileptic encephalopathy.
Intellectual disability v3.22 SCN8A Sarah Leigh Mode of inheritance for gene: SCN8A was changed from MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.21 SCN8A Sarah Leigh Phenotypes for gene: SCN8A were changed from Cognitive impairment with or without cerebellar ataxia, 614306Epileptic encephalopathy, early infantile, 13, 614558; COGNITIVE IMPAIRMENT WITH OR WITHOUT CEREBELLAR ATAXIA to ?Cognitive impairment with or without cerebellar ataxia,614306; Epileptic encephalopathy, early infantile,614558; Seizures, benign familial infantile,617080
Intellectual disability v3.20 SCN8A Sarah Leigh Publications for gene: SCN8A were set to
Intellectual disability v3.19 SCAMP5 Sarah Leigh Added comment: Comment on mode of pathogenicity: Heterozygous c.538G>T, p.Gly180Trp seeming to have a dominant-negative effect resulting in autistic spectrum disorder, intellectual disability and seizures. While homozygous c.271C>T, p.R91W seems to have a loss of function effect resulting in early onset epilepsy and Parkinson’s disease.
Intellectual disability v3.19 SCAMP5 Sarah Leigh Mode of pathogenicity for gene: SCAMP5 was changed from Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments to Other
Intellectual disability v3.18 SCAMP5 Sarah Leigh Classified gene: SCAMP5 as Amber List (moderate evidence)
Intellectual disability v3.18 SCAMP5 Sarah Leigh Added comment: Comment on list classification: Not associated with phenotype in OMIM (last edited on 10/06/2014) or in Gen2Phen. Two variants have been identified in three unrelated cases (one monoallelic, one biallelic). Supportive functional studies have been reported.
It would appear that the two variants reported so far in this gene result in differing mode of pathogenicity and phenotypic features. With heterozygous c.538G>T, p.Gly180Trp seeming to have a dominant-negative effect resulting in autistic spectrum disorder, intellectual disability and seizures. While homozygous c.271C>T, p.R91W seems to have a loss of function effect resulting in early onset epilepsy and Parkinson’s disease. This may be due to different functional domains of the mature protein being altered.
Intellectual disability v3.18 SCAMP5 Sarah Leigh Gene: scamp5 has been classified as Amber List (Moderate Evidence).
Intellectual disability v3.17 SCAMP5 Sarah Leigh Added comment: Comment on mode of inheritance: Based on the reporting of a de novo heterozygous varaiant (NM_001178111.1:c.538G>T) in two unrelated cases (PMID: 31439720) and a homozygous variant (NM_001178111:c.271C>T, rs747966691) in two members of a Chinese consanguienious family (PMID: 32020363).
Intellectual disability v3.17 SCAMP5 Sarah Leigh Mode of inheritance for gene: SCAMP5 was changed from MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.16 SCAMP5 Sarah Leigh Publications for gene: SCAMP5 were set to 31439720; 20071347
Intellectual disability v3.15 RNF13 Sarah Leigh reviewed gene: RNF13: Rating: GREEN; Mode of pathogenicity: Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.15 RNF113A Sarah Leigh Classified gene: RNF113A as Green List (high evidence)
Intellectual disability v3.15 RNF113A Sarah Leigh Added comment: Comment on list classification: Associated with relevant phenotype in OMIM and as possible Gen2Phen gene for X-linked trichothiodystrophy. At least 3 terminating variants reported in unrelated cases. Supportive functional studies also reported.
Intellectual disability v3.15 RNF113A Sarah Leigh Gene: rnf113a has been classified as Green List (High Evidence).
Intellectual disability v3.14 RNF113A Sarah Leigh Publications for gene: RNF113A were set to 25612912; 29144457
Intellectual disability v3.13 RARS Sarah Leigh Classified gene: RARS as Green List (high evidence)
Intellectual disability v3.13 RARS Sarah Leigh Added comment: Comment on list classification: Associated with relevant phenotype in OMIM and as confirmed Gen2Phen gene. At least 19 variants reported in at least 13 cases of Hypomyelinating Leukodystrophy exhibinting intellectual disability to varying degrees. Supportive functional studies were also reported.
Intellectual disability v3.13 RARS Sarah Leigh Gene: rars has been classified as Green List (High Evidence).
Intellectual disability v3.12 RARS Sarah Leigh commented on gene: RARS
Intellectual disability v3.12 RARS Sarah Leigh Tag new-gene-name tag was added to gene: RARS.
Intellectual disability v3.12 RALGAPA1 Sarah Leigh Classified gene: RALGAPA1 as Green List (high evidence)
Intellectual disability v3.12 RALGAPA1 Sarah Leigh Added comment: Comment on list classification: Associated with relevant phenotype in OMIM and as probable Gen2Phen gene for RALGAPA1-related neurodevelopmental disorder. At least 5 variants reported in at least 4 unrelated cases.
Intellectual disability v3.12 RALGAPA1 Sarah Leigh Gene: ralgapa1 has been classified as Green List (High Evidence).
Intellectual disability v3.11 RALGAPA1 Sarah Leigh Added comment: Comment on phenotypes: Intellectual disability;hypotonia;infantile spasms.
Intellectual disability v3.11 RALGAPA1 Sarah Leigh Phenotypes for gene: RALGAPA1 were changed from Intellectual disability; hypotonia; infantile spasms. to Neurodevelopmental disorder with hypotonia, neonatal respiratory insufficiency, and thermodysregulation 618797
Intellectual disability v3.10 PUM1 Sarah Leigh Classified gene: PUM1 as Green List (high evidence)
Intellectual disability v3.10 PUM1 Sarah Leigh Added comment: Comment on list classification: Associated with relevant phenotype in OMIM, but not associated with phenotype in Gen2Phen. At least 3 SNVs in at least 5 unrelated cases and CNVs spanning PUM1 in 9 cases. Supportive functional studies also reported.
Intellectual disability v3.10 PUM1 Sarah Leigh Gene: pum1 has been classified as Green List (High Evidence).
Intellectual disability v3.9 PUM1 Sarah Leigh Added comment: Comment on phenotypes: Global developmental delay;Intellectual disability;Seizures;Abnormality of the face;Ataxia;Cryptorchidism
Intellectual disability v3.9 PUM1 Sarah Leigh Phenotypes for gene: PUM1 were changed from Global developmental delay; Intellectual disability; Seizures; Abnormality of the face; Ataxia; Cryptorchidism to Spinocerebellar ataxia 47 617931
Intellectual disability v3.8 PUM1 Sarah Leigh Publications for gene: PUM1 were set to 29474920; 30903679; 31859446
Intellectual disability v3.7 PIGP Sarah Leigh Classified gene: PIGP as Green List (high evidence)
Intellectual disability v3.7 PIGP Sarah Leigh Added comment: Comment on list classification: Associated with relevant phenotype in OMIM, but not associated with phenotype in Gen2Phen. At least 2 variants reported (rs768633670, rs778481061). rs768633670 were reported as a compound heterozygotes in one case and was present in at least two geographically separated consanguineous European families; suggesting a founder effect in the European population (PMID 32042915).
Supportive functional studies are also presented.
Intellectual disability v3.7 PIGP Sarah Leigh Gene: pigp has been classified as Green List (High Evidence).
Intellectual disability v3.6 PIGP Sarah Leigh Publications for gene: PIGP were set to 28334793; 31139695; 32042915
Intellectual disability v3.5 PIGP Sarah Leigh Phenotypes for gene: PIGP were changed from ?Epileptic encephalopathy, early infantile, 55, 617599; Generalized hypotonia; Global developmental delay; Seizures; Intellectual disability; Feeding difficulties; Cortical visual impairment to Epileptic encephalopathy, early infantile, 55, 617599; Generalized hypotonia; Global developmental delay; Seizures; Intellectual disability; Feeding difficulties; Cortical visual impairment
Intellectual disability v3.4 PIGP Sarah Leigh Publications for gene: PIGP were set to 28334793; 31139695; 32042915
Intellectual disability v3.4 PIGP Sarah Leigh Publications for gene: PIGP were set to 28334793; 31139695
Intellectual disability v3.3 SLC5A6 Zornitza Stark reviewed gene: SLC5A6: Rating: GREEN; Mode of pathogenicity: None; Publications: 31754459, 27904971, 31392107; Phenotypes: Developmental delay, epilepsy, neurodegeneration; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 RARS Zornitza Stark reviewed gene: RARS: Rating: GREEN; Mode of pathogenicity: None; Publications: 31814314; Phenotypes: Leukodystrophy, hypomyelinating, 9 (# 616140); Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 CXorf56 Zornitza Stark reviewed gene: CXorf56: Rating: GREEN; Mode of pathogenicity: None; Publications: 29374277, 31822863; Phenotypes: Mental retardation, X-linked 107, MIM# 301013; Mode of inheritance: X-LINKED: hemizygous mutation in males, biallelic mutations in females; Current diagnostic: yes
Intellectual disability v3.3 TNR Zornitza Stark gene: TNR was added
gene: TNR was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: TNR was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TNR were set to 32099069
Phenotypes for gene: TNR were set to Spastic para- or tetraparesis; Axial muscular hypotonia; Intellectual disability; Transient opisthotonus
Review for gene: TNR was set to GREEN
gene: TNR was marked as current diagnostic
Added comment: 13 individuals from 8 unrelated families reported.
Sources: Expert list
Intellectual disability v3.3 RUSC2 Zornitza Stark gene: RUSC2 was added
gene: RUSC2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: RUSC2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: RUSC2 were set to 27612186
Phenotypes for gene: RUSC2 were set to Mental retardation, autosomal recessive 61, MIM# 617773
Review for gene: RUSC2 was set to AMBER
Added comment: Two unrelated families reported.
Sources: Expert list
Intellectual disability v3.3 RUNX2 Zornitza Stark reviewed gene: RUNX2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Cleidocranial dysplasia, MIM# 119600; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 RSRC1 Zornitza Stark gene: RSRC1 was added
gene: RSRC1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: RSRC1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: RSRC1 were set to 28640246; 29522154
Phenotypes for gene: RSRC1 were set to Intellectual developmental disorder, autosomal recessive 70, MIM# 618402
Review for gene: RSRC1 was set to AMBER
Added comment: Two unrelated families reported, 8 affected individuals.
Sources: Expert list
Intellectual disability v3.3 RSPO4 Zornitza Stark reviewed gene: RSPO4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Anonychia congenita, MIM# 206800; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 RSPH3 Zornitza Stark reviewed gene: RSPH3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ciliary dyskinesia, primary, 32, MIM# 616481; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 RSPH1 Zornitza Stark reviewed gene: RSPH1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ciliary dyskinesia, primary, 24, MIM# 615481; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 RPS19 Zornitza Stark reviewed gene: RPS19: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Diamond-Blackfan anemia 1, MIM#105650; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 RPGRIP1 Zornitza Stark reviewed gene: RPGRIP1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Cone-rod dystrophy 13, MIM# 608194, Leber congenital amaurosis 6, MIM# 613826; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 RPE65 Zornitza Stark reviewed gene: RPE65: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Leber congenital amaurosis 2, MIM# 204100, Retinitis pigmentosa 20, MIM# 613794, Retinitis pigmentosa 87 with choroidal involvement, MIM# 618697; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.3 ROBO3 Zornitza Stark reviewed gene: ROBO3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Gaze palsy, familial horizontal, with progressive scoliosis, 1 607313; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 RNF13 Zornitza Stark reviewed gene: RNF13: Rating: GREEN; Mode of pathogenicity: None; Publications: 30595371; Phenotypes: Epileptic encephalopathy, early infantile, 73, MIM# 618379; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.3 RIC1 Zornitza Stark gene: RIC1 was added
gene: RIC1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: RIC1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: RIC1 were set to 31932796
Phenotypes for gene: RIC1 were set to Cleft lip; cataract; tooth abnormality; intellectual disability; facial dysmorphism; ADHD
Review for gene: RIC1 was set to AMBER
Added comment: Zebrafish model and consanguineous families but homozygous-by-descent. One to watch.
Sources: Expert list
Intellectual disability v3.3 RHEB Zornitza Stark reviewed gene: RHEB: Rating: GREEN; Mode of pathogenicity: None; Publications: 29051493; Phenotypes: Intellectual disability, Macrocephaly; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.3 RETREG1 Zornitza Stark reviewed gene: RETREG1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Neuropathy, hereditary sensory and autonomic, type IIB, MIM# 613115; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 MYO5B Zornitza Stark reviewed gene: MYO5B: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Microvillus inclusion disease, MIM# 251850; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 MYH9 Zornitza Stark reviewed gene: MYH9: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Macrothrombocytopenia and granulocyte inclusions with or without nephritis or sensorineural hearing loss, MIM# 155100; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 MYH8 Zornitza Stark reviewed gene: MYH8: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Trismus-pseudocamptodactyly syndrome, MIM# 158300; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 MYH6 Zornitza Stark reviewed gene: MYH6: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: {Sick sinus syndrome 3} 614090 3 Atrial septal defect 3, MIM# 614089, Cardiomyopathy, dilated, 1EE, MIM# 613252, Cardiomyopathy, hypertrophic, 14, MIM# 613251; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 MTHFS Zornitza Stark reviewed gene: MTHFS: Rating: GREEN; Mode of pathogenicity: None; Publications: 30031689, 31844630, 22303332; Phenotypes: Neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination, 618367; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.3 MSX2 Zornitza Stark reviewed gene: MSX2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Craniosynostosis 2, MIM# 604757, Parietal foramina 1, MIM# 168500, Parietal foramina with cleidocranial dysplasia, MIM# 168550; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 MSX1 Zornitza Stark reviewed gene: MSX1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ectodermal dysplasia 3, Witkop type 189500, Orofacial cleft 5 608874, Tooth agenesis, selective, 1, with or without orofacial cleft 106600; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 MPV17 Zornitza Stark reviewed gene: MPV17: Rating: GREEN; Mode of pathogenicity: None; Publications: 22593919; Phenotypes: Mitochondrial DNA depletion syndrome 6 (hepatocerebral type), OMIM #256810; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.3 MNX1 Zornitza Stark reviewed gene: MNX1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Currarino syndrome, OMIM #176450; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 MN1 Zornitza Stark reviewed gene: MN1: Rating: GREEN; Mode of pathogenicity: None; Publications: 31834374, 31839203; Phenotypes: Intellectual disability, dysmophic features, rhombencephalosynapsis; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.3 MMP13 Zornitza Stark reviewed gene: MMP13: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Metaphyseal anadysplasia 1, MIM# 602111, Metaphyseal dysplasia, Spahr type, MIM# 250400, Spondyloepimetaphyseal dysplasia, Missouri type, MIM# 602111; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.3 MGP Zornitza Stark reviewed gene: MGP: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Keutel syndrome, MIM# 245150; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 MFSD2A Zornitza Stark reviewed gene: MFSD2A: Rating: GREEN; Mode of pathogenicity: None; Publications: 26005865, 26005868, 24828044; Phenotypes: Microcephaly 15, primary, autosomal recessive, MIM# 616486; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 MFRP Zornitza Stark reviewed gene: MFRP: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Microphthalmia, isolated 5, MIM# 611040; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 METTL5 Zornitza Stark reviewed gene: METTL5: Rating: GREEN; Mode of pathogenicity: None; Publications: 29302074, 31564433; Phenotypes: Intellectual developmental disorder, autosomal recessive 72, MIM# 618665; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.3 MESP2 Zornitza Stark reviewed gene: MESP2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spondylocostal dysostosis 2, autosomal recessive, MIM# 608681; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 MC2R Zornitza Stark reviewed gene: MC2R: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Glucocorticoid deficiency, due to ACTH unresponsiveness, MIM# 202200; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 MATN3 Zornitza Stark reviewed gene: MATN3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spondyloepimetaphyseal dysplasia 608728, {Osteoarthritis susceptibility 2} 140600, Epiphyseal dysplasia, multiple, 5 607078; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.3 MAPRE2 Zornitza Stark reviewed gene: MAPRE2: Rating: GREEN; Mode of pathogenicity: None; Publications: 26637975; Phenotypes: Symmetric circumferential skin creases, congenital, 2, MIM# 616734; Mode of inheritance: BOTH monoallelic and biallelic (but BIALLELIC mutations cause a more SEVERE disease form), autosomal or pseudoautosomal
Intellectual disability v3.3 MAPK10 Zornitza Stark reviewed gene: MAPK10: Rating: RED; Mode of pathogenicity: None; Publications: 23329067, 16249883; Phenotypes: Intellectual disability, seizures; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 MAP3K1 Zornitza Stark reviewed gene: MAP3K1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: 46XY sex reversal 6, MIM# 613762; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 MAP1B Zornitza Stark reviewed gene: MAP1B: Rating: GREEN; Mode of pathogenicity: None; Publications: 31317654, 30150678, 30214071; Phenotypes: Intellectual disability, seizures, PVNH, dysmorphic features; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.3 MADD Zornitza Stark reviewed gene: MADD: Rating: GREEN; Mode of pathogenicity: None; Publications: 28940097; Phenotypes: Intellectual disability; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.3 NUP214 Zornitza Stark gene: NUP214 was added
gene: NUP214 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: NUP214 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NUP214 were set to 31178128
Phenotypes for gene: NUP214 were set to developmental delay; intellectual disability; epileptic encephalopathy; developmental regression; microcephaly
Review for gene: NUP214 was set to GREEN
gene: NUP214 was marked as current diagnostic
Added comment: Three unrelated families reported, regression on background of pre-existing neurodisability.
Sources: Expert list
Intellectual disability v3.3 NUP107 Zornitza Stark reviewed gene: NUP107: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: Galloway-Mowat syndrome 7, MIM# 618348, Nephrotic syndrome, type 11, MIM# 616730; Mode of inheritance: None
Intellectual disability v3.3 NRXN2 Zornitza Stark edited their review of gene: NRXN2: Added comment: One individual reported with autism and a paternally inherited variant in this gene, father had a language disorder. Another infant reported with severe EE and a maternally inherited variants in NRXN1 and a paternally inherited variant in NRXN2. Some animal data.; Changed publications: 21424692, 30709877, 25745399; Changed phenotypes: Autism
Intellectual disability v3.3 NR5A1 Zornitza Stark reviewed gene: NR5A1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: 46XY sex reversal 3, 612965, Premature ovarian failure 7, 612964, Adrenocortical insufficiency, Spermatogenic failure 8, 613957; Mode of inheritance: None
Intellectual disability v3.3 NR2F2 Zornitza Stark reviewed gene: NR2F2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Congenital heart defects, multiple types, 4, MIM# 615779; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 NPR2 Zornitza Stark reviewed gene: NPR2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Acromesomelic dysplasia, Maroteaux type, MIM# 602875, Epiphyseal chondrodysplasia, Miura type MIM#615923, Short stature with nonspecific skeletal abnormalities 616255; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.3 NPHS1 Zornitza Stark reviewed gene: NPHS1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Nephrotic syndrome, type 1, MIM# 256300; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 NPHP4 Zornitza Stark reviewed gene: NPHP4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Nephronophthisis 4, MIM# 606966, Senior-Loken syndrome 4, MIM# 606996; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 NPHP3 Zornitza Stark reviewed gene: NPHP3: Rating: GREEN; Mode of pathogenicity: None; Publications: 18371931; Phenotypes: Meckel syndrome 7, MIM# 267010; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 NOTCH2 Zornitza Stark reviewed gene: NOTCH2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Alagille syndrome 2, MIM#610205, Hajdu-Cheney syndrome, MIM#102500; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 NOG Zornitza Stark reviewed gene: NOG: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Brachydactyly, type B2, MIM# 611377, Multiple synostoses syndrome 1, MIM# 186500, Stapes ankylosis with broad thumbs and toes, MIM# 184460, Symphalangism, proximal, 1A, MIM# 185800, Tarsal-carpal coalition syndrome, MIM# 186570; Mode of inheritance: None
Intellectual disability v3.3 NODAL Zornitza Stark reviewed gene: NODAL: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Heterotaxy, visceral, 5, MIM# 270100; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 NMNAT1 Zornitza Stark reviewed gene: NMNAT1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Leber congenital amaurosis 9, MIM# 608553; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 NKX3-2 Zornitza Stark reviewed gene: NKX3-2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spondylo-megaepiphyseal-metaphyseal dysplasia, MIM# 613330; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 NHP2 Zornitza Stark reviewed gene: NHP2: Rating: AMBER; Mode of pathogenicity: None; Publications: 18523010, 31985013; Phenotypes: Dyskeratosis congenita, autosomal recessive 2, MIM# 613987, Høyeraal-Hreidarsson syndrome; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 NHEJ1 Zornitza Stark reviewed gene: NHEJ1: Rating: RED; Mode of pathogenicity: None; Publications: 16439204; Phenotypes: Severe combined immunodeficiency with microcephaly, growth retardation, and sensitivity to ionizing radiation; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 NGF Zornitza Stark reviewed gene: NGF: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Neuropathy, hereditary sensory and autonomic, type V, MIM# 608654; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 NEK1 Zornitza Stark reviewed gene: NEK1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Short-rib thoracic dysplasia 6 with or without polydactyly, MIM# 263520; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.3 NEDD4L Zornitza Stark reviewed gene: NEDD4L: Rating: GREEN; Mode of pathogenicity: None; Publications: 27694961; Phenotypes: Periventricular nodular heterotopia 7, MIM#617201; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.3 NDUFAF1 Zornitza Stark gene: NDUFAF1 was added
gene: NDUFAF1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: NDUFAF1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NDUFAF1 were set to 17557076; 21931170; 24963768
Phenotypes for gene: NDUFAF1 were set to Mitochondrial complex I deficiency, nuclear type 11, MIM#618234
Review for gene: NDUFAF1 was set to GREEN
gene: NDUFAF1 was marked as current diagnostic
Added comment: Three unrelated families described, DD/ID part of the phenotype, specifically mentioned in two families, child in third family died in infancy from HOCM.
Sources: Expert list
Intellectual disability v3.3 NDUFA2 Zornitza Stark gene: NDUFA2 was added
gene: NDUFA2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: NDUFA2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NDUFA2 were set to 18513682; 28857146
Phenotypes for gene: NDUFA2 were set to Mitochondrial complex I deficiency, nuclear type 13, MIM#618235
Review for gene: NDUFA2 was set to GREEN
gene: NDUFA2 was marked as current diagnostic
Added comment: Three unrelated families reported, DD/IDD in all.
Sources: Expert list
Intellectual disability v3.3 NCAPG2 Zornitza Stark gene: NCAPG2 was added
gene: NCAPG2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: NCAPG2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NCAPG2 were set to 30609410
Phenotypes for gene: NCAPG2 were set to Khan-Khan-Katsanis syndrome, MIM# 618460
Review for gene: NCAPG2 was set to GREEN
gene: NCAPG2 was marked as current diagnostic
Added comment: Two unrelated families and an animal model (zebrafish).
Sources: Expert list
Intellectual disability v3.3 NCAPD2 Zornitza Stark gene: NCAPD2 was added
gene: NCAPD2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: NCAPD2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NCAPD2 were set to 31056748; 27737959; 28097321
Phenotypes for gene: NCAPD2 were set to Microcephaly 21, primary, autosomal recessive, OMIM #617983
Review for gene: NCAPD2 was set to GREEN
gene: NCAPD2 was marked as current diagnostic
Added comment: 5 individuals from three unrelated families reported, some functional evidence.
Sources: Expert list
Intellectual disability v3.3 ZNF335 Zornitza Stark reviewed gene: ZNF335: Rating: GREEN; Mode of pathogenicity: None; Publications: 23178126, 27540107, 29652087; Phenotypes: Microcephaly 10, primary, autosomal recessive, OMIM #615095; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 ZNF148 Zornitza Stark reviewed gene: ZNF148: Rating: GREEN; Mode of pathogenicity: None; Publications: 27964749; Phenotypes: Global developmental delay, absent or hypoplastic corpus callosum, and dysmorphic facies, 617260; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.3 ZMPSTE24 Zornitza Stark reviewed gene: ZMPSTE24: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Mandibuloacral dysplasia with type B lipodystrophy, MIM# 608612, Restrictive dermopathy, lethal, MIM# 275210; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 ZIC3 Zornitza Stark reviewed gene: ZIC3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Heterotaxy, visceral, 1, X-linked 306955, Congenital heart defects, nonsyndromic, 1, X-linked, 306955, VACTERL association, X-linked, 314390; Mode of inheritance: X-LINKED: hemizygous mutation in males, biallelic mutations in females
Intellectual disability v3.3 ZIC1 Zornitza Stark reviewed gene: ZIC1: Rating: GREEN; Mode of pathogenicity: None; Publications: 26340333, 30391508; Phenotypes: Structural brain anomalies with impaired intellectual development and craniosynostosis, OMIM #618736; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.3 XYLT1 Zornitza Stark reviewed gene: XYLT1: Rating: GREEN; Mode of pathogenicity: None; Publications: 24581741, 22711505, 23982343; Phenotypes: Desbuquois dysplasia 2, OMIM# 615777; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 XPC Zornitza Stark reviewed gene: XPC: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Xeroderma pigmentosum, group C, MIM# 278720; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 WRAP53 Zornitza Stark reviewed gene: WRAP53: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Dyskeratosis congenita, autosomal recessive 3, OMIM# 613988; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 WNT7A Zornitza Stark reviewed gene: WNT7A: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Fuhrmann syndrome, MIM# 228930, Ulna and fibula, absence of, with severe limb deficiency, MIM# 276820; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 WNT5A Zornitza Stark reviewed gene: WNT5A: Rating: AMBER; Mode of pathogenicity: None; Publications: 17256787; Phenotypes: Robinow syndrome, autosomal dominant 1, OMIM# 180700; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 WNT3 Zornitza Stark reviewed gene: WNT3: Rating: RED; Mode of pathogenicity: None; Publications: 14872406; Phenotypes: Tetra-amelia syndrome 1, MIM# 273395; Mode of inheritance: None
Intellectual disability v3.3 WNT10B Zornitza Stark reviewed gene: WNT10B: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Split-hand/foot malformation 6, MIM#225300; Mode of inheritance: None
Intellectual disability v3.3 WNT1 Zornitza Stark reviewed gene: WNT1: Rating: GREEN; Mode of pathogenicity: None; Publications: 26671912; Phenotypes: Osteogenesis imperfecta, type XV, OMIM# 615220; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 WFS1 Zornitza Stark reviewed gene: WFS1: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: Wolfram syndrome 1, MIM# 222300, Wolfram-like syndrome, autosomal dominant, MIM# 614296; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.3 WDR35 Zornitza Stark reviewed gene: WDR35: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.3 WDR34 Zornitza Stark reviewed gene: WDR34: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.3 WDR19 Zornitza Stark reviewed gene: WDR19: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Short-rib thoracic dysplasia 5 with or without polydactyly, OMIM #614376, Nephronophthisis 13, OMIM #614377, Senior-Loken syndrome 8, OMIM#616307; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 WDFY3 Zornitza Stark edited their review of gene: WDFY3: Added comment: >10 individuals with heterozygous variants in this gene and mild/moderate intellectual disability now described in the literature. Some evidence for opposing effects on brain size depending on variant location.; Changed rating: GREEN; Changed publications: 31327001, 27008544; Set current diagnostic: yes
Intellectual disability v3.3 VSX2 Zornitza Stark reviewed gene: VSX2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Microphthalmia with coloboma 3, MIM# 610092, Microphthalmia, isolated 2, MIM# 610093; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.3 VARS2 Zornitza Stark gene: VARS2 was added
gene: VARS2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: VARS2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: VARS2 were set to 24827421; 25058219; 29137650; 29314548; 31064326
Phenotypes for gene: VARS2 were set to Combined oxidative phosphorylation deficiency 20, OMIM #615917
Review for gene: VARS2 was set to GREEN
gene: VARS2 was marked as current diagnostic
Added comment: ID is part of the phenotype of this metabolic disorder.
Sources: Expert list
Intellectual disability v3.3 VAMP1 Zornitza Stark reviewed gene: VAMP1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Myasthenic syndrome, congenital, 25, MIM# 618323; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 UVSSA Zornitza Stark reviewed gene: UVSSA: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: UV-sensitive syndrome 3 614640; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 USP7 Zornitza Stark reviewed gene: USP7: Rating: GREEN; Mode of pathogenicity: None; Publications: 30679821; Phenotypes: ID, Autism; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.3 USP18 Zornitza Stark reviewed gene: USP18: Rating: GREEN; Mode of pathogenicity: None; Publications: 31940699, 12833411, 27325888; Phenotypes: Pseudo-TORCH syndrome 2, OMIM #617397; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 USB1 Zornitza Stark reviewed gene: USB1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Poikiloderma with neutropenia, MIM# 604173; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 UROS Zornitza Stark reviewed gene: UROS: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Porphyria, congenital erythropoietic, MIM# 263700; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 UGT1A1 Zornitza Stark reviewed gene: UGT1A1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Crigler-Najjar syndrome, type I, OMIM #218800, Crigler-Najjar syndrome, type II, OMIM #606785; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 UGP2 Zornitza Stark reviewed gene: UGP2: Rating: GREEN; Mode of pathogenicity: None; Publications: 31820119; Phenotypes: Epileptic encephalopathy, intellectual disability, microcephaly; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TYRP1 Zornitza Stark reviewed gene: TYRP1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Albinism, oculocutaneous, type III, 203290; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TYR Zornitza Stark reviewed gene: TYR: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Albinism, oculocutaneous, type IA, 203100; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TXNL4A Zornitza Stark reviewed gene: TXNL4A: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Burn-McKeown syndrome, MIM# 608572; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TUBGCP2 Zornitza Stark gene: TUBGCP2 was added
gene: TUBGCP2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: TUBGCP2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TUBGCP2 were set to 31630790
Phenotypes for gene: TUBGCP2 were set to Lissencephaly; pachygyria; subcortical band heterotopia; microcephaly; intellectual disability
Review for gene: TUBGCP2 was set to GREEN
gene: TUBGCP2 was marked as current diagnostic
Added comment: Four unrelated families reported.
Sources: Expert list
Intellectual disability v3.3 TUBA8 Zornitza Stark reviewed gene: TUBA8: Rating: RED; Mode of pathogenicity: None; Publications: 19896110, 31481326, 28388629; Phenotypes: Cortical dysplasia, complex, with other brain malformations 8, MIM# 613180; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TSHR Zornitza Stark reviewed gene: TSHR: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Hypothyroidism, congenital, nongoitrous, 1, MIM# 275200; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TRPV4 Zornitza Stark reviewed gene: TRPV4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.3 TRPS1 Zornitza Stark reviewed gene: TRPS1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Trichorhinophalangeal syndrome, type I (MIM 190350), Trichorhinophalangeal syndrome, type III (MIM 190351); Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 TRPM3 Zornitza Stark reviewed gene: TRPM3: Rating: GREEN; Mode of pathogenicity: None; Publications: 31278393; Phenotypes: Intellectual disability, epilepsy; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 TRPM1 Zornitza Stark reviewed gene: TRPM1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Night blindness, congenital stationary (complete), 1C, autosomal recessive, MIM# 613216; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TRNT1 Zornitza Stark gene: TRNT1 was added
gene: TRNT1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: TRNT1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TRNT1 were set to 25193871; 23553769; 29170023; 27389523
Phenotypes for gene: TRNT1 were set to Sideroblastic anemia with B-cell immunodeficiency, periodic fevers, and developmental delay, OMIM #616084
Review for gene: TRNT1 was set to GREEN
gene: TRNT1 was marked as current diagnostic
Added comment: > 10 families reported with congenital sideroblastic anemia, B-cell deficiency, periodic fevers, and variable degrees of delayed psychomotor development.
Sources: Expert list
Intellectual disability v3.3 TRIP11 Zornitza Stark reviewed gene: TRIP11: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Achondrogenesis, type IA, MIM# 200600, Osteochondrodysplasia, MIM# 184260; Mode of inheritance: None
Intellectual disability v3.3 TRIM32 Zornitza Stark reviewed gene: TRIM32: Rating: RED; Mode of pathogenicity: None; Publications: 16606853; Phenotypes: Bardet-Biedl syndrome 11, MIM# 615988; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TRAPPC4 Zornitza Stark reviewed gene: TRAPPC4: Rating: GREEN; Mode of pathogenicity: None; Publications: 31794024; Phenotypes: intellectual disability, epilepsy, spasticity, microcephaly; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TRAPPC2 Zornitza Stark reviewed gene: TRAPPC2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spondyloepiphyseal dysplasia tarda, MIM# 313400; Mode of inheritance: X-LINKED: hemizygous mutation in males, biallelic mutations in females
Intellectual disability v3.3 TRAK1 Zornitza Stark reviewed gene: TRAK1: Rating: GREEN; Mode of pathogenicity: None; Publications: 28940097, 28364549, 29846532; Phenotypes: Epileptic encephalopathy, early infantile, 68, MIM# 618201; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TP73 Zornitza Stark gene: TP73 was added
gene: TP73 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: TP73 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TP73 were set to 31130284
Phenotypes for gene: TP73 were set to Intellectual disability; lissencephaly
Review for gene: TP73 was set to AMBER
Added comment: Two unrelated families, no functional data.
Sources: Expert list
Intellectual disability v3.3 TP63 Zornitza Stark reviewed gene: TP63: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ADULT syndrome, OMIM #103285, Ectrodactyly, ectodermal dysplasia, and cleft lip/palate syndrome 3, OMIM #604292, Hay-Wells syndrome, OMIM #106260, Limb-mammary syndrome, OMIM #603543, Orofacial cleft 8, OMIM #618149, Rapp-Hodgkin syndrome, OMIM #129400, Split-hand/foot malformation 4, OMIM #605289; Mode of inheritance: None
Intellectual disability v3.3 SPOP Zornitza Stark gene: SPOP was added
gene: SPOP was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: SPOP was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: SPOP were set to 32109420
Phenotypes for gene: SPOP were set to Intellectual disability; dysmorphism; microcephaly; macrocephaly
Mode of pathogenicity for gene: SPOP was set to Other
Review for gene: SPOP was set to GREEN
gene: SPOP was marked as current diagnostic
Added comment: Seven individuals reported with de novo missense variants in this gene. Gain-of-function variants associated with microcephaly whereas dominant-negative variants associated with macrocephaly.
Sources: Literature
Intellectual disability v3.3 TMPRSS6 Zornitza Stark reviewed gene: TMPRSS6: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Iron-refractory iron deficiency anemia 206200; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TMEM126B Zornitza Stark reviewed gene: TMEM126B: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Mitochondrial complex I deficiency, nuclear type 29, MIM# 618250; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TINF2 Zornitza Stark reviewed gene: TINF2: Rating: GREEN; Mode of pathogenicity: None; Publications: 1404302, 18252230, 21477109; Phenotypes: Revesz syndrome, MIM# 268130; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.3 TGFB3 Zornitza Stark reviewed gene: TGFB3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Arrhythmogenic right ventricular dysplasia 1, MIM# 107970, Loeys-Dietz syndrome 5, MIM# 615582; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 TGFB2 Zornitza Stark reviewed gene: TGFB2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Loeys-Dietz syndrome 4, MIM# 614816; Mode of inheritance: None
Intellectual disability v3.3 TGFB1 Zornitza Stark reviewed gene: TGFB1: Rating: AMBER; Mode of pathogenicity: None; Publications: 29483653; Phenotypes: Inflammatory bowel disease, immunodeficiency, and encephalopathy, MIM# 618213; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TET3 Zornitza Stark reviewed gene: TET3: Rating: GREEN; Mode of pathogenicity: None; Publications: 31928709; Phenotypes: Intellectual disability, dysmorphic features, abnormal growth, movement disorders; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.3 TENM3 Zornitza Stark gene: TENM3 was added
gene: TENM3 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: TENM3 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TENM3 were set to 30513139; 22766609; 27103084; 29753094
Phenotypes for gene: TENM3 were set to Microphthalmia, syndromic 15, MIM#615145; coloboma
Review for gene: TENM3 was set to GREEN
gene: TENM3 was marked as current diagnostic
Added comment: At least four unrelated families described with syndromic microphthalmia and bi-allelic variants in this gene, ID is part of the phenotype.
Sources: Expert list
Intellectual disability v3.3 TEK Zornitza Stark reviewed gene: TEK: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Glaucoma 3, primary congenital, E , MIM#617272, Venous malformations, multiple cutaneous and mucosal, MIM# 600195; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 TCTN3 Zornitza Stark reviewed gene: TCTN3: Rating: GREEN; Mode of pathogenicity: None; Publications: 22883145, 25118024, 26092869; Phenotypes: Joubert syndrome 18, OMIM #614815, Orofaciodigital syndrome IV, OMIM #258860; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.3 TCF12 Zornitza Stark reviewed gene: TCF12: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Craniosynostosis 3, MIM# 615314; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 TBXAS1 Zornitza Stark reviewed gene: TBXAS1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ghosal hematodiaphyseal syndrome, MIM# 231095; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TBX5 Zornitza Stark reviewed gene: TBX5: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Holt-Oram syndrome, MIM# 142900; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 TBX4 Zornitza Stark reviewed gene: TBX4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Amelia, posterior, with pelvic and pulmonary hypoplasia syndrome, MIM# 601360, Ischiocoxopodopatellar syndrome with or without pulmonary arterial hypertension, MIM# 147891; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.3 TBX3 Zornitza Stark reviewed gene: TBX3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ulnar-mammary syndrome, MIM# 181450; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 TBX22 Zornitza Stark reviewed gene: TBX22: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Abruzzo-Erickson syndrome, MIM# 302905, Cleft palate with ankyloglossia, MIM# 303400; Mode of inheritance: X-LINKED: hemizygous mutation in males, biallelic mutations in females
Intellectual disability v3.3 TBX20 Zornitza Stark reviewed gene: TBX20: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Atrial septal defect 4, MIM# 611363; Mode of inheritance: None
Intellectual disability v3.3 TBX15 Zornitza Stark reviewed gene: TBX15: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Cousin syndrome, MIM# 260660; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 TASP1 Zornitza Stark gene: TASP1 was added
gene: TASP1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: TASP1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TASP1 were set to 31209944; 31350873
Phenotypes for gene: TASP1 were set to Developmental delay; microcephaly; dysmorphic features; congenital abnormalities
Review for gene: TASP1 was set to GREEN
gene: TASP1 was marked as current diagnostic
Added comment: Four unrelated families reported; two with founder mutation. Protein interacts with KMT2A and KMT2D. Another de novo missense variant reported in a single infant with multiple congenital abnormalities, insufficient evidence for mono allelic disease at present.
Sources: Expert list
Intellectual disability v3.3 TANC2 Zornitza Stark reviewed gene: TANC2: Rating: GREEN; Mode of pathogenicity: None; Publications: 31616000; Phenotypes: Intellectual disability, autism, epilepsy; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.3 TAB2 Zornitza Stark reviewed gene: TAB2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Congenital heart defects, nonsyndromic, 2, MIM# 614980; Mode of inheritance: None
Intellectual disability v3.3 SUZ12 Zornitza Stark edited their review of gene: SUZ12: Changed phenotypes: Imagawa-Matsumoto syndrome, MIM# 618786, Intellectual disability, Overgrowth
Intellectual disability v3.3 SUZ12 Zornitza Stark reviewed gene: SUZ12: Rating: GREEN; Mode of pathogenicity: None; Publications: 31736240, 30019515, 28229514; Phenotypes: Intellectual disability, Overgrowth; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 SUCLA2 Zornitza Stark gene: SUCLA2 was added
gene: SUCLA2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: SUCLA2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SUCLA2 were set to 27913098; 15877282; 23759946; 17287286; 17301081
Phenotypes for gene: SUCLA2 were set to Mitochondrial DNA depletion syndrome 5 (encephalomyopathic with or without methylmalonic aciduria); OMIM #612073
Review for gene: SUCLA2 was set to GREEN
Added comment: ID is part of the phenotype of this mitochondrial disorder.
Sources: Expert list
Intellectual disability v3.3 STT3A Zornitza Stark reviewed gene: STT3A: Rating: GREEN; Mode of pathogenicity: None; Publications: 23842455, 30701557, 28424003; Phenotypes: Congenital disorder of glycosylation, type Iw, OMIM #615596; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 STS Zornitza Stark reviewed gene: STS: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.3 STAT1 Zornitza Stark reviewed gene: STAT1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.3 STAR Zornitza Stark reviewed gene: STAR: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Lipoid adrenal hyperplasia, MIM# 201710; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 SRY Zornitza Stark reviewed gene: SRY: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.3 SPEG Zornitza Stark reviewed gene: SPEG: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Centronuclear myopathy 5, OMIM #615959; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 SPAG1 Zornitza Stark reviewed gene: SPAG1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ciliary dyskinesia, primary, 28, MIM# 615505; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 SOX17 Zornitza Stark reviewed gene: SOX17: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Vesicoureteral reflux 3, MIM# 613674; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 RASA1 Zornitza Stark reviewed gene: RASA1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Capillary malformation-arteriovenous malformation 1, MIM# 608354; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 SNX27 Zornitza Stark reviewed gene: SNX27: Rating: GREEN; Mode of pathogenicity: None; Publications: 25894286, 31721175, 21300787, 23524343; Phenotypes: intellectual disability, seizures; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 SMG8 Zornitza Stark gene: SMG8 was added
gene: SMG8 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: SMG8 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SMG8 were set to 31130284
Phenotypes for gene: SMG8 were set to Intellectual disability
Review for gene: SMG8 was set to AMBER
Added comment: Two unrelated families, no functional data.
Sources: Expert list
Intellectual disability v3.3 SMCHD1 Zornitza Stark reviewed gene: SMCHD1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Bosma arhinia microphthalmia syndrome, OMIM #603457, Fascioscapulohumeral muscular dystrophy 2, digenic, OMIM #158901; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 DDC Lothar Schlueter reviewed gene: DDC: Rating: GREEN; Mode of pathogenicity: None; Publications: 28100251, 30952622, 30689738, 25597765, 24788355; Phenotypes: Aromatic L-amino acid decarboxylase deficiency 608643, floppy child, dystonia, hypotonia, developmental delay, oculogyric crisis; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 SLC9A7 Zornitza Stark gene: SLC9A7 was added
gene: SLC9A7 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: SLC9A7 was set to X-LINKED: hemizygous mutation in males, biallelic mutations in females
Publications for gene: SLC9A7 were set to 30335141
Phenotypes for gene: SLC9A7 were set to Intellectual developmental disorder, X-linked 108; OMIM #301024
Review for gene: SLC9A7 was set to AMBER
Added comment: 6 males from 2 unrelated families with hemizygous missense mutation in the SLC9A7 gene. The mutation segregated with the disorder in the family. In vitro functional expression studies in CHO cells (AP-1 cells) showed that the mutation caused decreased levels of protein expression and reduced oligosaccharide maturation/glycosylation compared to wildtype, indicating impaired posttranslational processing. Subcellular localization studies indicated that protein trafficking was unaffected by the mutation. However, examination of the trans-Golgi compartment suggested a gain-of-function effect and a perturbation of glycosylation of secretory cargo. Serum transferrin studies in 1 patient suggested a glycosylation defect. One to watch.
Sources: Expert list
Intellectual disability v3.3 SLC1A1 Zornitza Stark gene: SLC1A1 was added
gene: SLC1A1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: SLC1A1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SLC1A1 were set to Dicarboxylic aminoaciduria, MIM#222730
Review for gene: SLC1A1 was set to GREEN
gene: SLC1A1 was marked as current diagnostic
Added comment: ID is part of the phenotype of this metabolic disorder.
Sources: Expert list
Intellectual disability v3.3 SKIV2L Zornitza Stark reviewed gene: SKIV2L: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Trichohepatoenteric syndrome 2, MIM# 614602; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 SIX5 Zornitza Stark reviewed gene: SIX5: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Branchiootorenal syndrome 2 610896; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 SIX1 Zornitza Stark reviewed gene: SIX1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Branchiootic syndrome 3, MIM# 608389, Deafness, autosomal dominant 23, MIM# 605192; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 SH3PXD2B Zornitza Stark reviewed gene: SH3PXD2B: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Frank-ter Haar syndrome, MIM# 249420; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 SFXN4 Zornitza Stark gene: SFXN4 was added
gene: SFXN4 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: SFXN4 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SFXN4 were set to 31059822; 24119684
Phenotypes for gene: SFXN4 were set to Combined oxidative phosphorylation deficiency 18, MIM#615578
Review for gene: SFXN4 was set to GREEN
gene: SFXN4 was marked as current diagnostic
Added comment: Three unrelated families reported, mild ID as well as other neurological features are part of the phenotype.
Sources: Expert list
Intellectual disability v3.3 SEC31A Zornitza Stark gene: SEC31A was added
gene: SEC31A was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: SEC31A was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SEC31A were set to 30464055
Phenotypes for gene: SEC31A were set to Neurodevelopmental disorder with spastic quadriplegia, optic atrophy, seizures, and structural brain anomalies, OMIM #618651
Review for gene: SEC31A was set to AMBER
Added comment: Single family with two affected sibs with functional data (drosophila), one to watch.
Sources: Expert list
Intellectual disability v3.3 SEC23B Zornitza Stark reviewed gene: SEC23B: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ?Cowden syndrome 7 616858, Dyserythropoietic anemia, congenital, type II 224100; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.3 SCN1B Zornitza Stark reviewed gene: SCN1B: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: Epileptic encephalopathy, early infantile, 52, MIM#617350; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.3 SCN11A Zornitza Stark reviewed gene: SCN11A: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Neuropathy, hereditary sensory and autonomic, type VII, MIM#615548; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 SCARF2 Zornitza Stark reviewed gene: SCARF2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Van den Ende-Gupta syndrome, MIM# 600920; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 SCAMP5 Zornitza Stark reviewed gene: SCAMP5: Rating: GREEN; Mode of pathogenicity: Other; Publications: 31439720; Phenotypes: Intellectual disability, seizures, autism; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.3 SBF1 Zornitza Stark gene: SBF1 was added
gene: SBF1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: SBF1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SBF1 were set to 24799518; 23749797; 30039846; 28902413
Phenotypes for gene: SBF1 were set to Charcot-Marie-Tooth disease, type 4B3, MIM# 615284
Review for gene: SBF1 was set to GREEN
Added comment: At least 4 families with multiple affected individuals described. Some have had central features including microcephaly and DD/ID, it is likely this gene causes a mixed picture.
Sources: Expert list
Intellectual disability v3.3 SBDS Zornitza Stark reviewed gene: SBDS: Rating: RED; Mode of pathogenicity: None; Publications: 19906387; Phenotypes: Shwachman-Diamond syndrome, MIM#260400; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 SARS2 Zornitza Stark gene: SARS2 was added
gene: SARS2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: SARS2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SARS2 were set to 21255763; 24034276
Phenotypes for gene: SARS2 were set to Hyperuricemia, pulmonary hypertension, renal failure, and alkalosis, MIM#613845
Review for gene: SARS2 was set to GREEN
gene: SARS2 was marked as current diagnostic
Added comment: DD/ID is part of the phenotype. Two unrelated families reported, highly specific phenotype.
Sources: Expert list
Intellectual disability v3.3 SALL4 Zornitza Stark reviewed gene: SALL4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Duane-radial ray syndrome, MIM# 607323; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 SOX3 Zornitza Stark reviewed gene: SOX3: Rating: AMBER; Mode of pathogenicity: None; Publications: 29175558, 30125608, 12428212, 15800844; Phenotypes: Mental retardation, X-linked, with isolated growth hormone deficiency, MIM#300123, Panhypopituitarism, X-linked, MIM#312000; Mode of inheritance: X-LINKED: hemizygous mutation in males, biallelic mutations in females
Intellectual disability v3.3 PUM1 Zornitza Stark reviewed gene: PUM1: Rating: GREEN; Mode of pathogenicity: None; Publications: 29474920, 25768905; Phenotypes: Spinocerebellar ataxia 47, MIM#617931; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 PSAT1 Zornitza Stark reviewed gene: PSAT1: Rating: AMBER; Mode of pathogenicity: None; Publications: 26960553, 17436247, 25152457; Phenotypes: Phosphoserine aminotransferase deficiency, MIM# 610992, Neu-Laxova syndrome 2, MIM# 616038; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 PRSS56 Zornitza Stark reviewed gene: PRSS56: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Microphthalmia, isolated 6, MIM# 613517; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 PROP1 Zornitza Stark reviewed gene: PROP1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Pituitary hormone deficiency, combined, 2, MIM# 262600; Mode of inheritance: None
Intellectual disability v3.3 PRKAR1A Zornitza Stark reviewed gene: PRKAR1A: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: Acrodysostosis 1, with or without hormone resistance, MIM# 101800; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.3 PRDM12 Zornitza Stark reviewed gene: PRDM12: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Neuropathy, hereditary sensory and autonomic, type VIII, MIM# 616488; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.3 PPP1R12A Zornitza Stark gene: PPP1R12A was added
gene: PPP1R12A was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: PPP1R12A was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: PPP1R12A were set to 31883643
Phenotypes for gene: PPP1R12A were set to Intellectual disability; holoprosencephaly; disorder of sex development
Review for gene: PPP1R12A was set to GREEN
gene: PPP1R12A was marked as current diagnostic
Added comment: 12 individuals reported.
Sources: Expert list
Intellectual disability v3.3 PPA2 Zornitza Stark reviewed gene: PPA2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Sudden cardiac failure, infantile, MIM# 617222; Mode of inheritance: None
Intellectual disability v3.3 Rebecca Foulger Panel version has been signed off
Intellectual disability v3.1 POMK Zornitza Stark gene: POMK was added
gene: POMK was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: POMK was set to BIALLELIC, autosomal or pseudoautosomal
Phenotypes for gene: POMK were set to Muscular dystrophy-dystroglycanopathy (congenital with brain and eye anomalies), type A, 12, MIM# 615249
Review for gene: POMK was set to GREEN
gene: POMK was marked as current diagnostic
Added comment: ID is part of the phenotype.
Sources: Expert list
Intellectual disability v3.1 POLR1D Zornitza Stark reviewed gene: POLR1D: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Treacher Collins syndrome 2, MIM# 613717; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.1 POLR1C Zornitza Stark reviewed gene: POLR1C: Rating: GREEN; Mode of pathogenicity: None; Publications: 26151409; Phenotypes: Leukodystrophy, hypomyelinating, 11, MIM# 616494; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.1 POLD1 Zornitza Stark reviewed gene: POLD1: Rating: RED; Mode of pathogenicity: None; Publications: 31449058; Phenotypes: Intellectual disability, immunodeficiency, Mandibular hypoplasia, deafness, progeroid features, and lipodystrophy syndrome, MIM#615381; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.1 POC1B Zornitza Stark reviewed gene: POC1B: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Cone-rod dystrophy 20 615973; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.1 PNPT1 Zornitza Stark reviewed gene: PNPT1: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: Combined oxidative phosphorylation deficiency 13, MIM#614932; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.1 PMS2 Zornitza Stark reviewed gene: PMS2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Mismatch repair cancer syndrome, MIM# 276300; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.1 PLOD2 Zornitza Stark reviewed gene: PLOD2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Bruck syndrome 2 609220; Mode of inheritance: None
Intellectual disability v3.0 PKHD1 Zornitza Stark reviewed gene: PKHD1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Polycystic kidney disease 4, with or without hepatic disease 263200; Mode of inheritance: None
Intellectual disability v3.0 PKD1L1 Zornitza Stark reviewed gene: PKD1L1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Heterotaxy, visceral, 8, autosomal, MIM# 617205; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 PITX3 Zornitza Stark reviewed gene: PITX3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Anterior segment dysgenesis 1, multiple subtypes, MIM# 107250, cataract; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 PITX2 Zornitza Stark reviewed gene: PITX2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Axenfeld-Rieger syndrome, type 1, MIM# 180500; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 PISD Zornitza Stark gene: PISD was added
gene: PISD was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: PISD was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PISD were set to 31263216; 30858161
Phenotypes for gene: PISD were set to intellectual disability; cataract; microcephaly; deafness; skeletal dysplasia
Review for gene: PISD was set to GREEN
Added comment: Three unrelated families reported.
Sources: Expert list
Intellectual disability v3.0 PIK3R1 Zornitza Stark reviewed gene: PIK3R1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: SHORT syndrome, MIM#269880; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 PIK3C2A Zornitza Stark reviewed gene: PIK3C2A: Rating: GREEN; Mode of pathogenicity: None; Publications: 31034465; Phenotypes: Oculoskeletodental syndrome, 618440; Mode of inheritance: None
Intellectual disability v3.0 PIGS Zornitza Stark gene: PIGS was added
gene: PIGS was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: PIGS was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PIGS were set to 30269814
Phenotypes for gene: PIGS were set to Glycosylphosphatidylinositol biosynthesis defect 18, MIM# 618143
Review for gene: PIGS was set to GREEN
gene: PIGS was marked as current diagnostic
Added comment: Three unrelated families reported. Severe neurological phenotype ranging from fetal akinesia to ID/EE.
Sources: Expert list
Intellectual disability v3.0 PIGH Zornitza Stark edited their review of gene: PIGH: Added comment: I note this gene is Green on the epilepsy panel, and I agree this family of genes cause similar phenotypes, there is some functional data to support the gene-disease relationship, so we have rated it Green on both panels.; Changed rating: GREEN; Changed publications: 29573052, 29603516
Intellectual disability v3.0 PIBF1 Zornitza Stark gene: PIBF1 was added
gene: PIBF1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: PIBF1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PIBF1 were set to 26167768; 30858804; 29695797
Phenotypes for gene: PIBF1 were set to Joubert syndrome 33; OMIM #617767
Review for gene: PIBF1 was set to GREEN
gene: PIBF1 was marked as current diagnostic
Added comment: 7 families altogether: 3 of these are Hutterite and share the same founder variant.
Sources: Expert list
Intellectual disability v3.0 PGM1 Zornitza Stark reviewed gene: PGM1: Rating: RED; Mode of pathogenicity: None; Publications: 24499211; Phenotypes: Congenital disorder of glycosylation, type It, MIM# 614921; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 PET100 Zornitza Stark reviewed gene: PET100: Rating: GREEN; Mode of pathogenicity: None; Publications: 24462369, 25293719, 31406627; Phenotypes: Mitochondrial complex IV deficiency, MIM# 220110; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.0 PDP1 Zornitza Stark gene: PDP1 was added
gene: PDP1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: PDP1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PDP1 were set to 19184109; 15855260; 31392110
Phenotypes for gene: PDP1 were set to Pyruvate dehydrogenase phosphatase deficiency, MIM#608782
Review for gene: PDP1 was set to GREEN
gene: PDP1 was marked as current diagnostic
Added comment: DD/ID is part of the phenotype of this metabolic condition.
Sources: Expert list
Intellectual disability v3.0 PDHB Zornitza Stark gene: PDHB was added
gene: PDHB was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: PDHB was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PDHB were set to 15138885; 26014431
Phenotypes for gene: PDHB were set to Pyruvate dehydrogenase E1-beta deficiency, MIM#614111
Review for gene: PDHB was set to GREEN
gene: PDHB was marked as current diagnostic
Added comment: DD/ID is a feature of this metabolic disorder.
Sources: Expert list
Intellectual disability v3.0 PDE6G Zornitza Stark reviewed gene: PDE6G: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Retinitis pigmentosa 57 613582; Mode of inheritance: None
Intellectual disability v3.0 PDE10A Zornitza Stark gene: PDE10A was added
gene: PDE10A was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: PDE10A was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PDE10A were set to 27058446
Phenotypes for gene: PDE10A were set to Dyskinesia, limb and orofacial, infantile-onset, MIM#616921
Review for gene: PDE10A was set to GREEN
gene: PDE10A was marked as current diagnostic
Added comment: Two unrelated families and functional data (animal model). Note that allelic disorder, Striatal degeneration, autosomal dominant, MIM#616922, is caused by heterozygous variants and ID is not part of the phenotype.
Sources: Expert list
Intellectual disability v3.0 PAX9 Zornitza Stark reviewed gene: PAX9: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Tooth agenesis, selective, 3 604625; Mode of inheritance: None
Intellectual disability v3.0 PAX3 Zornitza Stark reviewed gene: PAX3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Craniofacial-deafness-hand syndrome, MIM#122880, Waardenburg syndrome, type 1, MIM#193500, Waardenburg syndrome, type 3, MIM#148820; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 PAPSS2 Zornitza Stark reviewed gene: PAPSS2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Brachyolmia 4 with mild epiphyseal and metaphyseal changes, MIM# 612847; Mode of inheritance: None
Intellectual disability v3.0 PAM16 Zornitza Stark gene: PAM16 was added
gene: PAM16 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: PAM16 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PAM16 were set to 24786642; 27354339
Phenotypes for gene: PAM16 were set to Spondylometaphyseal dysplasia, Megarbane-Dagher-Melike type, MIM#613320
Review for gene: PAM16 was set to GREEN
gene: PAM16 was marked as current diagnostic
Added comment: DD/ID is part of the phenotype of this skeletal dysplasia.
Sources: Expert list
Intellectual disability v3.0 OXR1 Zornitza Stark reviewed gene: OXR1: Rating: GREEN; Mode of pathogenicity: None; Publications: 31785787; Phenotypes: Intellectual disability, seizures, cerebellar atrophy; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.0 OTULIN Zornitza Stark reviewed gene: OTULIN: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Autoinflammation, panniculitis, and dermatosis syndrome, MIM# 617099; Mode of inheritance: None
Intellectual disability v3.0 OTOGL Zornitza Stark reviewed gene: OTOGL: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Deafness, autosomal recessive 84B, MIM# 614944; Mode of inheritance: None
Intellectual disability v3.0 ORC6 Zornitza Stark edited their review of gene: ORC6: Added comment: Intellect is typically normal.; Changed publications: 26381604; Changed phenotypes: Meier Gorlin syndrome
Intellectual disability v3.0 LZTFL1 Zornitza Stark gene: LZTFL1 was added
gene: LZTFL1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: LZTFL1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: LZTFL1 were set to 22510444; 23692385; 27312011
Phenotypes for gene: LZTFL1 were set to Bardet-Biedl syndrome 17, MIM#615994
Review for gene: LZTFL1 was set to GREEN
gene: LZTFL1 was marked as current diagnostic
Added comment: Two unrelated families and functional evidence.
Sources: Expert list
Intellectual disability v3.0 LYRM7 Zornitza Stark gene: LYRM7 was added
gene: LYRM7 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: LYRM7 was set to BIALLELIC, autosomal or pseudoautosomal
Phenotypes for gene: LYRM7 were set to Mitochondrial complex III deficiency, nuclear type 8, MIM#615838
Review for gene: LYRM7 was set to GREEN
gene: LYRM7 was marked as current diagnostic
Added comment: Condition is characterised by progressive deterioration but some individuals described as developmentally delayed from birth.
Sources: Expert list
Intellectual disability v3.0 LTBP3 Zornitza Stark reviewed gene: LTBP3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Dental anomalies and short stature 601216, Geleophysic dysplasia 3 617809; Mode of inheritance: None
Intellectual disability v3.0 LTBP2 Zornitza Stark reviewed gene: LTBP2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Weill-Marchesani syndrome 3, recessive, MIM# 614819, Glaucoma 3, primary congenital, MIM# 613086, Microspherophakia and/or megalocornea, with ectopia lentis and with or without secondary glaucoma, MIM# 251750; Mode of inheritance: None
Intellectual disability v3.0 LSS Zornitza Stark reviewed gene: LSS: Rating: GREEN; Mode of pathogenicity: None; Publications: 30723320; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 LRRC6 Zornitza Stark reviewed gene: LRRC6: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ciliary dyskinesia, primary, 19, MIM# 614935; Mode of inheritance: None
Intellectual disability v3.0 LRP4 Zornitza Stark reviewed gene: LRP4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Cenani-Lenz syndactyly syndrome, MIM# 212780, Sclerosteosis 2, MIM# 614305; Mode of inheritance: None
Intellectual disability v3.0 LMX1B Zornitza Stark reviewed gene: LMX1B: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 LMNA Zornitza Stark reviewed gene: LMNA: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 LMAN2L Zornitza Stark gene: LMAN2L was added
gene: LMAN2L was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: LMAN2L was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: LMAN2L were set to 31020005; 26566883
Phenotypes for gene: LMAN2L were set to Intellectual disability; epilepsy
Review for gene: LMAN2L was set to AMBER
Added comment: 1 consanguineous family with 7 individuals with ID and epilepsy, with homozygous LMAN2L missense mutation. Segregated with disease in family, and unaffected family members were heterozygous variant carriers. No functional studies.

1 non-consanguineous family with 4 affected with heterozygous frameshift LMAN2L mutation. Segregates in family. Mutation eliminates LMAN2L's endoplasmic reticulum retention signal and mislocalizes the protein from that compartment to the plasma membrane.

Amber or Red.
Sources: Expert list
Intellectual disability v3.0 LIPT1 Zornitza Stark gene: LIPT1 was added
gene: LIPT1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: LIPT1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: LIPT1 were set to 24341803; 24256811; 29681092
Phenotypes for gene: LIPT1 were set to Lipoyltransferase 1 deficiency, MIM#616299
Review for gene: LIPT1 was set to GREEN
gene: LIPT1 was marked as current diagnostic
Added comment: Cognitive development is affected in this metabolic condition.
Sources: Expert list
Intellectual disability v3.0 LIAS Zornitza Stark reviewed gene: LIAS: Rating: GREEN; Mode of pathogenicity: None; Publications: 24334290, 22152680; Phenotypes: Hyperglycinemia, lactic acidosis, and seizures, MIM#614462; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.0 LHX4 Zornitza Stark reviewed gene: LHX4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 LHX3 Zornitza Stark reviewed gene: LHX3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Pituitary hormone deficiency, combined, 3, MIM# 221750; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 LGI4 Zornitza Stark reviewed gene: LGI4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Arthrogryposis multiplex congenita, neurogenic, with myelin defect, MIM#617468; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 LFNG Zornitza Stark reviewed gene: LFNG: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 LEMD3 Zornitza Stark reviewed gene: LEMD3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 LDB3 Zornitza Stark reviewed gene: LDB3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 LAS1L Zornitza Stark reviewed gene: LAS1L: Rating: GREEN; Mode of pathogenicity: None; Publications: 25644381, 25644381; Phenotypes: Wilson-Turner syndrome, MIM# 309585; Mode of inheritance: X-LINKED: hemizygous mutation in males, biallelic mutations in females; Current diagnostic: yes
Intellectual disability v3.0 LAMB2 Zornitza Stark gene: LAMB2 was added
gene: LAMB2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: LAMB2 was set to BIALLELIC, autosomal or pseudoautosomal
Phenotypes for gene: LAMB2 were set to Pierson syndrome, MIM#609049
gene: LAMB2 was marked as current diagnostic
Added comment: Cognitive impairment described in survivors.
Sources: Expert list
Intellectual disability v3.0 KLHL40 Zornitza Stark reviewed gene: KLHL40: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Nemaline myopathy 8, autosomal recessive 615348; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 KLF7 Zornitza Stark gene: KLF7 was added
gene: KLF7 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: KLF7 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: KLF7 were set to 29251763
Phenotypes for gene: KLF7 were set to Intellectual disability
Review for gene: KLF7 was set to GREEN
gene: KLF7 was marked as current diagnostic
Added comment: Four unrelated individuals with de novo missense variants; animal model data supportive.
Sources: Expert list
Intellectual disability v3.0 KLF1 Zornitza Stark reviewed gene: KLF1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 KIT Zornitza Stark reviewed gene: KIT: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 KIRREL3 Zornitza Stark reviewed gene: KIRREL3: Rating: RED; Mode of pathogenicity: None; Publications: 19012874; Phenotypes: Intellectual disability; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 KIF22 Zornitza Stark reviewed gene: KIF22: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spondyloepimetaphyseal dysplasia with joint laxity, type 2 603546; Mode of inheritance: None
Intellectual disability v3.0 KDM6B Zornitza Stark reviewed gene: KDM6B: Rating: GREEN; Mode of pathogenicity: None; Publications: 31124279; Phenotypes: Intellectual disability; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.0 KDM3B Zornitza Stark reviewed gene: KDM3B: Rating: GREEN; Mode of pathogenicity: None; Publications: 30929739; Phenotypes: Intellectual disability, short stature; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.0 KCTD1 Zornitza Stark reviewed gene: KCTD1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 KCNQ1 Zornitza Stark reviewed gene: KCNQ1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 KCNN3 Zornitza Stark gene: KCNN3 was added
gene: KCNN3 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: KCNN3 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: KCNN3 were set to 31155282
Phenotypes for gene: KCNN3 were set to Zimmermann-Laband syndrome 3; OMIM# 618658
Review for gene: KCNN3 was set to GREEN
gene: KCNN3 was marked as current diagnostic
Added comment: Three unrelated individuals reported.
Sources: Expert list
Intellectual disability v3.0 KCNMA1 Zornitza Stark reviewed gene: KCNMA1: Rating: GREEN; Mode of pathogenicity: Other; Publications: 27567911, 29545233, 26195193, 31427379; Phenotypes: Cerebellar atrophy, developmental delay, and seizures, MIM# 617643, Paroxysmal nonkinesigenic dyskinesia, 3, with or without generalized epilepsy, MIM#609446; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 KCNK4 Zornitza Stark reviewed gene: KCNK4: Rating: GREEN; Mode of pathogenicity: None; Publications: 30290154; Phenotypes: Facial dysmorphism, hypertrichosis, epilepsy, intellectual/developmental delay, and gingival overgrowth syndrome 618381; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.0 KCND3 Zornitza Stark reviewed gene: KCND3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spinocerebellar ataxia 19, MIM#607346; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 KCNC3 Zornitza Stark reviewed gene: KCNC3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spinocerebellar ataxia 13, MIM#605259; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 KBTBD13 Zornitza Stark reviewed gene: KBTBD13: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Nemaline myopathy 6, autosomal dominant, MIM# 609273; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 KAT8 Zornitza Stark reviewed gene: KAT8: Rating: GREEN; Mode of pathogenicity: None; Publications: 31794431; Phenotypes: Intellectual disability, seizures, autism, dysmorphic features; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 JAK3 Zornitza Stark reviewed gene: JAK3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 JAGN1 Zornitza Stark reviewed gene: JAGN1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Neutropenia, severe congenital, 6, autosomal recessive 616022; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 JAG1 Zornitza Stark reviewed gene: JAG1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Alagille syndrome; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 IRF6 Zornitza Stark reviewed gene: IRF6: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 IREB2 Zornitza Stark gene: IREB2 was added
gene: IREB2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: IREB2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: IREB2 were set to 30915432; 31243445; 11175792
Phenotypes for gene: IREB2 were set to Neurodegeneration, early-onset, with choreoathetoid movements and microcytic anemia, MIM#618451
Review for gene: IREB2 was set to GREEN
gene: IREB2 was marked as current diagnostic
Added comment: Two affected individuals from unrelated families with functional evidence including highly specific, concordant phenotype in mice.
Sources: Expert list
Intellectual disability v3.0 IQSEC3 Zornitza Stark gene: IQSEC3 was added
gene: IQSEC3 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: IQSEC3 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: IQSEC3 were set to 31130284
Phenotypes for gene: IQSEC3 were set to Intellectual disability
Review for gene: IQSEC3 was set to AMBER
Added comment: Two unrelated families, no functional data.
Sources: Expert list
Intellectual disability v3.0 IQSEC1 Zornitza Stark reviewed gene: IQSEC1: Rating: GREEN; Mode of pathogenicity: None; Publications: 31607425; Phenotypes: Intellectual developmental disorder with short stature and behavioral abnormalities, MIM# 618687; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.0 SCN4A Zornitza Stark reviewed gene: SCN4A: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Hyperkalemic periodic paralysis, type 2, MIM# 170500, Hypokalemic periodic paralysis, type 2, MIM# 613345, Myasthenic syndrome, congenital, 16, MIM# 614198, Myotonia congenita, atypical, acetazolamide-responsive 608390, Paramyotonia congenita 168300; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.0 INPPL1 Zornitza Stark reviewed gene: INPPL1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Opsismodysplasia, MIM# 258480; Mode of inheritance: None
Intellectual disability v3.0 IMPAD1 Zornitza Stark reviewed gene: IMPAD1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Chondrodysplasia with joint dislocations, GPAPP type, MIM# 614078; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 IL11RA Zornitza Stark reviewed gene: IL11RA: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Craniosynostosis and dental anomalies, MIM# 614188; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 IHH Zornitza Stark reviewed gene: IHH: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Acrocapitofemoral dysplasia, MIM# 607778, Brachydactyly, type A1, MIM# 112500; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.0 IGF2 Zornitza Stark reviewed gene: IGF2: Rating: RED; Mode of pathogenicity: None; Publications: 31544945, 26154720; Phenotypes: Growth restriction, severe, with distinctive facies, MIM#616489; Mode of inheritance: None
Intellectual disability v3.0 IFT80 Zornitza Stark reviewed gene: IFT80: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 IFT27 Zornitza Stark gene: IFT27 was added
gene: IFT27 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: IFT27 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: IFT27 were set to 24488770; 30761183
Phenotypes for gene: IFT27 were set to Bardet-Biedl syndrome 19, MIM#615996
Review for gene: IFT27 was set to AMBER
Added comment: Two families with functional evidence.
Sources: Expert list
Intellectual disability v3.0 IFT122 Zornitza Stark reviewed gene: IFT122: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 IFITM5 Zornitza Stark reviewed gene: IFITM5: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HYLS1 Zornitza Stark reviewed gene: HYLS1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Hydrolethalus syndrome, MIM#236680; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 HYDIN Zornitza Stark reviewed gene: HYDIN: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HYAL1 Zornitza Stark reviewed gene: HYAL1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HSPG2 Zornitza Stark reviewed gene: HSPG2: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: Schwartz-Jampel syndrome, type 1, MIM#255800; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 HSF4 Zornitza Stark reviewed gene: HSF4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HSD3B7 Zornitza Stark reviewed gene: HSD3B7: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HR Zornitza Stark reviewed gene: HR: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HPSE2 Zornitza Stark reviewed gene: HPSE2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HPS1 Zornitza Stark reviewed gene: HPS1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HPGD Zornitza Stark reviewed gene: HPGD: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HOXD13 Zornitza Stark reviewed gene: HOXD13: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HOXC13 Zornitza Stark reviewed gene: HOXC13: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HOXA13 Zornitza Stark reviewed gene: HOXA13: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HNMT Zornitza Stark gene: HNMT was added
gene: HNMT was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: HNMT was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: HNMT were set to 26206890; 30744146
Phenotypes for gene: HNMT were set to Mental retardation, autosomal recessive 51, MIM#616739
Review for gene: HNMT was set to GREEN
Added comment: 7 individuals from two unrelated families, some functional evidence and other circumstantial evidence linking this gene to brain function. Borderline Amber/Green.
Sources: Expert list
Intellectual disability v3.0 HNF4A Zornitza Stark reviewed gene: HNF4A: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HMGCS2 Zornitza Stark reviewed gene: HMGCS2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: HMG-CoA synthase-2 deficiency, MIM# 605911; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 HADHB Zornitza Stark gene: HADHB was added
gene: HADHB was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: HADHB was set to BIALLELIC, autosomal or pseudoautosomal
Phenotypes for gene: HADHB were set to Trifunctional protein deficiency, MIM#609015
Review for gene: HADHB was set to GREEN
gene: HADHB was marked as current diagnostic
Added comment: ID is part of the phenotype.
Sources: Expert list
Intellectual disability v3.0 HADH Zornitza Stark reviewed gene: HADH: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: 3-hydroxyacyl-CoA dehydrogenase deficiency, MIM#231530, Hyperinsulinemic hypoglycemia, familial, 4, MIM#609975; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 GUCY2C Zornitza Stark reviewed gene: GUCY2C: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GRM6 Zornitza Stark reviewed gene: GRM6: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GRIA1 Zornitza Stark reviewed gene: GRIA1: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.0 GRHL3 Zornitza Stark reviewed gene: GRHL3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GPSM2 Zornitza Stark reviewed gene: GPSM2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Chudley-McCullough syndrome, MIM#604213; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 GPR179 Zornitza Stark reviewed gene: GPR179: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GPC4 Zornitza Stark gene: GPC4 was added
gene: GPC4 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: GPC4 was set to X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Publications for gene: GPC4 were set to 30982611
Phenotypes for gene: GPC4 were set to Keipert syndrome OMIM# 301026
Review for gene: GPC4 was set to GREEN
gene: GPC4 was marked as current diagnostic
Added comment: 10 individuals from 6 families reported, functional studies in mice. Mild to moderate ID part of the phenotype.
Sources: Expert list
Intellectual disability v3.0 GOT2 Zornitza Stark reviewed gene: GOT2: Rating: GREEN; Mode of pathogenicity: None; Publications: 31422819; Phenotypes: Epileptic encephalopathy, early infantile, 82, MIM# 618721; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.0 GNE Zornitza Stark gene: GNE was added
gene: GNE was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: GNE was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Phenotypes for gene: GNE were set to Sialuria, MIM#269921
Review for gene: GNE was set to GREEN
gene: GNE was marked as current diagnostic
Added comment: Metabolic disorder with varying degrees of ID being a feature.
Bi-allelic variants cause Nonaka myopathy, MIM#605820
Sources: Expert list
Intellectual disability v3.0 GNAI3 Zornitza Stark reviewed gene: GNAI3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 HDAC4 Zornitza Stark reviewed gene: HDAC4: Rating: AMBER; Mode of pathogenicity: None; Publications: 24715439, 20691407, 31209962; Phenotypes: Brachydactyly mental retardation syndrome, Brachydactyly without intellectual disability; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 GLS Zornitza Stark gene: GLS was added
gene: GLS was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: GLS was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: GLS were set to 30970188
Phenotypes for gene: GLS were set to Global developmental delay, progressive ataxia, and elevated glutamine, MIM# 618412
Review for gene: GLS was set to GREEN
Added comment: Three unrelated individuals described with compound het variants, however, note one of these is a triplet expansion in the 5' UTR.
Sources: Expert list
Intellectual disability v3.0 GLMN Zornitza Stark reviewed gene: GLMN: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GLE1 Zornitza Stark reviewed gene: GLE1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GJB1 Zornitza Stark reviewed gene: GJB1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Charcot-Marie-Tooth neuropathy, X-linked dominant, 1, MIM#302800; Mode of inheritance: None
Intellectual disability v3.0 GJA8 Zornitza Stark reviewed gene: GJA8: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GJA3 Zornitza Stark reviewed gene: GJA3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GJA1 Zornitza Stark reviewed gene: GJA1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Atrioventricular septal defect 3, MIM#600309, Craniometaphyseal dysplasia, autosomal recessive, MIM#218400, Erythrokeratodermia variabilis et progressiva 3, MIM#617525, Hypoplastic left heart syndrome 1, MIM#241550, Oculodentodigital dysplasia, MIM#164200, Oculodentodigital dysplasia, autosomal recessive, MIM#257850, Palmoplantar keratoderma with congenital alopecia, MIM#104100, Syndactyly, type III, MIM# 186100; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.0 GHR Zornitza Stark reviewed gene: GHR: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Growth hormone insensitivity, partial, MIM#604271, Laron dwarfism, MIM#262500; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.0 GDF6 Zornitza Stark reviewed gene: GDF6: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GDF5 Zornitza Stark reviewed gene: GDF5: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GBA2 Zornitza Stark reviewed gene: GBA2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spastic paraplegia 46, autosomal recessive, MIM#614409; Mode of inheritance: None
Intellectual disability v3.0 GATA6 Zornitza Stark reviewed gene: GATA6: Rating: GREEN; Mode of pathogenicity: None; Publications: 22158542; Phenotypes: Pancreatic agenesis and congenital heart defects, MIM#600001; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 GATA4 Zornitza Stark reviewed gene: GATA4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GATA2 Zornitza Stark reviewed gene: GATA2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GAS8 Zornitza Stark reviewed gene: GAS8: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GALK1 Zornitza Stark reviewed gene: GALK1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 GAA Zornitza Stark reviewed gene: GAA: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FZD6 Zornitza Stark reviewed gene: FZD6: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FYCO1 Zornitza Stark reviewed gene: FYCO1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FXN Zornitza Stark reviewed gene: FXN: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FTL Zornitza Stark reviewed gene: FTL: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Neurodegeneration with brain iron accumulation 3, MIM#606159, Hyperferritinemia-cataract syndrome, MIM#600886, L-ferritin deficiency, dominant and recessive, MIM#615604; Mode of inheritance: None
Intellectual disability v3.0 FRY Zornitza Stark reviewed gene: FRY: Rating: AMBER; Mode of pathogenicity: None; Publications: 31487712, 27457812, 21937992; Phenotypes: Intellectual disability; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 FOXN1 Zornitza Stark reviewed gene: FOXN1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FOXF1 Zornitza Stark reviewed gene: FOXF1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FOXE3 Zornitza Stark reviewed gene: FOXE3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FOXE1 Zornitza Stark reviewed gene: FOXE1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FOXC2 Zornitza Stark reviewed gene: FOXC2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FOXC1 Zornitza Stark reviewed gene: FOXC1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FLVCR1 Zornitza Stark reviewed gene: FLVCR1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ataxia, posterior column, with retinitis pigmentosa, MIM#609033; Mode of inheritance: None
Intellectual disability v3.0 FLT4 Zornitza Stark reviewed gene: FLT4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FLNB Zornitza Stark reviewed gene: FLNB: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FKBP14 Zornitza Stark reviewed gene: FKBP14: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FHL1 Zornitza Stark reviewed gene: FHL1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FGFR1 Zornitza Stark edited their review of gene: FGFR1: Added comment: Gene causes several phenotypes but this specific phenotype caused by germline variants is associated with significant ID.; Changed publications: 23812909; Changed phenotypes: Hartsfield syndrome, MIM# 615465
Intellectual disability v3.0 TKFC Zornitza Stark gene: TKFC was added
gene: TKFC was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: TKFC was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TKFC were set to 32004446
Phenotypes for gene: TKFC were set to Developmental delay; cataracts; liver dysfunction
Review for gene: TKFC was set to AMBER
Added comment: Two unrelated individuals reported.
Sources: Expert list
Intellectual disability v3.0 RALGAPA1 Zornitza Stark gene: RALGAPA1 was added
gene: RALGAPA1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: RALGAPA1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: RALGAPA1 were set to 32004447
Phenotypes for gene: RALGAPA1 were set to Intellectual disability; hypotonia; infantile spasms.
Review for gene: RALGAPA1 was set to GREEN
gene: RALGAPA1 was marked as current diagnostic
Added comment: Four unrelated individuals reported.
Sources: Expert list
Intellectual disability v3.0 FGF3 Zornitza Stark reviewed gene: FGF3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Deafness, congenital with inner ear agenesis, microtia, and microdontia, MIM#610706; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 FGF14 Zornitza Stark reviewed gene: FGF14: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: Spinocerebellar ataxia 27, MIM# 609307; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.0 FGF10 Zornitza Stark reviewed gene: FGF10: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 FDFT1 Zornitza Stark reviewed gene: FDFT1: Rating: GREEN; Mode of pathogenicity: None; Publications: 29909962; Phenotypes: Squalene synthase deficiency, MIM#618156; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.0 FBXW4 Zornitza Stark reviewed gene: FBXW4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FBP1 Zornitza Stark reviewed gene: FBP1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 FBN1 Zornitza Stark reviewed gene: FBN1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FARSB Zornitza Stark gene: FARSB was added
gene: FARSB was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: FARSB was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: FARSB were set to 29573043; 1916114; 29979980; 30014610
Phenotypes for gene: FARSB were set to Rajab syndrome, MIM#613658; interstitial lung disease; brain calcifications; microcephaly; intellectual disability
Review for gene: FARSB was set to GREEN
gene: FARSB was marked as current diagnostic
Added comment: 7 unrelated families reported.
Sources: Expert list
Intellectual disability v3.0 FAR1 Zornitza Stark reviewed gene: FAR1: Rating: AMBER; Mode of pathogenicity: None; Publications: 25439727; Phenotypes: Peroxisomal fatty acyl-CoA reductase 1 disorder, MIM#616154; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 FAM20A Zornitza Stark reviewed gene: FAM20A: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FAM161A Zornitza Stark reviewed gene: FAM161A: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 FAAH2 Zornitza Stark reviewed gene: FAAH2: Rating: RED; Mode of pathogenicity: None; Publications: 25885783; Phenotypes: Neuropsychiatric disorder; Mode of inheritance: X-LINKED: hemizygous mutation in males, biallelic mutations in females
Intellectual disability v3.0 FA2H Zornitza Stark reviewed gene: FA2H: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 EYA1 Zornitza Stark reviewed gene: EYA1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 EXT2 Zornitza Stark reviewed gene: EXT2: Rating: GREEN; Mode of pathogenicity: Other; Publications: ; Phenotypes: Seizures, scoliosis, and macrocephaly syndrome, MIM#616682; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.0 EXOSC8 Zornitza Stark gene: EXOSC8 was added
gene: EXOSC8 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: EXOSC8 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: EXOSC8 were set to 24989451; 29656927
Phenotypes for gene: EXOSC8 were set to Pontocerebellar hypoplasia, type 1C, MIM#616081
Review for gene: EXOSC8 was set to GREEN
gene: EXOSC8 was marked as current diagnostic
Added comment: Complex neurological phenotype includes ID.
Sources: Expert list
Intellectual disability v3.0 EVC2 Zornitza Stark reviewed gene: EVC2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ellis-van Creveld syndrome, MIM#225500; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 EVC Zornitza Stark reviewed gene: EVC: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ellis-van Creveld syndrome, MIM#225500; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 ERMARD Zornitza Stark reviewed gene: ERMARD: Rating: RED; Mode of pathogenicity: None; Publications: 24056535, 27087860; Phenotypes: Periventricular nodular heterotopia 6, MIM#615544; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 ERF Zornitza Stark reviewed gene: ERF: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Chitayat syndrome, MIM#617180, Craniosynostosis 4, MIM#600775; Mode of inheritance: None
Intellectual disability v3.0 ERCC4 Zornitza Stark reviewed gene: ERCC4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Xeroderma pigmentosum, group F, MIM#278760, XFE progeroid syndrome, MIM# 610965; Mode of inheritance: None
Intellectual disability v3.0 EOGT Zornitza Stark reviewed gene: EOGT: Rating: RED; Mode of pathogenicity: None; Publications: 31368252; Phenotypes: Adams-Oliver syndrome 4, MIM#615297; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 ENPP1 Zornitza Stark reviewed gene: ENPP1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 ELN Zornitza Stark reviewed gene: ELN: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Supravalvar aortic stenosis; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 EIF2A Zornitza Stark gene: EIF2A was added
gene: EIF2A was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: EIF2A was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: EIF2A were set to 31130284
Phenotypes for gene: EIF2A were set to Intellectual disability; epilepsy
Review for gene: EIF2A was set to AMBER
Added comment: Two unrelated families reported, no functional data.
Sources: Expert list
Intellectual disability v3.0 ATAD3A Zornitza Stark reviewed gene: ATAD3A: Rating: GREEN; Mode of pathogenicity: None; Publications: 32004445; Phenotypes: Harel-Yoon syndrome 617183; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.0 EDNRA Zornitza Stark reviewed gene: EDNRA: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Mandibulofacial dysostosis with alopecia, MIM# 616367; Mode of inheritance: None
Intellectual disability v3.0 EDA Zornitza Stark reviewed gene: EDA: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 ECEL1 Zornitza Stark reviewed gene: ECEL1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 EARS2 Zornitza Stark gene: EARS2 was added
gene: EARS2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: EARS2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: EARS2 were set to 22492562
Phenotypes for gene: EARS2 were set to Combined oxidative phosphorylation deficiency 12, MIM#614924
Review for gene: EARS2 was set to GREEN
gene: EARS2 was marked as current diagnostic
Added comment: ID is part of the phenotype, particularly in those severely affected.
Sources: Expert list
Intellectual disability v3.0 DYNC2H1 Zornitza Stark reviewed gene: DYNC2H1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Short-rib thoracic dysplasia 3 with or without polydactyly, MIM#613091; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 DVL1 Zornitza Stark reviewed gene: DVL1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Robinow syndrome, autosomal dominant 2 616331; Mode of inheritance: None
Intellectual disability v3.0 DSTYK Zornitza Stark reviewed gene: DSTYK: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 DSPP Zornitza Stark reviewed gene: DSPP: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 DPM3 Zornitza Stark reviewed gene: DPM3: Rating: RED; Mode of pathogenicity: None; Publications: 19576565, 28803818, 30931530, 31469168; Phenotypes: Muscular dystrophy-dystroglycanopathy (limb-girdle), type C, 15 612937; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 DNM1L Zornitza Stark gene: DNM1L was added
gene: DNM1L was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: DNM1L was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Phenotypes for gene: DNM1L were set to Encephalopathy, lethal, due to defective mitochondrial peroxisomal fission 1, MIM#614388
Mode of pathogenicity for gene: DNM1L was set to Other
Review for gene: DNM1L was set to GREEN
gene: DNM1L was marked as current diagnostic
Added comment: Dominant and recessive disease described depending on domain affected; dominant negative effect of heterozygous missense variants. LoF/LoF or LoF/missense for AR variants.
Sources: Expert list
Intellectual disability v3.0 DNAAF4 Zornitza Stark reviewed gene: DNAAF4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 DNAAF3 Zornitza Stark reviewed gene: DNAAF3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 DMP1 Zornitza Stark reviewed gene: DMP1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 DLL4 Zornitza Stark reviewed gene: DLL4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 DLL3 Zornitza Stark reviewed gene: DLL3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 DLL1 Zornitza Stark reviewed gene: DLL1: Rating: GREEN; Mode of pathogenicity: None; Publications: 31353024; Phenotypes: Intellectual disability, autism, seizures, variable brain abnormalities, scoliosis; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.0 DENND5A Zornitza Stark reviewed gene: DENND5A: Rating: GREEN; Mode of pathogenicity: None; Publications: 27431290, 27866705; Phenotypes: Epileptic encephalopathy, early infantile, 49 617281; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 DDOST Zornitza Stark changed review comment from: Single family reported with supportive functional data, Amber at best.; to: Single family reported with supportive functional data, gene is RED on CDG panel.
Intellectual disability v3.0 DDOST Zornitza Stark reviewed gene: DDOST: Rating: RED; Mode of pathogenicity: None; Publications: 22305527; Phenotypes: Congenital disorder of glycosylation, type Ir, MIM# 614507; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 DDB2 Zornitza Stark reviewed gene: DDB2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 DCC Zornitza Stark reviewed gene: DCC: Rating: RED; Mode of pathogenicity: None; Publications: 31697046; Phenotypes: Agenesis of the corpus callosum; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 CYP7B1 Zornitza Stark reviewed gene: CYP7B1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spastic paraplegia 5A, autosomal recessive, MIM# 270800; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CYP2U1 Zornitza Stark reviewed gene: CYP2U1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spastic paraplegia 56, autosomal recessive, MIM#615030; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CYP1B1 Zornitza Stark reviewed gene: CYP1B1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 CTU2 Zornitza Stark gene: CTU2 was added
gene: CTU2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: CTU2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CTU2 were set to 27480277; 26633546
Phenotypes for gene: CTU2 were set to Microcephaly, facial dysmorphism, renal agenesis, and ambiguous genitalia syndrome, MIM#618142
Review for gene: CTU2 was set to GREEN
Added comment: Multiple Saudi families reported with same homozygous variant; founder effect. Severe disorder of infancy.
Sources: Expert list
Intellectual disability v3.0 CTSK Zornitza Stark reviewed gene: CTSK: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 CTSF Zornitza Stark reviewed gene: CTSF: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ceroid lipofuscinosis, neuronal, 13, Kufs type, MIM#615362; Mode of inheritance: None
Intellectual disability v3.0 CTNS Zornitza Stark reviewed gene: CTNS: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 CRYGD Zornitza Stark Deleted their comment
Intellectual disability v3.0 CRYGD Zornitza Stark commented on gene: CRYGD: ID is not part of the phenotype.
Intellectual disability v3.0 CRYGD Zornitza Stark reviewed gene: CRYGD: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 CRYBB3 Zornitza Stark reviewed gene: CRYBB3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 CRYBB2 Zornitza Stark reviewed gene: CRYBB2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 CRYBB1 Zornitza Stark reviewed gene: CRYBB1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 CRYBA1 Zornitza Stark reviewed gene: CRYBA1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 CRYAA Zornitza Stark reviewed gene: CRYAA: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 CRX Zornitza Stark reviewed gene: CRX: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 CRB1 Zornitza Stark commented on gene: CRB1
Intellectual disability v3.0 COMP Zornitza Stark reviewed gene: COMP: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 COL9A3 Zornitza Stark reviewed gene: COL9A3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 COL9A2 Zornitza Stark reviewed gene: COL9A2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 COL9A1 Zornitza Stark reviewed gene: COL9A1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 COL6A1 Zornitza Stark reviewed gene: COL6A1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 COL4A4 Zornitza Stark reviewed gene: COL4A4: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 COL4A3 Zornitza Stark reviewed gene: COL4A3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 COL2A1 Zornitza Stark reviewed gene: COL2A1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 COL1A1 Zornitza Stark reviewed gene: COL1A1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v3.0 COL18A1 Zornitza Stark reviewed gene: COL18A1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Knobloch syndrome, type 1, MIM#267750; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 COL11A1 Zornitza Stark reviewed gene: COL11A1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Stickler syndrome, type II, MIM# 604841; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 COL10A1 Zornitza Stark reviewed gene: COL10A1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Metaphyseal chondrodysplasia, Schmid type, MIM# 156500; Mode of inheritance: None
Intellectual disability v3.0 CNTNAP1 Zornitza Stark gene: CNTNAP1 was added
gene: CNTNAP1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: CNTNAP1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CNTNAP1 were set to 28374019; 29511323; 27668699
Phenotypes for gene: CNTNAP1 were set to Hypomyelinating neuropathy, congenital, 3, MIM#618186; Lethal congenital contracture syndrome 7, MIM# 616286
Review for gene: CNTNAP1 was set to GREEN
gene: CNTNAP1 was marked as current diagnostic
Added comment: Multiple affected individuals reported; ID is part of the phenotype.
Sources: Expert list
Intellectual disability v3.0 CLDN19 Zornitza Stark reviewed gene: CLDN19: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Hypomagnesemia 5, renal, with ocular involvement, MIM# 248190; Mode of inheritance: None
Intellectual disability v3.0 CLCN7 Zornitza Stark reviewed gene: CLCN7: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Osteopetrosis; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.0 CIB2 Zornitza Stark reviewed gene: CIB2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Deafness, autosomal recessive 48, MIM# 609439, Usher syndrome; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CHUK Zornitza Stark reviewed gene: CHUK: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Cocoon syndrome, MIM# 613630; Mode of inheritance: None
Intellectual disability v3.0 CHSY1 Zornitza Stark reviewed gene: CHSY1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Temtamy preaxial brachydactyly syndrome 605282; Mode of inheritance: None
Intellectual disability v3.0 CHST3 Zornitza Stark reviewed gene: CHST3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spondyloepiphyseal dysplasia with congenital joint dislocations, MIM# 143095; Mode of inheritance: None
Intellectual disability v3.0 CHRNG Zornitza Stark reviewed gene: CHRNG: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Escobar syndrome, MIM# 265000, Multiple pterygium syndrome, lethal type, MIM# 253290; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CHRDL1 Zornitza Stark reviewed gene: CHRDL1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Megalocornea 1, X-linked, MIM# 309300; Mode of inheritance: X-LINKED: hemizygous mutation in males, biallelic mutations in females
Intellectual disability v3.0 CHM Zornitza Stark reviewed gene: CHM: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Choroideremia, MIM# 303100; Mode of inheritance: X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Intellectual disability v3.0 CHD1 Zornitza Stark gene: CHD1 was added
gene: CHD1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: CHD1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: CHD1 were set to 28866611
Phenotypes for gene: CHD1 were set to Pilarowski-Bjornsson syndrome, MIM#617682
Mode of pathogenicity for gene: CHD1 was set to Other
Review for gene: CHD1 was set to GREEN
gene: CHD1 was marked as current diagnostic
Added comment: Six unrelated individuals with heterozygous variants reported. Possible dominant negative mechanism: reported variants are missense, and an individual with a deletion did not have a neurological phenotype.
Sources: Expert list
Intellectual disability v3.0 CEP104 Zornitza Stark reviewed gene: CEP104: Rating: GREEN; Mode of pathogenicity: None; Publications: 26477546; Phenotypes: Joubert syndrome 25, MIM# 616781; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CDH3 Zornitza Stark reviewed gene: CDH3: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ectodermal dysplasia, ectrodactyly, and macular dystrophy 225280, Hypotrichosis, congenital, with juvenile macular dystrophy 601553; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CDH23 Zornitza Stark reviewed gene: CDH23: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Deafness, Usher syndrome; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CDH2 Zornitza Stark reviewed gene: CDH2: Rating: GREEN; Mode of pathogenicity: None; Publications: 31585109; Phenotypes: Intellectual disability, corpus callosum abnormalities, congenital abnormalities; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.0 CCT5 Zornitza Stark reviewed gene: CCT5: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Neuropathy, hereditary sensory, with spastic paraplegia, MIM# 256840; Mode of inheritance: None
Intellectual disability v3.0 CCNO Zornitza Stark reviewed gene: CCNO: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ciliary dyskinesia, primary, 29, MIM# 615872; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CCDC88A Zornitza Stark edited their review of gene: CCDC88A: Added comment: Two unrelated families now plus mouse model.; Changed publications: 26917597, 30392057; Set current diagnostic: yes
Intellectual disability v3.0 CCDC65 Zornitza Stark reviewed gene: CCDC65: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ciliary dyskinesia, primary, 27, MIM# 615504; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CCDC40 Zornitza Stark reviewed gene: CCDC40: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ciliary dyskinesia, primary, 15, MIM# 613808; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CCDC114 Zornitza Stark reviewed gene: CCDC114: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ciliary dyskinesia, primary, 20, MIM# 615067; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CCDC103 Zornitza Stark reviewed gene: CCDC103: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Ciliary dyskinesia, primary, 17, MIM# 614679; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 CARS2 Zornitza Stark reviewed gene: CARS2: Rating: GREEN; Mode of pathogenicity: None; Publications: 30139652; Phenotypes: Combined oxidative phosphorylation deficiency 27, MIM#616672; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 EBP Zornitza Stark reviewed gene: EBP: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: Chondrodysplasia punctata, X-linked dominant MIM#302960, Conradi-Hunermann syndrome, MEND syndrome, MIM#300960; Mode of inheritance: X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males); Current diagnostic: yes
Intellectual disability v3.0 SCN4A Andrea Haworth commented on gene: SCN4A
Intellectual disability v3.0 CACNA2D2 Zornitza Stark reviewed gene: CACNA2D2: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: Cerebellar atrophy with seizures and variable developmental delay, MIM#618501; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.0 CA5A Zornitza Stark reviewed gene: CA5A: Rating: RED; Mode of pathogenicity: None; Publications: 26913920; Phenotypes: Hyperammonemia due to carbonic anhydrase VA deficiency, MIM# 615751; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 C8orf37 Zornitza Stark changed review comment from: Two unrelated individuals reported with BBS; note gene has an association with retinal ciliopathies.; to: Two unrelated individuals reported with BBS; note gene has an association with retinal ciliopathies. Suggested rating Amber.
Intellectual disability v3.0 C8orf37 Zornitza Stark reviewed gene: C8orf37: Rating: ; Mode of pathogenicity: None; Publications: 26854863, 27008867; Phenotypes: Bardet-Biedl syndrome 21, MIM#617406; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 C4orf26 Zornitza Stark reviewed gene: C4orf26: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Amelogenesis imperfecta, type IIA4, MIM# 614832; Mode of inheritance: None
Intellectual disability v3.0 C2orf71 Zornitza Stark reviewed gene: C2orf71: Rating: ; Mode of pathogenicity: None; Publications: ; Phenotypes: Retinitis pigmentosa 54 613428; Mode of inheritance: None
Intellectual disability v3.0 C2CD3 Zornitza Stark reviewed gene: C2CD3: Rating: GREEN; Mode of pathogenicity: None; Publications: 30097616, 27094867, 26477546, 24997988,; Phenotypes: Orofaciodigital syndrome XIV, MIM# 615948; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.0 C19orf12 Zornitza Stark reviewed gene: C19orf12: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Neurodegeneration with brain iron accumulation 4, MIM#614298; Mode of inheritance: None
Intellectual disability v3.0 BMPR1B Zornitza Stark reviewed gene: BMPR1B: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Acromesomelic dysplasia, Demirhan type MIM#609441, Brachydactyly, type A1, D, MIM#616849, Brachydactyly, type A2, MIM# 112600; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.0 BMPER Zornitza Stark reviewed gene: BMPER: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Diaphanospondylodysostosis, MIM# 608022; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 BICD2 Zornitza Stark reviewed gene: BICD2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spinal muscular atrophy, lower extremity-predominant, 2A, autosomal dominant, MIM#615290; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 BHLHA9 Zornitza Stark reviewed gene: BHLHA9: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Syndactyly, mesoaxial synostotic, with phalangeal reduction, MIM# 609432; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 BGN Zornitza Stark reviewed gene: BGN: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Meester-Loeys syndrome, MIM# 300989, Spondyloepimetaphyseal dysplasia, X-linked, MIM#300106; Mode of inheritance: X-LINKED: hemizygous mutation in males, biallelic mutations in females
Intellectual disability v3.0 BFSP2 Zornitza Stark reviewed gene: BFSP2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Cataract 12, multiple types, MIM# 611597; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 BCORL1 Zornitza Stark reviewed gene: BCORL1: Rating: GREEN; Mode of pathogenicity: None; Publications: 24123876, 30941876; Phenotypes: Shukla-Vernon syndrome, MIM# 301029; Mode of inheritance: X-LINKED: hemizygous mutation in males, biallelic mutations in females; Current diagnostic: yes
Intellectual disability v3.0 B9D2 Zornitza Stark gene: B9D2 was added
gene: B9D2 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: B9D2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: B9D2 were set to 26092869; 21763481
Phenotypes for gene: B9D2 were set to Joubert syndrome 34, MIM#614175; Meckel syndrome 10, MIM#614175
Review for gene: B9D2 was set to GREEN
gene: B9D2 was marked as current diagnostic
Added comment: Two unrelated individuals with Joubert syndrome and bi-allelic variants reported; single family with two affected individuals also reported with homozygous variant in this gene and more severe Meckel phenotype, overall supporting gene-disease association for a ciliopathy with CNS involvement. ID is part of the phenotype of these conditions.
Sources: Expert list
Intellectual disability v3.0 B9D1 Zornitza Stark reviewed gene: B9D1: Rating: GREEN; Mode of pathogenicity: None; Publications: 24886560, 21493627; Phenotypes: Joubert syndrome 27, MIM#617120, Meckel syndrome 9, MIM#614209; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.0 ATP8B1 Zornitza Stark reviewed gene: ATP8B1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Cholestasis, benign recurrent intrahepatic, MIM# 243300, Cholestasis, intrahepatic, of pregnancy, 1, MIM#147480, Cholestasis, progressive familial intrahepatic 1, MIM# 211600; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v3.0 ATP6V1B1 Zornitza Stark reviewed gene: ATP6V1B1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Renal tubular acidosis with deafness 267300; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 ATP6AP1 Zornitza Stark gene: ATP6AP1 was added
gene: ATP6AP1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: ATP6AP1 was set to X-LINKED: hemizygous mutation in males, biallelic mutations in females
Publications for gene: ATP6AP1 were set to 27231034
Phenotypes for gene: ATP6AP1 were set to Immunodeficiency 47, MIM#300972
Review for gene: ATP6AP1 was set to GREEN
gene: ATP6AP1 was marked as current diagnostic
Added comment: 11 males from 6 unrelated families with primarily an immunodeficiency disorder; six patients from 3 families who carried the same variant (E346K) had neurologic features, including seizures, mild intellectual disability, and behavioral abnormalities
Sources: Expert list
Intellectual disability v3.0 ATP1A2 Zornitza Stark reviewed gene: ATP1A2: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: Alternating hemiplegia of childhood 1, MIM# 104290; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability v3.0 ATAD1 Zornitza Stark gene: ATAD1 was added
gene: ATAD1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: ATAD1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: ATAD1 were set to 28180185
Phenotypes for gene: ATAD1 were set to Hyperekplexia 4, MIM#618011
Review for gene: ATAD1 was set to GREEN
Added comment: Severe progressive neurological disorder, severe/profound intellectual disability is a feature
Sources: Expert list
Intellectual disability v3.0 ASTN1 Zornitza Stark gene: ASTN1 was added
gene: ASTN1 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: ASTN1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: ASTN1 were set to 29706646; 27431290; 26539891
Phenotypes for gene: ASTN1 were set to Intellectual disability
Review for gene: ASTN1 was set to GREEN
gene: ASTN1 was marked as current diagnostic
Added comment: Three families reported as part of large cohorts albeit proposing multiple novel candidate genes with minimal detail and no functional validation.
Sources: Expert list
Intellectual disability v3.0 ARHGEF6 Zornitza Stark reviewed gene: ARHGEF6: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: MENTAL RETARDATION X-LINKED TYPE 46; Mode of inheritance: None
Intellectual disability v3.0 ANKH Zornitza Stark reviewed gene: ANKH: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Craniometaphyseal dysplasia, MIM#123000; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 ALG9 Zornitza Stark reviewed gene: ALG9: Rating: GREEN; Mode of pathogenicity: None; Publications: 28932688; Phenotypes: Congenital disorder of glycosylation, type Il, MIM#608776; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 ALG14 Zornitza Stark gene: ALG14 was added
gene: ALG14 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: ALG14 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: ALG14 were set to 30221345; 23404334; 28733338
Phenotypes for gene: ALG14 were set to Myasthenic syndrome, congenital, 15, without tubular aggregates, MIM#616227; Intellectual disability
Review for gene: ALG14 was set to GREEN
gene: ALG14 was marked as current diagnostic
Added comment: 5 individuals from unrelated families described in the literature: one with myasthenic syndrome, no report of ID; second with predominantly ID phenotype; and three more with a neurodegenerative phenotype.
Sources: Expert list
Intellectual disability v3.0 ALDOB Zornitza Stark changed review comment from: Metabolic decompensation on exposure to fructose, including hypoglycaemia, but ID is not an intrinsic feature of this condition.; to: Metabolic decompensation on exposure to fructose, including hypoglycaemia, but ID is not an intrinsic feature of this condition. ID only reported in the absence of treatment.
Intellectual disability v3.0 ALDOB Zornitza Stark reviewed gene: ALDOB: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Fructose intolerance, hereditary, MIM# 229600; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 AHCY Zornitza Stark reviewed gene: AHCY: Rating: ; Mode of pathogenicity: None; Publications: 31957987, 27671891, 30121674, 28779239; Phenotypes: Hypermethioninemia with deficiency of S-adenosylhomocysteine hydrolase, MIM#613752; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 AGPS Zornitza Stark reviewed gene: AGPS: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Rhizomelic chondrodysplasia punctata, type 3, MIM#600121; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 AGMO Zornitza Stark gene: AGMO was added
gene: AGMO was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: AGMO was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: AGMO were set to 31555905
Phenotypes for gene: AGMO were set to microcephaly; intellectual disability; epilepsy
Review for gene: AGMO was set to GREEN
gene: AGMO was marked as current diagnostic
Added comment: Three unrelated families and functional data.
Sources: Expert list
Intellectual disability v3.0 AGL Zornitza Stark reviewed gene: AGL: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Glycogen storage disease IIIa, MIM# 232400; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 AFG3L2 Zornitza Stark reviewed gene: AFG3L2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spastic ataxia 5, autosomal recessive, MIM#614487; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 ADGRG6 Zornitza Stark reviewed gene: ADGRG6: Rating: RED; Mode of pathogenicity: None; Publications: 30549416; Phenotypes: Lethal congenital contracture syndrome 9, OMIM #616503; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 ADD3 Zornitza Stark gene: ADD3 was added
gene: ADD3 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: ADD3 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: ADD3 were set to 29768408; 23836506
Phenotypes for gene: ADD3 were set to Cerebral palsy, spastic quadriplegic, 3, MIM#617008
Review for gene: ADD3 was set to GREEN
gene: ADD3 was marked as current diagnostic
Added comment: Four families reported in the literature with bi-allelic variants in this gene causing intellectual disability.
Sources: Expert list
Intellectual disability v3.0 ADCY5 Zornitza Stark reviewed gene: ADCY5: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Dyskinesia, familial, with facial myokymia, MIM#606703; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v3.0 ADAMTS10 Zornitza Stark gene: ADAMTS10 was added
gene: ADAMTS10 was added to Intellectual disability. Sources: Expert list
Mode of inheritance for gene: ADAMTS10 was set to BIALLELIC, autosomal or pseudoautosomal
Phenotypes for gene: ADAMTS10 were set to Weill-Marchesani syndrome 1, recessive, MIM#277600
Review for gene: ADAMTS10 was set to AMBER
Added comment: Mild intellectual disability is described in around 10% of affected individuals.
Sources: Expert list
Intellectual disability v3.0 ACADSB Zornitza Stark reviewed gene: ACADSB: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: 2-methylbutyrylglycinuria, MIM# 610006; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 ABCC6 Zornitza Stark reviewed gene: ABCC6: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Arterial calcification, generalized, of infancy, 2, MIM#614473, Pseudoxanthoma elasticum, MIM#264800; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v3.0 ABAT Zornitza Stark reviewed gene: ABAT: Rating: GREEN; Mode of pathogenicity: None; Publications: 10407778, 20052547, 27596361, 28411234,; Phenotypes: GABA-transaminase deficiency, MIM#613163; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v3.0 ZSWIM6 Louise Daugherty commented on gene: ZSWIM6
Intellectual disability v3.0 ZSWIM6 Louise Daugherty Tag watchlist was removed from gene: ZSWIM6.
Intellectual disability v3.0 UFM1 Louise Daugherty Tag watchlist was removed from gene: UFM1.
Intellectual disability v3.0 TRMT1 Louise Daugherty Tag watchlist was removed from gene: TRMT1.
Intellectual disability v3.0 TRMT1 Louise Daugherty commented on gene: TRMT1
Intellectual disability v3.0 TRAF7 Louise Daugherty Tag watchlist was removed from gene: TRAF7.
Intellectual disability v3.0 TRAF7 Louise Daugherty commented on gene: TRAF7
Intellectual disability v3.0 TCF20 Louise Daugherty edited their review of gene: TCF20: Changed rating: GREEN
Intellectual disability v3.0 TCF20 Louise Daugherty Tag watchlist was removed from gene: TCF20.
Intellectual disability v3.0 TCF20 Louise Daugherty commented on gene: TCF20: As a result of watchlist tag audit the watchlist tag was removed from TCF20 this is now a green gene with sufficient evidence/review
Intellectual disability v3.0 SYNJ1 Louise Daugherty Tag watchlist was removed from gene: SYNJ1.
Intellectual disability v3.0 SYNJ1 Louise Daugherty commented on gene: SYNJ1
Intellectual disability v3.0 SLC6A9 Louise Daugherty edited their review of gene: SLC6A9: Changed rating: GREEN
Intellectual disability v3.0 SLC6A9 Louise Daugherty Tag watchlist was removed from gene: SLC6A9.
Intellectual disability v3.0 SLC6A9 Louise Daugherty commented on gene: SLC6A9: As a result of watchlist tag audit the watchlist tag was removed from SLC6A9- this is now a green gene with sufficient evidence/review
Intellectual disability v3.0 SETD1B Louise Daugherty Tag watchlist was removed from gene: SETD1B.
Intellectual disability v3.0 SETD1B Louise Daugherty commented on gene: SETD1B: As a result of watchlist tag audit the watchlist tag was removed from SETD1B- this is now a green gene with sufficient evidence/review
Intellectual disability v3.0 RLIM Louise Daugherty commented on gene: RLIM: As a result of watchlist tag audit the watchlist tag was removed from RLIM- this is now a green gene with sufficient evidence/review
Intellectual disability v3.0 RLIM Louise Daugherty Tag watchlist was removed from gene: RLIM.
Intellectual disability v3.0 MSL3 Louise Daugherty commented on gene: MSL3: As a result of watchlist tag audit the watchlist tag was removed from MSL3- this is now a green gene with sufficient evidence/review
Intellectual disability v3.0 MSL3 Louise Daugherty Tag watchlist was removed from gene: MSL3.
Intellectual disability v3.0 MSL3 Louise Daugherty commented on gene: MSL3: As a result of watchlist tag audit the watchlist tag was removed from MSL3- this is now a green gene with sufficient evidence/review
Intellectual disability v3.0 MED25 Louise Daugherty Tag watchlist was removed from gene: MED25.
Intellectual disability v3.0 MED25 Louise Daugherty commented on gene: MED25: As a result of watchlist tag audit the watchlist tag was removed from MED25- this is now a green gene with sufficient evidence/review
Intellectual disability v3.0 KDM1A Louise Daugherty Tag watchlist was removed from gene: KDM1A.
Intellectual disability v3.0 KDM1A Louise Daugherty commented on gene: KDM1A: As a result of watchlist tag audit the watchlist tag was removed from KDM1A- this is now a green gene with sufficient evidence/review
Intellectual disability v3.0 GRIA2 Louise Daugherty Tag watchlist was removed from gene: GRIA2.
Intellectual disability v3.0 GRIA2 Louise Daugherty commented on gene: GRIA2: As a result of watchlist tag audit the watchlist tag was removed from GRIA2- this is now a green gene with sufficient evidence/review
Intellectual disability v3.0 DLG4 Louise Daugherty Tag watchlist was removed from gene: DLG4.
Intellectual disability v3.0 DLG4 Louise Daugherty commented on gene: DLG4
Intellectual disability v3.0 CTDP1 Louise Daugherty Tag watchlist was removed from gene: CTDP1.
Intellectual disability v3.0 CTDP1 Louise Daugherty commented on gene: CTDP1
Intellectual disability v3.0 CSNK2A1 Louise Daugherty Tag watchlist was removed from gene: CSNK2A1.
Intellectual disability v3.0 CSNK2A1 Louise Daugherty commented on gene: CSNK2A1
Intellectual disability v3.0 CLCN4 Louise Daugherty Tag watchlist was removed from gene: CLCN4.
Intellectual disability v3.0 CLCN4 Louise Daugherty commented on gene: CLCN4
Intellectual disability v3.0 ALG11 Louise Daugherty Tag watchlist was removed from gene: ALG11.
Intellectual disability v3.0 ALG11 Louise Daugherty commented on gene: ALG11
Intellectual disability v3.0 VAMP1 Louise Daugherty Tag watchlist was removed from gene: VAMP1.
Intellectual disability v3.0 VAMP1 Louise Daugherty commented on gene: VAMP1: As a result of watchlist tag audit the watchlist tag was removed from VAMP1- this is now a green gene.
Intellectual disability v3.0 SUPT16H Konstantinos Varvagiannis gene: SUPT16H was added
gene: SUPT16H was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: SUPT16H was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: SUPT16H were set to http://dx.doi.org/10.1136/jmedgenet-2019-106193
Phenotypes for gene: SUPT16H were set to Global developmental delay; Intellectual disability; Abnormality of the corpus callosum
Penetrance for gene: SUPT16H were set to Complete
Review for gene: SUPT16H was set to AMBER
Added comment: Bina et al (2020 - http://dx.doi.org/10.1136/jmedgenet-2019-106193) report on 4 unrelated individuals with heterozygous SNVs affecting SUPT16H as well as 1 further with microdeletion spanning this gene.

The phenotype consisted of DD with subsequent ID in a subset of them (ages of the cohort: 2y-14y), autistic features in few, abnormalities of the corpus callosum (for 3 with available MRI images), variable gastrointestinal problems in some, and possibly minor dysmorphic features.

SUPT16H encodes a subunit of the FACT (facilitates chromatin transcription) complex, a chromatin-specific factor required for transcription elongation as well as for DNA replication and repair (OMIM citing Belotserkovskaya et al. 2003 - PMID: 12934006). The 2 subunits of the complex [Spt16 (encoded by SUPT16H) and SSRP1] are essential for histone regulation. As the authors note, Spt16 interacts with the histone dimer H2A-H2B during transcription to allow RNA polymerase access to previously coiled DNA [cited PMIDs : 9489704, 10421373 / A recent study by Liu et al 2019 (PMID: 31775157) appears highly relevant].

SUPT16H has a Z-score of 5.1 in gnomAD and a pLI of 1 (%HI of 22.56 in Decipher).

SNVs :
4 de novo missense SNVs were identified following exome sequencing (NM_007192.3:c.484A>G or I162V / L432P / N571S / R734W), all absent from gnomAD and mostly predicted to be deleterious (I162V predicted benign, tolerated, disease-causing by PolyPhen2, SIFT, MutationTaster respectively and had a CADD score of 13.61). Prior work-up for these individuals (incl. CMA in some / MS-MLPA for Angelman s. in 1 / metabolic investigations) had (probably) not revealed an apparent cause, with small CNVs inherited from healthy parents (a 4q13.3 dup / 20q13.2 del - coordinates not provided).

There were no studies performed for the identified variants.

CNVs :
A 5th individual reported by Bina et al was found to harbor a 2.05 Mb 14q11.2 deletion spanning SUPT16H. The specific deletion also spanned CHD8 while the same individual harbored also a 30.17 Mb duplication of 18p11.32q12.1.

CNVs spanning SUPT16H reported to date, also span the (very) proximal CHD8. [Genomic coordinates (GRCh38) for SUPT16H and CHD8 as provided by OMIM : 14:21,351,471-21,384,018 / 14:21,385,198-21,456,122]. Haploinsufficiency of CHD8 is associated with a distinctive syndrome with overgrowth and ID (Douzgou et al 2019 - PMID: 31001818). The phenotype of SUPT16H-CHD8 duplications is discussed in other studies/reviews. [Smol et al 2020 - PMID: 31823155 / Smyk et al 2016 - PMID: 26834018].

Animal models were not commented on by Bina et al (possibly not available for mouse : http://www.informatics.jax.org/marker/MGI:1890948 / https://www.mousephenotype.org/data/genes/MGI:1890948 ).
Sources: Literature
Intellectual disability v3.0 TET3 Konstantinos Varvagiannis gene: TET3 was added
gene: TET3 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: TET3 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: TET3 were set to https://doi.org/10.1016/j.ajhg.2019.12.007
Phenotypes for gene: TET3 were set to Global developmental delay; Intellectual disability; Macrocephaly; Growth abnormality; Seizures; Autistic behavior; Abnormality of movement; Abnormality of the face
Penetrance for gene: TET3 were set to Complete
Review for gene: TET3 was set to GREEN
Added comment: Beck et al (2020 - DOI: https://doi.org/10.1016/j.ajhg.2019.12.007) report on individuals with monoallelic de novo or biallelic pathogenic TET3 variants.

For both inheritance modes (AR/AD) DD/ID were among the observed features (mild-severe - individuals from families 2, 4 and 6 for whom presence of ID was not commented, relevance to the current panel is suggested from the developmental milestones in the supplement. One individual presented DD without ID). Other features included hypotonia (in 8), ASD/autistic features (in 5), seizures (2 unrelated subjects for each inheritance mode). Postnatal growth abnormalities were observed in many, in most cases involving head size (with/without abnormal stature) and few presented abnormal prenatal growth. Variable movement disorders were observed in some. Some facial features appeared to be more common (eg. long face, tall forehead, etc).

Most were referred for their DD. Extensive prior genetic investigations had (mostly) come out normal (with possible contribution of a 16p11.2 dup in an individual with monoallelic variant or a 16q22 dup in another with biallelic TET3 variants). Monoallelic / biallelic variants in all subjects were identified following exome sequencing.

TET3 encodes a methylcytosine dioxygenase (the TET family consisting of 3 enzymes, TET1, TET2, TET3). These enzymes are involved in DNA demethylation through a series of reactions beginning with the conversion of 5-methyl cytosine [5mc] to 5-hydromethylcytosine [5hmC].

5 individuals from 3 families (1/3 consanguineous) harbored biallelic missense variants. 5 different missense variants were observed. Heterozygous parents appeared to be mildly affected (eg. having learning difficulties, etc).

6 individuals from 5 families harbored monoallelic variants [3 truncating (of which 2 localizing in the last exon), 2 missense SNVs]. In one family the variant was inherited from a similarly affected parent. In all other cases the variant had occured de novo. No additional TET3 variants were identified, with the limitations of WES.

All missense mutations, whether observed in individuals with biallelic or monoallelic variants, were located within the catalytic domain or - for a single variant (NM_001287491.1:c.2254C>T / p.Arg752Cys) - adjacent to it.

Functional studies were carried out only for (all) missense variants observed in individuals with biallelic variants. Conversion of 5mC to 5hmC is the first step in DNA demethylation. In HEK293 cells overexpressing either wt or variants, production of 5hmc was measured. 4/5 missense variants evaluated demonstrated a defect in converting 5mC to 5hmC, Arg752Cys being an exception (as also predicted by its localization).

DD/ID and abnormal growth are also features of disorders of the epigenetic machinery (DNA methylation machinery, histone machinery, chromatin remodelers, other chromatin-associated proteins). Similarly to TET3, both monoallelic and biallelic variants in KDM5B, encoding for another component of the epigenetic machinery, have been identified in individuals with ID.

Mouse models discussed by the authors [several Refs provided though not here reviewed] : The gene has been shown to be highly expressed in oocytes, zygotes and neurons and to play a role in demethylation of the paternal genome after fertilization. (From the MGI: 'mice inheriting a null allele from a germ cell conditional null mother display impaired reprogramming of the paternal genome resulting in reduced embryo viability'). Beck et al also note that Tet3 inhibition or depletion in differentiated neurons can impact synaptic function [PMIDs cited: 25915473, 24757058, 26711116].
Sources: Literature
Intellectual disability v3.0 PIGP Konstantinos Varvagiannis changed review comment from: Please consider upgrading this gene to Green.

A recent study Vetro et al. (2020 - https://doi.org/10.1212/NXG.0000000000000387) identified 4 additional affected individuals with severe EIEE, belonging to a large inbred family. Following extensive genetic investigations (all of which were non-diagnostic) these subjects were found to harbor in homozygosity the frameshift variant also reported in the 2 previous studies (NM_153681.2:c.456delA / p.Glu153AsnfsTer34 or NM_153682.2:c.384delA / p.Glu129AsnfsTer34). Reduced expression of the GPI-anchor protein CD16 was demonstrated in granulocytes of affected individuals.; to: Please consider upgrading this gene to Green.

In a recent study, Vetro et al. (2020 - https://doi.org/10.1212/NXG.0000000000000387) identified 4 additional affected individuals with severe EIEE, belonging to a large inbred family. Following extensive genetic investigations (all of which were non-diagnostic) these subjects were found to harbor in homozygosity the frameshift variant also reported in the 2 previous studies (NM_153681.2:c.456delA / p.Glu153AsnfsTer34 or NM_153682.2:c.384delA / p.Glu129AsnfsTer34). Reduced expression of the GPI-anchor protein CD16 was demonstrated in granulocytes of affected individuals.
Intellectual disability v3.0 PIGP Konstantinos Varvagiannis edited their review of gene: PIGP: Added comment: Please consider upgrading this gene to Green.

A recent study Vetro et al. (2020 - https://doi.org/10.1212/NXG.0000000000000387) identified 4 additional affected individuals with severe EIEE, belonging to a large inbred family. Following extensive genetic investigations (all of which were non-diagnostic) these subjects were found to harbor in homozygosity the frameshift variant also reported in the 2 previous studies (NM_153681.2:c.456delA / p.Glu153AsnfsTer34 or NM_153682.2:c.384delA / p.Glu129AsnfsTer34). Reduced expression of the GPI-anchor protein CD16 was demonstrated in granulocytes of affected individuals.; Changed publications: 28334793, 31139695, https://doi.org/10.1212/NXG.0000000000000387
Intellectual disability v3.0 ZNF292 Konstantinos Varvagiannis commented on gene: ZNF292: Correction to the phrase "Manual review of some relevant LoF variants in gnomAD suggested that they represent false positive calls":

Irrespective of the variants identified in their cohort, Mirzaa et al. reviewed many pLoF variants which are listed in gnomAD. The authors suggested that some of these variants may not represent true LoF variants.

Eg. NM_015021.3:c.2690C>A ( https://gnomad.broadinstitute.org/variant/6-87966037-C-A ) which appears to be a stopgain variant (Ser[TCA]>Ter[TAA]) is probably not a true LoF variant. It always occurred in cis (/the same reads) with NM_015021.3:c.2689T>C (Ser[TCA] to Pro[CCA]). This is visible in the IGV graph of gnomAD (url above).

Thus, gnomAD lists 2 single-nucleotide variants affecting the same codon, one next to the other. However, as the 2 SNVs always occurred in cis, this represents a single missense multi-nucleotide variant (Ser[TCA]>Gln[CAA]) [ NM_015021.3(ZNF292_v001):c.2689_2690delinsCA ].

Similar observations were made for other variants seen in gnomAD.
Intellectual disability v3.0 NUS1 Konstantinos Varvagiannis edited their review of gene: NUS1: Added comment: Please consider upgrading this gene (NUS1 is also rated Green in the epilepsy panel).

Den et al (2019 - PMID: 31656175) reported on 2 additional unrelated individuals (aged 17 and 59y) both presenting intellectual disability, epilepsy , involuntary movements, ataxia and scoliosis. Both were found to harbor the same splicing variant in NUS1 (NM_138459.4:c.691+1C>A) following exome sequencing. Using lymphoblastoid cell lines from both individuals it was demonstrated that the variant creates a new splice donor site in exon 3 further creating a new reading frame and producing a premature termination codon [c.601_691del or p.(Arg202Glnfs*9)]. Using cyclohexamide, it was further shown that the mutant mRNA is partially subjected to NMD. [Additional variants identified by exome for the 2 subjects were non diagnostic (/VUS). An SPTAN1 nonsense variant identified in one was inherited from an unaffected parent (dominant-negative mechanism listed in G2P for this gene / in ClinVar all pLoF variants are submitted as VUS)].
-----; Changed rating: GREEN; Changed publications: 25066056, 29100083, 24824130, 30348779, 31656175
Intellectual disability v3.0 RNF113A Konstantinos Varvagiannis reviewed gene: RNF113A: Rating: GREEN; Mode of pathogenicity: None; Publications: 25612912, 31880405, 31793730, 29133357, 30506991, 15256591, 24026126, 23555887; Phenotypes: ; Mode of inheritance: X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Intellectual disability v3.0 MTHFS Konstantinos Varvagiannis changed review comment from: Biallelic pathogenic MTHFS variants cause Neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination (# 618367).

The gene encodes 5,10-Methenyltetrahydrofolate synthetase which catalyzes conversion of 5-formyltetrahydrofolate (5-FTHF or folinic acid) to 5,10-methenyltetrahydrofolate (5,10-MTHF).

At least 3 unrelated individuals have been reported. The phenotype appears to be relevant to both epilepsy and ID gene panels and the role of variants/the gene supported by enzymatic activity studies, 5-FTHF accumulation, 5,10-MTHF levels (low/low-normal), the role of folate metabolism pathway overall and some supporting (metabolic) evidence from the mouse model.
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Rodan et al (2018 - PMID: 30031689) reported on 2 individuals both presenting with microcephaly, severe global DD, epilepsy, progressive spasticity and cerebral hypomyelination upon MRI imaging. Short stature was also feature in both.

The 1st patient was an 8-year-old male who following exome sequencing was found to harbor 2 missense variants each inherited from a carrier parent. (NM_006441.3:c.434G>A / p.R145Q and c.107T>C / p.L36P). A further AFG3L2 indel was not felt to fit with his phenotype (and the onset of the related disorder appears to occur later).

Previous investigations included extensive metabolic testing, CMA, Angelman syndrome methylation analysis, GFAP, POLG1, TYMP sequencing, mitochondrial genome analysis and an XL-ID gene panel (further suggesting relevance of this gene to the current panel) were all non-diagnostic.

CSF 5-MTHF levels were initially on the low-normal range, subsequently found to be decreased (upon folinic acid supplementation) and later normalized upon use of another regimen.

MTHFS activity was measured in control fibroblasts as well as fibroblasts from this individual, with the latter demonstrating no enzyme activity. Accumulation (30x elevation) of 5-FTHF (the substrate of MTHFS) was demonstrated in patient fibroblasts.

The 2nd patient was a 11-year-old male with similar features incl. global DD (standing/walking/single words at/after 4 years of age, limited vocabulary and articulation upon last examination).

Extensive metabolic work-up as well as genetic testing for an epilepsy panel, vanishing white matter disease gene panel, mitochondrial genome as well as specific gene sequencing (LAMA2, POLR3A, POLR3B) were all non-diagnostic. Trio exome revealed 2 MTHFS variants in trans configuration (c.484C>T / p.Q162X and c.434G>A / p.R145Q).
---
Romero et al (2019 - PMID: 31844630) reported on a 4-year-old female with congenital microcephaly, severe global DD (nonverbal/nonambulatory at the age of 4), spasticity, epilepsy and cerebral hypomyelination.

Extensive investigations prior to exome sequencing revealed macrocytic anemia, decreased CSF 5-MTHF and elevated neopterin, 2 CNVs of uncertain significance upon CMA with additional long ROH on chr15. Methylation studies were negative. The child was homozygous for c.220C>T / p.R74X (RefSeq is probably NM_006441.3. MTHFS lies on chr15. The parents were unrelated but came from the same town). There were no other candidate variants from the exome analysis.

Both articles discuss extensively the role of the folate metabolism pathway overall in nucleic acid synthesis, AA metabolism, neurotransmitter synthesis, methylation as well as 5-FTHF / 5,10-MTHF in particular in myelin stabilization and DNA synthesis (eg. according to Romero et al. a defect in MTHFS would impair myelin production and also lead to decreased myelin stability).
---
A book chapter cited by Rodan et al (in N. Blau et al. (eds.), Physician’s Guide to the Diagnosis, Treatment, and Follow-Up of Inherited Metabolic Diseases - DOI: 10.1007/978-3-642-40337-8_10) included limited details on a patient with 'MTHFS gene mutation'. This individual had early speech delay, seizures beginning in infancy, ID, autistic features, recurrent infections and was found to have very low CSF 5-MTHF levels. [Details in p169 and table 10.6 - p173].
---
In a mouse model reported by Field et al (2011 - PMID: 22303332), Mthfs was disrupted through insertion of a gene trap vector between the first 2 exons. Heterozygous [Mthfs(gt/+)] mice were fertile and viable. Mthfs protein levels were slightly but not statistically significantly reduced in tissues measured. No homozygous embryos were recovered following intercrosses of heterozygous mice, suggesting that Mthfs is an essential gene. Mouse embryonic fibroblasts from heterozygous mice [Mthfs (gt/+)] exhibited reduced de novo purine biosynthesis, but did not exhibit altered de novo thymidylate biosynthesis. Plasma folate levels were altered in heterozygous mice on a standard (/control) diet.
Sources: Literature; to: Biallelic pathogenic MTHFS variants cause Neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination (# 618367).

The gene encodes 5,10-Methenyltetrahydrofolate synthetase which catalyzes conversion of 5-formyltetrahydrofolate (5-FTHF or folinic acid) to 5,10-methenyltetrahydrofolate (5,10-MTHF).

At least 3 unrelated individuals have been reported. The phenotype appears to be relevant to both epilepsy and ID gene panels and the role of variants/the gene supported by enzymatic activity studies, 5-FTHF accumulation, 5,10-MTHF levels (low/low-normal), the role of folate metabolism pathway overall and some supporting (metabolic) evidence from the mouse model.
---
Rodan et al (2018 - PMID: 30031689) reported on 2 individuals both presenting with microcephaly, severe global DD, epilepsy, progressive spasticity and cerebral hypomyelination upon MRI imaging. Short stature was also feature in both.

The 1st patient was an 8-year-old male who following exome sequencing was found to harbor 2 missense variants each inherited from a carrier parent. (NM_006441.3:c.434G>A / p.R145Q and c.107T>C / p.L36P). A further AFG3L2 indel was not felt to fit with his phenotype (and the onset of the related disorder appears to occur later).

Previous investigations included extensive metabolic testing, CMA, Angelman syndrome methylation analysis, GFAP, POLG1, TYMP sequencing, mitochondrial genome analysis and an XL-ID gene panel (further suggesting relevance of this gene to the current panel) were all non-diagnostic.

CSF 5-MTHF levels were initially on the low-normal range, subsequently found to be decreased (upon folinic acid supplementation) and later normalized upon use of another regimen.

MTHFS activity was measured in control fibroblasts as well as fibroblasts from this individual, with the latter demonstrating no enzyme activity. Accumulation (30x elevation) of 5-FTHF (the substrate of MTHFS) was demonstrated in patient fibroblasts.

The 2nd patient was a 11-year-old male with similar features incl. global DD (standing/walking/single words at/after 4 years of age, limited vocabulary and articulation upon last examination).

Extensive metabolic work-up as well as genetic testing for an epilepsy panel, vanishing white matter disease gene panel, mitochondrial genome as well as specific gene sequencing (LAMA2, POLR3A, POLR3B) were all non-diagnostic. Trio exome revealed 2 MTHFS variants in trans configuration (c.484C>T / p.Q162X and c.434G>A / p.R145Q).
---
Romero et al (2019 - PMID: 31844630) reported on a 4-year-old female with congenital microcephaly, severe global DD (nonverbal/nonambulatory at the age of 4), spasticity, epilepsy and cerebral hypomyelination.

Extensive investigations prior to exome sequencing revealed macrocytic anemia, decreased CSF 5-MTHF and elevated neopterin, 2 CNVs of uncertain significance upon CMA with additional long ROH on chr15. Methylation studies were negative. The child was homozygous for c.220C>T / p.R74X (RefSeq is probably NM_006441.3. MTHFS lies on chr15. The parents were unrelated but came from the same town). There were no other candidate variants from the exome analysis.

Both articles discuss extensively the role of the folate metabolism pathway overall in nucleic acid synthesis, AA metabolism, neurotransmitter synthesis, methylation as well as 5-FTHF / 5,10-MTHF in particular in myelin stabilization and DNA synthesis (eg. according to Romero et al. a defect in MTHFS would impair myelin production and also lead to decreased myelin stability).
---
A book chapter cited by Rodan et al (in N. Blau et al. (eds.), Physician’s Guide to the Diagnosis, Treatment, and Follow-Up of Inherited Metabolic Diseases - DOI: 10.1007/978-3-642-40337-8_10) included limited details on a patient with 'MTHFS gene mutation'. This individual had early speech delay, seizures beginning in infancy, ID, autistic features, recurrent infections and was found to have very low CSF 5-MTHF levels. [Details in p169 and table 10.6 - p173].
---
In a mouse model reported by Field et al (2011 - PMID: 22303332), Mthfs was disrupted through insertion of a gene trap vector between the first 2 exons. Heterozygous [Mthfs(gt/+)] mice were fertile and viable. Mthfs protein levels were slightly but not statistically significantly reduced in tissues measured. No homozygous embryos were recovered following intercrosses of heterozygous mice, suggesting that Mthfs is an essential gene. Mouse embryonic fibroblasts from heterozygous mice [Mthfs (gt/+)] exhibited reduced de novo purine biosynthesis, but did not exhibit altered de novo thymidylate biosynthesis. Plasma folate levels were altered in heterozygous mice on a standard (/control) diet.

[Please consider inclusion in other possibly relevant panels e.g. for metabolic disorders]
Sources: Literature
Intellectual disability v3.0 MTHFS Konstantinos Varvagiannis gene: MTHFS was added
gene: MTHFS was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: MTHFS was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: MTHFS were set to 30031689; 31844630; 22303332; https://doi.org/10.1007/978-3-642-40337-8_10
Phenotypes for gene: MTHFS were set to Neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination, 618367
Penetrance for gene: MTHFS were set to Complete
Review for gene: MTHFS was set to GREEN
Added comment: Biallelic pathogenic MTHFS variants cause Neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination (# 618367).

The gene encodes 5,10-Methenyltetrahydrofolate synthetase which catalyzes conversion of 5-formyltetrahydrofolate (5-FTHF or folinic acid) to 5,10-methenyltetrahydrofolate (5,10-MTHF).

At least 3 unrelated individuals have been reported. The phenotype appears to be relevant to both epilepsy and ID gene panels and the role of variants/the gene supported by enzymatic activity studies, 5-FTHF accumulation, 5,10-MTHF levels (low/low-normal), the role of folate metabolism pathway overall and some supporting (metabolic) evidence from the mouse model.
---
Rodan et al (2018 - PMID: 30031689) reported on 2 individuals both presenting with microcephaly, severe global DD, epilepsy, progressive spasticity and cerebral hypomyelination upon MRI imaging. Short stature was also feature in both.

The 1st patient was an 8-year-old male who following exome sequencing was found to harbor 2 missense variants each inherited from a carrier parent. (NM_006441.3:c.434G>A / p.R145Q and c.107T>C / p.L36P). A further AFG3L2 indel was not felt to fit with his phenotype (and the onset of the related disorder appears to occur later).

Previous investigations included extensive metabolic testing, CMA, Angelman syndrome methylation analysis, GFAP, POLG1, TYMP sequencing, mitochondrial genome analysis and an XL-ID gene panel (further suggesting relevance of this gene to the current panel) were all non-diagnostic.

CSF 5-MTHF levels were initially on the low-normal range, subsequently found to be decreased (upon folinic acid supplementation) and later normalized upon use of another regimen.

MTHFS activity was measured in control fibroblasts as well as fibroblasts from this individual, with the latter demonstrating no enzyme activity. Accumulation (30x elevation) of 5-FTHF (the substrate of MTHFS) was demonstrated in patient fibroblasts.

The 2nd patient was a 11-year-old male with similar features incl. global DD (standing/walking/single words at/after 4 years of age, limited vocabulary and articulation upon last examination).

Extensive metabolic work-up as well as genetic testing for an epilepsy panel, vanishing white matter disease gene panel, mitochondrial genome as well as specific gene sequencing (LAMA2, POLR3A, POLR3B) were all non-diagnostic. Trio exome revealed 2 MTHFS variants in trans configuration (c.484C>T / p.Q162X and c.434G>A / p.R145Q).
---
Romero et al (2019 - PMID: 31844630) reported on a 4-year-old female with congenital microcephaly, severe global DD (nonverbal/nonambulatory at the age of 4), spasticity, epilepsy and cerebral hypomyelination.

Extensive investigations prior to exome sequencing revealed macrocytic anemia, decreased CSF 5-MTHF and elevated neopterin, 2 CNVs of uncertain significance upon CMA with additional long ROH on chr15. Methylation studies were negative. The child was homozygous for c.220C>T / p.R74X (RefSeq is probably NM_006441.3. MTHFS lies on chr15. The parents were unrelated but came from the same town). There were no other candidate variants from the exome analysis.

Both articles discuss extensively the role of the folate metabolism pathway overall in nucleic acid synthesis, AA metabolism, neurotransmitter synthesis, methylation as well as 5-FTHF / 5,10-MTHF in particular in myelin stabilization and DNA synthesis (eg. according to Romero et al. a defect in MTHFS would impair myelin production and also lead to decreased myelin stability).
---
A book chapter cited by Rodan et al (in N. Blau et al. (eds.), Physician’s Guide to the Diagnosis, Treatment, and Follow-Up of Inherited Metabolic Diseases - DOI: 10.1007/978-3-642-40337-8_10) included limited details on a patient with 'MTHFS gene mutation'. This individual had early speech delay, seizures beginning in infancy, ID, autistic features, recurrent infections and was found to have very low CSF 5-MTHF levels. [Details in p169 and table 10.6 - p173].
---
In a mouse model reported by Field et al (2011 - PMID: 22303332), Mthfs was disrupted through insertion of a gene trap vector between the first 2 exons. Heterozygous [Mthfs(gt/+)] mice were fertile and viable. Mthfs protein levels were slightly but not statistically significantly reduced in tissues measured. No homozygous embryos were recovered following intercrosses of heterozygous mice, suggesting that Mthfs is an essential gene. Mouse embryonic fibroblasts from heterozygous mice [Mthfs (gt/+)] exhibited reduced de novo purine biosynthesis, but did not exhibit altered de novo thymidylate biosynthesis. Plasma folate levels were altered in heterozygous mice on a standard (/control) diet.
Sources: Literature
Intellectual disability v3.0 PUM1 Konstantinos Varvagiannis commented on gene: PUM1: 5 unrelated individuals with de novo pathogenic PUM1 variants have been reported in the literature. DD (5/5), ID (4/5 - relevant severity to the current panel), seizures (4/4 - absence/tonic-clonic, abnormal EEG) and variable other features (incl. facial dysmorphism, ataxia, cryptorchidism) appear to be part of the phenotype. 9 individuals with deletions spanning PUM1 and proximal genes presented similar features.

[1] PMID: 29474920 - Gennarino et al (2018)
[2] PMID: 30903679 - Bonnemason-Carrere et al (2019)
[3] PMID: 31859446 - Voet et al (2019) [with review of the literature]

SNVs in relevant individuals were identified by exome sequencing and were in all cases de novo.

Arg1147Trp was a recurrent variant reported in 3 unrelated subjects with ID and seizures (Refs 1,2,3 / NM_001020658.1:c.3439C>T). A nonsense variant was reported in an additional one with DD, ID, seizures and additional features (c.2509C>T / p.Arg837* - Ref3). One individual with a de novo missense variant (c.3416G>A / p.Arg1139Trp) with DD and ataxia, though without ID was reported in Ref1.

Details on 9 individuals with 0.3 - 5.6 Mb deletions spanning PUM1 and other genes are provided in Ref1. Features also included DD, ID, seizures, ataxia, etc.

Extensive initial investigations were reported for individuals in Refs 2 and 3 (various investigations incl. karyotype, SNP-array, targeted sequencing of OPHN1, KANSL1 or of a small panel of ID genes, biopsies and/or metabolic work-up) to rule out alternative causes. These only revealed a likely benign CNV and a GRIA3 SNV of uncertain significance in the case of an individual harboring the recurrent Arg1147Trp variant [Ref2].

Role of the gene (from OMIM):
Pumilio proteins, such as PUM1, negatively regulate gene expression by repressing translation of mRNAs to which they bind (Lee et al., 2016). A clinically significant PUM1 target is ataxin (ATXN1; 601556), mutation in which causes spinocerebellar ataxia-1 (SCA1; 601556).

Variant studies:
- Arg1147Trp was shown to be associated with normal PUM1 mRNA levels, but reduced (to ~43%) PUM1 protein levels in patient fibroblasts. ATXN1 mRNA and protein levels, as well as protein and/or mRNA levels of other PUM1 targets were shown to be increased (Ref1).
- In Ref1, in vitro transfection assays with wt or mt PUM1 were performed in HEK293T cells to evaluate repression of ATXN1 and E2F3. While overexpression of wt and Arg1147Trp were able to reduce ATXN1 and E2F3 levels, Arg1139Trp was not able to repress ATXN1 or E2F3.
- Upon overexpression in mouse hippocampal neurons, PUM1 missense mutations (among others Arg1139Trp and Arg1147Trp) were shown to alter neuronal morphology.

Overall haploinsufficiency is the proposed mechanism for the disorder for which the acronym PADDAS is used (Pumilio1-associated developmental disability, ataxia and seizure).

Milder mutations reducing PUM1 levels by 25% are associated with adult-onset ataxia without ID (PRCA or Pumilio1-related cerebellar ataxia) [Ref1].

Mouse models:
The role of PUM1 was first suggested in mouse models where Pum1 mutations were shown to lead to a SCA1-like phenotype (PMID cited : 12086639 - Watase et al 2002) further shown to be caused by increased Atxn1 mRNA and protein levels (PMID cited : 25768905 - Gennarino et al 2015).
The mouse model seems to recapitulate several of the features observed in affected individuals : Pum1 homozygous ko mice display among others hyperactivity, progressive cerebellar signs, spontaneous seizures as also observed in affected individuals (PMID cited : 25768905 - Gennarino et al 2015). Cryptorchidism was observed in 2 patients similar to testicular hypoplasia reported in Pum1 ko mice (PMID cited : 22342750 - Chen et al 2012).
- Heterozygous mice were evaluated in Ref1 with 69% or 75% exhibiting spontaneous seizures by the end of 30 or 35 wks respectively, with abnormal EEG activity already by 16 wks.

Additional individuals with PUM1 variants and a relevant phenotype of ID with or without seizures have been reported as part of the DDD study or as external submissions to Decipher and ClinVar :

https://decipher.sanger.ac.uk/search?q=PUM1#research-variants/results [ DDD4K.01387 participant ]
https://decipher.sanger.ac.uk/search?q=pum1#consented-patients/results [ external submission(s) ]
https://www.ncbi.nlm.nih.gov/clinvar/variation/431110/ [ splice-site variant in an individual with ID submitted prior to the 1st publication on the disorder ]
Intellectual disability v3.0 PUM1 Konstantinos Varvagiannis gene: PUM1 was added
gene: PUM1 was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen
Mode of inheritance for gene: PUM1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: PUM1 were set to 29474920; 30903679; 31859446
Phenotypes for gene: PUM1 were set to Global developmental delay; Intellectual disability; Seizures; Abnormality of the face; Ataxia; Cryptorchidism
Penetrance for gene: PUM1 were set to unknown
Review for gene: PUM1 was set to GREEN
Added comment: Please consider inclusion in both ID and epilepsy panels with probably green rating.
Sources: Literature, Radboud University Medical Center, Nijmegen
Intellectual disability v3.0 DLL1 Konstantinos Varvagiannis gene: DLL1 was added
gene: DLL1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DLL1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: DLL1 were set to 31353024
Phenotypes for gene: DLL1 were set to Global developmental delay; Intellectual disability; Morphological abnormality of the central nervous system; Seizures; Behavioral abnormality; Autism; Scoliosis
Penetrance for gene: DLL1 were set to unknown
Review for gene: DLL1 was set to GREEN
Added comment: Heterozygous DLL1 pathogenic variants cause Neurodevelopmental disorder with nonspecific brain abnormalities and with or without seizures (# 618709).

Fischer-Zirnsak et al (2019 - PMID: 31353024) reported on 15 affected individuals from 12 unrelated families.

Most common features included DD/ID (12/14), ASD (6/14 - belonging to 6 families) or other behavioral abnormalities, seizures (6/14 - from 6 unrelated families) and various brain MRI abnromalities. As commented by OMIM (based on the same ref) "Cognitive function ranges from severely impaired to the ability to attend schools with special assistance". Among other features, scoliosis was observed in 4. The authors could not identify a distinctive facial gestalt.

Variable initial investigations (where discussed/performed - also suggesting relevance to the current panel) included CMA, FMR1, FLNA, mitochondrial DNA analysis and metabolic work-up but had not revealed an alternative cause.

The DLL1 variants were identified by WES (with the exception of a 122-kb microdeletion spanning DLL1 and FAM120B detected by CMA). Nonsense, frame-shift, splice-site variants in positions predicted to result to NMD were identified in most. One individual was found to harbor a missense variant (NM_005618.3:c.536G>T / p.Cys179Phe) and another the aforementioned microdeletion.

The variant in several individuals had occurred as a de novo event. In 2 families, it was inherited from an also affected parent (an unaffected sib was non-carrier) while in 3 families parental studies were not possible/complete.

In frame insertion of 4 residues was demonstrated for a splice site variant, from LCLs of the corresponding individual. For another individual, material was unavailable for mRNA studies. The missense variant affected a cysteine (of the DSL domain) conserved in all Notch ligands while AA changes affecting the same position of JAG1 (another Notch ligand) have been described in patients with Alagille s.

Based on the variants identified and reports of deletions spanning DLL1 in the literature, haploinsufficiency is the proposed underlying mechanism. The gene has also a pLI of 1 and %HI of 4.65.

DLL1 encodes the Delta-like canonical Notch ligand 1. Notch signaling is an established pathway for brain morphogenesis. Previous in vivo and in vitro studies have demonstrated the role of DLL1 in CNS. The gene is highly expressed in neuronal precursor cells during embryogenesis. Expression of Dll1 (and other molecules of the Notch signalling pathway) in an oscillatory/sustained pattern and cell-cell interactions important for this pathway have been demonstrated to play a role in neuronal differentiation. [Most discussed by Fischer-Zirnsak et al with several refs provided / also Gray et al., 1999 - PMID: 10079256 & OMIM].

Animal models as summarized by the authors:
[Mouse] Loss of Dll1 in mice has been shown to increase neuronal differentiation, cause CNS hyperplasia and increased number of neurons (PMIDs cited: 9109488, 12397111, 20081190). Reduced Dll1 expression was associated with scoliosis and mild vertebral defects (cited PMIDs: 19562077, 14960495, 22484060 / among others Dll1 haploinsufficiency and dominant negative models studied). Scoliosis and vertebral segmentation defects were features in 4 and 1 individual, respectively in the cohort of 15.
[Zebrafish] Homozygous mutations in dlA, the zebrafish ortholog, disrupted the Delta-Notch signaling and led to patterning defects in the hindbrain and overproduction of neurons (cited: 15366005).

Please consider inclusion in other possibly relevant panels e.g. for ASD.
Sources: Literature
Intellectual disability v3.0 TFE3 Konstantinos Varvagiannis reviewed gene: TFE3: Rating: GREEN; Mode of pathogenicity: Other; Publications: 30595499, 31833172, https://doi.org/10.1126/scisignal.aax0926; Phenotypes: Global developmental delay, Intellectual disability, Abnormality of skin pigmentation, Coarse facial features, Seizures; Mode of inheritance: Other
Intellectual disability v3.0 MN1 Konstantinos Varvagiannis gene: MN1 was added
gene: MN1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: MN1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: MN1 were set to 31834374; 31839203; 15870292
Phenotypes for gene: MN1 were set to Central hypotonia; Feeding difficulties; Global developmental delay; Intellectual disability; Hearing impairment; Abnormality of facial skeleton; Craniosynostosis; Abnormality of the face; Abnormality of the cerebellum; Abnormality of the corpus callosum; Polymicrogyria
Penetrance for gene: MN1 were set to Complete
Review for gene: MN1 was set to GREEN
Added comment: Two studies by Mak et al (2019 - PMID: 31834374 / Ref1) and Miyake et al (2019 - PMID: 31839203 / Ref2) provide sufficient evidence for heterozygous MN1 C-terminal truncating variants (predicted to escape NMD - localizing within the last nucleotides of exon 1 or in exon 2) being associated with a distinctive phenotype and DD and ID among the features.

Mak et al also discuss on the phenotype of individuals with variants causing N-terminal truncation or with MN1 deletions (discussed at the end of this review).

Overlapping features for C-terminal truncating variants included hypotonia, feeding difficulties, global DD and ID, hearing loss, cranial shape defects (/craniosynostosis in few), highly suggestive/distinctive facial features (eg. frontal bossing, hypertelorism, downslanting palpebral-fissures, shallow orbits, short upturned nose, low-set/posteriorly rotated/dysplastic ears, etc) and brain MRI abnormalities (eg. rhomboencephalosynapsis or cerebellar dysplasia, polymicrogyria, dysplastic CC).

The majority of the affected individuals were investigated by WES/WGS with a single one tested by targeted MN1 Sanger sequencing due to highly suggestive features. Variable previous investigations incl. CMA in several, gene panel testing (Rasopathies, hearing loss, craniofacial panels, FMR1, etc) and metabolic work were normal in most. In a single case a likely pathogenic ACSL4 also explained part of the phenotype (Ref2). In the majority of these individuals, the variant had occured as a de novo event. Two sibs had inherited the truncating variant from a milder affected mosaic parent. A parental sample was not available for an additional individual.

p.(Arg1295*) or NM_002430.2:c.3883C>T was a recurrent variant, seen in several individuals and in both studies.

Several lines of evidence are provided for the MN1 variants and the role of the gene including:
- For few individuals for whom cell lines were available, variants were shown to escape NMD by cDNA/RT-PCR/RNA-seq [Ref1 & 2].
- The gene has a high expression in fetal brain [Ref2 / fig S2]
- MN1 (* 156100 - MN1 protooncogene, transcriptional regulator) has been proposed to play a role in cell proliferation and shown to act as transcription cofactor (increasing its transactivation capacity in synergy with coactivators EP300 and RAC3) [Discussion and Refs provided in Ref2].
- In vitro studies suggested increased protein stability (upon transfection of wt/mut constructs in HEK293T cells), enhanced MN1 aggregation in nuclei (when wt/mut GFP-tagged MN1 was expressed in HeLa cells), increased inhibitory effect on cell growth (MG63 cells - role of MN1 in cell proliferation discussed above) and retained transactivation activity (upon transient MN1 overexpression of wt/mt MN1 in HEK293T cells) for the variants. These seem to support a gain-of-function effect for the C-terminal truncating variants [Ref2].
- The truncating variants are proposed to raise the fraction of Intrinsically disordered regions (IDRs = regions without fixed tertiary structure) probably contributing to the above effects [Ref2].
- Expression of FLAG-tagged MN1 wt/mut MN1 followed by immunoprecipitation and mass spectrometry analysis (mCAT-Hela cells), provided evidence that MN1 is involved in transcriptional regulation: a. through binding ZBTB24 and RING1 E3 ubiquitin ligase (with mutant MN1 displaying impaired interaction with ZBTB24 and no binding to RING1) and/or b. through interaction with DNA-binding transcription factors PBX1 and PKNOX1. Proper MN1 degradation is proposed to mediate precise transcriptional regulation. [Ref2]
- Transcriptome analysis in LCLs from an affected individual suggested dysregulation of genes relevant to neuronal development (eg. LAMP, ITGA, etc) and GO analysis suggested enrichment for pathways possibly linked to the observed phenotypes [Ref2].
- Discussed in both Refs1/2, homozygous Mn1-ko mice display abnormal skull bone development and die at/shortly after birth as a result of cleft palate. Heterozygous Mn1-ko mice display hypoplastic membranous bones of the cranial skeleton and cleft palate (CP), the latter with incomplete penetrance [Meester-Smoor et al 2005 - PMID: 15870292]. This is thus compatible with the cranial shape defects observed in C-terminal truncations (while CP has been reported in gene deletions, bifid uvula was reported once in C-terminal and N-terminal truncating variants, in the latter case with submucous CP).
-----
The phenotype of other MN1 variants is discussed by Mak et al (Ref1) :
- 3 individuals with MN1 N-terminal truncating variants (eg. Ser179*, Pro365Thrfs*120, Ser472*) presented speech delay, mild conductive hearing loss and facial features different from C-terminal truncations. None of these individuals had significant ID.
- Microdeletions: One individual (#27) with 130 kb deletion harboring only MN1, presented microcephaly, DD and ID and mildly dysmorphic facial features. Deletions spanning MN1 and other genes (eg a 1.17 Mb deletion in ind. #28) and relevant cases from the literature reviewed, with mild DD/ID, variable palatal defects and/or facial dysmorphisms (distinct from the C-terminal truncating variants) among the frequent findings.

[Please consider inclusion in other possibly relevant gene panels eg. for hearing loss (conductive/sensorineural in 16/20 reported by Mak et al) or craniosynostosis, etc].
Sources: Literature
Intellectual disability v3.0 CXorf56 Konstantinos Varvagiannis gene: CXorf56 was added
gene: CXorf56 was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen
Mode of inheritance for gene: CXorf56 was set to X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Publications for gene: CXorf56 were set to 29374277; 31822863
Phenotypes for gene: CXorf56 were set to ?Mental retardation, X-linked 107, 301013
Penetrance for gene: CXorf56 were set to unknown
Review for gene: CXorf56 was set to AMBER
Added comment: Verkerk et al (2018 - PMID: 29374277) reported on a three-generation family with five males and one female presenting mild non-syndromic ID. Segregation was compatible with X-linked inheritance.

Multipoint linkage analysis with XL microsatellite markers demonstrated a linkage peak at Xq23-24 with LOD score of 3.3. Haplotype analysis and utilization of additional STR markers allowed narrowing to a region of 7.6 Mb containing 92 genes.

WGS in 3 affected males (spanning 3 generations) and 1 unaffected male and application of relevant filters for rare protein affecting variants within this region - present only in affected but absent in the unaffected individual - suggested a CXorf56 frameshift variant in exon 2 [NM_022101.3:c.159_160insTA / p.(Asp54*)] as the only relevant for this phenotype.

Sanger sequencing was performed for 25 family members with all 5 affected males and 1 affected female harboring this insertion and 8 unaffected females (also) shown to be carriers.

X-chromosome inactivation studies demonstrated that unaffected females had skewed inactivation (76-93%) of the variant allele, while the single affected female did not have a skewed XCI pattern (54%).

In EBV-transformed lymphoblasts grown with/without cycloheximide, mRNA levels were shown to be significantly lower in the affected female compared to unaffected ones (and corrected upon treatment with cycloheximide). mRNA levels were also significantly lower in cell lines from an affected male, with expression showing significant increase after treatment with cycloheximide. These results confirmed that nonsense-mediated decay applies.

The variant was absent from ExAC (where CXorf56 has a pLI of 0.93) and 188 healthy Dutch individuals.

The function of CXorf56 is not known. The gene appears to be expressed in brain and a (broad) range of other tissues [ https://gtexportal.org/home/gene/CXORF56 ].

Immunostaining in 8-week old murine brain, showed that the protein is present in the nucleus and cell soma of most neurons in brain cortex and cerebellum. Upon transfection of human CXorf56 cDNA in mouse primary hippocampal neurons, the protein localized in the nucleus, dendrites (co-localizing with Map2) and dendritic spines. As the authors note, the latter may suggest a role in synaptic function.

Overexpression in HEK293T cells demonstrated predominantly nuclear localization.

Mouse : Based on MGI (and an article by Cox et al. - PMID: 20548051 / both cited by the authors) male chimeras hemizygous for a gene trapped allele have abnormal midbrain-hindbrain boundary morphology, decreased forebrain size, while a subset hemizygous for a different gene trapped allele show growth delay [ http://www.informatics.jax.org/marker/MGI:1924894 ].

-----

Rocha et al (2019 - PMID: 31822863) report on 9 affected individuals with mild to severe ID belonging to 3 unrelated families. Additional features in this cohort - observed in some - included abnormal reflexes, fine tremor, seizures (in 3), abnormal gait, etc.

In the 1st family, 3 males presented with (severe/severe/moderate) ID and 2 females with mild ID. Following a normal CMA and FMR1 testing, trio plus exome sequencing revealed a CXorf56 in-frame deletion [NM_022101.3:c.498_503del / p.(Glu167_Glu168del)]. Sanger sequencing in 9 members, confirmed presence of the variant in one unaffected mother, all her affected sons (2) and daughers(2) and an affected grandson and absence in 2 remaining unaffected daughters. Skewing of XCI was seen in blood cells from affected females (97 and 83%) while the unaffected mother had complete inactivation of the carrier X-chromosome. The authors commented that even minor reductions in CXorf56 (suggested by XCI in affected females) may be detrimental and/or that inactivation for this gene may be different than that of AR gene (which was studied instead) or in other tissues.

In family 2, an affected mother (with learning difficulties) and her 2 sons - the most severely affected presenting moderate ID - harbored a frameshift variant [c.303_304delCTinsACCC / p.(Phe101Leufs*20)].

A male with ID belonging to a 3rd family, for which no further information was available, was found to harbor the c.498_503del variant (also discussed above) as a de novo event.

It has been commented that individuals with Xq24 deletions spanning CXorf56 present with ID, although (all) such deletions reported in the literature also span the neighboring UBE2A gene, associated with Mental retardation, X-linked syndromic, Nascimento-type (MIM #300860).

-----

In OMIM, the CXorf56-related phenotype is ?Mental retardation, X-linked 107 (# 301013), based only on the report by Verkerk et al.

This gene is included in gene panels for ID offered by some diagnostic laboratories (incl. Radboudumc).

-----

Overall, CXorf56 can be considered for inclusion in the ID panel either with amber (function of the gene unknown, skewed XCI also in affected females in the 2nd reference) or with green rating (several individuals from 4 families, compatible segregation studies and females presenting a milder phenotype than males or unaffected, LOD score in the 1st report, studies confirming lower mRNA levels and NMD, gene expressed in human brain, expression in mouse brain cortex and cerebellum, evidence from transfection studies in mouse hippocampal neurons).

[Note : penetrance was here set to unknown / It was complete for males, incomplete for females].
Sources: Literature, Radboud University Medical Center, Nijmegen
Intellectual disability v3.0 UGP2 Konstantinos Varvagiannis gene: UGP2 was added
gene: UGP2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: UGP2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: UGP2 were set to 31820119
Phenotypes for gene: UGP2 were set to Seizures; Global developmental delay; Intellectual disability; Feeding difficulties; Abnormality of vision; Abnormality of the face
Penetrance for gene: UGP2 were set to Complete
Review for gene: UGP2 was set to GREEN
Added comment: Perenthaler et al. (2019 - PMID: 31820119) provide evidence that homozygosity for a variant abolishing the start codon of the UGP2 transcript (NM_001001521.1) encoding the predominant (short) protein isoform in brain, leads to a severe epileptic encephalopathy.

This variant (chr2:64083454A>G / NM_001001521.1:c.1A>G - p.?) is also predicted to result in a substitution of a methionine at position 12 by a valine of the longer UGP2 transcript (NM_006759.3:c.34A>G - p.Met12Val).

The 2 isoforms differ only by 11 amino acids at the N-terminal and are otherwise expected to be functionally equivalent.

The authors provide details on 22 individuals from 15 families (some of which consanguineous).

Features included intractable seizures (in all), absence of developmental milestones (in all), progressive microcephaly, visual impairment. The authors reported also presence of somewhat similar facial features. Some of these individuals passed away early.

Previous work-up in several of them (incl. SNP-array, gene panel testing and metabolic investigations) had not revealed any abnormality, apart from ROH in some individuals. In all cases, the homozygous UGP2 SNV was the only P/LP variant for the neurodevelopmental phenotype following exome/genome sequencing. Segregation studies in affected/unaffected family members were compatible.

Families came from the Netherlands (but mostly from) India, Pakistan and Iran. Presence of a region of homozygosity shared between individuals from different families suggested that the variant might represent a mutation that originated several generations ago (in the area of Balochistan). The variant is present 15x in gnomAD, only in heterozygous state (in Asian mostly, reported once in Ashkenazi Jewish or Europeans) [ https://gnomad.broadinstitute.org/variant/2-64083454-A-G ].

UGP2 encodes UDP-glucose pyrophosphorylase which is an essential enzyme in sugar metabolism, catalyzing conversion of glucose-1-phosphate to UDP-glucose. UDP-glucose, in turn, serves as precursor for production of glycogen by glycogen synthase.

The authors provide several lines of evidence for a the role of the gene in the CNS as well as for the deleterious effect of the specific variant :
- In patient fibroblasts total UGP2 levels were not signifficantly different compared to parent / control fibroblasts, the longer isoform being upregulated (and stable) when the shorter is missing. Immunocytochemistry demonstrated similar localization of UGP2 in the case of mutant or wt cells. Enzymatic activity (/capacity to produce UDP-glucose) was similar between homozygous mut, heterozygous and wt fibroblasts.
- In H9-derived neural stem cells, Western Blot, RT-PCR and qRT-PCR suggested that the short isoform is the predominant one. (In embryonic stem cells, or fibroblasts the ratio between short and long isoform was lower).
- Analysis of RNA-seq data from human fetal tissues suggested that the short isoform is the predominant in brain.
- UGP2 was detected upon immunohistochemistry in fetal brain tissues from first to third trimester of pregnancy while Western Blot confirmed preferential expression of the shorter isoform.
- Homozygous embryonic (ESC) or neural stem cells (NSC) for the variant (knock-in/KI) or for a frameshift variant (knock-out/KO) were generated. Study of NSCs demonstrated reduced total UGP2 protein expression upon Western Blot in the case of KI cells and depleted in KO ones. Transcriptome analysis did not show major transcriptome alterations in KI/KO ESCs compared to wt. In NSC KI/KO cells transcriptome alterations were observed compared to wt with upregulation among others of genes for synaptic processes and genes implicated in epilepsy.
- The absence of UGP2 was shown to result in reduced ability of KO/KI NSCs to produce UDP-glucose, reduced capacity to synthesize glycogen under hypoxia (rescued in the case of KO cells by overexpression of wt or long isoform), defects of protein glycosylation as well as in increased unfolded protein response (/susceptibility to ER stress). These alterations are commented to be possibly implicated in pathogenesis of epilepsy, progressive microcephaly, etc.
- A CRISPR-Cas9 zebrafish model leading with loss of ugp2a and hypomorphic ugp2b (the zebrafish homologs of UGP2) demonstrated abnormal behavior, reduced eye movements and increased frequency/duration of movements upon stimulation with a potent convulsant (suggestive of increased seizure susceptibility).
- UGP knockout in drosophila is lethal while flies compound heterozygous for hypomorphic alleles are viable but show a movement defects due to altered synaptogenesis secondary to glycosylation defects (cited PMID: 27466186).
- The authors make speculations as for the occurrence of a single variant (and not others) eg. absence of UGP2 (in the case of LoF variants affecting both isoforms) would possibly be incompatible with life, Met12Val being tolerable for the long transcript not affecting stability/enzymatic activity (which may not be the case for other substitutions affecting Met12), etc.
Sources: Literature
Intellectual disability v3.0 ADPRHL2 Louise Daugherty Tag new-gene-name tag was added to gene: ADPRHL2.
Intellectual disability v3.0 ADPRHL2 Louise Daugherty commented on gene: ADPRHL2: Added new-gene-name tag, new approved HGNC gene symbol for ADPRHL2 is ADPRS
Intellectual disability v3.0 KAT8 Konstantinos Varvagiannis gene: KAT8 was added
gene: KAT8 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: KAT8 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: KAT8 were set to 31794431
Phenotypes for gene: KAT8 were set to Global developmental delay; Intellectual disability; Seizures; Abnormality of vision; Feeding difficulties; Abnormality of the cardiovascular system; Autism
Penetrance for gene: KAT8 were set to unknown
Review for gene: KAT8 was set to GREEN
Added comment: Heterozygous pathogenic missense KAT8 variants have been reported in individuals with DD, ID and epilepsy. Variants occurred as de novo events within the chromobarrel or the acetyltransferase domain and were all shown to affect H4K16 acetylation, as would be predicted by the gene's function (lysine acetyltransferase). Evidence from brain specific Kat8 knockout in mouse, supports the role of the gene in brain development. One similarly affected individual compound heterozygous for a nonsense and a missense variant (the former affecting subnuclear localization and the latter H4K16ac) was also reported, with carrier relatives being unaffected. Mutations in genes of the MSL/NSL complexes (with which KAT8 forms multisubunit complexes) or genes in other acetyltransferases of the same subfamily (MYST) as KAT8 cause neurodevelopmental disorders [Details provided below].
-----
Li et al. (2019 - PMID: 31794431) report on 8 unrelated individuals with heterozygous de novo pathogenic KAT8 variants, as well as an additional one compound heterozygous for a nonsense and a missense one.

Overlapping phenotype consisted of DD/ID (8/8), seizures/epilepsy (6/8), brain MRI anomalies as well as presence of variable facial dysmorphic features. Less frequent features included abnormal vision (5/8), feeding difficulties (3/8), cardiac anomalies (3/8), autism (in 1).

The (9th) individual with biallelic variants had similar phenotype of DD/ID, epilepsy, autism and dysmorphic facial features. Heterozygous parents and sister, the latter carrier for the missense variant, were all unaffected.

All individuals had undergone exome sequencing, while extensive other investigations for at least 7/9 had only revealed variants of uncertain significance/contribution to the phenotype or were normal.

KAT8 encodes lysine acetyltransferase 8, which acetylates histone H4 at lysine 16 (H4K16). It belongs to the MYST subfamily of lysine acetyltransferases, the other members of which include KAT6A, KAT6B (both involved in neurodevelopmental disorders) and KAT5.

KAT8 forms two stoichiometric multisubunitcomplexes, one with the MSL complex and the other with the NSL. Mutations in genes encoding for subunits of the NSL or MSL complex (eg. KANSL1 and MSL3) are associated with neurodevelopmental disorders.

Overall 6 missense SNVs were reported among the heterozygous patients, p.Tyr90Cys (NM_032188.2:c.269A>G) being a recurrent one seen in 3. The compound heterozygous patient had a missense (c.973C>T / p.Arg325Cys) and a nonsense variant (c.523A>T / p.Lys175*). All missense variants lied either in the chromobarrel domain or the acetyltransferase domain. Variants in the latter domain localized within the KAT8/Mof-specific region or - in the case of the compound heterozygous individual - within the acetyl-CoA binding motif.

FLAG-tagged KAT8 (either wt or for all missense SNVs) was transfected in HEK293 cells with vectors for HA-tagged MSL proteins. While the nonsense variant was difficult to express, missense SNVs were expressed to similar levels to wt, promoted expression of MSL proteins but resulted in defective H4K16 acetylation and to a lesser extent H4K5 acetylation. As a result all missense variants impaired acetylation. This was also the case for chromobarrel domain variants, while expression of a KAT8 lacking the chromobarrel domain confirmed its ability to form complex with the MSL proteins and the impairment of H4K16 acetylation.

The nonsense variant demonstrated abnormal subnuclear localization.

The mouse model provides extensive evidence for the involvement of KAT8 in cerebral development. Cerebrum-specific Kat8 knockout mice presented postnatal growth retardation, hyperactivity/irritability, pre-weaning lethality, and cerebral hypoplasia upon autopsy. Loss of Kat8 reduced the number of neural stem and progenitor cells available for embryonic cerebrocortical development, impaired cell proliferation and stimulated apoptosis. The article also provides additional evidence from mouse model.
Sources: Literature
Intellectual disability v3.0 RARS Konstantinos Varvagiannis gene: RARS was added
gene: RARS was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: RARS was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: RARS were set to 31814314; 28905880; 24777941
Phenotypes for gene: RARS were set to Cerebral hypomyelination; Global developmental delay; Intellectual disability; Seizures; Cerebral atrophy; Nystagmus; Ataxia; Feeding difficulties
Penetrance for gene: RARS were set to Complete
Review for gene: RARS was set to GREEN
Added comment: Biallelic pathogenic RARS1 variants cause Leukodystrophy, hypomyelinating, 9 (# 616140).

The current review was based primarily on PMID: 31814314 (Mendes et al, 2019) providing details on 20 affected individuals from 15 families. 5 of these patients were included in a previous publication (Wolf et al, 2014 - PMID: 24777941) sharing authors with this study.

Clinical presentation and severity can be highly variable. However, among the 15 patients of relevant age (5/20 deceased at an early age), ID was observed in 13 (in 6/13 mild-moderate, in 7/13 severe/profound). Epilepsy was reported in half (10/20) with seizures being refractory to treatment in most and the phenotype corresponding to an infantile epileptic encephalopathy. DD and seizures were the presenting feature in 7 and 5 patients respectively, while in other cases presenting features were less specific (eg. failure to thrive in 1/20, irritabilty in 2/20). As a result the gene appears to be relevant to both DD/ID and epilepsy panels.

RARS1 encodes the cytoplasmic arginyl-tRNA synthetase 1, which is a component of the aminoacyl-tRNA synthetase complex (OMIM and Wolf et al, 2014 - PMID: 24777941). Aminoacyl-tRNA synthetases catalyze the aminoacylation ('charging') of tRNA by (with) their cognate amino acid.

Utilisation of alternative initiation codons, from a single mRNA transcript, results in translation of a long and a short protein isoform (Zheng et al 2006 - PMID: 16430231). The long isoform is needed for the formation of the multi-synthetase complex (MSC), while the short is free in the cytoplasm and does not have any interaction with the MSC. The long isoform appears to be essential for protein synthesis (discussed with several refs provided in PMID: 28905880 - Nafisinia et al, 2017).

The role of variants has been supported in several patients by additional studies - among others :
[PMID 31814314] Impaired Arginyl-tRNA synthetase activity was demonstrated in fibroblasts from 3 patients. Activity was normal in one additional individual compound heterozygous for a variant affecting initiation codon and a missense one. Western blot however demonstrated presence mainly of the short protein isoform. The authors suggest that this isoform possibly contributed to enzymatic activity. The long isoform which is needed for the MSC complex was only represented by a faint band in the Western Blot of the same individual.
[PMID: 28905880] Using fibroblasts from an affected subject homozygous for a missense variant (NM_002887.3:c.5A>G / p.Asp2Gly) and controls, a 75% reduction of the long isoform was shown upon WB. The short isoform was present at similar levels. As the N-terminus (of the long isoform) mediates interaction with the MSC (and AIMP1), assembly of the latter was 99% reduced in patient fibroblasts. Proliferation of patient fibroblasts was significantly reduced when cultured in a medium with limited arginine, a finding which was thought to reflect inefficient protein synthesis.

Mutations in other genes encoding for aminoacyl-tRNA synthetases (eg. AARS1, VARS1) or scaffolding proteins of the multisynthetase complex (eg. AIMP1 and AIMP2) lead to neurodevelopmental disorders with overlapping phenotype [most genes rated green in both the ID and epilepsy panel].
Sources: Literature
Intellectual disability v3.0 SUZ12 Konstantinos Varvagiannis changed review comment from: ID can be a feature in individuals heterozygous for SUZ12 pathogenic variants. 13 affected individuals (from 12 families) have been reported:

[1] PMID 28229514 (Imagawa et al, 2017) : 1 individual
[2] PMID 30019515 (Imagawa et al, 2018) : 2 further unrelated subjects
[3] PMID 31736240 (Cyrus et al, 2019) : 10 additional subjects (from 9 families)

Reviewed by Cyrus et al, features observed in more than half of the (13) affected individuals included prenatal and/or postnatal overgrowth (in some only prenatal, others only postnatal, others did not manifest overgrowth at all), some suggestive facial features (eg. prominent forehead, hypertelorism, downslanting palpebral fissures, round face, broad/low nasal bridge), DD and ID (the latter in 7/13, in most cases mild), advanced bone age, musculoskeletal abnormalities and cryptorchidism. Less frequent features included brain MRI abnormalities (eg. CC hypoplasia/agenesis, etc.), umbilical hernias, respiratory abnormalities, cardiac anomalies (in one).

All were diagnosed with WES/WGS/panel testing, with few having additional findings upon this or prior testing (eg. CNVs/SNVs).

SUZ12 encodes one of the 4 core proteins of the PRC2 complex (the 3 other being encoded by EZH1/2, EED and RBBP4/7). The complex has a methyltransferase activity, catalyzing addition of up to 3 methyl groups on histone 3 at lysine residue 27 (H3K27), leading to chromatin compaction and further to gene silencing.

Mutations in genes encoding 2 other core components of the PRC2 complex - namely EZH2 and EED - cause Weaver and Cohen-Gibson syndrome with overlapping phenotype incl. overgrowth, advanced bone age, craniofacial features and DD/ID.

The SET domain of EZH1/2 and EED as well as the VEFS domain of SUZ12 are contributing to the catalytic activity.

SUZ12 variants reported to date include missense and pLoF variants (frameshift, nonsense, splice site ones) predicted to disrupt or eliminate the VEFS-box domain [almost all missense within this domain with the exception of one proximal to it (Arg535Gln) / pLoF causing truncation prior or within this domain (Arg654Ter might be an exception)] {NP_056170.2}.

Variants either occurred de novo or were inherited (~1/3), on some occasions from a mildly affected parent. Parental mosaicism has also been reported (eg. in ref1, and one or possibly two additional families in ref3).

Some preliminary assumptions on possible genotype-phenotype correlations (for overgrowth and ID related to missense/pLoF variants) are discussed in ref3.

SUZ12 is also be deleted in some patients with NF1 deletion (and a diagnosis of neurofibromatosis type 1). Deletion of SUZ12 has been proposed to contribute to the phenotype of these individuals (eg. overgrowth, cognitive development, facial features). [Discussed in ref1].

Functional studies have been carried out only in the first report (ref1) and demonstrated decreased trimethylation of H3K27 in the case of a missense variant. Overall a partial loss-of-function mechanism has been proposed for the variants.

Mouse models: A study by Pasini et al (PMID: 15385962) did not report phenotypic differences between wt and heterozygous Suz12 knockout mice (gene-trap vector) as for size, morphology and fertility. Total knockout resulted in embryonic lethality, significant growth retardation and several developmental defects. Loss of Suz12 was shown to result in absence of di- and tri-methylated H3K27 in the ko embryos. In another study cited (Miro et al - PMID: 19535498) heterozygous mice (replacement of exons 12-16 with a lacZ gene and neo cassette) displayed variable CNS defects with incomplete penetrance.

The role of the PRC2 complex and the phenotypes related to mutations in genes encoding its core components, are discussed in PMID: 31724824 (also by Cyrus et al, 2019).

SUZ12 is not associated with any phenotype in OMIM. In G2P it is included in the DD panel associated with Weaver-like overgrowth syndrome (disease confidence : confirmed). The gene is also included in gene panels for ID offered by some diagnostic laboratories (eg. GeneDx).
Sources: Literature; to: ID can be a feature in individuals heterozygous for SUZ12 pathogenic variants. 13 affected individuals (from 12 families) have been reported:

[1] PMID 28229514 (Imagawa et al, 2017) : 1 individual
[2] PMID 30019515 (Imagawa et al, 2018) : 2 further unrelated subjects
[3] PMID 31736240 (Cyrus et al, 2019) : 10 additional subjects (from 9 families)

Reviewed by Cyrus et al, features observed in more than half of the (13) affected individuals included prenatal and/or postnatal overgrowth (in some only prenatal, others only postnatal, others did not manifest overgrowth at all), some suggestive facial features (eg. prominent forehead, hypertelorism, downslanting palpebral fissures, round face, broad/low nasal bridge), DD and ID (the latter in 7/13, in most cases mild), advanced bone age, musculoskeletal abnormalities and cryptorchidism. Less frequent features included brain MRI abnormalities (eg. CC hypoplasia/agenesis, etc.), umbilical hernias, respiratory abnormalities, cardiac anomalies (in one).

All were diagnosed with WES/WGS/panel testing, with few having additional findings upon this or prior testing (eg. CNVs/SNVs).

SUZ12 encodes one of the 4 core proteins of the PRC2 complex (the 3 other being encoded by EZH1/2, EED and RBBP4/7). The complex has a methyltransferase activity, catalyzing addition of up to 3 methyl groups on histone 3 at lysine residue 27 (H3K27), leading to chromatin compaction and further to gene silencing.

Mutations in genes encoding 2 other core components of the PRC2 complex - namely EZH2 and EED - cause Weaver and Cohen-Gibson syndrome with overlapping phenotype incl. overgrowth, advanced bone age, craniofacial features and DD/ID.

The SET domain of EZH1/2 and EED as well as the VEFS domain of SUZ12 are contributing to the catalytic activity.

SUZ12 variants reported to date include missense and pLoF variants (frameshift, nonsense, splice site ones) predicted to disrupt or eliminate the VEFS-box domain [almost all missense within this domain with the exception of one proximal to it (Arg535Gln) / pLoF causing truncation prior or within this domain (Arg654Ter might be an exception)] {NP_056170.2}.

Variants either occurred de novo or were inherited (~1/3), on some occasions from a mildly affected parent. Parental mosaicism has also been reported (eg. in ref1, and one or possibly two additional families in ref3).

Some preliminary assumptions on possible genotype-phenotype correlations (for overgrowth and ID related to missense/pLoF variants) are discussed in ref3.

SUZ12 may also be deleted in some patients with NF1 deletion (and a diagnosis of neurofibromatosis type 1). Deletion of SUZ12 has been proposed to contribute to the phenotype of these individuals (eg. overgrowth, cognitive development, facial features). [Discussed in ref1].

Functional studies have been carried out only in the first report (ref1) and demonstrated decreased trimethylation of H3K27 in the case of a missense variant. Overall a partial loss-of-function mechanism has been proposed for the variants.

Mouse models: A study by Pasini et al (PMID: 15385962) did not report phenotypic differences between wt and heterozygous Suz12 knockout mice (gene-trap vector) as for size, morphology and fertility. Total knockout resulted in embryonic lethality, significant growth retardation and several developmental defects. Loss of Suz12 was shown to result in absence of di- and tri-methylated H3K27 in the ko embryos. In another study cited (Miro et al - PMID: 19535498) heterozygous mice (replacement of exons 12-16 with a lacZ gene and neo cassette) displayed variable CNS defects with incomplete penetrance.

The role of the PRC2 complex and the phenotypes related to mutations in genes encoding its core components, are discussed in PMID: 31724824 (also by Cyrus et al, 2019).

SUZ12 is not associated with any phenotype in OMIM. In G2P it is included in the DD panel associated with Weaver-like overgrowth syndrome (disease confidence : confirmed). The gene is also included in gene panels for ID offered by some diagnostic laboratories (eg. GeneDx).
Sources: Literature
Intellectual disability v3.0 SUZ12 Konstantinos Varvagiannis changed review comment from: ID can be a feature in individuals heterozygous for SUZ12 pathogenic variants. 13 affected individuals (from 12 families) have been reported:

[1] PMID 28229514 (Imagawa et al, 2017) : 1 individual
[2] PMID 30019515 (Imagawa et al, 2018) : 2 further unrelated subjects
[3] PMID 31736240 (Cyrus et al, 2019) : 10 newly diagnosed subjects (from 9 families)

Reviewed by Cyrus et al, features observed in more than half of the (13) affected individuals included prenatal and/or postnatal overgrowth (in some only prenatal, others only postnatal, others did not manifest overgrowth at all), some suggestive facial features (eg. prominent forehead, hypertelorism, downslanting palpebral fissures, round face, broad/low nasal bridge), DD and ID (the latter in 7/13, in most cases mild), advanced bone age, musculoskeletal abnormalities and cryptorchidism. Less frequent features included brain MRI abnormalities (eg. CC hypoplasia/agenesis, etc.), umbilical hernias, respiratory abnormalities, cardiac anomalies (in one).

All were diagnosed with WES/WGS/panel testing, with few having additional findings upon this or prior testing (eg. CNVs/SNVs).

SUZ12 encodes one of the 4 core proteins of the PRC2 complex (the 3 other being encoded by EZH1/2, EED and RBBP4/7). The complex has a methyltransferase activity, catalyzing addition of up to 3 methyl groups on histone 3 at lysine residue 27 (H3K27), leading to chromatin compaction and further to gene silencing.

Mutations in genes encoding 2 other core components of the PRC2 complex - namely EZH2 and EED - cause Weaver and Cohen-Gibson syndrome with overlapping phenotype incl. overgrowth, advanced bone age, craniofacial features and DD/ID.

The SET domain of EZH1/2 and EED as well as the VEFS domain of SUZ12 are contributing to the catalytic activity.

SUZ12 variants reported to date include missense and pLoF variants (frameshift, nonsense, splice site ones) predicted to disrupt or eliminate the VEFS-box domain [almost all missense within this domain with the exception of one proximal to it (Arg535Gln) / pLoF causing truncation prior or within this domain (Arg654Ter might be an exception)] {NP_056170.2}.

Variants either occurred de novo or were inherited (~1/3), on some occasions from a mildly affected parent. Parental mosaicism has also been reported (eg. in ref1, and one or possibly two additional families in ref3).

Some preliminary assumptions on possible genotype-phenotype correlations (for overgrowth and ID related to missense/pLoF variants) are discussed in ref3.

SUZ12 is also be deleted in some patients with NF1 deletion (and a diagnosis of neurofibromatosis type 1). Deletion of SUZ12 has been proposed to contribute to the phenotype of these individuals (eg. overgrowth, cognitive development, facial features). [Discussed in ref1].

Functional studies have been carried out only in the first report (ref1) and demonstrated decreased trimethylation of H3K27 in the case of a missense variant. Overall a partial loss-of-function mechanism has been proposed for the variants.

Mouse models: An study by Pasini et al (PMID: 15385962) did not report phenotypic differences between wt and heterozygous Suz12 knockout mice (gene-trap vector) as for size, morphology and fertility. Total knockout resulted in embryonic lethality, significant growth retardation and several developmental defects. Loss of Suz12 was shown to result in absence of di- and tri-methylated H3K27 in the ko embryos. In another study cited (Miro et al - PMID: 19535498) heterozygous mice (replacement of exons 12-16 with a lacZ gene and neo cassette) displayed variable CNS defects with incomplete penetrance.

The role of the PRC2 complex and the phenotypes related to mutations in genes encoding its core components, are discussed in PMID: 31724824 (also by Cyrus et al, 2019).

SUZ12 is not associated with any phenotype in OMIM. In G2P it is included in the DD panel associated with Weaver-like overgrowth syndrome (disease confidence : confirmed). The gene is also included in gene panels for ID offered by some diagnostic laboratories (eg. GeneDx).
Sources: Literature; to: ID can be a feature in individuals heterozygous for SUZ12 pathogenic variants. 13 affected individuals (from 12 families) have been reported:

[1] PMID 28229514 (Imagawa et al, 2017) : 1 individual
[2] PMID 30019515 (Imagawa et al, 2018) : 2 further unrelated subjects
[3] PMID 31736240 (Cyrus et al, 2019) : 10 additional subjects (from 9 families)

Reviewed by Cyrus et al, features observed in more than half of the (13) affected individuals included prenatal and/or postnatal overgrowth (in some only prenatal, others only postnatal, others did not manifest overgrowth at all), some suggestive facial features (eg. prominent forehead, hypertelorism, downslanting palpebral fissures, round face, broad/low nasal bridge), DD and ID (the latter in 7/13, in most cases mild), advanced bone age, musculoskeletal abnormalities and cryptorchidism. Less frequent features included brain MRI abnormalities (eg. CC hypoplasia/agenesis, etc.), umbilical hernias, respiratory abnormalities, cardiac anomalies (in one).

All were diagnosed with WES/WGS/panel testing, with few having additional findings upon this or prior testing (eg. CNVs/SNVs).

SUZ12 encodes one of the 4 core proteins of the PRC2 complex (the 3 other being encoded by EZH1/2, EED and RBBP4/7). The complex has a methyltransferase activity, catalyzing addition of up to 3 methyl groups on histone 3 at lysine residue 27 (H3K27), leading to chromatin compaction and further to gene silencing.

Mutations in genes encoding 2 other core components of the PRC2 complex - namely EZH2 and EED - cause Weaver and Cohen-Gibson syndrome with overlapping phenotype incl. overgrowth, advanced bone age, craniofacial features and DD/ID.

The SET domain of EZH1/2 and EED as well as the VEFS domain of SUZ12 are contributing to the catalytic activity.

SUZ12 variants reported to date include missense and pLoF variants (frameshift, nonsense, splice site ones) predicted to disrupt or eliminate the VEFS-box domain [almost all missense within this domain with the exception of one proximal to it (Arg535Gln) / pLoF causing truncation prior or within this domain (Arg654Ter might be an exception)] {NP_056170.2}.

Variants either occurred de novo or were inherited (~1/3), on some occasions from a mildly affected parent. Parental mosaicism has also been reported (eg. in ref1, and one or possibly two additional families in ref3).

Some preliminary assumptions on possible genotype-phenotype correlations (for overgrowth and ID related to missense/pLoF variants) are discussed in ref3.

SUZ12 is also be deleted in some patients with NF1 deletion (and a diagnosis of neurofibromatosis type 1). Deletion of SUZ12 has been proposed to contribute to the phenotype of these individuals (eg. overgrowth, cognitive development, facial features). [Discussed in ref1].

Functional studies have been carried out only in the first report (ref1) and demonstrated decreased trimethylation of H3K27 in the case of a missense variant. Overall a partial loss-of-function mechanism has been proposed for the variants.

Mouse models: A study by Pasini et al (PMID: 15385962) did not report phenotypic differences between wt and heterozygous Suz12 knockout mice (gene-trap vector) as for size, morphology and fertility. Total knockout resulted in embryonic lethality, significant growth retardation and several developmental defects. Loss of Suz12 was shown to result in absence of di- and tri-methylated H3K27 in the ko embryos. In another study cited (Miro et al - PMID: 19535498) heterozygous mice (replacement of exons 12-16 with a lacZ gene and neo cassette) displayed variable CNS defects with incomplete penetrance.

The role of the PRC2 complex and the phenotypes related to mutations in genes encoding its core components, are discussed in PMID: 31724824 (also by Cyrus et al, 2019).

SUZ12 is not associated with any phenotype in OMIM. In G2P it is included in the DD panel associated with Weaver-like overgrowth syndrome (disease confidence : confirmed). The gene is also included in gene panels for ID offered by some diagnostic laboratories (eg. GeneDx).
Sources: Literature
Intellectual disability v3.0 SUZ12 Konstantinos Varvagiannis gene: SUZ12 was added
gene: SUZ12 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: SUZ12 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: SUZ12 were set to 28229514; 30019515; 31736240; 15385962; 19535498; 31724824
Phenotypes for gene: SUZ12 were set to Overgrowth; Global developmental delay; Intellectual disability; Accelerated skeletal maturation; Abnormality of the skeletal system; Abnormality of the genitourinary system; Abnormality of the corpus callosum; Abnormality of the respiratory system; Abnormality of the abdominal wall
Penetrance for gene: SUZ12 were set to unknown
Review for gene: SUZ12 was set to GREEN
Added comment: ID can be a feature in individuals heterozygous for SUZ12 pathogenic variants. 13 affected individuals (from 12 families) have been reported:

[1] PMID 28229514 (Imagawa et al, 2017) : 1 individual
[2] PMID 30019515 (Imagawa et al, 2018) : 2 further unrelated subjects
[3] PMID 31736240 (Cyrus et al, 2019) : 10 newly diagnosed subjects (from 9 families)

Reviewed by Cyrus et al, features observed in more than half of the (13) affected individuals included prenatal and/or postnatal overgrowth (in some only prenatal, others only postnatal, others did not manifest overgrowth at all), some suggestive facial features (eg. prominent forehead, hypertelorism, downslanting palpebral fissures, round face, broad/low nasal bridge), DD and ID (the latter in 7/13, in most cases mild), advanced bone age, musculoskeletal abnormalities and cryptorchidism. Less frequent features included brain MRI abnormalities (eg. CC hypoplasia/agenesis, etc.), umbilical hernias, respiratory abnormalities, cardiac anomalies (in one).

All were diagnosed with WES/WGS/panel testing, with few having additional findings upon this or prior testing (eg. CNVs/SNVs).

SUZ12 encodes one of the 4 core proteins of the PRC2 complex (the 3 other being encoded by EZH1/2, EED and RBBP4/7). The complex has a methyltransferase activity, catalyzing addition of up to 3 methyl groups on histone 3 at lysine residue 27 (H3K27), leading to chromatin compaction and further to gene silencing.

Mutations in genes encoding 2 other core components of the PRC2 complex - namely EZH2 and EED - cause Weaver and Cohen-Gibson syndrome with overlapping phenotype incl. overgrowth, advanced bone age, craniofacial features and DD/ID.

The SET domain of EZH1/2 and EED as well as the VEFS domain of SUZ12 are contributing to the catalytic activity.

SUZ12 variants reported to date include missense and pLoF variants (frameshift, nonsense, splice site ones) predicted to disrupt or eliminate the VEFS-box domain [almost all missense within this domain with the exception of one proximal to it (Arg535Gln) / pLoF causing truncation prior or within this domain (Arg654Ter might be an exception)] {NP_056170.2}.

Variants either occurred de novo or were inherited (~1/3), on some occasions from a mildly affected parent. Parental mosaicism has also been reported (eg. in ref1, and one or possibly two additional families in ref3).

Some preliminary assumptions on possible genotype-phenotype correlations (for overgrowth and ID related to missense/pLoF variants) are discussed in ref3.

SUZ12 is also be deleted in some patients with NF1 deletion (and a diagnosis of neurofibromatosis type 1). Deletion of SUZ12 has been proposed to contribute to the phenotype of these individuals (eg. overgrowth, cognitive development, facial features). [Discussed in ref1].

Functional studies have been carried out only in the first report (ref1) and demonstrated decreased trimethylation of H3K27 in the case of a missense variant. Overall a partial loss-of-function mechanism has been proposed for the variants.

Mouse models: An study by Pasini et al (PMID: 15385962) did not report phenotypic differences between wt and heterozygous Suz12 knockout mice (gene-trap vector) as for size, morphology and fertility. Total knockout resulted in embryonic lethality, significant growth retardation and several developmental defects. Loss of Suz12 was shown to result in absence of di- and tri-methylated H3K27 in the ko embryos. In another study cited (Miro et al - PMID: 19535498) heterozygous mice (replacement of exons 12-16 with a lacZ gene and neo cassette) displayed variable CNS defects with incomplete penetrance.

The role of the PRC2 complex and the phenotypes related to mutations in genes encoding its core components, are discussed in PMID: 31724824 (also by Cyrus et al, 2019).

SUZ12 is not associated with any phenotype in OMIM. In G2P it is included in the DD panel associated with Weaver-like overgrowth syndrome (disease confidence : confirmed). The gene is also included in gene panels for ID offered by some diagnostic laboratories (eg. GeneDx).
Sources: Literature
Intellectual disability v3.0 Rebecca Foulger promoted panel to version 3.0
Intellectual disability v2.1143 AFF3 Konstantinos Varvagiannis changed review comment from: Voisin et al. (2019 - https://doi.org/10.1101/693937) report on 10 individuals with de novo missense AFF3 variants affecting a 9-amino-acid sequence (degron) important for the protein's degradation and summarize the phenotype of an additional individual previously described by Steichen-Gersdorf et al. (2008 - PMID: 18616733) with a 500 kb affecting only AFF3 (LAF4) and removing also this sequence.

The phenotype of missense variants consisted of kidney anomalies, mesomelic dysplasia, seizures, hypertrichosis, intellectual disability and pulmonary problems and was overlapping with that of the deletion. [10 of 11 subjects exhibited severe developmental epileptic encephalopathy].

9 probands harbored missense variants affecting the codon 258 while one individual had a variant affecting codon 260 [c.772G>T or p.Ala258Ser (x2), c.772G>A or p.Ala258Thr (x6), c.773C>T or p.Ala258Val (x1) and c.779T>G or p.(Val260Gly) (x1) - NM_001025108.1 / NP_001020279.1]. The deletion removed exons 4-13.

AFF1-4 are ALF transcription factor paralogs, components of the transcriptional super elongation complex regulating expression of genes involved in neurogenesis and development.

Using HEK293T cells expressing FLAG-tagged AFF3 (and AFF4) wt or mutants, accumulation of mutated forms was shown upon immunoblot.

Aff3+/- and/or -/- mice exhibit skeletal defects. These were more pronounced in homozygous mice which demonstrated also some elements in favor of kidney dysfunction and/or metabolic deregulation and possible neurological dysfunction (signs of impaired hearing and diminished grip strength). Homozygous mice had CNS anomalies (enlarged lateral ventricles and decreased corpus callosum size) similar to some affected individuals, although these were not observed in another Aff3-/- model. Knock-in mice modeling the microdeletion and the Ala258Thr variant displayed lower mesomelic limb deformities and early lethality respectively [cited PMIDs : 21677750, 25660031, knock-in model was part of the present study].

Accumulation of the protein in zebrafish (by overexpression of the human wt AFF3 mRNA), led to morphological defects.

Reanalysis of transcriptome data from previously generated HEK293T cell lines knocked down for AFF2, AFF3 and AFF4 by shRNAs (study) suggested that these transcription factors are not redundant.

Finally, CHOPS syndrome (#616368) due to mutations of AFF4 also leading to increased protein stability presents a partially overlapping phenotype (incl. cognitive impairment) to that of AFF3.
----
Shimizu et al. (8/2019 - PMID: 31388108) describe an additional individual with de novo AFF3 missense variant. The phenotype overlaps with that summarized by Voisin et al. incl. mesomelic dysplasia with additional skeletal anomalies, bilateral kidney hypoplasia and severe DD at the age of 2.5 years. Seizures and pulmonary problems were not observed. Although a different RefSeq is used the variant is among those also reported by Voisin et al. [NM_002285.2:c.697G>A (p.Ala233Thr) corresponding to NM_001025108.1:c.772G>A (p.Ala258Thr)].
----
In G2P, AFF3 is associated with Skeletal dysplasia with severe neurological disease (disease confidence : probable / ID and seizures among the assigned phenotypes). There is no associated phenotype in OMIM.
Some diagnostic laboratories include AFF3 in their ID panel (eg. among the many co-authors' affiliations GeneDx and Victorian Clinical Genetics - which was already listed as source for AFF3 in the current panel).
----
As a result this gene can be considered for upgrade to green (relevant phenotype and severity, sufficient cases, evidence for accumulation similar to AFF4, animal models, etc) or amber (pending publication of the article).

[Review modified to add additional reference/case report]; to: Voisin et al. (2019 - https://doi.org/10.1101/693937) report on 10 individuals with de novo missense AFF3 variants affecting a 9-amino-acid sequence (degron) important for the protein's degradation and summarize the phenotype of an additional individual previously described by Steichen-Gersdorf et al. (2008 - PMID: 18616733) with a 500 kb deletion affecting only AFF3 (LAF4) and removing also this sequence.

The phenotype of missense variants consisted of kidney anomalies, mesomelic dysplasia, seizures, hypertrichosis, intellectual disability and pulmonary problems and was overlapping with that of the deletion. [10 of 11 subjects exhibited severe developmental epileptic encephalopathy].

9 probands harbored missense variants affecting the codon 258 while one individual had a variant affecting codon 260 [c.772G>T or p.Ala258Ser (x2), c.772G>A or p.Ala258Thr (x6), c.773C>T or p.Ala258Val (x1) and c.779T>G or p.(Val260Gly) (x1) - NM_001025108.1 / NP_001020279.1]. The deletion removed exons 4-13.

AFF1-4 are ALF transcription factor paralogs, components of the transcriptional super elongation complex regulating expression of genes involved in neurogenesis and development.

Using HEK293T cells expressing FLAG-tagged AFF3 (and AFF4) wt or mutants, accumulation of mutated forms was shown upon immunoblot.

Aff3+/- and/or -/- mice exhibit skeletal defects. These were more pronounced in homozygous mice which demonstrated also some elements in favor of kidney dysfunction and/or metabolic deregulation and possible neurological dysfunction (signs of impaired hearing and diminished grip strength). Homozygous mice had CNS anomalies (enlarged lateral ventricles and decreased corpus callosum size) similar to some affected individuals, although these were not observed in another Aff3-/- model. Knock-in mice modeling the microdeletion and the Ala258Thr variant displayed lower mesomelic limb deformities and early lethality respectively [cited PMIDs : 21677750, 25660031, knock-in model was part of the present study].

Accumulation of the protein in zebrafish (by overexpression of the human wt AFF3 mRNA), led to morphological defects.

Reanalysis of transcriptome data from previously generated HEK293T cell lines knocked down for AFF2, AFF3 and AFF4 by shRNAs (study) suggested that these transcription factors are not redundant.

Finally, CHOPS syndrome (#616368) due to mutations of AFF4 also leading to increased protein stability presents a partially overlapping phenotype (incl. cognitive impairment) to that of AFF3.
----
Shimizu et al. (8/2019 - PMID: 31388108) describe an additional individual with de novo AFF3 missense variant. The phenotype overlaps with that summarized by Voisin et al. incl. mesomelic dysplasia with additional skeletal anomalies, bilateral kidney hypoplasia and severe DD at the age of 2.5 years. Seizures and pulmonary problems were not observed. Although a different RefSeq is used the variant is among those also reported by Voisin et al. [NM_002285.2:c.697G>A (p.Ala233Thr) corresponding to NM_001025108.1:c.772G>A (p.Ala258Thr)].
----
In G2P, AFF3 is associated with Skeletal dysplasia with severe neurological disease (disease confidence : probable / ID and seizures among the assigned phenotypes). There is no associated phenotype in OMIM.
Some diagnostic laboratories include AFF3 in their ID panel (eg. among the many co-authors' affiliations GeneDx and Victorian Clinical Genetics - which was already listed as source for AFF3 in the current panel).
----
As a result this gene can be considered for upgrade to green (relevant phenotype and severity, sufficient cases, evidence for accumulation similar to AFF4, animal models, etc) or amber (pending publication of the article).

[Review modified to add additional reference/case report]
Intellectual disability v2.1143 Rebecca Foulger List of related panels changed from Coarse facial features including Coffin-Siris-like disorders; ID; Moderate; severe or profound intellectual disability; Schizophrenia plus additional features; Intellectual disability - microarray; fragile X and sequencing to Coarse facial features including Coffin-Siris-like disorders; ID; Moderate; severe or profound intellectual disability; Schizophrenia plus additional features; Intellectual disability - microarray; fragile X and sequencing; R29
Panel types changed to Rare Disease 100K; GMS Rare Disease Virtual; Component Of Super Panel; GMS signed-off
Intellectual disability v2.1141 AKAP17A Rebecca Foulger Mode of inheritance for gene: AKAP17A was changed from BIALLELIC, autosomal or pseudoautosomal to Unknown
Intellectual disability v2.1140 AKAP17A Rebecca Foulger Deleted their review
Intellectual disability v2.1140 AKAP17A Rebecca Foulger Deleted their comment
Intellectual disability v2.1140 AKAP17A Rebecca Foulger changed review comment from: Comment on mode of inheritance: Set MOI to BIALLELIC. Pseudoautosomal region 1. Mode of inheritance has not been thoroughly checked, but assumed to be biallelic.; to: Comment on mode of inheritance: This gene is in the pseudoautosomal region shared between chromosomes X and Y. The mode of inheritance should therefore be set to Biallelic or Monoallelic once more cases establish the inheritance pattern.
Intellectual disability v2.1140 CSF2RA Rebecca Foulger Added comment: Comment on mode of inheritance: Changed MOI to BIALLELIC. Pseudoautosomal region 1. Mode of inheritance has been checked.
Intellectual disability v2.1140 CSF2RA Rebecca Foulger Mode of inheritance for gene: CSF2RA was changed from X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1139 AKAP17A Rebecca Foulger Added comment: Comment on mode of inheritance: Set MOI to BIALLELIC. Pseudoautosomal region 1. Mode of inheritance has not been thoroughly checked, but assumed to be biallelic.
Intellectual disability v2.1139 AKAP17A Rebecca Foulger Mode of inheritance for gene: AKAP17A was changed from Unknown to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1138 FA2H Rebecca Foulger Phenotypes for gene: FA2H were changed from Spastic paraplegia 35, autosomal recessive, 612319 to Spastic paraplegia 35, autosomal recessive, 612319; spastic paraplegia with ID; cognitive defects; Seizures
Intellectual disability v2.1137 FA2H Rebecca Foulger Publications for gene: FA2H were set to 24833714; 20104589
Intellectual disability v2.1136 FA2H Rebecca Foulger Classified gene: FA2H as Green List (high evidence)
Intellectual disability v2.1136 FA2H Rebecca Foulger Added comment: Comment on list classification: Upgraded from Amber to Green based on Green review by Alistair Pagnamenta: PMID:31135052 analysed a cohort of 19 cases with biallelic FA2H variants. Phenotype includes spastic paraplegia associated with ID: mild cognitive deficits were noted from childhood in 93% of cases, and were considered progressive in all but two cases.
Intellectual disability v2.1136 FA2H Rebecca Foulger Gene: fa2h has been classified as Green List (High Evidence).
Intellectual disability v2.1135 TRAPPC4 Konstantinos Varvagiannis gene: TRAPPC4 was added
gene: TRAPPC4 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: TRAPPC4 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TRAPPC4 were set to 31794024
Phenotypes for gene: TRAPPC4 were set to Feeding difficulties; Progressive microcephaly; Intellectual disability; Seizures; Spastic tetraparesis; Abnormality of the face; Scoliosis; Cortical visual impairment; Hearing impairment
Penetrance for gene: TRAPPC4 were set to Complete
Review for gene: TRAPPC4 was set to GREEN
Added comment: Van Bergen et al. (2019 - PMID: 31794024) report on 7 affected individuals from 3 famillies (only 1 of which consanguineous), all homozygous for a TRAPPC4 splicing variant.

Overlapping features included feeding difficulties, progressive microcephaly, severe to profound developmental disability (7/7 - DD also prior to the onset of seizures / regression also reported in 3), epilepsy (7/7 - onset in the first year), spastic quadriparesis. Other findings in some/few incl. scoliosis, cortical visual and hearing impairment. Some facial features were shared (eg. bitemporal narrowing, long philtrum, open mouth with thin tented upper lip, pointed chin, etc). Brain imaging demonstrated abnormalities in those performed (among others cerebral with/without cerebellar atrophy).

Work-up prior to exome sequencing was normal (highly variable incl. metabolic testing, CMA, MECP2, CDKL5, mitochondrial depletion studies, etc).

Exome of affected individuals (and parents +/- affected sibs in some families) revealed a homozygous TRAPPC4 splicing variant [NM_016146.5:c.454+3A>G / chr11:g.118890966A>G (hg19)]. Sanger sequencing confirmed variant in affecteds, heterozygosity in parents and compatible genotypes with disease status in sibs/other members.

Families were of Caucasian/Turkish and French-Canadian ethnicities. SNP array to compare haplotypes between affecteds in 2 families did not reveal a shared haplotype (/founder effect) and the variant is present in gnomAD (68/281054 - no hmz) in many populations (European/Asian/African/Latino) [https://gnomad.broadinstitute.org/variant/11-118890966-A-G].

mRNA studies in fibroblasts from an affected individual confirmed the splicing defect (2 RT-PCR products corresponding to wt and a shorter due to skipping of exon 3, the latter further confirmed by Sanger sequencing. The shorter transcript is not present in controls). qPCR revealed that the normal transript in patient fibroblasts was present at 6% of the level observed in control fibroblasts (or 54% in the case of a heterozygote parent compared to controls).

Western blot in patient fibroblasts, revealed presence of full-length protein in significantly reduced levels compared to fibroblasts from carrier parents or controls. There was no band using an antibody targeting the N-terminal region of the protein prior to exon 3, suggesting that NMD applies (skipping of ex3 is also predicted to lead to frameshift).

TRAPPC4 encodes one of the core proteins of the TRAPP complex. Use of different accessory proteins leads to formation of 2 distinct complexes (TRAPPII / III). The complex has an important role in intracellular trafficking. Both TRAPPII & TRAPPIII have a function in the secretory pathway, while complex III has a role also in autophagy. Core proteins are important for the complex stability. The TRAPP complex serves as a GEF for Ypt/Rab GTPases [several refs in article].

Mutations in genes for other proteins of the complex lead to neurodevelopmental disorders with associated ID ('TRAPPopathies' used by the authors / TRAPPC12, C6B, C9 green in the current panel).

Western blot suggested that levels of other TRAPP subunits (TRAPPC2 or C12) under denaturing conditions, although PAGE/size exclusion chromatography suggested that the levels of fully-assembled TRAPP complexes were lower in affected individuals.

Studies in patient fibroblasts showed a secretory defect (between ER, Golgi and the plasma membrane) which was restored upon lentiviral transduction with wt TRAPPC4 construct. Basal and starvation-induced autophagy were also impaired in patient fibroblasts (increased LC3 marker and LC3-positive structures / impaired co-localization with lysosomes) partly due to defective autophagosome formation (/sealing).

TRAPPC4 is the human orthologue of the yeast Trs23. In a yeast model of reduced Trs23 (due to temperature instability) the authors demonstrated impaired assembly of the TRAPP core. The yeast model recapitulated the autophagy as well as well as the secretory defect observed in patient fibroblasts.
Sources: Literature
Intellectual disability v2.1135 SNX27 Konstantinos Varvagiannis gene: SNX27 was added
gene: SNX27 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: SNX27 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SNX27 were set to 25894286; 31721175; 21300787; 23524343
Phenotypes for gene: SNX27 were set to Generalized hypotonia; Global developmental delay; Intellectual disability; Seizures
Penetrance for gene: SNX27 were set to Complete
Review for gene: SNX27 was set to GREEN
gene: SNX27 was marked as current diagnostic
Added comment: Evidence from 2 publications suggests that DD, ID and seizures are part of the phenotype of individuals with biallelic SNX27 pathogenic variants :
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Damseh, Danson et al (2015 - PMID: 25894286) first reported on a consanguineous family with 4 affected sibs, homozygous for an SNX27 pathogenic variant. Features incl. hypotonia soon after birth, failure to thrive, severely delayed psychomotor development with no milestone acquisition, occurrence of myoclonic seizures with 3 individuals deceased early. Exome sequencing in one revealed a few candidate variants, with an SNX27 frameshift one [NM_030918.6:c.515_516del - p.(His172Argfs*6) / absent from ExAC] being the only retained following Sanger segregation studies. Using fibroblasts from an affected individual, Western blot with an antibody which would also bind prior to the truncation site, was consistent with dramatically reduced/absent SNX27 truncated mutant protein. Protein levels of VPS35, a component of the retromer responsible for direct cargo binding (not mediated by a cargo adaptor as SNX27), were normal.
---------
Parente et al (2019 - PMID: 31721175) reported on a 13-year-old male with motor and language delay, ADHD, ID (kindergarten academic level at the age of 13) and seizures with onset at the age of 9 years (GTC, with abnormal EEG and postical SV tachycardia). Variable physical findings were reported. White matter hyperintesities were noted upon initial brain MRI (but were less marked in subsequent ones). Initial genetic testing (Alexander's disease, CMA, FMR1) was normal. Exome revealed compound heterozygosity for 2 SNX27 variants (NM_030918.5/NM_001330723.1 both apply c.510C>G - p.Tyr170* and c.1295G>A - p.Cys432Tyr) each inherited from healthy carrier parents. There were no other potentially causative variants. A parental history of - isolated - late onset seizures was reported (so this individual may not be considered for the seizure phenotype here).

The authors also reported on a further 31-year old affected male. This individual had infantile hypotonia, poor eye contact with subsequent significant DD, seizures (febrile/afebrile T-C with onset at the age of 14m) and ID estimated in the severe range. Variable - though somewhat different - physical findings were reported. Initial work-up included basic metabolic testing, standard karyotype, FISH for 15q11 and subtelomeric regions and PHF6 genetic testing - all normal. Exome (and subsequent Sanger confirmation/parental studies) revealed compound heterozygosity for a missense and a frameshift variant (c.989G>A / p.Arg330His and c.782dupT / p.Leu262Profs*6 same in NM_001330723.1, NM_030918.6).
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SNX27 encodes sorting nexin 27, a cargo adaptor for the retromer. The latter is a multi-protein complex essential for regulating the retrieval and recycling of transmembrane cargos from endosomes to the trans-Golgi network or the plasma membrane [Lucas et al 2016 - PMID: 27889239 / McNally et al 2018 - PMID: 30072228].

As summarized by Parente et al, the encoded protein by regulating composition of the cell surface influences several processes eg. neuronal excitability, synaptic plasticity, Wnt signaling etc. It has been shown to interact with surface receptors and their ligands including GIRK channels, 5-HT4, ionotropic glutamate receptors (incl. NMDA- and AMPA-type receptors) and mGluR5 [several refs. provided].

Knockout of Snx27 in mice resulted in embryonic lethality (16% hmz of the 25% expected), severe postnatal growth retardation and death within the first 3 weeks. Snx27(+/-) mice have normal neuroanatomy but exhibit cognitive deficits (in learning and memory) and defects in synaptic function/plasticity with reduced amounts of NMDA and AMPA receptors (Cai et al - PMID: 21300787, Wang et al - PMID: 23524343).
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The gene is included in gene panels for ID offered by some diagnostic laboratories (eg. GeneDx) and a current primary ID gene in SysID. There is no associated phenotype in OMIM/G2P.
Sources: Literature
Intellectual disability v2.1135 FA2H Alistair Pagnamenta reviewed gene: FA2H: Rating: GREEN; Mode of pathogenicity: None; Publications: PMID: 31135052, 20104589; Phenotypes: HSP, ID, Seizures; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1135 SLC5A6 Konstantinos Varvagiannis changed review comment from: SLC5A6 encodes the sodium dependent multivitamin transporter (SMVT), a transporter of biotin, pantothenate and lipoate. The transporter has a major role in vitamin uptake in the digestive system (among others is the sole transporter for intestinal uptake of biotin which is not synthesized and but must be obtained from exogenous sources) as well as transport across the blood-brain barrier (SMVT being responsible for 89% of biotin transport) [several refs provided by Subramanian et al and Byrne et al].

4 affected individuals from 3 families have been reported.

Subramanian et al (2017 - PMID: 27904971) et al reported on a girl with feeding difficulties and failure to thrive (requiring nasogastric tube placement), microcephaly, DD (at 15m developmental age corresponding to 6m with features suggestive of spastic cerebral palsy), occurrence of multiple infections, osteoporosis and pathologic bone fractures. MRIs suggested brain atrophy, thin CC and hypoplasia of the pons. Metabolic (AA, OA) investigations and array-CGH were normal. Whole exome sequencing revealed presence of a missense (Arg123Leu - RefSeq not provided) and a nonsense (Arg94Ter) SLC5A6 variant. Serum biotin was normal although - at the time - the child was on parenteral and G-T nutrition. Following administration of biotin, pantothenic acid and lipoic acid the child demonstrated among others improved motor and verbal skills, head growth and normalization of immunoglobulin levels. Transfection of mutants in human derived intestinal HuTu-80 cells and brain U87 cells was carried out and a 3H-biotin assay showed no induction in biotin uptake confirming impaired functionality of the transporter. While wt protein displayed normal expression/membrane localization, Arg94Ter was poorly expressed with ectopic localization (cytoplasm). Arg123Leu was retained predominantly intracellularly, probably in the ER as was further supported by colocalization with DsRed-ER. Evidence from the literature is provided that deficiencies of the specific vitamins explain the clinical features (DD, microcephaly, immunological defect, osteopenia, etc).

Schwantje et al (2019 - PMID: 31392107) described a girl with severe feeding problems, vomiting with blood (suspected Mallory-Weiss syndrome), poor weight gain and delayed gross motor development. The child presented an episode of gastroenteritis associated with reduced consciousness, circulatory insufficiency and metabolic derangement (hypoglycemia, severe metabolic acidosis, hyperammonemia, mild lactate elevation, ketonuria). Investigations some months prior to the admission (?) were suggestive of a metabolic disorder due to elevated plasma C3-carnitine, C5-OH-carnitine and elevated urinary excretion of 3-OH-isovaleric acid (biotinidase deficiency was considered in the DD but enzymatic activity was only marginally decreased). Biotin supplementation was initiated. Trio-exome sequencing (at 3yrs) demonstrated compound heterozygosity for 2 frameshift variants [NM_021095.2:c.422_423del / p.(Val141Alafs*34) and c.1865_1866del]. Following this result, increase of biotin supplementation and introduction of pantothenic acid, GI symptoms (incl. chronic diarrhea) resolved and the child displayed improved appetite and growth, yet a stable motor delay. The authors cite previous studies of conditional ko mice, displaying intestinal mucosal abnormalities and growth defects (similar to the child's problems), prevented by biotin and pantothenic acid supplementation.

Byrne et al (2019 - PMID: 31754459) reported on a sibling pair with severe motor/speech developmental regression following a plateau (at 12m and 14m), development of ataxia and dyskinetic movements (both), seizures (one). Feeding difficulties, reflux and failure to thrive required N-G/gastrostomy feeding while both presented GI hemorrhage (in the case of the older sib, lethal). Other features in the youngest sib included brain MRI abnormalities (cerebral/cerebellar atrophy, thin CC, etc) and IgG deficiency. Biochemical, single-gene testing and mtDNA sequencing were not diagnostic. Exome in one, revealed presence of a frameshift [c.422_423del as above] and a missense variant (Arg400Thr). Sanger sequencing confirmed variants in both sibs and heterozygosity in parents. HeLa cells transfected with empty vector, wt or mut expression constructs confirmed significantly decreased 3H-biotin uptake for mut constructs compared to wt (and similar to empty vector). Parenteral triple vitamin replacement at the age of ~7 years resulted in improved overall condition, regain of some milestones, attenuation of vomiting, and resolution of peripheral neuropathy. Seizure were well-controlled (as was the case before treatment) despite persistence of epileptiform discharges. Again the authors cite studies of conditional (intestine-specific) SLC5A6 ko mice, with those viable (~1/3) demonstrating growth retardation, decreased boned density and GI abnormalities (similar to affected individuals). The phenotype could be rescued by oversupplementation of biotin and pantothenic acid (PMIDs cited: 23104561, 29669219).

[Please consider inclusion in other relevant panels eg. metabolic disorders]
Sources: Literature; to: SLC5A6 encodes the sodium dependent multivitamin transporter (SMVT), a transporter of biotin, pantothenate and lipoate. The transporter has a major role in vitamin uptake in the digestive system (among others is the sole transporter for intestinal uptake of biotin which is not synthesized but must be obtained from exogenous sources) as well as transport across the blood-brain barrier (SMVT being responsible for 89% of biotin transport) [several refs provided by Subramanian et al and Byrne et al].

4 affected individuals from 3 families have been reported.

Subramanian et al (2017 - PMID: 27904971) et al reported on a girl with feeding difficulties and failure to thrive (requiring nasogastric tube placement), microcephaly, DD (at 15m developmental age corresponding to 6m with features suggestive of spastic cerebral palsy), occurrence of multiple infections, osteoporosis and pathologic bone fractures. MRIs suggested brain atrophy, thin CC and hypoplasia of the pons. Metabolic (AA, OA) investigations and array-CGH were normal. Whole exome sequencing revealed presence of a missense (Arg123Leu - RefSeq not provided) and a nonsense (Arg94Ter) SLC5A6 variant. Serum biotin was normal although - at the time - the child was on parenteral and G-T nutrition. Following administration of biotin, pantothenic acid and lipoic acid the child demonstrated among others improved motor and verbal skills, head growth and normalization of immunoglobulin levels. Transfection of mutants in human derived intestinal HuTu-80 cells and brain U87 cells was carried out and a 3H-biotin assay showed no induction in biotin uptake confirming impaired functionality of the transporter. While wt protein displayed normal expression/membrane localization, Arg94Ter was poorly expressed with ectopic localization (cytoplasm). Arg123Leu was retained predominantly intracellularly, probably in the ER as was further supported by colocalization with DsRed-ER. Evidence from the literature is provided that deficiencies of the specific vitamins explain the clinical features (DD, microcephaly, immunological defect, osteopenia, etc).

Schwantje et al (2019 - PMID: 31392107) described a girl with severe feeding problems, vomiting with blood (suspected Mallory-Weiss syndrome), poor weight gain and delayed gross motor development. The child presented an episode of gastroenteritis associated with reduced consciousness, circulatory insufficiency and metabolic derangement (hypoglycemia, severe metabolic acidosis, hyperammonemia, mild lactate elevation, ketonuria). Investigations some months prior to the admission (?) were suggestive of a metabolic disorder due to elevated plasma C3-carnitine, C5-OH-carnitine and elevated urinary excretion of 3-OH-isovaleric acid (biotinidase deficiency was considered in the DD but enzymatic activity was only marginally decreased). Biotin supplementation was initiated. Trio-exome sequencing (at 3yrs) demonstrated compound heterozygosity for 2 frameshift variants [NM_021095.2:c.422_423del / p.(Val141Alafs*34) and c.1865_1866del]. Following this result, increase of biotin supplementation and introduction of pantothenic acid, GI symptoms (incl. chronic diarrhea) resolved and the child displayed improved appetite and growth, yet a stable motor delay. The authors cite previous studies of conditional ko mice, displaying intestinal mucosal abnormalities and growth defects (similar to the child's problems), prevented by biotin and pantothenic acid supplementation.

Byrne et al (2019 - PMID: 31754459) reported on a sibling pair with severe motor/speech developmental regression following a plateau (at 12m and 14m), development of ataxia and dyskinetic movements (both), seizures (one). Feeding difficulties, reflux and failure to thrive required N-G/gastrostomy feeding while both presented GI hemorrhage (in the case of the older sib, lethal). Other features in the youngest sib included brain MRI abnormalities (cerebral/cerebellar atrophy, thin CC, etc) and IgG deficiency. Biochemical, single-gene testing and mtDNA sequencing were not diagnostic. Exome in one, revealed presence of a frameshift [c.422_423del as above] and a missense variant (Arg400Thr). Sanger sequencing confirmed variants in both sibs and heterozygosity in parents. HeLa cells transfected with empty vector, wt or mut expression constructs confirmed significantly decreased 3H-biotin uptake for mut constructs compared to wt (and similar to empty vector). Parenteral triple vitamin replacement at the age of ~7 years resulted in improved overall condition, regain of some milestones, attenuation of vomiting, and resolution of peripheral neuropathy. Seizure were well-controlled (as was the case before treatment) despite persistence of epileptiform discharges. Again the authors cite studies of conditional (intestine-specific) SLC5A6 ko mice, with those viable (~1/3) demonstrating growth retardation, decreased boned density and GI abnormalities (similar to affected individuals). The phenotype could be rescued by oversupplementation of biotin and pantothenic acid (PMIDs cited: 23104561, 29669219).

[Please consider inclusion in other relevant panels eg. metabolic disorders]
Sources: Literature
Intellectual disability v2.1135 SLC5A6 Konstantinos Varvagiannis gene: SLC5A6 was added
gene: SLC5A6 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: SLC5A6 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SLC5A6 were set to 27904971; 31392107; 31754459; 23104561; 29669219
Phenotypes for gene: SLC5A6 were set to Feeding difficulties; Failure to thrive; Global developmental delay; Developmental regression; Intellectual disability; Seizures; Microcephaly; Cerebral atrophy; Abnormality of the corpus callosum; Vomiting; Chronic diarrhea; Gastrointestinal hemorrhage; Abnormal immunoglobulin level; Osteopenia; Abnormality of metabolism/homeostasis
Penetrance for gene: SLC5A6 were set to Complete
Review for gene: SLC5A6 was set to GREEN
Added comment: SLC5A6 encodes the sodium dependent multivitamin transporter (SMVT), a transporter of biotin, pantothenate and lipoate. The transporter has a major role in vitamin uptake in the digestive system (among others is the sole transporter for intestinal uptake of biotin which is not synthesized and but must be obtained from exogenous sources) as well as transport across the blood-brain barrier (SMVT being responsible for 89% of biotin transport) [several refs provided by Subramanian et al and Byrne et al].

4 affected individuals from 3 families have been reported.

Subramanian et al (2017 - PMID: 27904971) et al reported on a girl with feeding difficulties and failure to thrive (requiring nasogastric tube placement), microcephaly, DD (at 15m developmental age corresponding to 6m with features suggestive of spastic cerebral palsy), occurrence of multiple infections, osteoporosis and pathologic bone fractures. MRIs suggested brain atrophy, thin CC and hypoplasia of the pons. Metabolic (AA, OA) investigations and array-CGH were normal. Whole exome sequencing revealed presence of a missense (Arg123Leu - RefSeq not provided) and a nonsense (Arg94Ter) SLC5A6 variant. Serum biotin was normal although - at the time - the child was on parenteral and G-T nutrition. Following administration of biotin, pantothenic acid and lipoic acid the child demonstrated among others improved motor and verbal skills, head growth and normalization of immunoglobulin levels. Transfection of mutants in human derived intestinal HuTu-80 cells and brain U87 cells was carried out and a 3H-biotin assay showed no induction in biotin uptake confirming impaired functionality of the transporter. While wt protein displayed normal expression/membrane localization, Arg94Ter was poorly expressed with ectopic localization (cytoplasm). Arg123Leu was retained predominantly intracellularly, probably in the ER as was further supported by colocalization with DsRed-ER. Evidence from the literature is provided that deficiencies of the specific vitamins explain the clinical features (DD, microcephaly, immunological defect, osteopenia, etc).

Schwantje et al (2019 - PMID: 31392107) described a girl with severe feeding problems, vomiting with blood (suspected Mallory-Weiss syndrome), poor weight gain and delayed gross motor development. The child presented an episode of gastroenteritis associated with reduced consciousness, circulatory insufficiency and metabolic derangement (hypoglycemia, severe metabolic acidosis, hyperammonemia, mild lactate elevation, ketonuria). Investigations some months prior to the admission (?) were suggestive of a metabolic disorder due to elevated plasma C3-carnitine, C5-OH-carnitine and elevated urinary excretion of 3-OH-isovaleric acid (biotinidase deficiency was considered in the DD but enzymatic activity was only marginally decreased). Biotin supplementation was initiated. Trio-exome sequencing (at 3yrs) demonstrated compound heterozygosity for 2 frameshift variants [NM_021095.2:c.422_423del / p.(Val141Alafs*34) and c.1865_1866del]. Following this result, increase of biotin supplementation and introduction of pantothenic acid, GI symptoms (incl. chronic diarrhea) resolved and the child displayed improved appetite and growth, yet a stable motor delay. The authors cite previous studies of conditional ko mice, displaying intestinal mucosal abnormalities and growth defects (similar to the child's problems), prevented by biotin and pantothenic acid supplementation.

Byrne et al (2019 - PMID: 31754459) reported on a sibling pair with severe motor/speech developmental regression following a plateau (at 12m and 14m), development of ataxia and dyskinetic movements (both), seizures (one). Feeding difficulties, reflux and failure to thrive required N-G/gastrostomy feeding while both presented GI hemorrhage (in the case of the older sib, lethal). Other features in the youngest sib included brain MRI abnormalities (cerebral/cerebellar atrophy, thin CC, etc) and IgG deficiency. Biochemical, single-gene testing and mtDNA sequencing were not diagnostic. Exome in one, revealed presence of a frameshift [c.422_423del as above] and a missense variant (Arg400Thr). Sanger sequencing confirmed variants in both sibs and heterozygosity in parents. HeLa cells transfected with empty vector, wt or mut expression constructs confirmed significantly decreased 3H-biotin uptake for mut constructs compared to wt (and similar to empty vector). Parenteral triple vitamin replacement at the age of ~7 years resulted in improved overall condition, regain of some milestones, attenuation of vomiting, and resolution of peripheral neuropathy. Seizure were well-controlled (as was the case before treatment) despite persistence of epileptiform discharges. Again the authors cite studies of conditional (intestine-specific) SLC5A6 ko mice, with those viable (~1/3) demonstrating growth retardation, decreased boned density and GI abnormalities (similar to affected individuals). The phenotype could be rescued by oversupplementation of biotin and pantothenic acid (PMIDs cited: 23104561, 29669219).

[Please consider inclusion in other relevant panels eg. metabolic disorders]
Sources: Literature
Intellectual disability v2.1135 TMX2 Rebecca Foulger Classified gene: TMX2 as Green List (high evidence)
Intellectual disability v2.1135 TMX2 Rebecca Foulger Added comment: Comment on list classification: Promoted TMX2 from Amber to Green to match Green review by Ivone Leong and new evidence from Konstantinos Varvagiannis.
Intellectual disability v2.1135 TMX2 Rebecca Foulger Gene: tmx2 has been classified as Green List (High Evidence).
Intellectual disability v2.1134 TMX2 Ivone Leong edited their review of gene: TMX2: Added comment: Based on the new evidence submitted from the expert reviewer, there is now enough evidence to promote this gene to Green status.; Changed rating: GREEN
Intellectual disability v2.1134 CNOT3 Konstantinos Varvagiannis reviewed gene: CNOT3: Rating: GREEN; Mode of pathogenicity: None; Publications: 28135719, 31201375, 24121232; Phenotypes: Intellectual developmental disorder with speech delay, autism, and dysmorphic facies, MIM 618672; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown; Current diagnostic: yes
Intellectual disability v2.1134 OXR1 Konstantinos Varvagiannis gene: OXR1 was added
gene: OXR1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: OXR1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: OXR1 were set to https://doi.org/10.1016/j.ajhg.2019.11.002
Phenotypes for gene: OXR1 were set to Central hypotonia; Global developmental delay; Delayed speech and language development; Intellectual disability; Seizures; Abnormality of the cerebellum
Penetrance for gene: OXR1 were set to Complete
Review for gene: OXR1 was set to GREEN
Added comment: Wang et al (2019 - https://doi.org/10.1016/j.ajhg.2019.11.002 ) report on 5 individuals (from 3 families) with biallelic OXR1 LoF variants.

Common features included hypotonia (4/5), severe global DD (5/5) and speech delay (5/5), ID (5/5), epilepsy (5/5) with cerebellar dysplasia/atrophy (5/5) and in some scoliosis.

All were investigated by exome sequencing and were found to harbor biallelic loss-of-function variants (2 splice-site, a stopgain and a frameshift one) either in homozygosity (2 consanguineous families) or in compound heterozygosity. In all cases parental segregation studies were compatible and in one family, an unaffected sib shown to be carrier.

Althouhgh OXR1 has been shown to affect several processes (among others DNA lesions induced by oxidative stress in E.coli, neuronal maintenance, mitochondrial morphology and DNA maintenance, etc), its mechanism of action is still not well defined. There are 6 RefSeq transcripts, the longest (NM_018002.3) encoding 3 protein domains (LysM, GRAM, TLDc). The TLDc domain is encoded by all transcripts.

Identified variants affected (probably all - fig1D) transcripts expressed in the CNS, namely NM_018002.3, NM_001198532.1, NM_181354.4. The 3 transcripts not expressed in the CNS are NM_001198533.1, NM_001198534.1 and NM_001198535.1.

Western blot with 2 different antibodies which would bind upstream of the truncation site failed to detect presence of truncated proteins in 2 affected individuals from 2 families.

The Drosophila homolog of OXR is mustard (mtd). The authors provide evidence that loss of mtd is lethal. This was however rescued by expression of an 80kb fly BAC clone covering mtd, or the fly mtd-RH isoform cDNA, or a short human OXR1 cDNA containing only the TLDc domain or a human NCOA7 cDNA. The latter is another human mtd homolog which also contains the TLDc domain. As a result the TLDc domain compensated sufficiently for loss of mtd.

Flies that survived displayed bang sensitivity and climbing defects the former assay being suggestive of susceptibility to seizures and the latter of impaired neurological/muscular function.

The authors provided evidence that mtd is broadly expressed in the fly CNS. RNAi mediated mtd knockdown specific to neurons (elav/nSyb-GAL4 expression of mtd RNAi) led to lethal eclosion defects for RNAis targeting most (18)/all(23) mtd isoforms. Lifespan was increased upon expression of human OXR1 cDNA. Neuronal loss and vacuolization was demonstrated and additional experiments in R7 photoreceptors showed presence of aberrant lysosomal structures (autolysosomes, autophagosomes and/or endolysosomes).

Aberrant lysosomal structures were also observed in fibroblasts from affected individuals (accumulation of lysosomes and/or presence of highly aberrant compartments with content typical of lysosomal dysfunction).

Overall the data presented suggest a critical role for OXR1 in lysosomal biology.

Although previous reports suggested that OXR1 is involved in oxidative stress resistance, studies performed by the authors suggested that oxidative stress is probably not the driver of the mutant fly defects.
Sources: Literature
Intellectual disability v2.1134 PDE6D Ellen McDonagh Classified gene: PDE6D as Amber List (moderate evidence)
Intellectual disability v2.1134 PDE6D Ellen McDonagh Added comment: Comment on list classification: Gene added by external reviewer, and promoted to Amber due to one family and a recent additional case.
Intellectual disability v2.1134 PDE6D Ellen McDonagh Gene: pde6d has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1133 PCYT2 Ellen McDonagh Classified gene: PCYT2 as Green List (high evidence)
Intellectual disability v2.1133 PCYT2 Ellen McDonagh Added comment: Comment on list classification: This gene was added by an external reviewer and rated Green. This is currently Green on the Hereditary spastic paraplegia gene panel (Version 1.210), and confirmed with Zerin Hyder (Genomics England Clinical Team) that this is appropriate to be Green on the ID panel.
Intellectual disability v2.1133 PCYT2 Ellen McDonagh Gene: pcyt2 has been classified as Green List (High Evidence).
Intellectual disability v2.1132 SVBP Rebecca Foulger Classified gene: SVBP as Green List (high evidence)
Intellectual disability v2.1132 SVBP Rebecca Foulger Added comment: Comment on list classification: Updated rating to Green to match Green review by Catherine Snow. Phenotypes include global DD and intellectual disability in >3 families.
Intellectual disability v2.1132 SVBP Rebecca Foulger Gene: svbp has been classified as Green List (High Evidence).
Intellectual disability v2.1131 PNPT1 Rebecca Foulger commented on gene: PNPT1
Intellectual disability v2.1131 PNPT1 Rebecca Foulger Phenotypes for gene: PNPT1 were changed from Combined oxidative phosphorylation deficiency 13, 614932; Deafness, autosomal recessive 70, 614934 to Combined oxidative phosphorylation deficiency 13, 614932; Deafness, autosomal recessive 70, 614934; developmental delay; intellectual disability
Intellectual disability v2.1131 PNPT1 Rebecca Foulger Publications for gene: PNPT1 were set to
Intellectual disability v2.1129 PNPT1 Konstantinos Varvagiannis changed review comment from: Biallelic PNPT1 pathogenic variants cause Combined oxidative phosphorylation deficiency 13 (MIM 614932). Despite phenotypic variability - common to disorders resulting from mitochondrial dysfunction - DD and ID of relevant severity to the current panel have been reported in several individuals published in the literature. Seizures may also be observed.

Rius et al (2019 - PMID: 31752325) provide an overview of 24 affected individuals (7 new and 17 from previous studies). Neurodevelopmental features are summarized in fig.1 and additional details are provided in the supplement. Based on this review, seizures were present in 7 individuals (of the 18 for whom this information was available).

PNPT1 encodes the mitochondrial polynucleotide phosphorylase, involved in the import of nuclear-encoded RNA to mitochondria. Loss of its activity has been shown to result in combined respiratory chain deficiency. However, as discussed by Rius et al and previous articles as well, OXPHOS studies in affected individuals may be normal or suggestive of only mild impairement due to tissue specificity and different assay methods used (eg. spectrophotometric vs dipstick activity assays). The same applies to lactate which was normal or mildly elevated in some affected individuals.

Missense, pLoF function variants as well as a synonymous one leading to aberrant splicing (NM_033109.4:c.1818T>G) have been reported.

Overall, this gene might be considered for upgrade to green rating.; to: Biallelic PNPT1 pathogenic variants cause Combined oxidative phosphorylation deficiency 13 (MIM 614932). Despite phenotypic variability - common to disorders resulting from mitochondrial dysfunction - DD and ID of relevant severity to the current panel have been reported in several individuals published in the literature. Seizures may also be observed.

Rius et al (2019 - PMID: 31752325) provide an overview of 24 affected individuals (7 new and 17 from previous studies). Neurodevelopmental features are summarized in fig.1 and additional details are provided in the supplement. Based on this review, seizures were present in 7 individuals (of the 18 for whom this information was available).

PNPT1 encodes the mitochondrial polynucleotide phosphorylase, involved in the import of nuclear-encoded RNA to mitochondria. Loss of its activity has been shown to result in combined respiratory chain deficiency. However, as discussed by Rius et al and previous articles as well, OXPHOS studies in affected individuals may be normal or suggestive of only mild impairment due to tissue specificity and different assay methods used (eg. spectrophotometric vs dipstick activity assays). The same applies to lactate which was normal or mildly elevated in some affected individuals.

Missense, pLoF function variants as well as a synonymous one leading to aberrant splicing (NM_033109.4:c.1818T>G) have been reported.

Overall, this gene might be considered for upgrade to green rating.
Intellectual disability v2.1129 PNPT1 Konstantinos Varvagiannis reviewed gene: PNPT1: Rating: GREEN; Mode of pathogenicity: None; Publications: 31752325; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1129 PIK3C2A Catherine Snow Classified gene: PIK3C2A as Amber List (moderate evidence)
Intellectual disability v2.1129 PIK3C2A Catherine Snow Gene: pik3c2a has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1128 NTNG2 Ellen McDonagh Classified gene: NTNG2 as Green List (high evidence)
Intellectual disability v2.1128 NTNG2 Ellen McDonagh Added comment: Comment on list classification: Gene added by external reviewer and rated Green. 11 unrelated families reported with homozygous variants in this gene with a neurodevelopmental disorder including global developmental delay, plus functional evidence. Promoted to Green.
Intellectual disability v2.1128 NTNG2 Ellen McDonagh Gene: ntng2 has been classified as Green List (High Evidence).
Intellectual disability v2.1128 PIK3C2A Catherine Snow gene: PIK3C2A was added
gene: PIK3C2A was added to Intellectual disability. Sources: Expert Review
Mode of inheritance for gene: PIK3C2A was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PIK3C2A were set to 31034465
Phenotypes for gene: PIK3C2A were set to Oculoskeletodental syndrome, 618440
Review for gene: PIK3C2A was set to AMBER
Added comment: PIK3C2A is on a number of panels including a Green rating on Skeletal dysplasia (Version 1.244) clinical support advised that as PIK3C2A phenotype includes DD, gene should be rated as Amber on this panel.
Sources: Expert Review
Intellectual disability v2.1127 ZNF292 Catherine Snow Deleted their review
Intellectual disability v2.1127 ZNF292 Catherine Snow edited their review of gene: ZNF292: Changed rating: AMBER
Intellectual disability v2.1127 ZNF292 Catherine Snow reviewed gene: ZNF292: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.1127 FAM160B1 Ellen McDonagh Classified gene: FAM160B1 as Red List (low evidence)
Intellectual disability v2.1127 FAM160B1 Ellen McDonagh Added comment: Comment on list classification: Gene added by external reviewer, and promoted from grey to Red as the function of the protein/gene is still unknown at this stage. One family and another unrelated individual reported with developmental delay/ID and variants in this gene, however this will be kept red until further evidence arises.
Intellectual disability v2.1127 FAM160B1 Ellen McDonagh Gene: fam160b1 has been classified as Red List (Low Evidence).
Intellectual disability v2.1126 SCAMP5 Ellen McDonagh Classified gene: SCAMP5 as Amber List (moderate evidence)
Intellectual disability v2.1126 SCAMP5 Ellen McDonagh Added comment: Comment on list classification: Gene added by external Reviewer, and promoted to Amber due to review and overall evidence.
Intellectual disability v2.1126 SCAMP5 Ellen McDonagh Gene: scamp5 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1125 ZNF292 Ellen McDonagh Classified gene: ZNF292 as Amber List (moderate evidence)
Intellectual disability v2.1125 ZNF292 Ellen McDonagh Added comment: Comment on list classification: Gene added by external reviewer. Promoted from grey to Amber due to the evidence presented, and reflecting the rating of 'probable' in Gene2Phenotype for ZNF292-related developmental disorder. At this stage, this has not been made Green due to uncertainty regarding the penetrance and the comment from the reviewer regarding manual review of some relevant LoF variants in gnomAD suggested that they represent false positive calls.
Intellectual disability v2.1125 ZNF292 Ellen McDonagh Gene: znf292 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1124 AP1B1 Catherine Snow Classified gene: AP1B1 as Amber List (moderate evidence)
Intellectual disability v2.1124 AP1B1 Catherine Snow Gene: ap1b1 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1123 AP1B1 Catherine Snow reviewed gene: AP1B1: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1123 FDFT1 Catherine Snow Classified gene: FDFT1 as Amber List (moderate evidence)
Intellectual disability v2.1123 FDFT1 Catherine Snow Gene: fdft1 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1122 FDFT1 Catherine Snow reviewed gene: FDFT1: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.1122 TMX2 Konstantinos Varvagiannis edited their review of gene: TMX2: Changed publications: 31586943, 31270415, 31735293
Intellectual disability v2.1122 TMX2 Konstantinos Varvagiannis edited their review of gene: TMX2: Added comment: A recent report by Vandervore, Schot et al. following the previous review (Am J Hum Genet. 2019 Nov 12 - PMID: 31735293), provides further evidence that biallelic TMX2 mutations cause malformations of cortical development, microcephaly, DD and ID and epilepsy.

As a result this gene should probably be considered for inclusion in the ID/epilepsy panels with green rating.

Overall, 14 affected subjects from 10 unrelated families are reported in the aforementioned study. The majority had severe DD/ID (failure to achieve milestones, absent speech/ambulation and signs of cerebral palsy) with few having a somewhat milder impairment. 12 (of the 14) presented with epilepsy (spasms, myoclonic seizures, focal seizures with/without generalization or generalized tonic-clonic seizures) with onset most often in early infancy. Upon brain MRI (in 12 individuals), 5 presented polymicrogyria, 2 others pachygyria, 4 with brain atrophy, etc.

All individuals were found to harbor biallelic TMX2 mutations by exome sequencing while previous investigations in several had ruled out alternative causes (infections, metabolic or chromosomal anomalies). Missense variants, an in-frame deletion as well as pLoF (stopgain/frameshift) variants were reported. [NM_015959.3 used as ref below].

The effect of variants was supported by mRNA studies, eg. RT-qPCR/allele specific RT-qPCR. The latter proved reduced expression for a frameshift variant (c.391dup / p.Leu131Profs*6) most likely due to NMD. Total mRNA levels were also 23% lower in an individual compound htz for a missense variant and a stopgain one localized in the last exon (c.757C>T / p.Arg253*). As for the previously reported c.614G>A (p.Arg205Gln), affecting the last nucleotide of exon 6, total mRNA in skin fibroblasts from a homozygous individual was not significantly decreased. RNA-Seq however demonstrated the presence of 4 different transcripts (roughly 25% each), one representing the regular mRNA, one with intron 6 retention (also present at low levels in healthy individuals), one with loss of 11 nucleotides within exon 6 and a fourth one due to in-frame skipping of exon 6.

*To the best of my understanding :

Thioredoxin (TRX)-related transmembrane proteins (TMX) belong to the broader family of oxidoreductases of protein disulfide isomerase (PDI) having an important role in protein folding.

Study of the data from the Allen Human Brain Atlas suggest relevant fetal expression also increasing during postnatal life.

As RNA-seq was carried out for 2 individuals, GO analysis suggested that the most deregulated clusters of genes are implicated in post-translational protein modifications (as would be expected for PDIs), membranes and synapse while pathway analysis suggested that relevant categories were inhibited eg. nervous system development/function and cell growth/proliferation/survival.

Upon transfection of HEK293T cells, exogenous TMX2 was shown to co-localize with calnexin (CNX) to the (ER) mitochondria-associated-membrane. Mass-spectrometry based analysis of co-immunoprecipitated proteins confirmed interaction with CNX but also other regulators of calcium homeostasis, mitochondrial membrane components and respiratory chain NADH dehydrogenase.

Study of the mitochondrial activity of TMX2-deficient fibroblasts suggested reduced respiratory reserve capacity, compensated by increased glycolytic activity.

TMX2 occurs in both reduced and oxidized monomeric form. It also forms (homo)dimers with the ratio of dimers/monomers increasing under conditions of oxidative stress. Variant TMX2 increased propensity to form dimers, thus mimicking increased oxidative state. This was observed under stress but also under native conditions.

---------; Changed rating: GREEN
Intellectual disability v2.1122 WDFY3 Ivone Leong Classified gene: WDFY3 as Amber List (moderate evidence)
Intellectual disability v2.1122 WDFY3 Ivone Leong Added comment: Comment on list classification: Gene promoted from Red to Amber based on evidence provided by expert reviewer. All affected individuals have mild-moderate ID, therefore the gene has been rated Amber.
Intellectual disability v2.1122 WDFY3 Ivone Leong Gene: wdfy3 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1121 WDFY3 Ivone Leong Publications for gene: WDFY3 were set to 27008544
Intellectual disability v2.1120 IQSEC1 Catherine Snow Classified gene: IQSEC1 as Amber List (moderate evidence)
Intellectual disability v2.1120 IQSEC1 Catherine Snow Gene: iqsec1 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1119 IQSEC1 Catherine Snow reviewed gene: IQSEC1: Rating: AMBER; Mode of pathogenicity: None; Publications: 31607425; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1119 SVBP Catherine Snow Phenotypes for gene: SVBP were changed from Neurodevelopmental disorder with ataxia, hypotonia, and microcephaly, 618569 to Neurodevelopmental disorder with ataxia, hypotonia, and microcephaly, 618569
Intellectual disability v2.1119 SVBP Catherine Snow Mode of inheritance for gene: SVBP was changed from BIALLELIC, autosomal or pseudoautosomal to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1119 SVBP Catherine Snow Phenotypes for gene: SVBP were changed from Neurodevelopmental disorder with ataxia, hypotonia, and microcephaly, 618569 to Neurodevelopmental disorder with ataxia, hypotonia, and microcephaly, 618569
Intellectual disability v2.1119 SVBP Catherine Snow Publications for gene: SVBP were set to 26350204; 31363758; 30607023
Intellectual disability v2.1119 SVBP Catherine Snow Phenotypes for gene: SVBP were changed from to Neurodevelopmental disorder with ataxia, hypotonia, and microcephaly, 618569
Intellectual disability v2.1118 SVBP Catherine Snow Publications for gene: SVBP were set to 26350204
Intellectual disability v2.1118 SVBP Catherine Snow Mode of inheritance for gene: SVBP was changed from Unknown to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1117 SVBP Catherine Snow reviewed gene: SVBP: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: Neurodevelopmental disorder with ataxia, hypotonia, and microcephaly, 618569; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1117 NSF Ivone Leong Classified gene: NSF as Red List (low evidence)
Intellectual disability v2.1117 NSF Ivone Leong Added comment: Comment on list classification: New gene submitted by expert reviewed. Based on the evidence provided it was decided that there is currently not enough evidence to establish a gene-phenotype association. Therefore, this gene has been given a Red rating.
Intellectual disability v2.1117 NSF Ivone Leong Gene: nsf has been classified as Red List (Low Evidence).
Intellectual disability v2.1116 KCNT2 Ivone Leong Classified gene: KCNT2 as Green List (high evidence)
Intellectual disability v2.1116 KCNT2 Ivone Leong Added comment: Comment on list classification: New gene submitted by expert reviewer. Based on the evidence provided it was decided that there is enough evidence for this gene to be given Green status.
Intellectual disability v2.1116 KCNT2 Ivone Leong Gene: kcnt2 has been classified as Green List (High Evidence).
Intellectual disability v2.1115 KCNT2 Ivone Leong Added comment: Comment on mode of pathogenicity: Variants have gain-of-function effect.
Intellectual disability v2.1115 KCNT2 Ivone Leong Mode of pathogenicity for gene: KCNT2 was changed from None to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Intellectual disability v2.1114 KCNT2 Ivone Leong Phenotypes for gene: KCNT2 were changed from ?Epileptic encephalopathy, early infantile 57, MIM 617771 to ?Epileptic encephalopathy, early infantile 57, 617771
Intellectual disability v2.1113 TMX2 Ivone Leong Classified gene: TMX2 as Amber List (moderate evidence)
Intellectual disability v2.1113 TMX2 Ivone Leong Added comment: Comment on list classification: New gene submitted by expert reviewer. Based on the submitted evidence the gene has been given an Amber rating until further evidence is available to promote it to Green status.
Intellectual disability v2.1113 TMX2 Ivone Leong Gene: tmx2 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1112 CNOT2 Ivone Leong Classified gene: CNOT2 as Green List (high evidence)
Intellectual disability v2.1112 CNOT2 Ivone Leong Added comment: Comment on list classification: New gene added by expert reviewer. There is enough evidence to promote this gene to Green status.
Intellectual disability v2.1112 CNOT2 Ivone Leong Gene: cnot2 has been classified as Green List (High Evidence).
Intellectual disability v2.1111 CNOT2 Ivone Leong Phenotypes for gene: CNOT2 were changed from Intellectual developmental disorder with nasal speech, dysmorphic facies, and variable skeletal anomalies, MIM 618608 to Intellectual developmental disorder with nasal speech, dysmorphic facies, and variable skeletal anomalies, 618608
Intellectual disability v2.1110 DMXL2 Ivone Leong Classified gene: DMXL2 as Green List (high evidence)
Intellectual disability v2.1110 DMXL2 Ivone Leong Added comment: Comment on list classification: Promoted from Red to Green based on expert reviewer's comments/evidence.
Intellectual disability v2.1110 DMXL2 Ivone Leong Gene: dmxl2 has been classified as Green List (High Evidence).
Intellectual disability v2.1109 DMXL2 Ivone Leong Phenotypes for gene: DMXL2 were changed from Sensorineural Hearing Loss; ORPHA90636; OMIM:612186 to Sensorineural Hearing Loss; ORPHA90636; Epileptic encephalopathy, early infantile, 81, 618663; ?Polyendocrine-polyneuropathy syndrome, 616113
Intellectual disability v2.1108 DMXL2 Ivone Leong Publications for gene: DMXL2 were set to 25248098
Intellectual disability v2.1107 VAMP7 Eleanor Williams Added comment: Comment on mode of inheritance: This gene is in the pseudoautosomal region shared between chromosomes X and Y. The mode of inheritance should therefore be set to Biallelic or Monoallelic once more cases establish the inheritance pattern.
Intellectual disability v2.1107 VAMP7 Eleanor Williams Mode of inheritance for gene: VAMP7 was changed from X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) to Unknown
Intellectual disability v2.1106 SPRY3 Eleanor Williams Added comment: Comment on mode of inheritance: This gene is in the pseudoautosomal region shared between chromosomes X and Y. The mode of inheritance should therefore be set to Biallelic or Monoallelic once more cases establish the inheritance pattern.
Intellectual disability v2.1106 SPRY3 Eleanor Williams Mode of inheritance for gene: SPRY3 was changed from X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) to Unknown
Intellectual disability v2.1105 SLC25A6 Eleanor Williams Added comment: Comment on mode of inheritance: This gene is in the pseudoautosomal region shared between chromosomes X and Y. The mode of inheritance should therefore be set to Biallelic or Monoallelic once more cases establish the inheritance pattern.
Intellectual disability v2.1105 SLC25A6 Eleanor Williams Mode of inheritance for gene: SLC25A6 was changed from X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) to Unknown
Intellectual disability v2.1104 P2RY8 Eleanor Williams Added comment: Comment on mode of inheritance: This gene is in the pseudoautosomal region shared between chromosomes X and Y. The mode of inheritance should therefore be set to Biallelic or Monoallelic once more cases establish the inheritance pattern.
Intellectual disability v2.1104 P2RY8 Eleanor Williams Mode of inheritance for gene: P2RY8 was changed from X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) to Unknown
Intellectual disability v2.1103 PLCXD1 Eleanor Williams Added comment: Comment on mode of inheritance: This gene is in the pseudoautosomal region shared between chromosomes X and Y. The mode of inheritance should therefore be set to Biallelic or Monoallelic once more cases establish the inheritance pattern.
Intellectual disability v2.1103 PLCXD1 Eleanor Williams Mode of inheritance for gene: PLCXD1 was changed from X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) to Unknown
Intellectual disability v2.1102 DMXL2 Konstantinos Varvagiannis changed review comment from: This gene can be considered for upgrade to green rating (ID and epilepsy with >=4 relevant individuals/families/variants and >=2 studies, role of the protein, effect of variants in most cases demonstrated, phenotypic similarities with other disorders affecting autophagy, some evidence from animal models, etc).

Rare heterozygous variants disrupting DMXL2 (intragenic losses/gains, SNVs, CNVs affecting also additional genes) have been reported in individuals with variable neurodevelopmental disorders (ASD and ID) or psychiatric phenotypes [Costain et al. 2019 - PMID: 30732576 - summarized in Table 1]. (Highly) variable expressivity and possibly incomplete penetrance were proposed in the respective study. As a result evidence for ID/seizures due to monoallelic variants appears to be relatively limited.

DD, ID and (probably) epilepsy appear however to be features in several individuals with biallelic pathogenic variants as summarized in the studies below.

OMIM recently added a relevant entry with the DMXL2-associated phenotypes being the following:
- Epileptic encephalopathy, early infantile, 81; EIEE81 - 618663 (AD) [based on refs 2,3]
- ?Deafness, autosomal dominant 71 - 617605 (AD) [DD/ID/seizures are not part of the phenotype]
- ?Polyendocrine-polyneuropathy syndrome - 616113 (AR) [based on ref1]

DMXL2 is not associated with any phenotype in G2P. In SysID it is listed as a candidate ID gene based on the report by Tata et al (ref1). This gene is included in some gene panels for ID.

[1] Tata el al. (2014 - PMID: 25248098) reported on 3 sibs born to consanguineous Senegalese parents, presenting with a progressive endocrine and neurodevelopmental disorder. Features incl. incomplete puberty, central hypothyroidism, abnormal glucose regulation, moderate ID (3/3) and peripheral polyneuropathy. Seizures were not part of the phenotype. Linkage analysis suggested 2 candidate regions on chromosomes 13 and 15 with a LOD score of 2.5. High throughput sequencing of genes within these regions (~500) in an affected member and parent revealed a 15 bp in-frame deletion of DMXL2 (NM_015263.4:c.5827_5841del / p.Asp1943_Ser1947del). Sanger sequencing of other affected and unaffected members supported AR inheritance. RT-qPCR demonstrated that DMXL2 mRNA levels in blood lymphocytes were significantly lower in homozygous patients compared to heterozygous or wt family members or controls. The authors demonstrated that the encoded protein (rabconnectin-3a) is a synaptic protein (expressed in exocytosis vesicles) at the ends of axons of GnRH producing neurons. Neuron-specific deletion of one allele in mice resulted in delayed puberty and very low fertility. Adult mice had lower number of GnRH neurons in hypothalamus. siRNA-mediated downregulation of Dmxl2 expression in an insulin-secreting cell line resulted in only slight insulin secretion in response to augmenting concentrations of glucose, providing evidence of involvement of the protein in control of regulated insulin secretion.
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[2] Maddirevula et al. (2019 - PMID: 30237576) reported briefly on a 36 months old boy, born to consanguineous parents, homozygous for a frameshift DMXL2 variant [individual 17-3220 | NM_001174117.1:c.4349_4350insTTACATGA or p.(Glu1450Aspfs*23)]. Features included focal seizures (onset at the age of 3m) with subsequent global DD, absent eye contact, cerebral atrophy and macrocephaly. This individual was identified following re-evaluation of exome data in a database of ~1550 exomes specifically for homozygous variants that would have been classified earlier as LP/P if the respective gene had sufficient evidence for association with a disorder. The family was not reported to have other affected members. As the authors noted, the boy was not known to have the multi-endocrine abnormalities reported by Tata et al. There are no additional information provided (eg. on confirmation of variants, etc).
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[3] Esposito et al. (2019 - PMID: 31688942) report on 3 sibling pairs (all 3 families unrelated) with biallelic DMXL2 mutations and summarize previous evidence on the gene and the DMXL2-related phenotypes.

All presented a highly similar phenotype of Ohtahara syndrome (seizures with onset in the first days of life, tonic/myoclonic/occasionaly focal, burst-suppression upon EEG), profound DD/ID, quadriparesis, sensorineural hearing loss and presence of dysmorphic features. Sibs from 2 families presented evidence of peripheral polyneuropathy. Early brain MRIs revealed thin CC and hypomyelination in all, with later scans suggestive of gray and white matter shrinkage with leukoencephalopathy. None achieved developmental skills following birth with 5/6 deceased by the age of 9 years.

Exome sequencing revealed biallelic DMXL2 variants in all, with compatible parental segregation studies (NM_015263.3):
- Fam1 (2 sibs) : c.5135C>T (p.Ala1712Val) in trans with c.4478C>G (p.Ser1493*)
- Fam2 (2 sibs) : homozygosity for c.4478C>A (p.Ser1493*)
- Fam3 (2 sibs) : homozygosity for c.7518-1G>A

Heterozygous parents (aged 39-59) did not exhibit hearing impairment [report of a single multigenerational family by Chen et al (2017 - PMID: 27657680) where a heterozygous missense variant segregated with hearing loss - respective OMIM entry: ?Deafness, autosomal dominant 71 - 617605].

In patients' fibroblasts, effect of the variants on mRNA/protein expression was demonstrated with mRNA expressed only in a patient from family 1, and degraded/absent for the 2 stopgain SNVs affecting codon 1493. Skipping of ex31 leading to frameshift/introduction of a PTC was shown for the splice variant (p.Trp2508Argfs*4 secondary to c.7518-1G>A). Protein was also absent upon western-blot.

DMXL2 encodes a vesicular protein, DmX-Like protein 2 or rabconnectin-3a (cited Tata et al).

The gene is expressed in brain ( https://www.gtexportal.org/home/gene/DMXL2 ).

As Esposito et al comment, it is known to regulate the trafficking and activity of v-ATPase the latter having a role in acidifying intracellular organelles and promoting endosomal maturation (cited PMIDs : 25248098, 19758563, 22875945, 24802872).

In line with this, staining of patients' fibroblasts using the acidotropic dye LysoTracker demonstrated increased signal, reversed by re-expression of DMXL2 protein. Overall an acidic shift in pH with impairment of lysosomal structures and function was suggested. The authors provided additional evidence for altered lysosomal function and associated autophagy with accumulation of autophagy receptors (eg p62) and substrates (polyubiquitinated proteins). Vacuolization and accumulation of atypical fusion-like structures was shown upon ultrastractural analysis.

shRNA-mediated downregulation/silencing of Dmxl2 in mouse hippocampal neurons resulted also in altered lysosomal structures and defective autophagy. The neurons exhibited impaired neurite elongation and synapse formation.

The authors suggest similarities with Vici syndrome, where biallelic EPG5 mutations result in autophagic defects and clinical manifestations of DD/ID/epilepsy.

Dmxl2 homozygous ko mice display embryonic lethality with heterozygous mice displaying macrocephaly and corpus callosum dysplasia (cited PMIDs: 25248098, 30735494) .; to: This gene can be considered for upgrade to green rating (ID and epilepsy with >=4 relevant individuals/families/variants and >=2 studies, role of the protein, effect of variants in most cases demonstrated, phenotypic similarities with other disorders affecting autophagy, some evidence from animal models, etc).

Rare heterozygous variants disrupting DMXL2 (intragenic losses/gains, SNVs, CNVs affecting also additional genes) have been reported in individuals with variable neurodevelopmental disorders (ASD and ID) or psychiatric phenotypes [Costain et al. 2019 - PMID: 30732576 - summarized in Table 1]. (Highly) variable expressivity and possibly incomplete penetrance were proposed in the respective study. As a result evidence for ID/seizures due to monoallelic variants appears to be relatively limited.

DD, ID and (probably) epilepsy appear however to be features in several individuals with biallelic pathogenic variants as summarized in the studies below.

OMIM recently added a relevant entry with the DMXL2-associated phenotypes being the following:
- Epileptic encephalopathy, early infantile, 81; EIEE81 - 618663 (AR) [based on refs 2,3]
- ?Deafness, autosomal dominant 71 - 617605 (AD) [DD/ID/seizures are not part of the phenotype]
- ?Polyendocrine-polyneuropathy syndrome - 616113 (AR) [based on ref1]

DMXL2 is not associated with any phenotype in G2P. In SysID it is listed as a candidate ID gene based on the report by Tata et al (ref1). This gene is included in some gene panels for ID.

[1] Tata el al. (2014 - PMID: 25248098) reported on 3 sibs born to consanguineous Senegalese parents, presenting with a progressive endocrine and neurodevelopmental disorder. Features incl. incomplete puberty, central hypothyroidism, abnormal glucose regulation, moderate ID (3/3) and peripheral polyneuropathy. Seizures were not part of the phenotype. Linkage analysis suggested 2 candidate regions on chromosomes 13 and 15 with a LOD score of 2.5. High throughput sequencing of genes within these regions (~500) in an affected member and parent revealed a 15 bp in-frame deletion of DMXL2 (NM_015263.4:c.5827_5841del / p.Asp1943_Ser1947del). Sanger sequencing of other affected and unaffected members supported AR inheritance. RT-qPCR demonstrated that DMXL2 mRNA levels in blood lymphocytes were significantly lower in homozygous patients compared to heterozygous or wt family members or controls. The authors demonstrated that the encoded protein (rabconnectin-3a) is a synaptic protein (expressed in exocytosis vesicles) at the ends of axons of GnRH producing neurons. Neuron-specific deletion of one allele in mice resulted in delayed puberty and very low fertility. Adult mice had lower number of GnRH neurons in hypothalamus. siRNA-mediated downregulation of Dmxl2 expression in an insulin-secreting cell line resulted in only slight insulin secretion in response to augmenting concentrations of glucose, providing evidence of involvement of the protein in control of regulated insulin secretion.
-----------
[2] Maddirevula et al. (2019 - PMID: 30237576) reported briefly on a 36 months old boy, born to consanguineous parents, homozygous for a frameshift DMXL2 variant [individual 17-3220 | NM_001174117.1:c.4349_4350insTTACATGA or p.(Glu1450Aspfs*23)]. Features included focal seizures (onset at the age of 3m) with subsequent global DD, absent eye contact, cerebral atrophy and macrocephaly. This individual was identified following re-evaluation of exome data in a database of ~1550 exomes specifically for homozygous variants that would have been classified earlier as LP/P if the respective gene had sufficient evidence for association with a disorder. The family was not reported to have other affected members. As the authors noted, the boy was not known to have the multi-endocrine abnormalities reported by Tata et al. There are no additional information provided (eg. on confirmation of variants, etc).
-----------
[3] Esposito et al. (2019 - PMID: 31688942) report on 3 sibling pairs (all 3 families unrelated) with biallelic DMXL2 mutations and summarize previous evidence on the gene and the DMXL2-related phenotypes.

All presented a highly similar phenotype of Ohtahara syndrome (seizures with onset in the first days of life, tonic/myoclonic/occasionaly focal, burst-suppression upon EEG), profound DD/ID, quadriparesis, sensorineural hearing loss and presence of dysmorphic features. Sibs from 2 families presented evidence of peripheral polyneuropathy. Early brain MRIs revealed thin CC and hypomyelination in all, with later scans suggestive of gray and white matter shrinkage with leukoencephalopathy. None achieved developmental skills following birth with 5/6 deceased by the age of 9 years.

Exome sequencing revealed biallelic DMXL2 variants in all, with compatible parental segregation studies (NM_015263.3):
- Fam1 (2 sibs) : c.5135C>T (p.Ala1712Val) in trans with c.4478C>G (p.Ser1493*)
- Fam2 (2 sibs) : homozygosity for c.4478C>A (p.Ser1493*)
- Fam3 (2 sibs) : homozygosity for c.7518-1G>A

Heterozygous parents (aged 39-59) did not exhibit hearing impairment [report of a single multigenerational family by Chen et al (2017 - PMID: 27657680) where a heterozygous missense variant segregated with hearing loss - respective OMIM entry: ?Deafness, autosomal dominant 71 - 617605].

In patients' fibroblasts, effect of the variants on mRNA/protein expression was demonstrated with mRNA expressed only in a patient from family 1, and degraded/absent for the 2 stopgain SNVs affecting codon 1493. Skipping of ex31 leading to frameshift/introduction of a PTC was shown for the splice variant (p.Trp2508Argfs*4 secondary to c.7518-1G>A). Protein was also absent upon western-blot.

DMXL2 encodes a vesicular protein, DmX-Like protein 2 or rabconnectin-3a (cited Tata et al).

The gene is expressed in brain ( https://www.gtexportal.org/home/gene/DMXL2 ).

As Esposito et al comment, it is known to regulate the trafficking and activity of v-ATPase the latter having a role in acidifying intracellular organelles and promoting endosomal maturation (cited PMIDs : 25248098, 19758563, 22875945, 24802872).

In line with this, staining of patients' fibroblasts using the acidotropic dye LysoTracker demonstrated increased signal, reversed by re-expression of DMXL2 protein. Overall an acidic shift in pH with impairment of lysosomal structures and function was suggested. The authors provided additional evidence for altered lysosomal function and associated autophagy with accumulation of autophagy receptors (eg p62) and substrates (polyubiquitinated proteins). Vacuolization and accumulation of atypical fusion-like structures was shown upon ultrastractural analysis.

shRNA-mediated downregulation/silencing of Dmxl2 in mouse hippocampal neurons resulted also in altered lysosomal structures and defective autophagy. The neurons exhibited impaired neurite elongation and synapse formation.

The authors suggest similarities with Vici syndrome, where biallelic EPG5 mutations result in autophagic defects and clinical manifestations of DD/ID/epilepsy.

Dmxl2 homozygous ko mice display embryonic lethality with heterozygous mice displaying macrocephaly and corpus callosum dysplasia (cited PMIDs: 25248098, 30735494) .
Intellectual disability v2.1102 DMXL2 Konstantinos Varvagiannis reviewed gene: DMXL2: Rating: GREEN; Mode of pathogenicity: None; Publications: 25248098, 30237576, 31688942; Phenotypes: Epileptic encephalopathy, early infantile, 81, MIM 618663, ?Polyendocrine-polyneuropathy syndrome, MIM 616113; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown; Current diagnostic: yes
Intellectual disability v2.1102 IL3RA Eleanor Williams Added comment: Comment on mode of inheritance: This gene is in the pseudoautosomal region shared between chromosomes X and Y. The mode of inheritance should therefore be set to Biallelic or Monoallelic once more cases establish the inheritance pattern.
Intellectual disability v2.1102 IL3RA Eleanor Williams Mode of inheritance for gene: IL3RA was changed from X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) to Unknown
Intellectual disability v2.1101 DHRSX Eleanor Williams Added comment: Comment on mode of inheritance: This gene is in the pseudoautosomal region shared between chromosomes X and Y. The mode of inheritance should therefore be set to Biallelic or Monoallelic once more cases establish the inheritance pattern.
Intellectual disability v2.1101 DHRSX Eleanor Williams Mode of inheritance for gene: DHRSX was changed from X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) to Unknown
Intellectual disability v2.1100 CRLF2 Eleanor Williams Added comment: Comment on mode of inheritance: This gene is in the pseudoautosomal region shared between chromosomes X and Y. The mode of inheritance should therefore be set to Biallelic or Monoallelic once more cases establish the inheritance pattern.
Intellectual disability v2.1100 CRLF2 Eleanor Williams Mode of inheritance for gene: CRLF2 was changed from X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) to Unknown
Intellectual disability v2.1099 AKAP17A Eleanor Williams Added comment: Comment on mode of inheritance: This gene is in the pseudoautosomal region shared between chromosomes X and Y. The mode of inheritance should therefore be set to Biallelic or Monoallelic once more cases establish the inheritance pattern.
Intellectual disability v2.1099 AKAP17A Eleanor Williams Mode of inheritance for gene: AKAP17A was changed from X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) to Unknown
Intellectual disability v2.1098 ZNF292 Konstantinos Varvagiannis gene: ZNF292 was added
gene: ZNF292 was added to Intellectual disability. Sources: Radboud University Medical Center, Nijmegen,Literature
Mode of inheritance for gene: ZNF292 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: ZNF292 were set to 31723249; 29904178
Phenotypes for gene: ZNF292 were set to Intellectual disability; Autism; Attention deficit hyperactivity disorder; Abnormality of the face; Abnormal muscle tone; Abnormality of nervous system morphology; Growth abnormality; Feeding difficulties; Abnormality of the skeletal system; Abnormality of the cardiovascular system; Microcephaly; Seizures
Penetrance for gene: ZNF292 were set to Incomplete
Review for gene: ZNF292 was set to GREEN
gene: ZNF292 was marked as current diagnostic
Added comment: Mirzaa et al. (2019 - PMID: 31723249) report on 28 individuals (from 27 families) with putatively pathogenic ZNF292 variants.

Main features consisted of DD and ID (27/28 - mild in 40%, moderate in 22%, severe in 11%) with or without ASD and ADHD. A single individual had no evidence of ID but had speech delay and ASD at the age of 6. Additional features (by diminishing order of frequency) included presence of non-specific dysmorphic features (~45%), abnormal tone, brain MRI abnormalities, growth failure, feeding difficulties, skeletal and cardiac anomalies, microcephaly and epilepsy (~11%).

As the authors comment, ZNF292 encodes a zinc finger protein, acting as a transcription factor.

Evidence is provided that gene has high expression in the developing human brain, with its expression being higher in prenatal development and diminishing postnatally. Znf292 is also expressed in adult mouse brain (highest in hippocampus/Purkinje cells).

Variants were identified by exome or targeted panel sequencing (targeted capture/molecular inversion probes). Previous investigations (eg. aCGH, analysis of relevant genes) had probably ruled out alternative causes in most with few having VUS or possibly relevant additional variants (eg. a KDM5C stopgain variant in a male).

24 putatively pathogenic variants were observed in this cohort, all predicting LoF (stopgain, frameshift or splice variants). All were de novo with the exception of one family where the variant was inherited from an affected parent. Almost all were absent from gnomAD and had CADD scores > 35.

Most variants lied within the last and largest exon that encodes a DNA binding domain. RT-PCR on RNA from 2 individuals harboring such variants confirmed that NMD does not apply. This exon however represents ~88% of the total coding length so the distribution of variants in this (NMD escaping) region was consistent with what would also be expected by chance.

ZNF292 has a pLI of 1 in gnomAD. Manual review of some relevant LoF variants in gnomAD suggested that they represent false positive calls.

As a result, the effect of variants is not clear although haploinsufficiency is still possible based also on phenotype of (larger) deletions spanning this gene (cited: Engwerda et al - PMID: 29904178 / The study focuses on deletions of the broader 6q. A possible role of ZNF292 is discussed as autism was present in 4/10 individuals with deletions encompassing this gene).

Based on the aforementioned cohort with one individual being diagnosed with mild ID only as an adult and/or presence of 5 pLoF variants in gnomAD the authors propose that some variants may be incompletely penetrant or associated with only mild features.

Finally, 15 additional individuals (belonging to 12 families) harbored variants for which pathogenicity was suspected (but could not be concluded) due to insufficient phenotypic information, lack of sufficient parental studies or missense variants. In this cohort variants were mostly pLoF, while 3 individuals (incl. 2 sibs) had a de novo missense SNV.
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Other studies were not here reviewed as some of the individuals reported were published previously in larger cohorts.
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There is no associated phenotype in OMIM / G2P. SysID includes this gene among the candidate ID ones.
ZNF292 is included in gene panels for ID offered by some diagnostic laboratories (incl. Radboudumc and GeneDx).
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Overall ZNF292 could be added to the ID panel probably with green (or amber) rating.

[Please consider inclusion in other possibly relevant panels eg. autism, epilepsy]
Sources: Radboud University Medical Center, Nijmegen, Literature
Intellectual disability v2.1098 CNOT2 Konstantinos Varvagiannis gene: CNOT2 was added
gene: CNOT2 was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen
Mode of inheritance for gene: CNOT2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: CNOT2 were set to 31512373; 31145527; 28135719; 28159701; 30768759; 21505450; 18076123; 22247066
Phenotypes for gene: CNOT2 were set to Intellectual developmental disorder with nasal speech, dysmorphic facies, and variable skeletal anomalies, MIM 618608
Penetrance for gene: CNOT2 were set to unknown
Review for gene: CNOT2 was set to GREEN
gene: CNOT2 was marked as current diagnostic
Added comment: Heterozygous pathogenic CNOT2 variants cause Intellectual developmental disorder with nasal speech, dysmorphic facies, and variable skeletal anomalies (MIM 618608 - recently added disorder in OMIM). Larger 12q15 deletions, spanning CNOT2 have been reported in patients with similar phenotype.

Relevant individuals - most discussed below - include 2 patients with truncating de novo mutation, 1 with de novo intragenic deletion, few with small deletions spanning also 2-3 additional proximal genes and others with larger 12q15 deletions encompassing CNOT2 and several other genes.

Overall the phenotype - summarized by Uehara et al. (Ref1 - below) - seems to consist of language delay, mild motor delay (in most), some suggestive facial features (upslanted palpebral fissures, anteverted nares, thin upper lip and micrognathia). Nasal speech has also been reported in some individuals.

As commented by Uehara et al. (Ref1), CNOT2 (CCR4-NOT transcription complex subunit 2) is a member of the carbon catabolite repressor 4 complex (CCR4-NOT), the latter having an important role in deadenylation of mRNA and global mRNA expression. Disruption of the complex - which can be caused by loss of one of its components - results in various human disorders incl. neural diseases. siRNA CNOT2 depletion has been shown to induce CCR4-NOT disruption (cited PMIDs: 16284618, 29438013, 31006510, 21299754).

The type of variants (truncating, intragenic deletion, larger deletions) and the highly overlapping phenotypes in the respective patients suggest happloinsufficiency as the underlying mechanism. CNOT2 has also a pLI of 1 in gnomAD (o/e =0.06) and a %HI in Decipher of 4.39.

The gene appears to have relevant expression (https://www.proteinatlas.org/ENSG00000111596-CNOT2/tissue).
Animal models have not been discussed (or phenotypes possibly not sufficiently studied - MGI for Cnot2 : http://www.informatics.jax.org/marker/MGI:1919318).

CNOT2 is not associated with any phenotype in G2P. It is listed among the ID candidate genes in SysID.
This gene is included in gene panels for ID offered by some diagnostic laboratories (incl. Radboudumc).

Overall CNOT2 could be considered for inclusion in the ID panel with amber (DD although outcome is not known, presumed dysfunction of the CCR4-NOT complex, variant studies or animal models not available) or green rating (sufficient cases and variants, consistent phenotype).
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Individuals with CNOT2-only disruption:
[1] PMID: 31512373 (Uehara et al., 2019) - A 6 y.o. male investigated for hypotonia, feeding problems, DD (speech and motor), macrocephaly (+3 SD) and some possibly suggestive facial/other features was found to harbor a de novo stopgain variant (NM_001199302.1: c.946A>T, p.Lys316Ter) after trio exome sequencing. The variant and its de novo occurrence were confirmed by Sanger sequencing. NMD was the predicted effect (variant in ex11 of 21 / effect not further studied). Previous metabolic work-up and chromosomal testing had not revealed an alternative diagnosis.
[2] PMID: 31145527 (Alesi et al. 2019) - A 13 y.o. boy with hypotonia, failure to thrive, DD and following a specific schooling program for children with learning difficulties is reported. The authors comment on the facial phenotype (incl. upslanted p-f, anteverted nares, etc). Other features included valvular/supravalvular pulm. stenosis, mid aortic insufficiency, renal anomalies/failure, skeletal anomalies. Speech was nasal. CMA revealed an 85-kb 12q15 deletion spanning only CNOT2 (exons 3-15). Real-time PCR in proband and parents confirmed the variant and its de novo occurrence.
[3] PMID: 28135719 (DDD study, 2017) - An individual with developmental disorder and a de novo (validated) frameshift variant was identified [DDD4K.00807 - NM_014515.5:c.1158del / p.(L387Sfs*3)]. Phenotype in Decipher incl. abnormality of head/neck, nervous, skeletal system and growth. [https://decipher.sanger.ac.uk/ddd/research-variant/16b4f7866652f08e25a194f65535b4c5#overview].

Individuals with disruption of additional proximal genes due to CNVs:
[4] PMID: 28159701 (Alesi et al. 2017) - The authors report on a 29 y.o. individual with history of DD, learning difficulties, ID (WAIS-R IQ of 48 at the age of 17 y), some dysmorphic facial features. Additional features incl. recurrent infections, nasal voice as well as skeletal anomalies. CMA revealed a 742 kb microdeletion spanning CNOT2, KCNMB4 and PTPRB. Real-time PCR confirmed deletion and it's de novo occurrence in the proband.
[5] PMID: 30768759 (Uehara et al. 2019) - A female investigated among others for global DD (walking/1st words at 24m), mild ID, submucosal cleft palate with some distinctive facial features (upslanted p-f, micrognathia, etc) was found to harbor a 1.32-Mb deletion of 12q15 encompassing CNOT2 and 14 other genes. Given the phenotypic resemblance to patients with 12q15 deletions, the previously defined smallest region of overlap (ref 4,6), the LoF SNV in Decipher the authors suggested that CNOT2 is the critical gene for the phenotype of 12q15 deletion syndrome.

Larger deletions defining the smallest region of overlap
[6] PMID: 21505450 (Vergult et al. 2011) - 3 patients with de novo microdeletions of ~ 2.5 Mb in size with a 1.34 MB common region of overlap are reported. Learning diability, DD, nasal speech and hypothyroidism were among the common features.
[7] PMID: 18076123 (Schluth et al. 2008) - A girl with large (~10 Mb) de novo deletion of 12q15 - q21.2 identified by BAC array was described. The phenotype consisted of hypotonia, DD, moderate ID, growth delay and facial dysmorphic features.
[8] PMID: 22247066 (Lopez et al. 2012) - A patient with ID and features of Floating-Harbor syndrome was found to harbor a 4.7 Mb de novo 12q15-q21.1 deletion spanning CNOT2 and 18 additional genes.
[..]
Sources: Literature, Radboud University Medical Center, Nijmegen
Intellectual disability v2.1098 TMX2 Konstantinos Varvagiannis gene: TMX2 was added
gene: TMX2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: TMX2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TMX2 were set to 31586943; 31270415
Phenotypes for gene: TMX2 were set to Global developmental delay; Intellectual disability; Seizures; Microcephaly; Abnormal cortical gyration
Penetrance for gene: TMX2 were set to Complete
Review for gene: TMX2 was set to AMBER
Added comment: PMID: 31586943 - Ghosh et al. 2019 - reported on 8 individuals from 4 consanguineous families from the Middle East and Central Asia, all with a phenotype of DD/ID, seizures and microcephaly with lissencephaly (microlissencephaly is the term applying to the combination of two) upon brain MRI.

All patients were investigated by exome sequencing and the variant localized within a region of ROH which was common to all 4 families. All were homozygous for a TMX2 missense variant (NM_001144012.2:c.500G>A or p.Arg167Gln / NM_015959.4:c.614G>A p.Arg205Gln or hg38 - Chr11:g.57739039G>A). The variant was considered to be the best candidate, upon review of all other homozygous ones.

Sanger sequencing confirmed homozygosity for the variant in affected subjects, with additional compatible segregation studies including parents in all families as well as unaffected sibs (in two families).

Despite presence of the same mutation in all, several proximal to this variant SNPs did not appear to be shared among the families studied, thus suggesting that the variant had arisen within different haplotype blocks.

The authors comment that the variant was not previously identified in public databases. (The variant seems to correspond to rs370455806, present in 10 htz individuals in gnomAD, as well as in the GME database [GME Genotype Count 992:0:1 (hmz?) | Allele Count: 2,1984] . GME includes primarily - although not necessarily - healthy individuals).

This SNV affecting the last nucleotide of an exon of several transcripts (correct ref. is NM_001144012.2 as appears in the supplement / using NM_001347898.1 as in the fig./text the variant would lie within an intron), an eventual splicing effect was studied. mRNA transcript levels were assessed following RT-PCR using different sets of primers. There was no evidence of novel splice isoforms but mRNA levels were reduced compared to controls (15-50% in affected individuals, to a lesser level in carriers). This led to the hypothesis that NMD of an aberrantly spliced mRNA might apply, although this was not proven.

TMX2 encodes a protein disulfide isomerase (PDI). PDIs are transmembrane ER proteins which have a critical role in protein folding (PMID cited: 12670024). There were no relevant studies carried out in the article.

As for animal models, the authors comment that mice homozygous for null mutations display preweaning lethality with complete penetrance.(http://www.informatics.jax.org/diseasePortal/popup?isPhenotype=true&markerID=MGI:1914208&header=mortality/aging).
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Previously, Schot el al. (ESHG Conference 2018 Oral Presentation - Mutations in the thioredoxin related gene TMX2 cause primary microcephaly, polymicrogyria and severe neurodegeneration with impaired mitochondrial energy metabolism - available in PMID: 31270415 / https://www.nature.com/articles/s41431-019-0407-4 ) reported on 7 individuals from 5 unrelated families with biallelic TMX2 mutations. A newborn with microcephaly, polymicrogyria who died of refractory epilepsy, was compound heterozygous for 2 TMX2 variants. 6 additional individuals (from 4 unrelated families) with similar phenotype were found to harbor biallelic TMX2 mutations. It was commented that TMX2 is enriched in mitochondria-associated membrane of the ER with a role in ER stress protection and regulation of neuronal apoptosis. In line with this, fibroblasts from 2 unrelated patients showed secondary OXPHOS deficiency and increased glycolytic activity (the latter possibly as a compensatory mechanism).
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There is no associated phenotype in OMIM/G2P/SysID.
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Overall this gene could be considered for inclusion in the ID/epilepsy panel probably with amber (/red) rating pending further evidence.
Sources: Literature
Intellectual disability v2.1098 KCNT2 Konstantinos Varvagiannis gene: KCNT2 was added
gene: KCNT2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: KCNT2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: KCNT2 were set to 29069600; 29740868
Phenotypes for gene: KCNT2 were set to ?Epileptic encephalopathy, early infantile 57, MIM 617771
Penetrance for gene: KCNT2 were set to unknown
Review for gene: KCNT2 was set to GREEN
Added comment: Heterozygous pathogenic KCNT2 variants cause ?Epileptic encephalopathy, early infantile, 57 (MIM 617771).

At least 3 unrelated affected individuals have been reported :

- PMID: 29069600 - Gururaj et al. 2017 : a male child with EOEE (hypotonia, profound DD and intractable infantile seizures) due to a de novo KCNT2 missense variant (NM_001287819.1:c.720T>A or p.Phe240Leu) identified by exome sequencing.

- PMID: 29740868 - Ambrosino et al. 2018 : A girl with phenotype corresponding to West syndrome later evolving to Lennox-Gastaut syndrome. At the age of 9 years the girl displayed severe ID. Trio exome sequencing revealed a de novo missense KCNT2 variant (NM_001287820.2:c.569G>A or p.Arg190His). A 14 y.o. female recruited through the DDD study with phenotype corresponding to epilepsy of infancy with migrating focal seizures. The girl had poor language development and severe learning disability. Infective and metabolic causes were initially ruled out. Trio exome sequencing revealed a de novo missense SNV (c.569G>C or Arg190Pro).

Overall KCNT2 has been commented to contribute to a phenotypic spectrum similar and overlapping to that of KCNT1 (Ambrosino et al.). [KCNT1 is rated green in both epilepsy and ID panels].

KCNT2 was recently included in the epilepsy panel as green (functional studies summarized in the respective reviews). The gene was also recently added to G2P, associated with 'Developmental and infantile epileptic encephalopathy'. It is not commonly included in gene panels for ID offered by diagnostic laboratories.

As a result, KCNT2 could be considered for inclusion in the ID panel with green (or amber) rating.
Sources: Literature
Intellectual disability v2.1098 NSF Konstantinos Varvagiannis gene: NSF was added
gene: NSF was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: NSF was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: NSF were set to 31675180
Phenotypes for gene: NSF were set to Seizures; EEG with burst suppression; Global developmental delay; Intellectual disability
Penetrance for gene: NSF were set to unknown
Mode of pathogenicity for gene: NSF was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: NSF was set to AMBER
Added comment: Suzuki et al. (2019 - PMID: 31675180) report on 2 unrelated individuals with de novo missense NSF variants. Overall the phenotype corresponded to an early infantile epileptic encephalopathy. The first patient developed vomiting and tonic seizures immediately after birth, with burst-suppression pattern upon EEG. Trio exome sequencing, followed by Sanger sequencing of proband and parents, revealed a de novo missense variant (NM_006178.3:c.1375G>A / p.Ala459Thr), absent from public databases and predicted in silico to be deleterious (CADD score of 30). The girl died 36 days after birth due to respiratory failure. Another subject, having necessitated mechanical ventilation due to absence of spontaneous respiration after birth, developed myoclonic seizures. EEG showed a burst-suppression pattern. At the age of 3, she was noted to have persistence of seizures and profound ID. Trio exome sequencing identified a missense NSF variant (c.1688C>T / p.Pro563Leu) also confirmed and shown to be de novo by Sanger sequencing. Again the variant was absent from public datasets and had a CADD score of 34. While expression of wt NSF allele in the developing eye of Drosophila had no effect, expression of mutants severely affected eye development - suggesting a dominant negative effect. NSF encodes a homo-hexameric AAA ATPase, which is recruited by SNAPs (Soluble NSF Attachment Proteins) - and the latter by SNAREs (SNAP REceptors) - thus having a role in vesicular transport and membrane fusion. There is currently no associated phenotype in OMIM/G2P. Overall, this gene could be considered for inclusion probably with amber/red rating pending further evidence (eg. additional work-up or alternative causes/explanations not discussed).
Sources: Literature
Intellectual disability v2.1098 WDFY3 Konstantinos Varvagiannis reviewed gene: WDFY3: Rating: GREEN; Mode of pathogenicity: None; Publications: 27008544, 31327001, 25198012, 28191889; Phenotypes: ?Microcephaly 18, primary, autosomal dominant - MIM 617520; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown; Current diagnostic: yes
Intellectual disability v2.1098 SCAMP5 Konstantinos Varvagiannis gene: SCAMP5 was added
gene: SCAMP5 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: SCAMP5 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: SCAMP5 were set to 31439720; 20071347
Phenotypes for gene: SCAMP5 were set to Global developmental delay; Intellectual disability; Seizures; Abnormality of nervous system morphology; Behavioral abnormality
Penetrance for gene: SCAMP5 were set to unknown
Mode of pathogenicity for gene: SCAMP5 was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: SCAMP5 was set to AMBER
Added comment: PMID: 31439720 (Hubert et al. 2019) reported on 2 unrelated individuals with severe ID, seizures behavioral and brain MRI abnormalities (white matter hyperintensity and mesial temporal sclorosis), both harboring the same missense SCAMP5 mutation as a de novo event (NM_001178111.1:c.538G>T or p.Gly180Trp).

Previously aCGH +/- metabolic workup were non diagnostic.

The occurrence of the same de novo variant in both as well as the similar presentation (incl. MRI images) suggested SCAMP5 as the most probable candidate gene, despite presence of few other variants in both.

SCAMP5 is highly expressed in brain (https://www.proteinatlas.org/ENSG00000198794-SCAMP5) and previous studies have suggested a role in synaptic vesicle trafficking (PMIDs cited: 29562188, 25057210, etc).

Cultured skin fibroblasts from affected individuals failed to express SCAMP5.

Scamp is the Drosophila orthologue, with previous studies having demonstrated that mutants display defects in climbing, olfactory-assisted memory and susceptibility to heat induced seizures (PMIDs cited: 25478561, 19144841). Expression of the Scamp Gly302Trp variant in Drosophila ('equivalent' to the SCAMP5 Gly180Trp) revealed strongly reduced levels for the variant compared with wt upon Western Blot, either due to reduced expression or due to increased turnover. Overall the effect of Gly302Trp expression was similar to Scamp knockdown by RNAi (eg. rough eye phenotype, reduced ability to climb the walls of a graded tube after tapping, less/no flies reaching adult stage) but significantly different compared to wt.

As a result, a dominant-negative effect was presumed.
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PMID: 20071347 (Castermans et al. 2010) is cited as a previous report of a relevant affected individual. In this study a 40 y.o. male with early DD, mild ID (IQ of 63) and ASD was found to harbor a de novo apparently balanced t(1;15) translocation affecting CLIC4 and PPCDC (both not associated with ID). [1-Mb resolution aCGH revealed no relevant CNVs].

Studies were however focused on SCAMP5 given that the gene is located downstream of / proximal to PPCDC, has brain-enriched expression as well as involvement in synaptic trafficking and demonstrated:
- Less than 50% expression upon quantitative RT-PCR in patients leukocytes, compared to control.
- Silencing and overexpression of Scamp5 in mouse β-TC3 cells resulted in increased and suppressed respectively secretion of large dense-core vesicles (LDCVs).
- Given conservation of some components involved in secretion of dense core granules (DCGs) in platelets and LDCVs in neuronal cells, study of patient platelets - where SCAMP5 was confirmed to be expressed - suggested an altered pattern of DCGs.
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SCAMP5 is not associated with any phenotype in OMIM/G2P/SysID and not commonly included in gene panels for ID.
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Overall, this gene could be considered for inclusion in the ID and epilepsy panels probably with amber (# of unrelated individuals, 1 recurrent de novo variant and 1 regulatory effect, gene expressed in brain with a role in synaptic vesicle trafficking) or red rating (pending further evidence).
Sources: Literature
Intellectual disability v2.1098 FAM160B1 Konstantinos Varvagiannis gene: FAM160B1 was added
gene: FAM160B1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: FAM160B1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: FAM160B1 were set to 27431290; 31353455
Phenotypes for gene: FAM160B1 were set to Central hypotonia; Global developmental delay; Intellectual disability; Abnormality of the face
Penetrance for gene: FAM160B1 were set to Complete
Review for gene: FAM160B1 was set to AMBER
Added comment: Anazi et al. (2017 - PMID: 27431290) in a study of 337 subjects with ID, reported on a consanguineous family (15DG2696) with 3 affected sibs. The proband, a 7 y.o. boy had hypotonia, DD, mild ID (IQ of 69), some facial dysmorphic features as well as increased skin elasticity and joint hypermobility. Initial investigations included metabolic testing for OA and CDGs, FMR1 and aCGH. A 4 y.o. sister and a 3 y.o. brother of the proband had similar presentation of DD. Exome sequencing, autozygosity mapping and segregation studies suggested a FAM160B1 hmz missense SNV as the likely causal variant (NM_001135051.1:c.248T>C or p.Leu83Pro). There were no other candidate variants. As the encoded protein has a yet unknown function, with uncertain in silico 3D modeling, the authors speculated disruption of helices affecting fold/(ligand binding) function as the underlying effect of this variant.

Mavioğlu et al. (2019 - PMID: 31353455) reported on a 38 y.o. female with history of motor and language delay, severe ID, ataxia, behavioral abrnormalities as well as some dysmorphic features. This individual was born to consanguineous parents (2nd cousins). There was history of a deceased, similarly affected sib. Initial investigations included metabolic work-up (plasma AA, urinary OA) and karyotyping. SNP genotyping in the family (parents, affected sib, 3 unaffected sibs) and multipoint linkage analysis for AR inheritance, yielded a maximum LOD score of 2.15. Selection of homozygous regions unique to the patient (but not present in unaffected sibs) did not suggest any known ID gene. Exome sequencing of the proband, with analysis of the variants in candidate regions revealed a homozygous stopgain SNV (NM_020940.4:c.115G>T or p.Glu39*) as the best candidate variant (with few others not considered to be relevant). FAM160B1 has a pLI of 1, LoF variants in public databases have MAFs below 0.000034 with no recorded homozygotes. In silico predictions suggested a deleterious effect (CADD score of 40, etc). The previous report by Anazi and fulfilment of the ACMG criteria for its classification of this variant as pathogenic led to its consideration as causal of the patient's phenotype.

Study of the expression of the 2 isoforms of the gene (isoform1: NM_020940, 2:NM_001135051) revealed that the first is ubiquitously expressed and the second only in testes. [To my understanding the 2 isoforms seem to differ only in their last exon, the 2 reported variants affecting both isoforms - http://genome.ucsc.edu/cgi-bin/hgTracks?db=hg19&lastVirtModeType=default&lastVirtModeExtraState=&virtModeType=default&virtMode=0&nonVirtPosition=&position=chr10%3A116577123%2D116663023&hgsid=777553295_dPP9DgaheaF82gTRTfZO6XS5lEzA ]

The function of this gene remains unknown. Animal models/phenotypes are probably not available.

There is no associated phenotype in OMIM/G2P. SysID lists FAM160B1 as a candidate ID gene.
FAM160B1 is not commonly included in gene panels for ID offered by diagnostic laboratories.

As a result this gene can be considered for inclusion in the current panel probably with amber (2 families/variants, variable ID as a feature) or red rating pending further evidence (given the partial phenotypic overlap, unknown function of the gene, variants not further studied, no animal models).
Sources: Literature
Intellectual disability v2.1098 PCYT2 Konstantinos Varvagiannis gene: PCYT2 was added
gene: PCYT2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: PCYT2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PCYT2 were set to 31637422
Phenotypes for gene: PCYT2 were set to Global developmental delay; Developmental regression; Intellectual disability; Spastic paraparesis; Seizures; Spastic tetraparesis; Cerebral atrophy; Cerebellar atrophy
Penetrance for gene: PCYT2 were set to Complete
Review for gene: PCYT2 was set to GREEN
Added comment: Vaz et al. (2019 - PMID: 31637422 - DDD study among the co-authors) report on 5 individuals - from 4 families - with biallelic PCYT2 mutations.

The phenotype corresponded to a complex hererditary paraplegia with global DD, regression (4/5), ID (mild in 3/5, severe in 2/5), spastic para-/tetraparesis, epilepsy (5/5 - variable onset 2-16 yrs - focal or tonic-clonic seizures) and progressive cerebral and cerebellar atrophy.

Exome sequencing in all revealed biallelic PCYT2 variants, confirmed with Sanger s. in probands and their parents (NM_001184917.2 - corresponding to the canonical transcript used as Ref below):
- P1 (Fam1) : 2 missense SNVs in trans configuration, c.730C>T or p.His244Tyr and c.920C>T or p.Pro307Leu
- P2 (Fam2 - consanguineous of White British origin), P3 (Fam3 - Consanguineous of Turkish origin), P4,5 (Fam4 - consanguineous, unspecified origin) : homozygosity for c.1129C>T or p.Arg377Ter) affecting the last exon of 8/12 transcripts, including the canonical one.

Individuals with the same genotype displayed variable degrees of ID (eg P3 - severe / P2, P4,5 - mild ID).

For sibs in Fam4, homozygosity for a missense SACS variant led to consideration of the respective disorder (AR spastic ataxia of Charlevoix-Saguenay) though the variant was predicted to be tolerated in silico and notably the MRI images not suggestive.

All variants were absent from / had extremely low AF in public databases, with no homozygotes.

Posphatidylethanolamine (PE) is a membrane lipid, particularly enriched in human brain (45% of phospholypid fraction). PE is synthesized either via the CDP-ethanolamine pathway or by decarboxylation of phosphatidylserine in mitochondria. PCYT2 encodes CTP:phosophoethanolamine cytidyltransferase (ET) which is an ubiquitously expressed rate-limiting enzyme for PE biosynthesis in the former pathway.

In silico, the 2 missense variants - localizing in the CTP catalytic domain 2 - were predicted to be damaging, as well as to affect protein stability.

Fibroblasts of 3 patients (P1, P2, P3) representing all variants were studied:
- Enzymatic activity was shown to be significantly reduced (though not absent) compared to controls. Abnormalities were noted upon Western Blot incl. absence in all 3 patients studied of one of the 2 bands normally found in controls (probably representing the longer isoform), reduced intensity in all 3 of another band probably corresponding to a shorter isoform, and presence of an additional band of intermediate molec. mass in patients with the truncating variant.
- RT-PCR on mRNA from patient fibroblasts did not reveal (significant) reduction compared to controls.
- Lipidomic profile of patient fibroblasts was compatible with the location of the block in the phospholipid biosynthesis pathway and different from controls.

The lipidomic profile had similarities with what has been reported for EPT1 deficiency, the enzyme directly downstream of ET. The SELENO1-related phenotype (/EPT1 deficiency) is also highly overlapping.

CRISPR-Cas9 was used to generate pcyt2 partial or complete knockout (ko) zebrafish, targeting either the final (ex13) or another exon (ex3) respectively. mRNA expression was shown to be moderately reduced in the first case and severely reduced/absent in the second, compared to wt. Similarly, complete-ko (ex3) led to significantly lower survival, with impaired though somewhat better survival of partial-ko (ex13) zebrafish.

Complete knockout of Pcyt2 in mice is embryonically lethal (PMID cited: 17325045) while heterozygous mice develop features of metabolic syndrome (PMID cited: 22764088).

Given lethality in knockout zebrafish / mice and the residual activity (15-20%) in patient fibroblasts, the variants reported were thought to be hypomorphic and complete loss of function possibly incompatible with life.

PCYT2 is not associated with any phenotype in OMIM/G2P/SysID and not commonly included in gene panels for ID.

As a result this gene could included in the ID / epilepsy panels with green (~/>3 indiv/fam/variants with the nonsense found in different populations, consistent phenotype, lipidomics, in silico/in vitro/in vivo evidence) or amber rating.

[Please consider inclusion in other possibly relevant panels eg. for metabolic disorders, etc].
Sources: Literature
Intellectual disability v2.1098 PDE6D Konstantinos Varvagiannis gene: PDE6D was added
gene: PDE6D was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: PDE6D was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PDE6D were set to 24166846; 30423442
Phenotypes for gene: PDE6D were set to ?Joubert syndrome 22 - MIM 615665
Penetrance for gene: PDE6D were set to Complete
Review for gene: PDE6D was set to AMBER
gene: PDE6D was marked as current diagnostic
Added comment: Thomas et al. (2014 - PMID: 24166846) reported on a consanguineous Pakistani family with 3 members presenting variable polydactyly, brain anomalies (incl. molar tooth sign), microphthalmia/coloboma with retinal disease, renal hypoplasia suggestive of Joubert syndrome.

Genotyping with a SNP array identified a unique 17-Mb region of homozygosity on chr2 with LOD score of 2.6. The region contained 208 genes, of which 15 present in ciliary gene databases. A homozygous splicing variant appeared to be the only relevant, PDE6D being a ciliary gene within this region [NM_002601.4:c.140-1G>A]. Status of all affected members, parents and 2 unaffected sibs was verified with Sanger sequencing.

PDE6D encodes a phosphodiesterase that binds to prenyl groups and has a critical role in ciliogenesis (Humbert et al. - PMID: 23150559 and OMIM).
Several lines of evidence provided support a role for PDE6D and the reported variants :
- Study of PDE6D expression during human embryogenesis suggests ubiquitous localization and highest levels in organs affected in ciliopathies (CNS, kidney tubules, respiratory tract epitherlial cells).
- RT-PCR of mRNA from control/patient fibroblasts and sequencing confirmed the splicing defect leading to an in-frame deletion of exon 3.
- Wt and mutant protein both localized in the basal body of primary cilia (patient/control fibroblasts). Cilia in both cases had normal morphology.
- Experiments in RPE cells confirmed that INPP5E (involved in Joubert/MORM syndrome) interacts (/is probably a cargo of) PDE6D, a process dependent on prenylation.
- Exon 3 deletion was confirmed to disrupt PDE6D binding to INPP5E.
- Analysis by immunofluoresence of INPP5E localization using control/patient fibroblasts and renal tissue showed absence of INPP5E from primary cilia in the case of patient cells (but not controls) suggesting that PDE6D is important for trafficking INPP5E to the cilium.
- Previous study in mice suggested altered photoreceptor physiology in Pde6d (-/-) animals, resulting in a slowly progressing rod/cone dystrophy. The effect was however limited to the eye. (PMID cited : 17496142 - Zhang et al., 2007).
- Morpholino knockdown of pde6d resulted in pericardial edema, eye abnormalities (microphthalmia and disorganized retinal cell layers) and kidney morphogenesis defects (distended, blocked pronephric openings and proximal tubule cysts). Edema was rescued upon coinjection of morpholino with wt (but not mutant) mRNA. Similarly coinjection led to complete or partial rescue of eye development in the case of wt and mutant mRNA respectively supporting pathogenicity and (partial) loss-of-function effect for the variant.
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Mégarbané et al. (2019 - PMID: 30423442) reported on an affected 6 month-old boy born to Lebanese first-cousin parents. Features included hypotonia, developmental delay, microcephaly, oculomotor apraxia, postaxial polydactyly of hands and feet and presence of a molar tooth sign upon brain MRI. Renal and retinal anomalies were absent (also given his age). Exome sequencing revealed homozygosity for a frameshift PDE6D variant [NM_002601.3:c.367_368insG or p.(Leu123Cysfs*13)]. Sanger sequencing confirmed presence of the variant in the proband and carrier status of the parents. The variant affected the penultimate exon (note : present in only this longest transcript) and was not predicted to trigger NMD but rather lead to elimination of a highly conserved PDZ-interaction domain.
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The phenotype associated with biallelic PDE6D variants in OMIM is ?Joubert syndrome 22 - MIM 615665 based only on the 1st report ('delayed psychomotor development' among the features). There is no relevant entry in G2P. PDE6D is listed as a Current primary (/confirmed) ID gene in SysID (the aforementioned PMIDs cited).

This gene is included in gene panels for ID offered by some diagnostic laboratories (eg. GeneDx).
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Overall PDE6D could be considered for inclusion in the ID panel probably with amber rating (2 families/variants, DD but outcome otherwise unknown - evidence for the the gene causing JS seems however sufficient).
Sources: Literature
Intellectual disability v2.1098 NTNG2 Konstantinos Varvagiannis gene: NTNG2 was added
gene: NTNG2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: NTNG2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NTNG2 were set to 31372774; 31668703
Phenotypes for gene: NTNG2 were set to Central hypotonia; Global developmental delay; Intellectual disability; Behavioral abnormality; Microcephaly; Seizures
Penetrance for gene: NTNG2 were set to Complete
Review for gene: NTNG2 was set to GREEN
Added comment: [1] Abu-Libdeh et al. (2019 - PMID: 31372774) reported 8 individuals from 4 unrelated consanguineous families of Arab Muslim origin, all homozygous for NM_032536.3:c.376dup - p.(Ser126PhefsTer241). Common features included hypotonia, failure to achieve milestones and developmental stagnation without regression during the first year (~9m) of life and severe ID. Minimal purposeful hand use (grasping and bringing objects to mouth), hand stereotypies and bruxism were also observed. Microcephaly and impaired growth were almost universal (with the exception of 2 having an OFC at ~10% percentile). Relevant previous investigations were normal in all and included MECP2, SMN1, aCGH, metabolic testing, etc. The variant was identified by exome in all, and Sanger confirmed with compatible segregation studies in parents and sibs. The variant was found within a shared haplotype of ~4.35 Mb, probably due to a founder effect.

[2] Dias et al. (2019 - PMID: 31668703) described 16 individuals from 7 unrelated families from Iran, Mexico, Turkey, Egypt and Bangladesh. Parents were known to be consanguineous or shown to be distantly related. All patients were homozygous for missense variants private to each family (7 variants) identified following exome sequencing. Shared features incl. hypotonia, GDD, severe to profound ID and behavioral anomalies incl. autistic features/stereotypies (most), screaming/laughing spells (most), bruxism. Microcephaly (5/14), growth below average/FTT and GI problems were also observed.

Epilepsy was reported in 5 individuals belonging to 4 different families in these 2 studies (5/24 overall / 4 variants).

Netrin-G2, the encoded protein, is bound to the plasma membrane by GPI-anchors. Netrins-G2 and G1 (another member of the Netrin-G subfamily) are enriched in presynaptic terminals. Interaction with their cognate Netrin-G ligand trans-synaptic partners / receptors (NGL2, NGL1 respectively) has been shown to promote axon outgrowth, induce and maintain excitatory synapse formation. Complementary and non-overlapping expression in the developping and mature CNS has been shown for Netrin-G2/1 in mice (several references provided by Abu-Libdeh / Dias).

Variant effect : The frameshift variant was not studied by Abu-Libdeh et al. Variants in the 2nd ref. were all missense, displayed no-specific localization and were suggested to affect protein stability and/or expression at the cell surface as 4/7 involved loss or addition of cystein residues (possibly creating unpaired cysteins) and 2 of the remaining 3 were predicted to affect the hydrophobic core. In line with this, overexpression of wt/variant constructs in HeLa cells demonstrated substantially decreased cell surface expression for all variants.

Mouse models/phenotypes : Dias et al. showed that siRNA-mediated Ntng2 knockdown in N2a cells led to significant reduction in neurite number and length. Studied previously, Ntng2 knockout mice display impaired learning, memory, visual and motor functioning (PMID cited : 26746425).

NTNG2 is not associated with any phenotype in OMIM/G2P. SysID lists it among the candidate ID genes, citing PMID: 29302074 (not here reviewed & NTNG2 not in the main text).

Overall this gene can be considered for inclusion in the ID panel probably as green (>3 individuals/families/variants, consistent phenotype in both reports, role of the gene, in silico and in vitro studies, animal model, etc) or amber.

[Please consider inclusion in other panels if relevant eg. ASD panel (many individuals having autistic / Rett-like features or epilepsy) or epilepsy (>3 individuals/families/variants although most families were also consanguineous)]
Sources: Literature
Intellectual disability v2.1098 AP1B1 Konstantinos Varvagiannis gene: AP1B1 was added
gene: AP1B1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: AP1B1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: AP1B1 were set to 31630788; 31630791
Phenotypes for gene: AP1B1 were set to Failure to thrive; Abnormality of the skin; Hearing abnormality; Abnormality of copper homeostasis; Global developmental delay; Intellectual disability
Penetrance for gene: AP1B1 were set to Complete
Review for gene: AP1B1 was set to AMBER
Added comment: Boyden et al. (2019 - PMID: 31630788) and Alsaif et al (2019 - PMID: 31630791) report on the phenotype related to biallelic AP1B1 mutations.

Common features included failure to thrive, ichthyosis (with variable palmoplantar keratoderma/erythroderma/abnormal hair) and hearing loss. Each study focused on different additional features eg. thrombocytopenia or photophobia in all individuals reported by Boyden et al, while Alsaif et al. focused on abnormal copper metabolism (low plasma copper and ceruloplasmin) observed in all 3 affected individuals and enteropathy/hepatopathy observed in 2 sibs.

DD was observed in all 3 individuals (2 families) reported by Alsaif et al. and patient 424 reported by Boyden et al. ID was noted in all individuals of relevant age (2 from 2 families) in the study by Alsaif. Boyden commented that ID is not part of the phenotype. The adult (424) - despite his early DD - was noted to have normal intellect and had graduated college. The other patient (1325) was last followed up at 11 months (still DD was not reported).

AP1B1 encodes one of the large subunits (β1) of the adaptor protein complex 1. Each of the AP complexes is a heterotetramer composed of two large (one of γ, α, δ, ε and β1-β4 for AP-1 to AP-4 respectively), one medium (μ1-μ4) and one small (σ1-σ4) adaptin subunit. The complex is involved in vesicle-mediated transport.

Variants were confirmed in probands and carrier parents (NM_001127.3):
Boyden Pat424 (33y) : c.430T>C (p.Cys144Arg) in trans with c.2335delC (p.Leu779Serfs*26)
Boyden Pat1325 (11m) [consanguineous Ashkenazi Jewish family] : homozygosity for c.2374G>T (p.Glu792*)
Alsaif sibs P1,P2 (4y4m, 1y5m) [consanguineous - Pakistani origin] : homozygous for a chr22 75 kb deletion spanning only the promoter and ex1-2 of AP1B1
Alsaif P3 (4y6m) [consanguineous - Saudi origin] : homozygous for a c.38-1G>A

Variant / additional studies :
22q 75-kb deletion: PCR deletion mapping and Sanger delineated the breakpoints of the 22q12.2 del to chr22:29758984-29815476 (hg?). Complete absence of transcript upon RT-PCR (mRNA from fibrolasts).
Splicing variant (c.38-1G>A): RT-PCR confirmed replacement of the normal transcript by an aberrant harboring a 1 bp deletion (r.40del).
Stopgain variant (c.2374G>T): Western blot demonstrated loss of AP1B1 (and marked reduction also for AP1G1) in cultured keratinocytes of the homozygous patient.

Loss-of-function is the effect predicted by variants. Vesicular defects were observed in keratinocytes of an affected individual (homozygous for the nonsense variant). Rescue of these vesicular defects upon transduction with wt AP1B1 lentiviral construct confirmed the LoF effect. [Boyden et al.]

ATP7A and ATP7B, two copper transporters, have been shown to depend on AP-1 for their trafficking. Similar to MEDNIK syndrome, caused by mutations in AP1S1 and having an overlapping phenotype with AP1B1 (also including hypocupremia and hypoceruloplasminemia), fibroblasts from 2 affected individuals (from different families) demonstrated abnormal ATP7A trafficking. [Alsaif et al.]

Proteomic analysis of clathrin coated vesicles (2 ind from 2 fam) demonstrated that AP1B1 was the only AP1/AP2 CCV component consistently reduced in 2 individuals (from 2 families). [Alsaif et al.]

Boyden et al. provided evidence for abnormal differentiation and proliferation in skin from an affected individual. In addition E-cadherin and β-catenin were shown to be mislocalized in keratinocytes from this affected individual.

Loss of ap1b1 in zebrafish is not lethal but lead to auditory defects (/vestibular deficits). The inner ears appear to develop normally, although there is progressive degeneration of ear epithelia. There are no behavioral/neurological phenotypes listed for mouse models. [ http://www.informatics.jax.org/marker/MGI:1096368 ].

AP1B1 is not associated with any phenotype in OMIM/G2P/SysID.

Overall this gene could be considered for inclusion in the ID panel probably with amber rating.
Sources: Literature
Intellectual disability v2.1098 FDFT1 Konstantinos Varvagiannis gene: FDFT1 was added
gene: FDFT1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: FDFT1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: FDFT1 were set to 29909962
Phenotypes for gene: FDFT1 were set to Profound global developmental delay; Intellectual disability; Seizures; Abnormality of nervous system morphology; Cortical visual impairment; Abnormality of the skin; Abnormality of the face
Penetrance for gene: FDFT1 were set to Complete
Review for gene: FDFT1 was set to AMBER
Added comment: Biallelic pathogenic FDFT1 variants cause Squalene synthase deficiency (MIM 618156). 3 individuals from 2 families (and 3 variants) have been reported. DD, ID and seizures are part of the phenotype (3/3). The metabolic profile observed is specific and highly suggestive of disruption of the cholesterol biosynthesis pathway (at the specific level) while the clinical presentation is similar to other disorders of the pathway (SLO). The effect of 2 variants has been studied in detail (in one case mis-splicing demonstrated and in the other regulatory effect). Overall, this gene could be considered for inclusion in the ID/epilepsy panel with amber rating. As the gene is currently present only in the DDG2P panel, please consider adding it to relevant ones (eg. IEMs, undiagnosed metabolic disorders, etc). [Details provided below].
----
Coman et al. (2018 - PMID: 29909962) reported on 3 relevant individuals from 2 unrelated families.

The phenotype consisted of seizures (3/3 - neonatal onset - generalized), profound DD (ID can be inferred from the description in the supplement), variable brain MRI abnormalities (white matter loss, hypoplastic CC), cortical visual impairment, dry skin with photosensitivity as well facial dysmorphic features. Male subjects presented genital anomalies (cryptorchidism/hypospadias).

FDFT1 encodes squalene synthase, the enzyme which catalyzes conversion of farnesyl-pyrophosphate to squalene - the first specific step in cholesterol biosynthesis.

A specific pattern of metabolites was observed in all, similar to a pattern previously observed in animal models/humans treated with squalene synthase inhibitor or upon loading with farnesol (in animals). Overall the pattern was suggestive of a cholesterol biosynthesis defect at the level of squalene synthase as suggested by increased total farnesol levels (farnesyl-pyrophosphate + free farnesol), reduced/normal squalene, low plasma cholesterol as well as other metabolites.

Clinical features also resembled those observed in Smith-Lemli-Opitz syndrome (another disorder of cholesterol biosynthesis).

WES was carried out in affected individuals and their parents and revealed for sibs of the first family, compound heterozygosity for a maternally inherited 120-kb deletion spanning exons 6-10 of FDFT1 and CTSB and a paternally inherited FDFT1 variant in intron 8 (TC deletion/AG insertion). Variant studies for the latter included:
- Minigene splice assay demonstrating retention of 22 bp in intron 8.
- Partial splicing defect with both nl and mis-spliced cDNA (patient fibroblasts)
- Reduced protein levels in lymphoblasts/fibroblasts from both sibs upon Western blot.
Contribution of the CTSB deletion was considered unlikely (carrier mother was unaffected).

As for the 2nd family, WES data allowed identification of a homozygous deep-intronic (although this is transcript-specific) 16-bp deletion in the proband. Parents were carriers. For the specific variant :
- cDNA studies failed to detect 3 (of 10) isoforms which are normally present in control fibroblasts. Eventual NMD (which would be predicted if the deletion resulted in splicing defect) was eliminated given the absent effect of cyclohexamide addition, thus suggesting a regulatory effect.
- Given a predicted promoter/enhancer effect of the deleted region, a luciferase assay performed, suggested that the sequence had promoter capacity, with the construct containing the 16-bp deletion showing reduced promoter activity.

Fdft1 knockout mice demonstrate embryonic lethality around mid-gestation while they exhibit severe growth retardation and defective neural tube closure.

In G2P FDFT1 is associated with 'Defect in Cholesterol Biosynthesis' (confidence:possible/biallelic/LoF). The gene belongs to the Current primary ID gene group of SysID. It is not commonly included in gene panels for ID offered by diagnostic laboratories.
Sources: Literature
Intellectual disability v2.1098 IQSEC1 Konstantinos Varvagiannis gene: IQSEC1 was added
gene: IQSEC1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: IQSEC1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: IQSEC1 were set to 31607425
Phenotypes for gene: IQSEC1 were set to Central hypotonia; Global developmental delay; Intellectual disability; Behavioral abnormality; Short stature
Penetrance for gene: IQSEC1 were set to Complete
Review for gene: IQSEC1 was set to AMBER
Added comment: Ansar et al. (2019 - PMID: 31607425) reported on 5 individuals with biallelic IQSEC1 variants.

Common features included hypotonia, DD, speech impairment, severe ID, behavioral problems as well as short stature. Early-onset seizures were observed in 3 sibs (for whom there was also a paternal family history of seizures).

These subjects belonging to 2 consanguineous families from Pakistan and S. Arabia were found to harbor homozygous missense variants private to each family (Fam1: NM_001134382.2:c.1028C>T or p.Thr354Met following SNP genotyping of several members and exome of the proband | Fam2: c.962G>A or p.Arg321Gln following exome in 2 affected members). Sanger confirmation and study of parents (+/- sibs) were compatible.

The homozygous variant was the only candidate in the 1st family (also following exclusion of other causes of ID/short stature), and most likely/compatible with the patient's phenotype in the 2nd.

As the authors note, IQSEC1-3 encode guanine exchange factors (GEFs) for the ARF family of GTPases. IQSEC2 is a known XLID gene, while biallelic IQSEC3 mutations in ID have been recently reported (PMID: 31130284), all presenting phenotypic similarities (ID, short stature, speech defect).

Previous studies cited had shown that IQSEC1 & 2 are concentrated at the postsynaptic density of glutamatergic synapses in mammalian brain, playing a role in actin-dependent processes incl. AMPA receptor trafficing at synapses (all refs in article).

Drosophila model: The ortholog of IQSEC1, 2 and 3 is schizo and the phenotype associated with its loss is a growth cone guidance defect through dysregulation of the Slit-Robo pathway (all refs in article). The authors studied overexpression of either reference IQSEC1 cDNA or variant cDNAs in wt flies, the former only being toxic/lethal. Loss of schizo was also embryonically lethal but was partially rescued by expression of reference IQSEC1 cDNA. Expression of cDNA for the 2 variants did not rescue lethality. As a result LoF appears to be the underlying effect of both variants. The authors provided evidence that schizo is localized in glia and neurons at various stages of development and is important for proper axon guidance in both CNS and PNS. In Drosophila, schizo is also localized in photoreceptors and RNAi-mediated knockdown resulted in severely impaired sight (also observed in 1 patient).

Mouse model: Through generation of Iqsec1-floxed mice, it was demonstrated that targeted depletion of Iqsec1 in the cortex resulted in increased density/immature morphology of dendritic spines.

IQSEC1 is not associated with any phenotype in OMIM / G2P / SysID and not commonly included in gene panels for ID.

As a result, this gene could be considered for inclusion in the ID panel as probably as amber (2 families/variants).
Sources: Literature
Intellectual disability v2.1098 TAOK1 Rebecca Foulger Phenotypes for gene: TAOK1 were changed from to INTELLECTUAL DISABILITY; developmental delay
Intellectual disability v2.1097 TAOK1 Rebecca Foulger Publications for gene: TAOK1 were set to
Intellectual disability v2.1096 TAOK1 Rebecca Foulger Added comment: Comment on mode of inheritance: Set MOI to MONOALLELIC, to match Gene2Phenotype and PMID:31230721.
Intellectual disability v2.1096 TAOK1 Rebecca Foulger Mode of inheritance for gene: TAOK1 was changed from to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.1095 TAOK1 Ellen McDonagh reviewed gene: TAOK1: Rating: GREEN; Mode of pathogenicity: None; Publications: 31230721; Phenotypes: ; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.1095 TAOK1 Ellen Thomas Classified gene: TAOK1 as Green List (high evidence)
Intellectual disability v2.1095 TAOK1 Ellen Thomas Added comment: Comment on list classification: Recently reported DD gene
Intellectual disability v2.1095 TAOK1 Ellen Thomas Gene: taok1 has been classified as Green List (High Evidence).
Intellectual disability v2.1095 TAOK1 Ellen Thomas Classified gene: TAOK1 as Green List (high evidence)
Intellectual disability v2.1095 TAOK1 Ellen Thomas Added comment: Comment on list classification: Recently reported DD gene
Intellectual disability v2.1095 TAOK1 Ellen Thomas Gene: taok1 has been classified as Green List (High Evidence).
Intellectual disability v2.1095 TAOK1 Ellen Thomas Classified gene: TAOK1 as Green List (high evidence)
Intellectual disability v2.1095 TAOK1 Ellen Thomas Added comment: Comment on list classification: Recently reported DD gene
Intellectual disability v2.1095 TAOK1 Ellen Thomas Gene: taok1 has been classified as Green List (High Evidence).
Intellectual disability v2.1094 TAOK1 Ellen Thomas Classified gene: TAOK1 as Green List (high evidence)
Intellectual disability v2.1094 TAOK1 Ellen Thomas Added comment: Comment on list classification: Recently reported DD gene
Intellectual disability v2.1094 TAOK1 Ellen Thomas Gene: taok1 has been classified as Green List (High Evidence).
Intellectual disability v2.1094 TAOK1 Ellen Thomas Classified gene: TAOK1 as Green List (high evidence)
Intellectual disability v2.1094 TAOK1 Ellen Thomas Added comment: Comment on list classification: Recently reported DD gene
Intellectual disability v2.1094 TAOK1 Ellen Thomas Gene: taok1 has been classified as Green List (High Evidence).
Intellectual disability v2.1093 SIX3 Rebecca Foulger Phenotypes for gene: SIX3 were changed from Holoprosencephaly-2, 157170Schizensephaly, 269160; HOLOPROSENCEPHALY to Holoprosencephaly-2, 157170; Schizensephaly, 269160; HOLOPROSENCEPHALY
Intellectual disability v2.1092 SVBP Alistair Pagnamenta reviewed gene: SVBP: Rating: GREEN; Mode of pathogenicity: None; Publications: PMID: 31363758, 30607023; Phenotypes: brain abnormalities, microcephaly, intellectual disability, delayed gross motor development, spasticity, delayed speech development; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1092 NKAP Catherine Snow Phenotypes for gene: NKAP were changed from to Global developmental delay; Intellectual disability
Intellectual disability v2.1091 NKAP Catherine Snow Classified gene: NKAP as Green List (high evidence)
Intellectual disability v2.1091 NKAP Catherine Snow Added comment: Comment on list classification: NKAP reviewed by Konstantinos Varvagiannis following publication by Fiordaliso et al. (PMID:31587868) who identified 10 males from 8 unrelated families with missense mutations in NKAP (on Xq24) Hypotonia and tall stature with Marfanoid habitus was predominant phenotype. One variant (NM_024528:c.988G>A / p.Arg333Gln) was seen in 4 families and although origin was not provided for all families this variant was seen in brothers with parents from Slovakia and an individual with parents from Japan.
NKAP is not currently in OMIM or Gene2Phenotype.
Rating NKAP as Green as consistent phenotype observed, >3 unrelated individuals and some functional work in Zebrafish.
Intellectual disability v2.1091 NKAP Catherine Snow Gene: nkap has been classified as Green List (High Evidence).
Intellectual disability v2.1090 NKAP Catherine Snow Tag missense tag was added to gene: NKAP.
Intellectual disability v2.1090 METTL5 Rebecca Foulger Classified gene: METTL5 as Amber List (moderate evidence)
Intellectual disability v2.1090 METTL5 Rebecca Foulger Added comment: Comment on list classification: METTL5 was added to the panel and rated Green by Konstantinos Varvagiannis. There are just sufficient (3) cases from the literature (siblings in PMID:29302074 plus 2 families in PMID:31564433), and animal models (mice and zebrafish) exhibit microcephaly similar to the human phenotype. However, the Gly61Asp variant found in the PMID:29302074 siblings is currently classed as VUS and PMID:31564433 failed to demonstrate a functional impact for this variant on the encoded protein.

METTL5 has been recently added (October 2019) to DD-G2P with a probable rating for 'Autosomal-Recessive Intellectual Disability and Microcephaly'. METTL5 is not yet associated with a disorder in OMIM. Given the uncertainty of the functional significance of the Gly61Asp variant, on balance an Amber rating is appropriate at this time, pending further cases or functional evidence.
Intellectual disability v2.1090 METTL5 Rebecca Foulger Gene: mettl5 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1089 METTL5 Rebecca Foulger Publications for gene: METTL5 were set to 29302074; http://doi.org/10.1016/j.ajhg.2019.09.007; https://imgc2019.sciencesconf.org/data/abstract_book_complete.pdf
Intellectual disability v2.1088 METTL5 Rebecca Foulger Phenotypes for gene: METTL5 were changed from Delayed speech and language development; Intellectual disability; Microcephaly; Behavioral abnormality to Autosomal-Recessive Intellectual Disability and Microcephaly; Delayed speech and language development; Intellectual disability; Microcephaly; Behavioral abnormality
Intellectual disability v2.1088 NKAP Catherine Snow Publications for gene: NKAP were set to 26358559; 26350204
Intellectual disability v2.1087 TRAPPC6B Rebecca Foulger Classified gene: TRAPPC6B as Green List (high evidence)
Intellectual disability v2.1087 TRAPPC6B Rebecca Foulger Added comment: Comment on list classification: Updated rating from Amber to Green based on Aug 2019 review by Konstantinos Varvagiannis. Konstantinos notes an additional 2019 paper (Nair et al) who report a Lebanese patient with global DD and ID, who is homozygous for a nonsense variant in TRAPPC6B (p.Leu8*). The unaffected mother was a heterozygous carrier. In contrast to previous cases, the patient did not show any seizures, but the authors note he was only 3.5 years old at the time of writing, and will be monitored for seizure events. ID/DD is a consistent phenotype across cases. This takes the number of cases to 3 (with the 3 families in Marin-Valencia forming 1 case), with 3 separate variants. Therefore Green rating is appropriate.
Intellectual disability v2.1087 TRAPPC6B Rebecca Foulger Gene: trappc6b has been classified as Green List (High Evidence).
Intellectual disability v2.1086 CSDE1 Catherine Snow Classified gene: CSDE1 as Green List (high evidence)
Intellectual disability v2.1086 CSDE1 Catherine Snow Added comment: Comment on list classification: CSDE1 identified by Konstantinos Varvagiannis based on a publication by Guo et al. (PMID: 31579823) This is the first time CSDE1 has been associated with any diseases therefore it not currently in OMIM or Gene2Phenotype. However consistent phenotype of DD/ID and autism seen among all individuals with variants. With functional work on both mice and Drosophila.
Intellectual disability v2.1086 CSDE1 Catherine Snow Gene: csde1 has been classified as Green List (High Evidence).
Intellectual disability v2.1085 CSDE1 Catherine Snow Publications for gene: CSDE1 were set to http://doi.org/10.1126/sciadv.aax2166
Intellectual disability v2.1084 SMG9 Catherine Snow Publications for gene: SMG9 were set to 27018474; 30914295
Intellectual disability v2.1083 SMG9 Catherine Snow edited their review of gene: SMG9: Added comment: Maintaining Amber rating as although another individual with a variant has been identified in PMID: 31390136 there are still only full details of serve developmental delays for 2 unrelated families due to the young age of death of one reported individual in 27018474; Changed publications: 31390136
Intellectual disability v2.1083 PMPCB Catherine Snow changed review comment from: PMPCB identified by Konstantinos Varvagiannis following publication by Vögtle et al. (2018 - PMID: 29576218) who reported on by Vögtle et al. (2018 - PMID: 29576218) who identified 5 individuals from 4 unrelated families (in one case consanguineous) who have biallelic pathogenic PMPCB variants.
PMPCB is in OMIM and Gene2Phenotype with relevant phenotype. Individuals reported have stagnation in their development before onset of symptoms. PMPCB is Green on relevant Mitochondrial disorders panel (Version 2.1). As phenotype of DD is relevant to ID panel PMPCB is classified as Green.; to: PMPCB identified by Konstantinos Varvagiannis following publication by Vögtle et al. (2018 - PMID: 29576218) who identified 5 individuals from 4 unrelated families (in one case consanguineous) who have biallelic pathogenic PMPCB variants.
PMPCB is in OMIM and Gene2Phenotype with relevant phenotype. Individuals reported have stagnation in their development before onset of symptoms including, delayed psychomotor development and ID. PMPCB is Green on relevant Mitochondrial disorders panel (Version 2.1). As phenotype of DD is relevant to ID panel PMPCB is classified as Green.
Intellectual disability v2.1083 PMPCB Catherine Snow Publications for gene: PMPCB were set to
Intellectual disability v2.1083 PMPCB Catherine Snow Classified gene: PMPCB as Green List (high evidence)
Intellectual disability v2.1083 PMPCB Catherine Snow Gene: pmpcb has been classified as Green List (High Evidence).
Intellectual disability v2.1082 PMPCB Catherine Snow reviewed gene: PMPCB: Rating: GREEN; Mode of pathogenicity: None; Publications: 29576218; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1082 PCDH12 Catherine Snow Phenotypes for gene: PCDH12 were changed from intellectual disability; microcephaly; epilepsy; perithalamic hyperechogenicity; periventricular hyperechogenicity; midbrain abnormalities; hypothalamic abnormalities to intellectual disability; microcephaly; epilepsy; perithalamic hyperechogenicity; periventricular hyperechogenicity; midbrain abnormalities; hypothalamic abnormalities; Microcephaly, seizures, spasticity, and brain calcification, 251280
Intellectual disability v2.1081 PCDH12 Catherine Snow Classified gene: PCDH12 as Green List (high evidence)
Intellectual disability v2.1081 PCDH12 Catherine Snow Added comment: Comment on list classification: Following review by Konstantinos Varvagiannis on PCDH12, highlighted that here is now a sufficient number of published variants from unrelated families to classify PCDH12 as Green with ID reported in all.
Intellectual disability v2.1081 PCDH12 Catherine Snow Gene: pcdh12 has been classified as Green List (High Evidence).
Intellectual disability v2.1081 PCDH12 Catherine Snow Publications for gene: PCDH12 were set to 27164683
Intellectual disability v2.1080 CDH2 Catherine Snow Classified gene: CDH2 as Amber List (moderate evidence)
Intellectual disability v2.1080 CDH2 Catherine Snow Gene: cdh2 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1079 CDH2 Catherine Snow reviewed gene: CDH2: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.1079 APC2 Catherine Snow Classified gene: APC2 as Green List (high evidence)
Intellectual disability v2.1079 APC2 Catherine Snow Gene: apc2 has been classified as Green List (High Evidence).
Intellectual disability v2.1078 APC2 Catherine Snow Classified gene: APC2 as No list
Intellectual disability v2.1078 APC2 Catherine Snow Added comment: Comment on list classification: APC2 is in OMIM with a relevant clinical features but not in Gene2Phenotype. APC2 was identified by Konstantinos Varvagiannis who reviewed all variants. Sufficient number of individuals from unrelated families reported upon in the literature and three different variants identified. Therefore APC2 can be classified as Green
Intellectual disability v2.1078 APC2 Catherine Snow Gene: apc2 has been removed from the panel.
Intellectual disability v2.1077 TDP2 Catherine Snow Classified gene: TDP2 as Green List (high evidence)
Intellectual disability v2.1077 TDP2 Catherine Snow Gene: tdp2 has been classified as Green List (High Evidence).
Intellectual disability v2.1076 TDP2 Catherine Snow commented on gene: TDP2
Intellectual disability v2.1076 TANC2 Rebecca Foulger edited their review of gene: TANC2: Changed rating: AMBER
Intellectual disability v2.1076 TANC2 Rebecca Foulger changed review comment from: Comment on list classification: Updated rating from Red to Amber based on PMID:31616000 2019 article suggested by Andrea Haworth. Sufficient unrelated cases (19/20) with an ID/DD phenotype but the pathogenicity of the variants has not yet been verified. Therefore Amber with 'watchlist' tag is appropriate pending functional studies.; to: Comment on list classification: Updated rating from Red to Amber based on PMID:31616000 2019 article suggested by Andrea Haworth. Sufficient unrelated cases (19/20) with an ID/DD phenotype but the pathogenicity of the variants has not yet been verified. Not yet associated with a disorder in Gene2Phenotype or OMIM. Currently only 1 paper, therefore Amber with 'watchlist' tag is appropriate pending functional studies.
Intellectual disability v2.1076 TANC2 Rebecca Foulger Classified gene: TANC2 as Amber List (moderate evidence)
Intellectual disability v2.1076 TANC2 Rebecca Foulger Added comment: Comment on list classification: Updated rating from Red to Amber based on PMID:31616000 2019 article suggested by Andrea Haworth. Sufficient unrelated cases (19/20) with an ID/DD phenotype but the pathogenicity of the variants has not yet been verified. Therefore Amber with 'watchlist' tag is appropriate pending functional studies.
Intellectual disability v2.1076 TANC2 Rebecca Foulger Gene: tanc2 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1075 TANC2 Rebecca Foulger commented on gene: TANC2: Summary of PMID:31616000 (PMC:6794285) suggested by Andrea Haworth reviewer: Guo et al assembled phenotypic data for 19 probands and 1 affected sibling with TANC2 variants. Variants include 16 LGD (likely gene-disruptive) variants and three intragenic microdeletions. Phenotypes included ASD, ID, speech-language delay and childhood motor delay:
- 15/20 individuals had ASD/autism features (7 with a formal diagnosis).
- 19/20 individuals had some form of ID (17 with a formal diagnosis of borderline to severe ID, and 2 with learning difficulties without a formal diagnosis).
- 18/20 showed speech-language delay.
- 13/19 individuals had childhood motor delay.
- 11/20 individuals had a formal diagnosis of epilepsy (9) or suffered recurrent seizures (2).
Intellectual disability v2.1075 TANC2 Rebecca Foulger Phenotypes for gene: TANC2 were changed from to NDD syndrome; Neurodevelopmental Disorder; Intellectual disability; Childhood speech delay; Childhood motor delay
Intellectual disability v2.1074 TANC2 Rebecca Foulger Added comment: Comment on mode of inheritance: Set MOI as MONOALLELIC based on PMID:31616000 (Figure 2).
Intellectual disability v2.1074 TANC2 Rebecca Foulger Mode of inheritance for gene: TANC2 was changed from to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.1073 TDP2 Catherine Snow Mode of inheritance for gene: TDP2 was changed from MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1072 TANC2 Rebecca Foulger Publications for gene: TANC2 were set to 26350204
Intellectual disability v2.1071 PIGP Rebecca Foulger Classified gene: PIGP as Amber List (moderate evidence)
Intellectual disability v2.1071 PIGP Rebecca Foulger Added comment: Comment on list classification: PIGP was added to the panel and rated Green by Konstantinos Varvagiannis. Upgraded rating from Grey to Amber, and added watchlist tag, following review of literature and Amber rating on the Genetic epilepsy syndromes panel. Not yet associated with a disorder in Gene2Phenotype. 2 unrelated cases from the literature plus a third case from LOVD. Therefore Amber rating is appropriate.
Intellectual disability v2.1071 PIGP Rebecca Foulger Gene: pigp has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1070 PMPCA Rebecca Foulger Classified gene: PMPCA as Amber List (moderate evidence)
Intellectual disability v2.1070 PMPCA Rebecca Foulger Added comment: Comment on list classification: Updated rating from Grey to Amber. PMPCA was added and rated Green by Konstantinos Varvagiannis. Although there are sufficient (3) literature cases overall, the phenotype is variable across cases: 3 families with a possible Founder variant in PMID:25808372, no ID reported in PMID:26657514, 1 family in PMID:27148589 and 1 individual in PMID:30617178. Therefore rated Amber awaiting further cases.
Intellectual disability v2.1070 PMPCA Rebecca Foulger Gene: pmpca has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1069 PMPCA Rebecca Foulger commented on gene: PMPCA
Intellectual disability v2.1069 CA5A Rebecca Foulger commented on gene: CA5A
Intellectual disability v2.1069 CA5A Rebecca Foulger Mode of inheritance for gene: CA5A was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1068 CA5A Rebecca Foulger Phenotypes for gene: CA5A were changed from to Hyperammonemia due to carbonic anhydrase VA deficiency, 615751
Intellectual disability v2.1067 CA5A Rebecca Foulger Publications for gene: CA5A were set to
Intellectual disability v2.1066 TANC2 Andrea Haworth commented on gene: TANC2
Intellectual disability v2.1066 MED25 Rebecca Foulger Classified gene: MED25 as Green List (high evidence)
Intellectual disability v2.1066 MED25 Rebecca Foulger Added comment: Comment on list classification: Updated rating from Amber to Green based on the recent Lebanese cases reported by Nair et al (DOI:10.1159/000501114 and PMID:30800049). Advice and a Green review by Helen Brittain supports the upgrade to Green.
Intellectual disability v2.1066 MED25 Rebecca Foulger Gene: med25 has been classified as Green List (High Evidence).
Intellectual disability v2.1065 FBXW11 Catherine Snow Classified gene: FBXW11 as Green List (high evidence)
Intellectual disability v2.1065 FBXW11 Catherine Snow Gene: fbxw11 has been classified as Green List (High Evidence).
Intellectual disability v2.1064 FBXW11 Catherine Snow reviewed gene: FBXW11: Rating: GREEN; Mode of pathogenicity: None; Publications: 31402090, 16865294; Phenotypes: ; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.1064 SMPD4 Louise Daugherty Classified gene: SMPD4 as Green List (high evidence)
Intellectual disability v2.1064 SMPD4 Louise Daugherty Added comment: Comment on list classification: Changed from Amber to Green. Appropriate phenotypes, sufficient cases, support gene-disease association.
Intellectual disability v2.1064 SMPD4 Louise Daugherty Gene: smpd4 has been classified as Green List (High Evidence).
Intellectual disability v2.1063 SMPD4 Louise Daugherty Tag watchlist was removed from gene: SMPD4.
Intellectual disability v2.1063 SMPD4 Louise Daugherty Added comment: Comment on publications: Magini P et al. (October 2019) Loss of SMPD4 Causes a Developmental Disorder Characterized by Microcephaly and Congenital Arthrogryposis.
Intellectual disability v2.1063 SMPD4 Louise Daugherty Publications for gene: SMPD4 were set to
Intellectual disability v2.1062 TDP2 Konstantinos Varvagiannis gene: TDP2 was added
gene: TDP2 was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen
Mode of inheritance for gene: TDP2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: TDP2 were set to 24658003; 30109272; 31410782
Phenotypes for gene: TDP2 were set to Spinocerebellar ataxia, autosomal recessive 23, 616949)
Penetrance for gene: TDP2 were set to unknown
Review for gene: TDP2 was set to GREEN
gene: TDP2 was marked as current diagnostic
Added comment: Biallelic pathogenic TGP2 variants cause Spinocerebellar ataxia, autosomal recessive 23 (MIM 616949). At least 6 affected individuals from 4 families have been reported, in all cases homozygous for LoF variants (3 different). ID, epilepsy and ataxia are consistent features of the disorder.

TDP2 encodes a phosphodiesterase that is required for efficient repair of double strand breaks (DSBs) produced by abortive topoisomerase II (TOP2) activity.

The gene is expressed in fetal and adult human brain.

Evidence at the variant level (mRNA, protein levels) and additional studies for impairment of TOP2-induced DSB repair support a role.

Animal models (primarily mice) reproduce the DSB repair defect, provide some histopathological evidence, show transcriptional dysregulation of genes (in line with the role of TOP2 in transcription). They have however failed to reproduce relevant neurological phenotypes.

Published studies are summarized below.

TDP2 is included in gene panels for ID offered by some diagnostic laboratories (incl. Radboudumc and GeneDx). There is no associated phenotype in G2P. TDP2 is listed among the current primary ID genes in SysID.

Overall, this gene could be considered for inclusion in the ID and epilepsy panels probably as green (>=3 patients/families/variants, relevant ID and seizures in all, expression in brain, mRNA/protein levels tested, impaired activity) or amber (absence of neurological phenotypes in mouse model).
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[1] - PMID: 24658003 (Gómez-Herreros et al. 2014):
Reports 3 individuals from a consanguineous Irish family. Features included seizures (onset by 2m, 6m and 12y), ID (3/3) and ataxia (3/3).

A splicing variant (NM_016614.3:c.425+1G>A) was found in a 9.08-Mb region of homozygosity shared by all. A further ZNF193 missense variant localizing in the same region was thought unlikely to contribute to the phenotype (evidence also provided in subsequent study).

The effect of the specific variant was proven by abnormal mRNA size, lower mRNA levels due to NMD (corrected upon cyclohexamide treatment), loss of TDP2 protein upon WB, loss of protein activity in lymphoblastoid cells from affected individuals, decreased repair of DSBs and increased cell death upon addition of etoposide (which promotes TOP2 abortive activity).

The authors report very briefly on a further patient (from Egypt), with ID, 'reports of fits' and ataxia. This individual, with also affected sibs, was homozygous LoF (c.413_414delinsAA / p.Ser138*). Again, the authors were not able to detect TDP2 activity in blood from this subject.

As also commented:
- TDP2 has relevant expression in human (particularly adult) brain.
- Mouse model : Tdp2 is expressed in relevant tissues, absence of Tdp2 activity was observed in neural tissue of mice homoyzgous for an ex1-3 del, with impairment of DSB repair. The authors were unable to detect a neurological phenotype with behavioral analyses, preliminary assesment of seizure propensity. Mice did not show developmental defects. Histopathology however, revealed ~25% reduction in the density of interneurons in cerebellum (a 'hallmark of DSB repair' and associated with seizures and ataxia). Transcription of several genes was shown to be disregulated.
- Knockdown in zebrafish appears to affect left-right axis detremination (cited PMID: 18039968).

[2] - PMID: 30109272 (Zagnoli-Vieira et al. 2018):
A 6 y.o. male with seizures (onset by 5m), hypotonia, DD and ID, microcephaly and some additional clinical features and testing (ETC studies on muscle biopsy, +lactate, +(lactate/pyruvate) ratio) which could be suggestive of mitochondrial disorder. This individual from the US was homozygous for the c.425+1G>A variant but lacked the ZNF193 one (despite a shared haplotype with the Irish patients). Again absence of the protein was shown upon WB in patient fibroblasts, also supported by its activity. Complementation studies restored the DSB repair defect. The defect was specific to TOP2-induced DSBs as suggested by hypersensitivity to etoposide but not to ionizing radiation. CRISPR/Cas9 generated mutant human A549 cells demonstrated abnormal DSB repair. Fibroblasts / edited A549 cells failed to show mitochondrial defects (which were noted in muscle).

[3] - PMID: 31410782 (Ciaccio et al. 2019):
A girl born to consanguineous Italian parents, presented with moderate/severe ID, seizures (onset at 12y) and - among others - gait ataxia, tremor and dysmetria. MRI at the age of 12, demonstrated cerebellar atrophy (although previous exams were N). WES revealed a homozygous nonsense variant (c.400C>T / p.Arg134Ter) for which each parent was found to be carrier. Previous investigations included aCGH, NGS testing for epilepsy and metabolic testing.
Sources: Literature, Radboud University Medical Center, Nijmegen
Intellectual disability v2.1062 PCDH12 Konstantinos Varvagiannis reviewed gene: PCDH12: Rating: ; Mode of pathogenicity: None; Publications: 27164683, 28804758, 29556033, 30178464, 30459466, 18477666; Phenotypes: Microcephaly, seizures, spasticity, and brain calcification, 251280; Mode of inheritance: None; Current diagnostic: yes
Intellectual disability v2.1062 NKAP Konstantinos Varvagiannis reviewed gene: NKAP: Rating: GREEN; Mode of pathogenicity: None; Publications: DOI: 10.1016/j.ajhg.2019.09.009; Phenotypes: Global developmental delay, Intellectual disability, Tall stature, Scoliosis, Pectus excavatum, Pectus carinatum, Arachnodactyly, Camptodactyly, Abnormality of the cardiovascular system, Abnormality of the genitourinary system, Abnormality of the face, Obesity; Mode of inheritance: X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Intellectual disability v2.1062 APC2 Konstantinos Varvagiannis gene: APC2 was added
gene: APC2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: APC2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: APC2 were set to 31585108; 25753423; 19759310; 22573669
Phenotypes for gene: APC2 were set to Global developmental delay; Intellectual disability; Seizures; Morphological abnormality of the central nervous system
Penetrance for gene: APC2 were set to Complete
Review for gene: APC2 was set to GREEN
gene: APC2 was marked as current diagnostic
Added comment: Probably 14 individuals from 9 families (8 consanguineous) with biallelic APC2 LoF variants have been reported.

ID and brain abnormalities were features in all, although the presentation was quite different between sibs in the first report (PMID: 25753423 - mild/mod ID, ventriculomegaly and CC anomalies, macrocephaly with variable height, Sotos-like facial features) and 12 subsequently described patients (PMID: 31585108 - severe ID, P>A lissencephaly/CC anomalies/ventriculomegaly/paucity of white matter in (almost) all, gT-C/myoclonic seizures in 8/12 with onset 3m-6y, OFC in the low percentiles).

In all cases relevant alternative diagnoses (eg. macrocephaly/overgrowth syndromes - 1st report, mutations in other lissencephaly genes, metabolic disorders - 2nd) were ruled out.

APC2 encodes Adenomatous polyposis coli protein 2, expressed in the CNS.

All variants reported to date were LoF (stopgain/frameshift/splicing) and were supported by parental-only studies. Mutations in the 1st report as well as 4/8 variants from the 2nd report localized within the last exon (NM_005883.2 / longest of >=3 isoforms), although the 2nd report did not observe obvious genotype-phenotype correlations.

Despite a pLI of 1 in gnomAD, Lee et al. comment that heterozygous carriers did not have any noticeable phenotype. They further note that carriers were not examined by brain MRI, though. 27 heterozygous high-confidence variants appear in individuals in gnomAD. Finally as commented on, APC2 is not mutated in colon cancer.

Animal models: Apc -/- mice displayed disrupted neuronal migration, with defects of lamination of cerebral cortex and cerebellum supporting the observed brain abnormalities. In addition Apc2-deficient mice also presented impaired learning and memory abilities. Extensive additional studies have shown Apc2 co-localization with microtubules affecting their stabilization, distribution along actin fibers (all supporting a role in cytoskeletal organization) and regulation of Rac1 (a Rho GTPase). Generation of Neuro2a cells demonstrated abnormal localization mainly in cell bodies of mutant hAPC2 proteins (due to frameshift in the last exon / deletion of the C-terminal part) - different from wt (neurites, growth cones, cell bodies). The first patient report also provided evidence for Apc2 being a downstream effector of Nsd1, with Nsd1 knockdown brains displaying impaired migration / laminar positioning of cortical neurons (similar to Apc2-/- model) and rescued by forced expression of Apc2.

Relevant articles:
PMIDs: 19759310 and 22573669 (Shintani et al. 2009 & 2012) [mouse model]
PMID: 25753423 (Almuriekhi et al. 2015) [2 individuals + mouse model]
PMID: 31585108 (Lee et al. 2019) [12 individuals from 8 families]
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In OMIM, the APC2-related phenotype is ?Sotos syndrome 3 (MIM 617169 - AR). G2P does not have any associated phenotype for this gene. In SysID, APC2 belongs to the Current primary ID genes.
APC2 is included in gene panels for ID offered by some diagnostic laboratories (eg. Radboudumc, GeneDx).
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Overall, this gene could be considered for inclusion in the ID panel probably as green (>3 individuals/families/variants, highly specific pattern of lissencephaly in 12/14, mouse model supporting migration defects and impaired learning/memory) rather than amber (differences between the 1st and the other families reported as for the OFC and presence of lissencephaly).
Sources: Literature
Intellectual disability v2.1062 CDH2 Konstantinos Varvagiannis changed review comment from: Accogli et al. (2019 - PMID: 31585109) report on 9 individuals with de novo pathogenic CDH2 variants.

Overlapping features included axon pathfinding defects (corpus callosum agenesis/hypoplasia, mirror movements, Duane anomaly), cardiac, ocular and genital anomalies. Neurodevelopmental phenotypes included DD (8/9), ID (2/8 mild and 2/8 moderate, the remaining had either low-average/borderline int. functioning (2), did not present ID (2) or did not have relevant age for evaluation) and ASD (in 2).

CDH2 encodes cadherin-2 (N-cadherin) with high expression in neural tissue. As the authors note, the gene has important role in neural development, incl. proliferation and differentiation of neural progenitor cells, neural tube formation, synaptogenesis, neuronal migration and axon elongation. N-cadherin, similar to other classical cadherins has an extracellular domain with 5 extracellular cadherin (EC) domain repeats that mediate cell adhesion either in cis or in trans (between molecules of the same / different cells).

Mutations in other cadherins have been associated among others with neurodevelopmental disorders (eg. PCDH19, PCDH12, etc).

Variants in all cases were de novo, identified following trio-WES. 7 missense variants (6 of which clustering within the EC4-EC5 linker region or the EC5 domain - calculated p=1.37x10-4) and 2 frameshift ones predicted not to lead to NMD were identified.

One individual had an additional DNM1 variant, formally fulfilling ACMG criteria for pathogenic. The authors however felt that presentation of the specific subject (low-average/borderline int. functioning, absence of seizures and microcephaly) was not compatible with the phenotype of DNM1-encephalopathy .

Missense SNVs within the EC4-EC5 region, were shown to impair cell-cell adhesion by affecting both self-binding and trans adhesion to wt N-cadherin (in L cells studied). This supported a possible dominant-negative effect. A single variant in the EC2 domain - previously shown to be critical for adhesion - was thought to have a similar effect. The authors speculated that truncating variants may also act in a dominant-negative manner (as has been demonstrated for other cadherins) although LoF remains possible.

Cdh2 knockout in mice is embryonically lethal. Mouse with conditional inactivation of Cdh2 in the cerebral cortex leads to cortical disorganization and CCA similar to the human phenotypes (PMIDs cited: 9015265, 17222817). Other animal studies (mouse, zebrafish, chicken, dog, etc) are also cited to link with specific defects.

Heterozygous CDH2 variants affecting the ectodomain have been associated with ARVC (2 variants, one of which segregated with the disorder in a 3-generation family, the other identified in two unrelated families with several affecteds - refs. provided in the article). Cardiac abnormalities were noted in several subjects (incl. electrical activity in 2). [Amber rating of this gene in Arrhythmogenic cardiomyopathy panel].
------
The gene is not associated with any phenotype in OMIM / G2P / SysID and not commonly included in panels for ID.
------
As a result CDH2 could be considered for inclusion in the ID panel probably as amber (mild/moderate ID in 4/8, uncertainty regarding the underlying effect of some variants or additional phenotypes (ARVC)) or green (>3 individuals/variants/families, ID is a feature and in some cases of moderate degree).
Sources: Literature; to: Accogli et al. (2019 - PMID: 31585109) report on 9 individuals with de novo pathogenic CDH2 variants.

Overlapping features included axon pathfinding defects (corpus callosum agenesis/hypoplasia, mirror movements, Duane anomaly), cardiac, ocular and genital anomalies. Neurodevelopmental phenotypes included DD (8/9), ID (2/8 mild and 2/8 moderate, the remaining had either low-average/borderline int. functioning (2), did not present ID (2) or did not have relevant age for evaluation) and ASD (in 2).

CDH2 encodes cadherin-2 (N-cadherin) with high expression in neural tissue. As the authors note, the gene has important role in neural development, incl. proliferation and differentiation of neural progenitor cells, neural tube formation, synaptogenesis, neuronal migration and axon elongation. N-cadherin, similar to other classical cadherins has an extracellular domain with 5 extracellular cadherin (EC) domain repeats that mediate cell adhesion either in cis or in trans (between molecules of the same / different cells).

Mutations in other cadherins have been associated among others with neurodevelopmental disorders (eg. PCDH19, PCDH12, etc).

Variants in all cases were de novo, identified following trio-WES. 7 missense variants (6 of which clustering within the EC4-EC5 linker region or the EC5 domain - calculated p=1.37x10-4) and 2 frameshift ones predicted not to lead to NMD were identified.

One individual had an additional DNM1 variant, formally fulfilling ACMG criteria for pathogenic. The authors however felt that presentation of the specific subject (low-average/borderline int. functioning, absence of seizures and microcephaly) was not compatible with the phenotype of DNM1-encephalopathy .

Missense SNVs within the EC4-EC5 region, were shown to impair cell-cell adhesion by affecting both self-binding and trans adhesion to wt N-cadherin (in L cells studied). This supported a possible dominant-negative effect. A single variant in the EC2 domain - previously shown to be critical for adhesion - was thought to have a similar effect. The authors speculated that truncating variants may also act in a dominant-negative manner (as has been demonstrated for other cadherins) although LoF remains possible.

Cdh2 knockout in mice is embryonically lethal. Conditional inactivation of Cdh2 in the cerebral cortex leads to cortical disorganization and CCA similar to the human phenotypes (PMIDs cited: 9015265, 17222817). Other animal studies (mouse, zebrafish, chicken, dog, etc) are also cited to link with specific defects.

Heterozygous CDH2 variants affecting the ectodomain have been associated with ARVC (2 variants, one of which segregated with the disorder in a 3-generation family, the other identified in two unrelated families with several affecteds - refs. provided in the article). Cardiac abnormalities were noted in several subjects (incl. electrical activity in 2). [Amber rating of this gene in Arrhythmogenic cardiomyopathy panel].
------
The gene is not associated with any phenotype in OMIM / G2P / SysID and not commonly included in panels for ID.
------
As a result CDH2 could be considered for inclusion in the ID panel probably as amber (mild/moderate ID in 4/8, uncertainty regarding the underlying effect of some variants or additional phenotypes (ARVC)) or green (>3 individuals/variants/families, ID is a feature and in some cases of moderate degree).
Sources: Literature
Intellectual disability v2.1062 CDH2 Konstantinos Varvagiannis gene: CDH2 was added
gene: CDH2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CDH2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: CDH2 were set to 31585109; 9015265; 17222817
Phenotypes for gene: CDH2 were set to Abnormality of the corpus callosum; Abnormality of neuronal migration; Bimanual synkinesia; Duane anomaly; Abnormality of cardiovascular system; Abnormality of the eye; Abnormality of the genital system; Global developmental delay; Intellectual disability
Penetrance for gene: CDH2 were set to unknown
Review for gene: CDH2 was set to AMBER
Added comment: Accogli et al. (2019 - PMID: 31585109) report on 9 individuals with de novo pathogenic CDH2 variants.

Overlapping features included axon pathfinding defects (corpus callosum agenesis/hypoplasia, mirror movements, Duane anomaly), cardiac, ocular and genital anomalies. Neurodevelopmental phenotypes included DD (8/9), ID (2/8 mild and 2/8 moderate, the remaining had either low-average/borderline int. functioning (2), did not present ID (2) or did not have relevant age for evaluation) and ASD (in 2).

CDH2 encodes cadherin-2 (N-cadherin) with high expression in neural tissue. As the authors note, the gene has important role in neural development, incl. proliferation and differentiation of neural progenitor cells, neural tube formation, synaptogenesis, neuronal migration and axon elongation. N-cadherin, similar to other classical cadherins has an extracellular domain with 5 extracellular cadherin (EC) domain repeats that mediate cell adhesion either in cis or in trans (between molecules of the same / different cells).

Mutations in other cadherins have been associated among others with neurodevelopmental disorders (eg. PCDH19, PCDH12, etc).

Variants in all cases were de novo, identified following trio-WES. 7 missense variants (6 of which clustering within the EC4-EC5 linker region or the EC5 domain - calculated p=1.37x10-4) and 2 frameshift ones predicted not to lead to NMD were identified.

One individual had an additional DNM1 variant, formally fulfilling ACMG criteria for pathogenic. The authors however felt that presentation of the specific subject (low-average/borderline int. functioning, absence of seizures and microcephaly) was not compatible with the phenotype of DNM1-encephalopathy .

Missense SNVs within the EC4-EC5 region, were shown to impair cell-cell adhesion by affecting both self-binding and trans adhesion to wt N-cadherin (in L cells studied). This supported a possible dominant-negative effect. A single variant in the EC2 domain - previously shown to be critical for adhesion - was thought to have a similar effect. The authors speculated that truncating variants may also act in a dominant-negative manner (as has been demonstrated for other cadherins) although LoF remains possible.

Cdh2 knockout in mice is embryonically lethal. Mouse with conditional inactivation of Cdh2 in the cerebral cortex leads to cortical disorganization and CCA similar to the human phenotypes (PMIDs cited: 9015265, 17222817). Other animal studies (mouse, zebrafish, chicken, dog, etc) are also cited to link with specific defects.

Heterozygous CDH2 variants affecting the ectodomain have been associated with ARVC (2 variants, one of which segregated with the disorder in a 3-generation family, the other identified in two unrelated families with several affecteds - refs. provided in the article). Cardiac abnormalities were noted in several subjects (incl. electrical activity in 2). [Amber rating of this gene in Arrhythmogenic cardiomyopathy panel].
------
The gene is not associated with any phenotype in OMIM / G2P / SysID and not commonly included in panels for ID.
------
As a result CDH2 could be considered for inclusion in the ID panel probably as amber (mild/moderate ID in 4/8, uncertainty regarding the underlying effect of some variants or additional phenotypes (ARVC)) or green (>3 individuals/variants/families, ID is a feature and in some cases of moderate degree).
Sources: Literature
Intellectual disability v2.1062 MED25 Helen Brittain edited their review of gene: MED25: Added comment: There are now different variants (potentially each founders) in three populations, and several families, that have been reported in association with ID. Therefore the evidence for a green rating in terms of a gene:disease association now seems sufficient. To determine the extent of the phenotype, in terms of associated features, further cases would be beneficial. Therefore I would currently recommend a green rating for the ID panel.; Changed rating: GREEN; Changed phenotypes: Basel-Vanagait-Smirin-Yosef syndrome 616449; Changed mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1062 INTS1 Rebecca Foulger Phenotypes for gene: INTS1 were changed from Hypotonia; Global developmental delay; Cataract; Abnormality of the skeletal system to Neurodevelopmental disorder with cataracts, poor growth, and dysmorphic facies, 618571; Hypotonia; Global developmental delay; Cataract; Abnormality of the skeletal system
Intellectual disability v2.1061 AP2M1 Rebecca Foulger Phenotypes for gene: AP2M1 were changed from Seizures; Ataxia; Generalized hypotonia; Intellectual disability; Global developmental delay; Autistic behavior to Intellectual developmental disorder 60 with seizures, 618587; Seizures; Ataxia; Generalized hypotonia; Intellectual disability; Global developmental delay; Autistic behavior
Intellectual disability v2.1060 RAC3 Rebecca Foulger Phenotypes for gene: RAC3 were changed from Abnormality of brain morphology, Abnormal muscle tone, Neurodevelopmental delay, Intellectual disability; Abnormality of brain morphology; Abnormal muscle tone; Neurodevelopmental delay; Intellectual disability to Neurodevelopmental disorder with structural brain anomalies and dysmorphic facies, 618577; Abnormality of brain morphology, Abnormal muscle tone, Neurodevelopmental delay, Intellectual disability; Abnormality of brain morphology; Abnormal muscle tone; Neurodevelopmental delay; Intellectual disability
Intellectual disability v2.1059 PIGU Rebecca Foulger Phenotypes for gene: PIGU were changed from Global developmental delay; Intellectual disability; Seizures; Cerebral atrophy; Cerebellar hypoplasia; Scoliosis to Glycosylphosphatidylinositol biosynthesis defect 2, 618590; Global developmental delay; Intellectual disability; Seizures; Cerebral atrophy; Cerebellar hypoplasia; Scoliosis
Intellectual disability v2.1058 PIGQ Rebecca Foulger Phenotypes for gene: PIGQ were changed from SEVERE EARLY-ONSET EPILEPSY to SEVERE EARLY-ONSET EPILEPSY; Epileptic encephalopathy, early infantile, 77, 618548
Intellectual disability v2.1057 PIGB Rebecca Foulger Phenotypes for gene: PIGB were changed from Generalized hypotonia; Global developmental delay; Intellectual disability; Seizures; Hearing abnormality; Abnormality of vision; Elevated alkaline phosphatase; Abnormality of the head; Abnormality of the hand; Abnormality of the foot to Epileptic encephalopathy, early infantile, 80, 618580; Generalized hypotonia; Global developmental delay; Intellectual disability; Seizures; Hearing abnormality; Abnormality of vision; Elevated alkaline phosphatase; Abnormality of the head; Abnormality of the hand; Abnormality of the foot
Intellectual disability v2.1056 HNRNPR Catherine Snow Classified gene: HNRNPR as Green List (high evidence)
Intellectual disability v2.1056 HNRNPR Catherine Snow Gene: hnrnpr has been classified as Green List (High Evidence).
Intellectual disability v2.1055 HNRNPR Catherine Snow reviewed gene: HNRNPR: Rating: GREEN; Mode of pathogenicity: None; Publications: 31079900, 26795593; Phenotypes: Intellectual Disability; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.1055 DDX6 Catherine Snow Classified gene: DDX6 as Green List (high evidence)
Intellectual disability v2.1055 DDX6 Catherine Snow Gene: ddx6 has been classified as Green List (High Evidence).
Intellectual disability v2.1054 DDX6 Catherine Snow reviewed gene: DDX6: Rating: GREEN; Mode of pathogenicity: None; Publications: 31422817; Phenotypes: ; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.1054 TIMM50 Rebecca Foulger Classified gene: TIMM50 as Green List (high evidence)
Intellectual disability v2.1054 TIMM50 Rebecca Foulger Added comment: Comment on list classification: TIMM50 was added to the ID panel and rated Green by Konstantinos Varvagiannis. Not yet associated with a disorder in Gene2Phenotype but upgraded rating from Grey to Green following review of literature evidence. PMID:27573165 and PMID:31058414 report 5 patients from 3 families with a consistent ID and epilepsy phenotype accompanied by 3-methylglutaconic aciduria. In addition, PMID:30190335 report pyschomotor regression in their patient, and a conference abstract (Serajee et al. 2015) adds an additional case of developmental delay. Therefore ID appears a consistent phenotype of 3-methylglutaconic aciduria and with sufficient reported cases, a Green rating is appropriate.
Intellectual disability v2.1054 TIMM50 Rebecca Foulger Gene: timm50 has been classified as Green List (High Evidence).
Intellectual disability v2.1053 TIMM50 Rebecca Foulger commented on gene: TIMM50
Intellectual disability v2.1053 TIMM50 Rebecca Foulger Phenotypes for gene: TIMM50 were changed from 3-methylglutaconic aciduria, type IX (MIM 617698) to 3-methylglutaconic aciduria, type IX, 617698
Intellectual disability v2.1052 GABRA5 Rebecca Foulger Classified gene: GABRA5 as Green List (high evidence)
Intellectual disability v2.1052 GABRA5 Rebecca Foulger Added comment: Comment on list classification: Upgraded from Amber to Green following advice from Genomics England clinical team. The case reported in PMID:29961870 (Butler et al 2018) had delayed milestones and is reported to be non-verbal, which is a relevant phenotype for this panel. Overall 3 unrelated cases from 2 papers.
Intellectual disability v2.1052 GABRA5 Rebecca Foulger Gene: gabra5 has been classified as Green List (High Evidence).
Intellectual disability v2.1051 KCNMA1 Catherine Snow Phenotypes for gene: KCNMA1 were changed from GENERALIZED EPILEPSY AND PAROXYSMAL DYSKINESIA to Cerebellar atrophy, developmental delay, and seizures, 617643; Paroxysmal nonkinesigenic dyskinesia, 3, with or without generalized epilepsy, 609446
Intellectual disability v2.1050 KCNMA1 Catherine Snow Publications for gene: KCNMA1 were set to 15937479
Intellectual disability v2.1049 KCNMA1 Catherine Snow Mode of inheritance for gene: KCNMA1 was changed from MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v2.1048 KCNMA1 Catherine Snow Classified gene: KCNMA1 as Amber List (moderate evidence)
Intellectual disability v2.1048 KCNMA1 Catherine Snow Gene: kcnma1 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1047 KCNMA1 Catherine Snow reviewed gene: KCNMA1: Rating: AMBER; Mode of pathogenicity: None; Publications: 31427379, 31152168; Phenotypes: Cerebellar atrophy, developmental delay, and seizures, 617643; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v2.1047 SMG9 Konstantinos Varvagiannis reviewed gene: SMG9: Rating: GREEN; Mode of pathogenicity: None; Publications: 27018474, 31390136; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v2.1047 METTL5 Konstantinos Varvagiannis edited their review of gene: METTL5: Set current diagnostic: yes
Intellectual disability v2.1047 METTL5 Konstantinos Varvagiannis gene: METTL5 was added
gene: METTL5 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: METTL5 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: METTL5 were set to 29302074; http://doi.org/10.1016/j.ajhg.2019.09.007; https://imgc2019.sciencesconf.org/data/abstract_book_complete.pdf
Phenotypes for gene: METTL5 were set to Delayed speech and language development; Intellectual disability; Microcephaly; Behavioral abnormality
Penetrance for gene: METTL5 were set to Complete
Review for gene: METTL5 was set to GREEN
Added comment: [1] - PMID: 29302074 :
In a WES/WGS study of 404 consanguineous families with two or more offspring affected by ID, Hu et al. identified two sibs homozygous for a METTL5 missense variant [NM_014168:c.182G>A / p.Gly61Asp]. These 2 subjects, born to first cousin parents from Iran, presented with early learning impairment, aggressive behaviour, severe microcephaly (-7SD and -8SD) and ID formally evaluated to be in the severe range. Sanger confirmation of variants and segregation studies were performed for all available and informative members in families participating in the study. In silico predictions were all in favour of a deleterious effect (PolyPhen2, MutationTaster, SIFT, CADD) and the variant was absent from ExAC. The effect of the specific variant was studied in ref. 2 (below).

[2] - DOI: 10.1016/j.ajhg.2019.09.007 :
Richard et al. (2019) reported on 5 additional individuals from 2 consanguineous families. Common phenotype consisted of speech delay, moderate/severe ID (4/4), microcephaly (4/4 - though milder than in the first report), behavioral problems (ADHD, aggressiveness, autistic feat.) and possibly some overlapping facial features (nose and ear abnormalities). 3 sibs from the 1st family, from Pakistan, were homozygous for a frameshift variant (NM_014167.2:c.344_345delGA / p.Arg115Asnfs*19) while sibs from the 2nd family, from Yemen, were homozygous for p.Lys191Valfs*1 (c.571_572delAA). Confirmation and segregation studies supported a role for the variants.

The authors performed additional studies for METTL5 and all 3 variants reported to date, notably:
- Based on RNA-seq data from the Allen Brain Atlas, METTL5 is expressed in the developing and adult human brain (incl. cerebellar cortex, hippocampus and striatum).
- Immunostaining in mouse brain demonstrated ubiquitous expression (postnatal day 30).
- In rat hippocampal neurons, enrichment of METTL5 was found in the soma, the nucleus and pre- and post- synaptic regions.
- Myc-/GFP-tagged METTL5 wt or mutants were transiently expressed in COS7 cells, and were found in the cytoplasm and nucleus. Levels of the 2 frameshift variants were significantly reduced compared with wt, although this was not the case for Gly61Asp.
- Upon transfection of rat hippocampal neurons, METTL5-GFP tagged wt and mt proteins showed similar localicalization in nucleus and dendrites.
- Western blot on HEK293T cells transfected with Myc-METTL5 wt or mt constructs demonstrated decreased amounts for the frameshift (but not the missense) variants while comparison after addition of a proteasome inhibitor or cyclohexamide suggested that this is not probably due to decreased mutant protein - rather than mRNA (NMD) - stability.
- In zebrafish, morpholino knockdown of mettl5 led to reduced head size and head/body ratio (reproducing the microcephaly phenotype) and curved tails. Forebrain and midbrain sizes were also significantly reduced.

Based on the ACMG criteria, Gly61Asp is classified as VUS (PM2, PP1, PP3) and the frameshift ones as pathogenic (PS3, PM2, PM4, PP1, PP3).

The authors comment that METTL5 is an uncharacterized member of the methyltransferase superfamily (of 33 METTL proteins). Variants in other methyltransferase-like genes (mainly METTL23) have been associated with ID, while various histone-/DNA-/tRNA-/rRNA- methyltransferases such as EHMT1, DNMT3A, NSUN2, FTSJ1, etc have been implicated in ID. Given the role of methyltransferases in neurodevelopment and neuroplasticity, homology comparisons suggesting presence of relevant domain in METTL5 and accumulation of the protein in the nucleus, a role as epigenetic regulator is proposed (see also ref. 3).

[3] - Conference abstract by Helmut et al. ["A novel m6A RNA methyltransferase in mammals - characterization of Mettl5 mutant mice in the German Mouse Clinic" - Oral presentation in the 33rd International Mammalian Genome Conference Sept. 2019 - available at : https://imgc2019.sciencesconf.org/data/abstract_book_complete.pdf ]
The group using an in vitro methyltransferase assay, identified METTL5 as a m6A RNA methyltransferase. Generation of Mettl5-knockout mice using the CRISPR/Cas technology, suggested that homozygous mice are subviable, with lower body mass and abnormal growth of nasal bones in half. Homozygous mice were hypoactive and hypoexploratory during an open field test at the age of 8 weeks, while further alterations were observed in neurological functions. Phenotypic deviations were absent or very mild in heterozygous animals. As a result, the mouse model appeared to recapitulate relevant human phenotypes (microcephaly, ID and growth retardation).

----
There is no associated entry in OMIM (neither for the gene nor for a related disorder). G2P does not list any phenotype for this gene, either.

METTL5 is included in the SysID database as a current primary ID gene (cited: 27457812, 28097321 / Given the shared co-authors with the study by Richard et al. as well as the overlapping variants, these articles probably report on the same individuals recently described in more detail).

The gene is included in gene panels for ID offered by some diagnostic laboratories (eg. GeneDx).
----

Overall, METTL5 could be considered for inclusion in the ID panel probably as green (3 families, 3 variants, segregation, suggested role of the gene, relevant expression patterns, some evidence at the variant-level, zebrafish and mouse models) or amber (underlying effect of Gly61Asp unknown and variant classified as VUS).
Sources: Literature
Intellectual disability v2.1047 CSDE1 Konstantinos Varvagiannis gene: CSDE1 was added
gene: CSDE1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CSDE1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: CSDE1 were set to http://doi.org/10.1126/sciadv.aax2166
Phenotypes for gene: CSDE1 were set to Autism; Global developmental delay; Intellectual disability
Penetrance for gene: CSDE1 were set to unknown
Review for gene: CSDE1 was set to GREEN
Added comment: Guo et al. (2019 - DOI: 10.1126/sciadv.aax2166) report on 18 individuals from 18 unrelated families, with heterozygous likely gene disrupting (stopgain/frameshift/spice-site) CSDE1 variants.

Initial sequencing with MIPs found in 3 individuals from an autism cohort (4045 probands), while subsequent targeted sequencing of a larger cohort (autism spectrum/ID network) led to identification of 5 additional relevant individuals and Genematcher/collaborations a further 10 (the latter by WES).

Consistent phenotypes included ASD (10 of 15 formally evaluated), DD (motor: 15/17 - speech: 17/17) and ID (mild to severe in 14 of 16 assessed, in further 2 in the below-average range). Recurrent seizures or epilepsy were reported for 7 of 16 patients. Other variable features were anxiety or ADHD, increased OFC, ocular, hand and MRI anomalies.

The study was mainly focused on LGD variants with p.R123* (NM_001242891.1:c.367C>T) being a reccurrent one, found in 3 families.

8 of these variants were de novo, 8 further inherited (often from a less severely affected parent, although parental neuropsychiatric status was not available for individuals from all 3 groups). In 2 cases inheritance was unknown (only 1 parental sample available).

3 individuals with de novo missense variants were also identified. Features in those individuals also included ASD and/or DD and ID (2/3) [Table S1].

Arguments to support involvement of the CSDE1 variants included the:
- role of the gene encoding an RNA binding protein implicated in neuronal migration/differentiation (cited : 24012837, 29129916),
- statistically significant burden of the variants in the cohorts examined,
- relevant CSDE1 intolerance scores (pLI of 1 and %RVIS of 6.18),
- relevant human (mRNA) / mouse (protein) spatial and temporal expression patterns,
- exclusion of apparent alternative diagnoses to the extent possible in many subjects with CNVs/SNVs/ROH of uncertain significance in very few,
- cosegregation with rather similar neuropsychiatric phenotypes in case of carrier parents,
- enrichment of ASD-related genes (and FMRP targets) among CSDE1-binding targets,
- suppression of Ctnnb1 expression (at the protein level) affecting Wnt/β-catenin signalling,
- effect of knockdown and/or mutants in mouse (shRNA) and Drosophila (mt and siRNA) models affecting synapse formation and synaptic transmission,
- rescue of many of the previous phenotypes by expression of human CSDE1 (mice), expression of stabilized β-Catenin (mice) or RNAi-stable-dUNR (Drosophila) [also supporting LoF as the underlying effect of variants].

CSDE1 is not commonly included in gene panels for ID offered by diagnostic laboratories. There is no associated phenotype in OMIM/G2P.

Overall, this gene could be considered for inclusion in the ID panel probably as green (or amber).
Sources: Literature
Intellectual disability v2.1047 MED25 Rebecca Foulger Publications for gene: MED25 were set to 25792360; 25527630
Intellectual disability v2.1046 MED25 Rebecca Foulger changed review comment from: 10.1159/000501114 (Nair et al., 2019b) report an additional Lebanese family with 2 affected siblings with delayed psychomotor and language development, with craniofacial anomalies. A homozyogus p.Ile173Thr change in MED25 was found, which may be a Founder variant.; to: DOI:10.1159/000501114 (Nair et al., 2019b) report an additional Lebanese family with 2 affected siblings with delayed psychomotor and language development, with craniofacial anomalies. A homozyogus p.Ile173Thr change in MED25 was found, which may be a Founder variant.
Intellectual disability v2.1046 MED25 Rebecca Foulger commented on gene: MED25: 10.1159/000501114 (Nair et al., 2019b) report an additional Lebanese family with 2 affected siblings with delayed psychomotor and language development, with craniofacial anomalies. A homozyogus p.Ile173Thr change in MED25 was found, which may be a Founder variant.
Intellectual disability v2.1046 MED25 Rebecca Foulger commented on gene: MED25
Intellectual disability v2.1046 PMPCB Konstantinos Varvagiannis changed review comment from: Biallelic pathogenic PMPCB variants cause, Multiple mitochondrial dysfunctions syndrome 6 (MIM 617954).

5 relevant individuals from 4 unrelated families (in one case consanguineous) have been reported by Vögtle et al. (2018 - PMID: 29576218).

Onset of symptoms (eg. hypotonia) often preceded a period of developmental regression/stagnation which was common in all individuals and occurred within the first 2 years of life, usually following febrile illness. In all cases neurological features were severe (lack of ambulation/speech). Seizures were observed in 4 individuals from 3 families, with onset at the age of 11-24m. MRI images demonstrated T2 signal hyperintensities of the basal ganglia with cerebellar and cerebral atrophy in some. Deterioration with early death was reported on three occasions, though some years after symptom onset.

Following exclusion of other diagnoses in some cases (eg. aCGH, epilepsy panel), WES identified biallelic PMPCB missense variants, supported by Sanger confirmation and segregation studies. The following variants were reported (NM_004279.2):
- c.523C>T (p.Arg175Cys) in trans with c.601G>C (p.Ala201Pro) [Fam A and B]
- c.524G>A (p.Arg175His) in trans with c.530T>G (p.Val177Gly) [Fam C]
- c.1265T>C (p.Ile422Thr) in homozygous state [Fam D with 2 affected sibs]

The gene encodes the catalytic (beta) subunit of the mitochondrial processing protease (MPP) which is responsible for the cleavage/maturation of nuclear-encoded mitochondrial precursor proteins after their import in mitochondria. The alpha subunit is encoded by PMPCA (green rating proposed for this panel).

Extensive studies demonstrated (perhaps a better summary provided by OMIM):
- Reduced PMPCB protein levels in mitochondria isolated from patient fibroblasts or patient-derived pluripotent stem cells.
- Frataxin maturation was impaired with accumulation of the intermediate form and lower amounts of mature FXN, indicating decrease in MPP activity.
- Analysis of the homologous Mas1 S. cerevisiae mutants was carried out, with the exception of Ile422Thr (corresponding to Mas1 - Ile398Thr), the introduction of which did not yield viable yiest strains. Homologous mutations led to a temperature-sensitive phenotype with accumulation of immature/unprocessed precursor proteins and decrease of mature/processed forms both in vivo or in organello (following isolation of mitochondria). Under conditions of heat stress, Mas1 mutations decreased biogenesis of Fe-S clusters.
- Respiratory chain complexes I-III contain Fe-S clusters. In muscle biopsy from an affected individual, complex II activity was significantly reduced (although this was not the case in fibroblasts or liver biopsy). Dysfunction of mitochondrial and cytosolic Fe-S cluster-dependent enzymes (eg. aconitase) was also shown in muscle tissue.

Regression/stagnation with seizures/non-achievement of milestones may justify testing for an ID / epilepsy gene panel. In addition, metabolic studies or mitochondrial respiratory chain complex studies were sometimes non-informative (lactate elevated in 3/5 subjects) or not carried out at all / in relevant tissues (muscle biopsy in 2 individuals, fibroblasts/liver biopsy did not demonstrate reduced complex activity when tested).

PMPCB is included in the ID gene panel of Radboudumc, as well as the SysID database. The gene is included in the DD panel of G2P associated with "Neurodegeneration in Early Childhood" (disease confidence : probable).

As a result, PMPCB can be considered for inclusion in both epilepsy and ID panels as green (or amber).
Sources: Literature, Radboud University Medical Center, Nijmegen; to: Biallelic pathogenic PMPCB variants cause, Multiple mitochondrial dysfunctions syndrome 6 (MIM 617954).

5 relevant individuals from 4 unrelated families (in one case consanguineous) have been reported by Vögtle et al. (2018 - PMID: 29576218).

Onset of symptoms (eg. hypotonia) often preceded a period of developmental regression/stagnation which was common in all individuals and occurred within the first 2 years of life, usually following febrile illness. In all cases neurological features were severe (lack of ambulation/speech). Seizures were observed in 4 individuals from 3 families, with onset at the age of 11-24m. MRI images demonstrated T2 signal hyperintensities of the basal ganglia with cerebellar and cerebral atrophy in some. Deterioration with early death was reported on three occasions, though some years after symptom onset.

Following exclusion of other diagnoses in some cases (eg. aCGH, epilepsy panel), WES identified biallelic PMPCB missense variants, supported by Sanger confirmation and segregation studies. The following variants were reported (NM_004279.2):
- c.523C>T (p.Arg175Cys) in trans with c.601G>C (p.Ala201Pro) [Fam A and B]
- c.524G>A (p.Arg175His) in trans with c.530T>G (p.Val177Gly) [Fam C]
- c.1265T>C (p.Ile422Thr) in homozygous state [Fam D with 2 affected sibs]

The gene encodes the catalytic (beta) subunit of the mitochondrial processing protease (MPP) which is responsible for the cleavage/maturation of nuclear-encoded mitochondrial precursor proteins after their import in mitochondria. The alpha subunit is encoded by PMPCA (green rating proposed for this panel).

Extensive studies demonstrated (perhaps a better summary provided by OMIM):
- Reduced PMPCB protein levels in mitochondria isolated from patient fibroblasts or patient-derived pluripotent stem cells.
- Frataxin maturation was impaired with accumulation of the intermediate form and lower amounts of mature FXN, indicating decrease in MPP activity.
- Analysis of the homologous Mas1 S. cerevisiae mutants was carried out, with the exception of Ile422Thr (corresponding to Mas1 - Ile398Thr), the introduction of which did not yield viable yeast strains. Homologous mutations led to a temperature-sensitive phenotype with accumulation of immature/unprocessed precursor proteins and decrease of mature/processed forms both in vivo or in organello (following isolation of mitochondria). Under conditions of heat stress, Mas1 mutations decreased biogenesis of Fe-S clusters.
- Respiratory chain complexes I-III contain Fe-S clusters. In muscle biopsy from an affected individual, complex II activity was significantly reduced (although this was not the case in fibroblasts or liver biopsy). Dysfunction of mitochondrial and cytosolic Fe-S cluster-dependent enzymes (eg. aconitase) was also shown in muscle tissue.

Regression/stagnation with seizures/non-achievement of milestones may justify testing for an ID / epilepsy gene panel. In addition, metabolic studies or mitochondrial respiratory chain complex studies were sometimes non-informative (lactate elevated in 3/5 subjects) or not carried out at all / in relevant tissues (muscle biopsy in 2 individuals, fibroblasts/liver biopsy did not demonstrate reduced complex activity when tested).

PMPCB is included in the ID gene panel of Radboudumc, as well as the SysID database. The gene is included in the DD panel of G2P associated with "Neurodegeneration in Early Childhood" (disease confidence : probable).

As a result, PMPCB can be considered for inclusion in both epilepsy and ID panels as green (or amber).
Sources: Literature, Radboud University Medical Center, Nijmegen
Intellectual disability v2.1046 INTS6 Konstantinos Varvagiannis reviewed gene: INTS6: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.1046 PMPCB Konstantinos Varvagiannis edited their review of gene: PMPCB: Changed publications: 29576218
Intellectual disability v2.1046 PMPCB Konstantinos Varvagiannis gene: PMPCB was added
gene: PMPCB was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen
Mode of inheritance for gene: PMPCB was set to BIALLELIC, autosomal or pseudoautosomal
Phenotypes for gene: PMPCB were set to Multiple mitochondrial dysfunctions syndrome 6, 617954
Penetrance for gene: PMPCB were set to Complete
Review for gene: PMPCB was set to GREEN
gene: PMPCB was marked as current diagnostic
Added comment: Biallelic pathogenic PMPCB variants cause, Multiple mitochondrial dysfunctions syndrome 6 (MIM 617954).

5 relevant individuals from 4 unrelated families (in one case consanguineous) have been reported by Vögtle et al. (2018 - PMID: 29576218).

Onset of symptoms (eg. hypotonia) often preceded a period of developmental regression/stagnation which was common in all individuals and occurred within the first 2 years of life, usually following febrile illness. In all cases neurological features were severe (lack of ambulation/speech). Seizures were observed in 4 individuals from 3 families, with onset at the age of 11-24m. MRI images demonstrated T2 signal hyperintensities of the basal ganglia with cerebellar and cerebral atrophy in some. Deterioration with early death was reported on three occasions, though some years after symptom onset.

Following exclusion of other diagnoses in some cases (eg. aCGH, epilepsy panel), WES identified biallelic PMPCB missense variants, supported by Sanger confirmation and segregation studies. The following variants were reported (NM_004279.2):
- c.523C>T (p.Arg175Cys) in trans with c.601G>C (p.Ala201Pro) [Fam A and B]
- c.524G>A (p.Arg175His) in trans with c.530T>G (p.Val177Gly) [Fam C]
- c.1265T>C (p.Ile422Thr) in homozygous state [Fam D with 2 affected sibs]

The gene encodes the catalytic (beta) subunit of the mitochondrial processing protease (MPP) which is responsible for the cleavage/maturation of nuclear-encoded mitochondrial precursor proteins after their import in mitochondria. The alpha subunit is encoded by PMPCA (green rating proposed for this panel).

Extensive studies demonstrated (perhaps a better summary provided by OMIM):
- Reduced PMPCB protein levels in mitochondria isolated from patient fibroblasts or patient-derived pluripotent stem cells.
- Frataxin maturation was impaired with accumulation of the intermediate form and lower amounts of mature FXN, indicating decrease in MPP activity.
- Analysis of the homologous Mas1 S. cerevisiae mutants was carried out, with the exception of Ile422Thr (corresponding to Mas1 - Ile398Thr), the introduction of which did not yield viable yiest strains. Homologous mutations led to a temperature-sensitive phenotype with accumulation of immature/unprocessed precursor proteins and decrease of mature/processed forms both in vivo or in organello (following isolation of mitochondria). Under conditions of heat stress, Mas1 mutations decreased biogenesis of Fe-S clusters.
- Respiratory chain complexes I-III contain Fe-S clusters. In muscle biopsy from an affected individual, complex II activity was significantly reduced (although this was not the case in fibroblasts or liver biopsy). Dysfunction of mitochondrial and cytosolic Fe-S cluster-dependent enzymes (eg. aconitase) was also shown in muscle tissue.

Regression/stagnation with seizures/non-achievement of milestones may justify testing for an ID / epilepsy gene panel. In addition, metabolic studies or mitochondrial respiratory chain complex studies were sometimes non-informative (lactate elevated in 3/5 subjects) or not carried out at all / in relevant tissues (muscle biopsy in 2 individuals, fibroblasts/liver biopsy did not demonstrate reduced complex activity when tested).

PMPCB is included in the ID gene panel of Radboudumc, as well as the SysID database. The gene is included in the DD panel of G2P associated with "Neurodegeneration in Early Childhood" (disease confidence : probable).

As a result, PMPCB can be considered for inclusion in both epilepsy and ID panels as green (or amber).
Sources: Literature, Radboud University Medical Center, Nijmegen
Intellectual disability v2.1046 NUP188 Konstantinos Varvagiannis reviewed gene: NUP188: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.1046 CPD Konstantinos Varvagiannis changed review comment from: The gene was present in the current panel with red rating, though with no reviews.

In Pubmed there are no publications concerning eventual CPD-related phenotypes. There is no associated phenotype in OMIM or G2P, either. The gene is not included in the SysID and SFARI databases. The denovo-db lists 1 individual with autism and de novo LoF variant (NM_001304.4:c.2478C>G - p.Tyr826* - Iossifov et al. - PMID: 25363768) and 2 further with congenital heart disease. Still the gene encodes an enzyme (carboxyptidase D), so AR inheritance would seem more likely (?). [The gene has also a pLI of 0 in gnomAD and Z-score of 2.59]. CPD is not included in gene panels for ID offered by diagnostic laboratories (including also the current ID panel of VCGS which was listed as a source).

As a result, red rating (or removal from the current panel) seems appropriate.; to: The gene was present in the current panel with red rating, though with no reviews.

In Pubmed there are no publications concerning eventual CPD-related phenotypes. There is no associated phenotype in OMIM or G2P, either. The gene is not included in the SysID and SFARI databases. The denovo-db lists 1 individual with autism and de novo LoF variant (NM_001304.4:c.2478C>G - p.Tyr826* - Iossifov et al. - PMID: 25363768) and 2 further with congenital heart disease. Still the gene encodes an enzyme (carboxyptidase D), so AR inheritance would seem more likely (?). [The gene has also a pLI of 0 in gnomAD and Z-score of 2.59. In Decipher %HI is 31.31]. CPD is not included in gene panels for ID offered by diagnostic laboratories (including also the current ID panel of VCGS which was listed as a source).

As a result, red rating (or removal from the current panel) seems appropriate.
Intellectual disability v2.1046 CPD Konstantinos Varvagiannis reviewed gene: CPD: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.1046 CA5A Konstantinos Varvagiannis reviewed gene: CA5A: Rating: RED; Mode of pathogenicity: None; Publications: 26913920, 25834911, 24530203; Phenotypes: Hyperammonemia due to carbonic anhydrase VA deficiency (MIM 615751); Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1046 PMPCA Konstantinos Varvagiannis gene: PMPCA was added
gene: PMPCA was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen
Mode of inheritance for gene: PMPCA was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PMPCA were set to 25808372; 26657514; 27148589; 30617178
Phenotypes for gene: PMPCA were set to Spinocerebellar ataxia, autosomal recessive 2 (MIM 213200)
Penetrance for gene: PMPCA were set to Complete
Review for gene: PMPCA was set to GREEN
gene: PMPCA was marked as current diagnostic
Added comment: Biallelic pathogenic PMPCA variants cause Spinocerebellar ataxia, autosomal recessive 2 (SCAR2 - MIM 213200). More than 20 individuals from several unrelated families have been reported. At least 6 different pathogenic variants have been identified. Loss of PMPCA function is the suggested mechanism. ID is a feature of the disorder.

PMPCA encodes the α-subunit of mitochondrial processing peptidase (αMPP), a heterodimeric enzyme responsible for the cleavage of nuclear-encoded mitochondrial precursor proteins after import in the mitochondria (summary by Jobling et al and OMIM).

Arguments for involvement of the gene include the highly similar phenotype, segregation studies, expression of the gene in fetal and relevant adult tissues (in brain/cerebellum/cerebellar vermis), lower protein levels demonstrated for some variants, abnormal processing of frataxin (in line with the role of αMPP) demonstrated in most cases, rescue of the maturation defect upon transduction of wt PMPCA cDNA, disruption of REDOX balance in patient cells, etc.

Relevant studies are summarized below.

PMPCA is included in gene panels for ID offered by several diagnostic laboratories (incl. Radboud UMC, GeneDx, etc) and listed as a confirmed ID gene in SysID. It is not associated with any phenotype in G2P.

As a result, this gene can be considered for inclusion in the current panel probably as green (or amber).

----

[1] - Jobling et al. (2015 - PMID: 25808372) described the phenotype of 17 individuals from 4 families, all presenting with non-progressive cerebellar ataxia and the majority with ID of variable severity (15/17 - relevant to the current panel). Individuals from 3 of the families - all of Lebanese origin - were homozygous for NM_015160.3:c.1129G>A (p.Ala377Thr). A further similarly affected subject was compound heterozygous for c.287C>T (p.Ser96Leu) and c.1543G>A (p.Gly515Arg).

The homozygous variant in the first family was found within a 2.85 Mb linkage region on chr 9q34. An additional variant within this region (in CAMSAP1) was discarded following results in other families of the same origin.

Semi-quantitative RT-PCR demonstrated fetal expression of the PMPCA as well as relatively higher expression in adult brain, cerebellum and cerebellar vermis.

As for Ala377Thr, protein levels were shown to be lowest in affected individuals (LCLs, fibroblasts) and low - though somewhat higher - in carrier parents (LCL) compared to controls. RT-PCR on total RNA from LCLs did not show evidence of abnormal transcripts/additional splicing defect. Localization of mutant protein and morphology of mitochondrial reticulum was similar to controls. Maturation of frataxin - the protein depleted in Friedreich ataxia - was shown to be abnormal in patient lymphoblasts, compatible with the role of αMPP. In line with abnormal mitochondrial function, REDOX balance was increased in patient cells.

[2] - Choquet et al. (2016 - PMID: 26657514) reported on 2 sibs - born to distantly related parents. The authors noted a phenotype corresponding to SCAR2 although the presentation was somewhat milder, intellectual disability was not a feature (despite some learning difficulties in one) and ataxia was progressive. WES demonstrated homozygosity for NM_015160:c.766G>A (p.Val256Met). Western blot in patient lymphoblasts showed αMPP levels similar to carriers and controls. Abnormal maturation (accumulation of specific isoforms) was shown for frataxin.

[3] - Joshi et al. (2016 - PMID: 27148589) described the phenotype of 2 cousins belonging to a large Lebanese pedigree. Presentation in both was compatible with multisystem involvement incl. profound global DD, severe hypotonia, weakness, respiratory insufficiency, blindness suggestive of mitochondrial disorder. mtDNA, analyses of mitochondrial focused nuclear gene panel and aCGH were non-diagnostic. Both subjects were compound heterozygous for NM_015160.3:c.1066G>A (p.Gly356Ser) and c.1129G>A (p.Ala377Thr) following WES, with compatible segregation studies within the family. Western blot revealed PMPCA levels similar to control. Reduction of PMPCA staining and abnormally enlarged mitochondria were observed upon immunofluorescence in patient fibroblasts. Frataxin processing was abnormal. Lentiviral transduction of patient fibroblasts with wt PMPCA cDNA, led to increased PMPCA levels and correction of frataxin processing.

[4] - Rubegni et al. (2019 - PMID: 30617178) report on a 7-y.o. boy with global DD, spastic-ataxic gait and 'low IQ'. MRI images were suggestive of cerebellar atrophy with hyperintensity in the striatum. The child was homozygous for c.553C>T / p.Arg185Trp (reference not specified, although the variant would be compatible with NM_015160.3).
Sources: Literature, Radboud University Medical Center, Nijmegen
Intellectual disability v2.1046 TIMM50 Konstantinos Varvagiannis gene: TIMM50 was added
gene: TIMM50 was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen
Mode of inheritance for gene: TIMM50 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TIMM50 were set to 27573165; 30190335; 31058414; Serajee et al. (ASHG conference 2015 - abstract Nr. 2299T)
Phenotypes for gene: TIMM50 were set to 3-methylglutaconic aciduria, type IX (MIM 617698)
Penetrance for gene: TIMM50 were set to Complete
Review for gene: TIMM50 was set to GREEN
gene: TIMM50 was marked as current diagnostic
Added comment: Biallelic pathogenic TIMM50 variants cause 3-methylglutaconic aciduria, type IX (MIM 617698).

At least 9 affected individuals from 5 unrelated (but often consanguineous) families of variable origin have been reported (based on a conference abstract and PMIDs : 27573165, 30190335, 31058414).

TIMM50 encodes encodes a subunit of the mitochondrial presequence import machinery called the TIM23 complex. TIMM50 serves as a major receptor in the intermembrane space that binds to proteins on their way to cross the mitochondrial inner membrane (summary by Shahrour et al., 2017 and OMIM).

The highly overlapping patient clinical features [seizures, DD and ID - the latter in all age-appropriate individuals (5 from 3 families - refs 2,4)], metabolic investigations (lactate elevations in many, elevated urinary 3MGA in almost all, variable mitochondrial complex deficiencies in some), additional extensive functional evidence of mitochondrial dysfunction or the similar phenotypes in other types of 3-methylglutaconic aciduria all support a role for the gene.

[AUH- / CLPB- / DNAJC19- / HTRA2- / OPA3- / SERAC1-related methylglutaconic acidurias are all included as relevant disorders in the ID panel, with the respective genes rated green.]

TIMM50 is included in gene panels for ID offered by some diagnostic laboratories (incl. Radboudumc and GeneDx).

The gene is not associated with any phenotype in G2P

As a result this gene could be considered for inclusion/upgrade as green in both ID and epilepsy panels respectively.

---------

[1] - Serajee et al. (ASHG conference 2015 - abstract Nr. 2299T) reported on a patient born to consanguineous parents of South Asian ancestry with intractable epilepsy, microcephaly, DD and spastic quadriplegia. Metabolic investigations revealed increased urinary 3MGA. Two similarly affected sisters with demonstrated increase of 3MGA, were deceased following an infection. WES in the affected child, 2 unaffected sibs and the parents suggested a homozygous missense variant as the likely cause of the disorder in the proband (c.1114G>A / p.G372S - Reference not specified though the variant probably corresponds to ENST00000314349.4 and ClinVar's entry VCV000208697.1 - www.ncbi.nlm.nih.gov/clinvar/variation/208697/).

[2] - Shahroor et al. (2017, PMID: 27573165) reported on 2 consanguineous families, each with 2 affected individuals. Two sibs from the 1st family (of Bedouin origin) presented with seizures (onset at 3m and 4m respectively), DD and ID with slightly elevated plasma lactate and increased urinary 3MGA upon metabolic investigations. Enzymatic activities of mitochondrial complex I-V were carried out for 1 sib and were normal also after normalization for citrate synthase. Following a SNP array, WES was carried out in affected children and their parents. Both sibs were homozygous for a missense SNV [NM_001001563.1:c.755C>T / p.Thr252Met]. Segregation studies - also in 3 unaffected sibs - supported a role for the variant.

Two sibs from the 2nd family (of Muslim origin) presented with seizures (myoclonic jerks at 3m, generalized tonic movements at 2m - respectively) with DD and ID. Urinary 3MGA was elevated for both, with CSF lactate also elevated in one. WES revealed homozygosity for p.Arg217Trp (NM_001001563.1:c.649C>T) and segregation studies in parents and an unaffected sib were again compatible.

The authors could not demonstrate pathogenicity of the variants in a yeast based system although - as also commented on in Ref 4 - the human TIMM50 could not rescue the yeast ΔΤim50 growth defect and global conservation between the two proteins is poor.

[3] - Reyes et al. (2018, PMID: 30190335) reported on one individual with onset of infantile spasms at the age of 2m with hypsarrythmia upon EEG and psychomotor regression. Leigh-like features were noted upon brain MRI. Lactate was elevated in both plasma and CSF. Urinary 3MGA was normal. WES, Sanger confirmation and segregation studies demonstrated compound htz for 2 variants (NM_001001563:c.335C>A or p.S112* and c.569G>C or p.G190A). Functional studies demonstrated among others decrease in all components of the TIM23 complex and decreased mitochondrial membrane potential. Patient fibroblasts grown in glucose had lower levels of all complex II and IV subunits and one complex I subunit (due to the impairment in import system) with decreased mitochondrial respiration and increase in ROS production. Growth in galactose - shifting energy production toward OxPhos - caused massive cell death. The phenotype was rescued/substantially improved following complementation of patient fibroblasts with wt TIMM50.

[4] - Tort et al. (2019, PMID: 31058414) reported on a boy with seizures and ID (diagnosis of West syndrome), Leigh-like MRI anomalies, cardiomyopathy with elevated plasma and CSF lactate and persistent urinary elevation of 3MGA. The proband was found to be compound heterozygous for 2 TIMM50 variants [NM_001001563.5:c.341 G>A (p.Arg114Gln) in trans with c.805 G>A (p.Gly269Ser)] following WES and Sanger confirmation/segregation studies. In patient fibroblasts TIMM50 protein levels were severely reduced upon WB although mRNA levels were similar to control. Muscle biopsy revealed decreased activity of the complexes I-IV, when normalized to the citrate synthase activity. Accumulation of lipidic material in muscle fibers was shown to be associated with mitochondria upon EM. Expression and sublocalization of mitochondria-targeted proteins were not found to be affected in patient fibroblasts. In extracts from muscle biopsy reduced protein levels of SDHA, COX4L and MTCO1 were demonstrated, in line with the disruptions in the activities of the MRC. Mitochondrial morphology and network were shown to be altered in patient fibroblasts. Patient fibroblasts showed marked reduction of max respiratory capacity. Similar reduction was noted in CRISPR/Cas9 generated TIMM50-ko HEK293T cells, but rescued upon transient transfection with a plasmid encoding for wt TIMM50.

(Functional studies better summarized in the respective articles).
Sources: Literature, Radboud University Medical Center, Nijmegen
Intellectual disability v2.1046 KATNB1 Rebecca Foulger Classified gene: KATNB1 as Amber List (moderate evidence)
Intellectual disability v2.1046 KATNB1 Rebecca Foulger Added comment: Comment on list classification: Updated rating from Grey to Amber. Gene was added to the ID panel and rated Green by Konstantinos Varvagiannis. Although there are 3 publications reporting biallelic variants, the ID phenotype is variable with only mild cognitive delay in some cases (PMID:25521378), and psychomotor delay in another (PMID:26640080). KATNB1 is Green on the 'malformations of cortical development' panel. Therefore have rated Amber on the ID panel awaiting further cases.
Intellectual disability v2.1046 KATNB1 Rebecca Foulger Gene: katnb1 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1045 KATNB1 Rebecca Foulger Phenotypes for gene: KATNB1 were changed from Lissencephaly 6, with microcephaly (MIM 616212) to Lissencephaly 6, with microcephaly, MIM 616212
Intellectual disability v2.1044 KATNB1 Rebecca Foulger commented on gene: KATNB1
Intellectual disability v2.1044 MED13 Rebecca Foulger Classified gene: MED13 as Amber List (moderate evidence)
Intellectual disability v2.1044 MED13 Rebecca Foulger Gene: med13 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1043 MED13 Rebecca Foulger changed review comment from: Comment on list classification: Updated rating from Grey to Amber. Gene was added to panel and rated Amber by Konstantinos Varvagiannis. Probable rating in Gene2Phenotype for 'Neurodevelopment disorder' based on PMID:29740699 (Snijders Blok et al., 2018) who report on 13 patients. 11 variants were de novo and 1 (patient B) was inherited from an affected mother (patient C). All patients had developmental delay to some extent (speech delay in most cases, with motor development delayed in 7/13). ID is mild/borderline in at least 9 cases. There is not a clear genotype-phenotype correlation between variants, and it's unclear how some variants are deleterious, and therefore Amber rating is appropriate until further studies are published.; to: Comment on list classification: Updated rating from Grey to Amber. Gene was added to panel and rated Amber by Konstantinos Varvagiannis. Not yet associated with a disorder in OMIM. Probable rating in Gene2Phenotype for 'Neurodevelopment disorder' based on PMID:29740699 (Snijders Blok et al., 2018) who report on 13 patients. 11 variants were de novo and 1 (patient B) was inherited from an affected mother (patient C). All patients had developmental delay to some extent (speech delay in most cases, with motor development delayed in 7/13). ID is mild/borderline in at least 9 cases. There is not a clear genotype-phenotype correlation between variants, and it's unclear how some variants are deleterious, and therefore Amber rating is appropriate until further studies are published.
Intellectual disability v2.1043 MED13 Rebecca Foulger Classified gene: MED13 as No list
Intellectual disability v2.1043 MED13 Rebecca Foulger Added comment: Comment on list classification: Updated rating from Grey to Amber. Gene was added to panel and rated Amber by Konstantinos Varvagiannis. Probable rating in Gene2Phenotype for 'Neurodevelopment disorder' based on PMID:29740699 (Snijders Blok et al., 2018) who report on 13 patients. 11 variants were de novo and 1 (patient B) was inherited from an affected mother (patient C). All patients had developmental delay to some extent (speech delay in most cases, with motor development delayed in 7/13). ID is mild/borderline in at least 9 cases. There is not a clear genotype-phenotype correlation between variants, and it's unclear how some variants are deleterious, and therefore Amber rating is appropriate until further studies are published.
Intellectual disability v2.1043 MED13 Rebecca Foulger Gene: med13 has been removed from the panel.
Intellectual disability v2.1042 PAK1 Rebecca Foulger commented on gene: PAK1: Added missense tag: all variants published to-date are missense (PMID:30290153, PMID:31504246).
Intellectual disability v2.1042 PAK1 Rebecca Foulger Tag missense tag was added to gene: PAK1.
Intellectual disability v2.1042 PAK1 Rebecca Foulger Phenotypes for gene: PAK1 were changed from Intellectual developmental disorder with macrocephaly, seizures, and speech delay (MIM 618158) to Intellectual developmental disorder with macrocephaly, seizures, and speech delay, 618158
Intellectual disability v2.1041 PAK1 Rebecca Foulger Publications for gene: PAK1 were set to 30290153
Intellectual disability v2.1040 PAK1 Rebecca Foulger Classified gene: PAK1 as Green List (high evidence)
Intellectual disability v2.1040 PAK1 Rebecca Foulger Added comment: Comment on list classification: Updated rating from Amber to Green based on the additional 2019 paper reviewed by Konstantinos Varvagiannis. PMID:31504246 (Horn et al. 2019) report 4 unrelated individuals (2 Caucasian, 1 Moroccon, 1 Sephardi Jew). All 4 had developmental delay and moderate-profound ID amongst their phenotypes. All had novo missense PAK1 pathogenic variants: Leu470Arg, Ser133Pro, Pro121Ser, Ser110Thr. None of the variants were reported in gnomAD and all were predicted to be pathogenic. Two cases were previously reported in PMID:30290153 (Harms et al., 2018) and therefore this takes the total number over the threshold for a diagnostic-grade rating.
Intellectual disability v2.1040 PAK1 Rebecca Foulger Gene: pak1 has been classified as Green List (High Evidence).
Intellectual disability v2.1039 SMARCD1 Rebecca Foulger commented on gene: SMARCD1: The Green review by Cristina Dias supports the current Green rating of SMARCD1.
Intellectual disability v2.1039 CACNA2D2 Rebecca Foulger Classified gene: CACNA2D2 as Amber List (moderate evidence)
Intellectual disability v2.1039 CACNA2D2 Rebecca Foulger Added comment: Comment on list classification: Gene was added to panel and rated Amber by Konstantinos Varvagiannis. Updated rating from Grey to Amber: phenotype is relevant to panel (MIM:618501) but developmental delay is variable amongst patients, and therefore Amber rating most appropriate.
Intellectual disability v2.1039 CACNA2D2 Rebecca Foulger Gene: cacna2d2 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1038 CACNA2D2 Rebecca Foulger Phenotypes for gene: CACNA2D2 were changed from Cerebellar atrophy with seizures and variable developmental delay (MIM 618501) to Cerebellar atrophy with seizures and variable developmental delay, 618501
Intellectual disability v2.1037 SLC25A12 Rebecca Foulger Classified gene: SLC25A12 as Green List (high evidence)
Intellectual disability v2.1037 SLC25A12 Rebecca Foulger Added comment: Comment on list classification: Updated rating from Amber to Green based on additional publications reviewed by Konstantinos Varvagiannis and mouse model which includes developmental delay. PMID:31403263 (Kavanaugh et al., 2019) report a 12 year old patient with novel compound het SLC25A12 variants (p.A432V missense, and probable splice variant c.1447‐2_1447‐1delAG), each variant inherited from one parent. Clinical presentation included severe intellectual disability, and profound global developmental delay. Profound global DD was previously reported by PMID:24515575 (Falk et al, 2014), and pyschomotor delay previously reported by PMID:19641205 (Wilbom et al., 2009).
Intellectual disability v2.1037 SLC25A12 Rebecca Foulger Gene: slc25a12 has been classified as Green List (High Evidence).
Intellectual disability v2.1036 SLC25A12 Rebecca Foulger Publications for gene: SLC25A12 were set to 27290639; 25655951; 24515575; 19641205
Intellectual disability v2.1035 PAX7 Louise Daugherty changed review comment from: Comment on list classification: removed from panel, this gene is not relevant for this panel; to: Comment on list classification: downgraded to Red again, this gene is not pertinent. I have left the gene on the panel as the gene is on the ID panel from the Victorian Clinical Genetics Services
Intellectual disability v2.1035 PAX7 Louise Daugherty Classified gene: PAX7 as Red List (low evidence)
Intellectual disability v2.1035 PAX7 Louise Daugherty Gene: pax7 has been classified as Red List (Low Evidence).
Intellectual disability v2.1034 PAX7 Louise Daugherty Classified gene: PAX7 as No list
Intellectual disability v2.1034 PAX7 Louise Daugherty Added comment: Comment on list classification: removed from panel, this gene is not relevant for this panel
Intellectual disability v2.1034 PAX7 Louise Daugherty Gene: pax7 has been removed from the panel.
Intellectual disability v2.1033 PAX7 Louise Daugherty edited their review of gene: PAX7: Added comment: changed rating agree with external reviewer (Konstantinos Varvagiannis this gene is RED for ID but GREEN for Neuromuscular disorders; Changed rating: RED
Intellectual disability v2.1033 PAX7 Konstantinos Varvagiannis changed review comment from: All affected individuals reported to date had normal cognitive development. (From Feichtinger et al - PMID: 31092906 : "Cognitive development, socialization, and behavior are normal in all patients").; to: From Feichtinger et al - PMID: 31092906 : "Cognitive development, socialization, and behavior are normal in all patients".
Intellectual disability v2.1033 PAX7 Konstantinos Varvagiannis reviewed gene: PAX7: Rating: RED; Mode of pathogenicity: None; Publications: 31092906; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.1033 PAX7 Konstantinos Varvagiannis Deleted their review
Intellectual disability v2.1033 PAX7 Konstantinos Varvagiannis reviewed gene: PAX7: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.1033 PAX7 Louise Daugherty Phenotypes for gene: PAX7 were changed from to Hypotonia; Axial hypotonia; Ptosis; Scoliosis; Delayed motor milestones; Myopathy, congenital, progressive, with scoliosis, 618578
Intellectual disability v2.1032 PAX7 Louise Daugherty Added comment: Comment on publications: Added publication to support gene-disease association
Intellectual disability v2.1032 PAX7 Louise Daugherty Publications for gene: PAX7 were set to
Intellectual disability v2.1031 PAX7 Louise Daugherty Classified gene: PAX7 as Green List (high evidence)
Intellectual disability v2.1031 PAX7 Louise Daugherty Added comment: Comment on list classification: New gene added by external expert (Cristina Dias (The Francis Crick Institute) ) on Neuromuscular disorders panel v1.6 and reviewed by curation team: appropriate phenotype, sufficient cases and external expert review all support gene-disease association and relevance to this panel to rate gene to Green.
Intellectual disability v2.1031 PAX7 Louise Daugherty Gene: pax7 has been classified as Green List (High Evidence).
Intellectual disability v2.1030 PAX7 Louise Daugherty Mode of inheritance for gene: PAX7 was changed from BIALLELIC, autosomal or pseudoautosomal to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1030 PAX7 Louise Daugherty edited their review of gene: PAX7: Changed publications: 31092906
Intellectual disability v2.1030 PAX7 Louise Daugherty Mode of inheritance for gene: PAX7 was changed from BIALLELIC, autosomal or pseudoautosomal to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1030 PAX7 Louise Daugherty Mode of inheritance for gene: PAX7 was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1029 PAX7 Louise Daugherty reviewed gene: PAX7: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: Hypotonia, Axial hypotonia, Ptosis, Scoliosis, Delayed motor milestones, Myopathy, congenital, progressive, with scoliosis, 618578; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1029 GABRA5 Rebecca Foulger Classified gene: GABRA5 as Amber List (moderate evidence)
Intellectual disability v2.1029 GABRA5 Rebecca Foulger Added comment: Comment on list classification: Updated rating from Red to Amber following external review by Konstantinos Varvagiannis. Not yet associated with a disorder in Gene2Phenotype but linked to EIEE-70 in OMIM. There are three cases from 2 publications (PMIDs 29961870 and 31056671) of GABRA5 variants associated with early infantile epileptic encephalopathy and ID. However in Butler et al., development slowed at the time of seizure onset. Therefore rating Amber awaiting further clinical input.
Intellectual disability v2.1029 GABRA5 Rebecca Foulger Gene: gabra5 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1028 GABRA5 Rebecca Foulger Mode of inheritance for gene: GABRA5 was changed from to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.1027 GABRA5 Rebecca Foulger Phenotypes for gene: GABRA5 were changed from to Epileptic encephalopathy, early infantile, 79, 618559; developmental delay
Intellectual disability v2.1026 GABRA5 Rebecca Foulger Publications for gene: GABRA5 were set to
Intellectual disability v2.1025 GABRA5 Rebecca Foulger commented on gene: GABRA5
Intellectual disability v2.1025 GABRA2 Rebecca Foulger Classified gene: GABRA2 as Green List (high evidence)
Intellectual disability v2.1025 GABRA2 Rebecca Foulger Added comment: Comment on list classification: Updated rating from Grey to Green: GABRA2 was added to the panel and rated Green by Konstantinos Varvagiannis. Not yet associated with a disorder in Gene2Phenotype but there are sufficient cases from from the literature (PMIDs:29422393, 29961870, 31032849, https://doi.org/10.1101/678219) of GABRA2 variants associated with developmental delay/intellectual disability.
Intellectual disability v2.1025 GABRA2 Rebecca Foulger Gene: gabra2 has been classified as Green List (High Evidence).
Intellectual disability v2.1024 GABRA2 Rebecca Foulger commented on gene: GABRA2: Summary of evidence (refer to Konstantinos Varvagiannis' review for further details):

PMID:29422393, Orenstein et al., 2018 report a male of unrelated Ashkenazi Jewish parents with EIEE-78 and a de novo heterozygous variant in GABRA2 (N335H). Development was severely delayed. Functional studies were not performed but the variant was absent in ExAC and gnomAD controls.

PMID:29961870, Butler et al. 2018 report an 11 year old girl with EIEE-78 and a de novo heterozygous variant in GABRA2 (T292K). Development was delayed, the patient was nonverbal and had profound intellectual disability plus microcephaly.

PMID:31032849, Maljevic et al., 2019 decribe 5 patients (3 sporadic cases and 2 siblings) with four novel de novo GABRA2 missense variants (Val284Ala, Leu291Val, Met263Thr, Phe325Leu). All patients showed some degree of ID (mild to profound).

https://doi.org/10.1101/678219: Sanchis-Juan et al., 2019 identified a de novo missense variant in GABRA2 gene (Pro280Leu) in a 10 year old girl with EIEE and developmental delay. At age-10, she had severe
impairment of language, hand stereotypies, disruptive behavior and repetitive movements.
Intellectual disability v2.1024 GABRA2 Rebecca Foulger commented on gene: GABRA2
Intellectual disability v2.1024 GABRA2 Rebecca Foulger Phenotypes for gene: GABRA2 were changed from Epileptic encephalopathy, early infantile, 78, 618557) to Epileptic encephalopathy, early infantile, 78, 618557; intellectual disability; developmental delay
Intellectual disability v2.1024 GABRA2 Rebecca Foulger Tag missense tag was added to gene: GABRA2.
Intellectual disability v2.1024 GABRA2 Rebecca Foulger Phenotypes for gene: GABRA2 were changed from Epileptic encephalopathy, early infantile, 78 (MIM 618557) to Epileptic encephalopathy, early infantile, 78, 618557)
Intellectual disability v2.1023 PIGP Rebecca Foulger commented on gene: PIGP
Intellectual disability v2.1023 PIGP Rebecca Foulger Phenotypes for gene: PIGP were changed from Generalized hypotonia; Global developmental delay; Seizures; Intellectual disability; Feeding difficulties; Cortical visual impairment to ?Epileptic encephalopathy, early infantile, 55, 617599; Generalized hypotonia; Global developmental delay; Seizures; Intellectual disability; Feeding difficulties; Cortical visual impairment
Intellectual disability v2.1022 SMARCD1 Cristina Dias reviewed gene: SMARCD1: Rating: GREEN; Mode of pathogenicity: None; Publications: PMID: 30879640; Phenotypes: developmental delay, intellectual disability, hypotonia, feeding difficulties, small hands, small feet; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v2.1022 CACNA2D2 Konstantinos Varvagiannis gene: CACNA2D2 was added
gene: CACNA2D2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CACNA2D2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CACNA2D2 were set to 23339110; 24358150; 30410802; 29997391; 31402629; 11487633; 11756448; 4177347; 14660671; 15331424
Phenotypes for gene: CACNA2D2 were set to Cerebellar atrophy with seizures and variable developmental delay (MIM 618501)
Penetrance for gene: CACNA2D2 were set to Complete
Review for gene: CACNA2D2 was set to AMBER
gene: CACNA2D2 was marked as current diagnostic
Added comment: Gene reviewed for the epilepsy panel. Due to the phenotype of EE, with variable GDD (severe in many cases) and/or ID (either specifically commented on or inferred in some cases, although not universal) this gene might also be relevant for the current panel. CACNA2D2 is also included in gene panels for ID offered by some diagnostic laboratories (eg. GeneDx) as well as the SysID database. There is no associated phenotype in G2P.

Copied from the epilepsy panel:

Biallelic pathogenic CACNA2D2 variants cause Cerebellar atrophy with seizures and variable developmental delay (MIM 618501).

A recent OMIM update, a subsequent relevant publication by Punatha et al. as well as several additional LP/P variants in ClinVar for the phenotype of epileptic encephalopathy, support possible upgrade to green.

The following affected individuals appear to be relevant [NM_006030.3 used as RefSeq unless otherwise specified]:

[1] Edvardson et al. (PMID: 23339110) - 3 sibs born to consanguineous parents with EIEE, severe GDD / ID (inferred from the descritpion, at least for the oldest one), cerebellar atrophy and movement abnormalities. A CACNA2D2 variant (c.3137T>C / p.Leu1046Pro) was found in affected individuals by SNP-arrays and WES in one of them. Functional studies (reduction in current density of calcium channels in Xenopus laevis oocytes) supported the deleterious effect of the variant. A role of a rare hmz CESLR3 variant could not be ruled out.

[2] Pippucci et al. (PMID: 24358150) - 1 individual born to consanguineous parents, presenting with EE (onset at 1-2 m), severe GDD, cerebellar atrophy and choreiform movements. Homozygosity for a LoF variant (c.1294delA - p.Asn432fs) was found by WES. The role of the variant was further supported by expression studies (80% reduced mRNA levels, protein levels estimated at 3% of control / milder effect in htz parents). The proband was also hmz for a CESLR3 variant. Previous studies incl. 'high-resolution karyotype' and metabolic investigations.

[3] Butler et al. (PMID: 30410802) - A 5 y.o. male, with EE (seizure onset at 7m / GDD) and cerebellar atrophy. Compound heterozygosity for c.782C>T (p.Pro261Leu) and c.3137T>C (p.Leu1046Pro) was demonstrated by WES and supported by segregation studies.

[4] Valence et al. (PMID: 29997391) - Reported on a 20 y.o. male belonging to a cohort of 20 individuals with congenital ataxia, all from consaguineous families. This individual, who had cerebellar atrophy, ataxia, a single episode of febrile seizures and normal cognitive impairment was homozygosity for c.2971G>A (p.Asp991Asn). RT-PCR revealed presence of a normal length transcript as well as an additional, longer one, due to a concurrent splicing effect (activation of a cryptic donor splice site and retention of 4 bases of intronic sequence). Presence of both nl/abn length transcripts was presumed to explain the mild phenotype (variability also commented in OMIM).

[5] Punatha et al. (PMID: 31402629) - 3 affected individuals from 2 consanguineous families presenting with early onset EE (onset 1-7m), GDD/ID, cerebelar atrophy and ataxia. Sibs from the first family were homozygous for c.1778G>C (p.Arg593Pro). An affected 5 y.o. child from the 2nd family was homozygous for c.485_486delAT (p.Tyr162Ter). Mutations were found by WES in regions of AOH.

The following variants - not reported in the literature - have been submitted in ClinVar as LP / P for EE:
[VCV000645106.1] NM_006030.4:c.1389+2T>C - EIEE with suppression bursts - Likely Pathogenic (Invitae)
[VCV000570589.1] NM_006030.4:c.1956_1960del (p.Asn652fs) - EIEE - Pathogenic (Invitae)
[VCV000578284.1] NM_006030.4:c.1555C>T (p.Gln519Ter) - EIEE - Pathogenic (Invitae)
[VCV000653393.1] NM_006030.4:c.851dup (p.Ala286fs) - EIEE with suppression bursts - Pathogenic (Invitae)
[VCV000411003.1] NM_006030.4:c.485_486del (p.Tyr161_Tyr162insTer) - EIEE - Pathogenic (Invitae)

Additional ones have been reported as LP / P although the condition is not specified.
[VCV000620551.1] NM_006030.4:c.1023C>A (p.Cys341Ter) - Likely pathogenic (GeneDx)
[VCV000373439.2] NM_006030.4:c.1846-1G>A - Likely pathogenic (GeneDx)
[VCV000423330.2] NM_006030.4:c.200dup (p.His68fs) - Pathogenic (GeneDx).

The aforementioned laboratories include CACNA2D2 in gene panels for epilepsy (Invitae) and/or ID (GeneDx).

A role for the CACNA2D2 is supported by :
- The highly overlapping features (with the exception of the milder phenotype reported by Valence et al.) incl. early onset of seizures, GDD, cerebellar atrophy in all (9/9 incl. the individual reported by Valence, as evaluated Punatha et al). Ataxia was a feature in many (with movement abnormalities also in the remaining ones).
- The role of the gene encoding the alpha-2-delta-2 auxiliary subunit of high voltage-gated calcium channels. Auxiliary subunits modulate calcium current and channel activation and inactivation kinetics, and may be involved in proper assembly and membrane localization of the channels (summary by Edvardson and OMIM).
- Functional / expression studies for some of the variants (as in Refs 1,2,4).
- Relevant expression patterns (notably in cerebellum) [GTEx project]
- Mouse models recapitulating the human phenotypes (summarized by Edvardson et al) : The 'ducky' mouse model (due to biallelic Cacna2d2 mutations) presenting absence epilepsy, spike-wave seizures and ataxia. Dysgenesis of the cerebellum is among the neuropathological findings (PMIDs cited : 11487633, 11756448, 4177347). The 'entla' mouse model (also AR due to an in-frame duplication) presents also epilepsy and ataxia (PMID : 14660671). Targeted knockout in another mouse model resulted also in ataxic gait, seizure susceptibility and cerebellar anomalies/degeneration (PMID: 15331424).

[Please consider inclusion in other relevant panels eg. for cerebellar anomalies / ataxia].
Sources: Literature
Intellectual disability v2.1022 GABRA2 Konstantinos Varvagiannis changed review comment from: Heterozygous pathogenic GABRA2 variants cause Epileptic encephalopathy, early infantile, 78 (MIM 618557) [new OMIM entry].

At least 8 relevant individuals have been reported to date in the following studies:
- Orenstein et al. (2018 - PMID: 29422393) - 1 individual
- Butler et al. (2018 - PMID: 29961870) - 1 subject
- Maljevic et al. (2019 - PMID: 31032849 - 3 unrelated children as well as 2 affected sibs
- Sanchis-Juan et al. (2019 - bioRxiv / https://doi.org/10.1101/678219) - 1 further patient

In all affected individuals the variants were missense and - in almost all cases - had occurred as de novo events. The 2 sibs reported by Maljevic however, had inherited a missense variant from their unaffected mosaic parent.

Clinical descriptions for individuals from the 3 studies are provided in OMIM and also summarized in the suppl. table 1 by Sanchis-Juan et al. (https://www.biorxiv.org/content/biorxiv/early/2019/06/21/678219/DC2/embed/media-2.xlsx). Seizures, DD and ID (relevant to the current panel) are among the reported features. Functional studies have been performed for most of the variants and are summarized for each one in the OMIM entry for GABRG2 and the aforementioned table as well.

The following variants have been reported (NM_000807.2): c.1003A>C - p.Asn335His (dn) / c.875C>A - Thr292Lys (dn) / c.871C>G - p.Leu291Val (dn) / c.788T>C - p.Met263Thr (dn) / c.851T>C - p.Val284Ala (dn) / c.975C>A - p.Phe325Leu (inherited from mosaic parent) / c.839C>T - p.Pro280Leu (dn - Sanchis-Juan et al).

As commented by Jenkins and Escayg (2019 - PMID: 31032848 / both among the authors of the 1st report) as well as by Sanchis-Juan et al., both loss- and gain- of function effects explain the pathogenicity of the various mutations reported to date. [In gnomAD GABRA2 has a Z-score for missense variants of 3.13 as well as a pLI of 1].
------
GABRA2 is not associated with any phenotype in G2P.
This gene is not commonly included in gene panels for ID offered by diagnostic laboratories.
------
As a result, GABRA2 can be considered for inclusion in the epilepsy and ID panels probably as green (several relevant individuals, several reported variants with supporting functional studies for most, etc.).

[Consider inclusion in other possibly relevant gene panels eg. for ASD which was feature in some patients at relevant age and/or among those evaluated].; to: Heterozygous pathogenic GABRA2 variants cause Epileptic encephalopathy, early infantile, 78 (MIM 618557) [new OMIM entry].

At least 8 relevant individuals have been reported to date in the following studies:
- Orenstein et al. (2018 - PMID: 29422393) - 1 individual
- Butler et al. (2018 - PMID: 29961870) - 1 subject
- Maljevic et al. (2019 - PMID: 31032849 - 3 unrelated children as well as 2 affected sibs
- Sanchis-Juan et al. (2019 - bioRxiv / https://doi.org/10.1101/678219) - 1 further patient

In all affected individuals the variants were missense and - in almost all cases - had occurred as de novo events. The 2 sibs reported by Maljevic however, had inherited a missense variant from their unaffected mosaic parent.

Clinical descriptions for individuals from the 3 studies are provided in OMIM and also summarized, Maljevic - Table 1 (7 patients) and/or in the suppl. table 1 by Sanchis-Juan et al. (8 patients) (https://www.biorxiv.org/content/biorxiv/early/2019/06/21/678219/DC2/embed/media-2.xlsx). Seizures, DD and ID (relevant to the current panel) are among the reported features. Functional studies have been performed for most of the variants and are summarized for each one in the OMIM entry for GABRG2 and the aforementioned table as well.

The following variants have been reported (NM_000807.2): c.1003A>C - p.Asn335His (dn) / c.875C>A - Thr292Lys (dn) / c.871C>G - p.Leu291Val (dn) / c.788T>C - p.Met263Thr (dn) / c.851T>C - p.Val284Ala (dn) / c.975C>A - p.Phe325Leu (inherited from mosaic parent) / c.839C>T - p.Pro280Leu (dn - Sanchis-Juan et al).

As commented by Jenkins and Escayg (2019 - PMID: 31032848 / both among the authors of the 1st report) as well as by Sanchis-Juan et al., both loss- and gain- of function effects explain the pathogenicity of the various mutations reported to date. [In gnomAD GABRA2 has a Z-score for missense variants of 3.13 as well as a pLI of 1].
------
GABRA2 is not associated with any phenotype in G2P.
This gene is not commonly included in gene panels for ID offered by diagnostic laboratories.
------
As a result, GABRA2 can be considered for inclusion in the epilepsy and ID panels probably as green (several relevant individuals, several reported variants with supporting functional studies for most, etc.).

[Consider inclusion in other possibly relevant gene panels eg. for ASD which was feature in some patients at relevant age and/or among those evaluated].
Intellectual disability v2.1022 GABRA2 Konstantinos Varvagiannis reviewed gene: GABRA2: Rating: GREEN; Mode of pathogenicity: None; Publications: 29422393, 29961870, 31032849, 31032848, doi.org/10.1101/678219; Phenotypes: Epileptic encephalopathy, early infantile, 78 (MIM 618557); Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.1022 GABRA2 Konstantinos Varvagiannis Deleted their review
Intellectual disability v2.1022 GABRA2 Konstantinos Varvagiannis gene: GABRA2 was added
gene: GABRA2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: GABRA2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: GABRA2 were set to 29422393; 29961870; 31032849; 31032848; doi.org/10.1101/678219
Phenotypes for gene: GABRA2 were set to Epileptic encephalopathy, early infantile, 78 (MIM 618557)
Penetrance for gene: GABRA2 were set to unknown
Review for gene: GABRA2 was set to GREEN
Added comment: Heterozygous pathogenic GABRA2 variants cause Epileptic encephalopathy, early infantile, 78 (MIM 618557) [new OMIM entry].

At least 8 relevant individuals have been reported to date in the following studies:
- Orenstein et al. (2018 - PMID: 29422393) - 1 individual
- Butler et al. (2018 - PMID: 29961870) - 1 subject
- Maljevic et al. (2019 - PMID: 31032849 - 3 unrelated children as well as 2 affected sibs
- Sanchis-Juan et al. (2019 - bioRxiv / https://doi.org/10.1101/678219) - 1 further patient

In almost all affected individuals, the variants were missense and had occurred as de novo events. The 2 sibs reported by Maljevic however, had inherited a missense variant from their unaffected mosaic parent.

Clinical descriptions for individuals from the 3 studies are provided in OMIM and also summarized in the suppl. table 1 by Sanchis-Juan et al. (https://www.biorxiv.org/content/biorxiv/early/2019/06/21/678219/DC2/embed/media-2.xlsx?download=true). Seizures, DD and ID (relevant to the current panel) are among the reported features. Functional studies have been performed for most of the variants and are summarized for each one in the OMIM entry for GABRG2 and the aforementionned table as well.

The following variants have been reported (NM_000807.2): c.1003A>C - p.Asn335His (dn) / c.875C>A - Thr292Lys (dn) / c.871C>G - p.Leu291Val (dn) / c.788T>C - p.Met263Thr (dn) / c.851T>C - p.Val284Ala (dn) / c.975C>A - p.Phe325Leu (inherited from mosaic parent) / c.839C>T - p.Pro280Leu (dn - Sanchis-Juan et al).

As commented by Jenkins and Escayg (2019 - PMID: 31032848 / both among the authors of the 1st report) as well as by Sanchis-Juan et al., both loss- and gain- of function effects explain the pathogenicity of the various reported (all) missense mutations. [In gnomAD GABRA2 has a Z-score for missense variants of 3.13 as well as a pLI of 1].
------
GABRA2 is not associated with any phenotype in G2P.
This gene is not commonly included in gene panels for ID offered by diagnostic laboratories.
------
As a result, GABRA2 can be considered for inclusion in the epilepsy and ID panels probably as green (several relevant individuals, several reported variants with supporting functional studies for most, etc.).

[Consider inclusion in other possibly relevant gene panels eg. for ASD which was feature in some patients at relevant age and/or among those evaluated].
Sources: Literature
Intellectual disability v2.1022 GABRA5 Konstantinos Varvagiannis reviewed gene: GABRA5: Rating: GREEN; Mode of pathogenicity: None; Publications: 29961870, 31056671; Phenotypes: Epileptic encephalopathy, early infantile, 79 (MIM 618559); Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown; Current diagnostic: yes
Intellectual disability v2.1022 PIGP Konstantinos Varvagiannis gene: PIGP was added
gene: PIGP was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: PIGP was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PIGP were set to 28334793; 31139695
Phenotypes for gene: PIGP were set to Generalized hypotonia; Global developmental delay; Seizures; Intellectual disability; Feeding difficulties; Cortical visual impairment
Penetrance for gene: PIGP were set to Complete
Review for gene: PIGP was set to GREEN
gene: PIGP was marked as current diagnostic
Added comment: Johnstone et al. (2017 - PMID: 28334793) report on 2 sibs born to non-consanguineous parents of French-Irish ancestry. Both presented with seizures (onset at the age of 2 and 7 weeks respectively), hypotonia and profound DD. Other features included CVI and feeding difficulties. Extensive metabolic testing as well as prior genetic testing (ARX, STXBP1, MECP2, aCGH) in the family were non-diagnostic. WES suggested the presence of 2 PIGP variants with Sanger sequencing used for confirmation and segregation studies.

PIGP encodes a subunit of the enzyme that catalyzes the first step of glycophosphatidylinositol (GPI) anchor biosynthesis. Mutations in other genes whose proteins are in complex with PIGP (PIGA, PIGC, PIGQ, PIGY, DPM2) lead to similar phenotypes. The phenotype overall was also overlapping with the inherited GPI deficiencies (belonging to the broader group of CDGs).

PIGP has 2 isoforms, which differ by 24 amino acids due to utilization of alternative start codons [corresponding to NM_153681.2 (158 aa) and NM_153682.2 (134 aa)].

The variants identified affected both transcripts with the first SNV leading either to loss of the start codon (NM_153682.2:c.2T>C - p.Met1Thr) or to substitution of a methionine at position 25(NM_153681.2:c.74T>C;p.Met25Thr). The second variant led to frameshift in the last exon of both transcripts predicting a longer protein product (NM_153681.2:c.456delA / p.Glu153AsnfsTer34 or NM_153682.2:c.384delA / p.Glu129AsnfsTer34).

Overall extensive studies demonstrated decreased levels of PIGP mRNA in patient fibroblast, decreased amounts of mutant protein in transfected HEK293 cells. The decreased levels of GPI-APs further supported the effect of variants :

- mRNA levels in patient fibroblasts were reduced compared to controls. Conclusions could not be drawn from Western blot, since no antibodies could specifically detect PIGP. HEK293 cells transfected of mt or wt HA-tagged PIGP cDNA led to undetectable amounts for the first variant (both M1T/M25T) and a protein product of increased molecular weight for the frameshift one.
- Flow cytometry of patient granulocytes indicated reduced signal of CD16 (a GPI-anchored protein) and FLAER (binding directly to the GPI anchor).
- Reduced levels of GPI-APs were also observed in PIGP deficient HAP1 cells transfected with either wt, or mutant PIGP cDNA (of both isoforms for the M1T/M25T or isoform 2 for the frameshift mutation).

--------

Krenn et al. (2019 - PMID: 31139695) described a patient born to non-consanguineous Polish parents. Features were highly similar to those reported by Johnstone et al. and incl. intractable infantile seizures (onset at 7m), hypotonia, severe DD and feeding difficulties. Metabolic work-up failed to identify an alternative diagnosis. WES revealed homozygosity for the frameshift variant reported by Johnstone et al. Sanger sequencing confirmed the variant and carrier state in both parents. Identified ROH of less than 7 Mb in the WES data, suggested a founder mutation rather than unreported consanguinity. The variant is present 9 times in gnomAD (AF of 3.2e-5 / no homozygotes). Flow cytometry of patient granulocytes, revealed markedly reduced expression of GPI-APs (CD157, CD59, FLAER) compared to parents/controls.

ALP was normal in all aforementioned individuals (probably in line with PIGP being involved in the 1st step of the GPI anchor biosynthesis).

--------

A further individual with phenotype of EIEE-55;GPIBD-14 is reported in LOVD [Individual #00246132]. This individual, born to consanguineous parents, was tested by WES and found to be homozygous for a frameshift variant, also affecting the last exon in both transcripts (NM_153681.2:c.384delA (p.Glu129ArgfsTer7) / NM_153682.2:c.312delA (p.Glu105ArgfsTer7). This was probably in agreement with segregation studies according to the respective entry. The specific variant is reported as pathogenic [variant ID #0000500090].

--------

?Epileptic encephalopathy, early infantile, 55 (MIM 617599) is the corresponding phenotype in OMIM. There is no relevant G2P entry.
PIGP is included in gene panels for ID offered by some diagnostic laboratories (eg. GeneDx).

--------

As a result, PIGP can be considered for inclusion in the ID/epilepsy panels probably as green (3 individuals, role of the gene and similarity to other inherited GPI deficiencies, extensive supporting studies) or amber.

(Please consider inclusion in other possibly relevant panels eg. CDGs, etc).
Sources: Literature
Intellectual disability v2.1022 SLC25A12 Konstantinos Varvagiannis reviewed gene: SLC25A12: Rating: GREEN; Mode of pathogenicity: None; Publications: 31403263, 24515575, 19641205, 27290639, 26633542; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v2.1022 ARSE Louise Daugherty Tag new-gene-name tag was added to gene: ARSE.
Intellectual disability v2.1022 ARSE Louise Daugherty commented on gene: ARSE
Intellectual disability v2.1022 H3F3B Louise Daugherty Tag new-gene-name tag was added to gene: H3F3B.
Intellectual disability v2.1022 H3F3B Louise Daugherty commented on gene: H3F3B
Intellectual disability v2.1022 H3F3A Louise Daugherty Tag new-gene-name tag was added to gene: H3F3A.
Intellectual disability v2.1022 H3F3A Louise Daugherty commented on gene: H3F3A
Intellectual disability v2.1022 HIST1H4C Louise Daugherty Tag new-gene-name tag was added to gene: HIST1H4C.
Intellectual disability v2.1022 HIST1H4C Louise Daugherty commented on gene: HIST1H4C: Added new-gene-name tag, new approved HGNC gene symbol for HIST1H4C is H4C3
Intellectual disability v2.1022 HIST1H4B Louise Daugherty Tag new-gene-name tag was added to gene: HIST1H4B.
Intellectual disability v2.1022 HIST1H4B Louise Daugherty commented on gene: HIST1H4B: Added new-gene-name tag, new approved HGNC gene symbol for HIST1H4B is H4C2
Intellectual disability v2.1022 HIST1H1E Louise Daugherty Tag new-gene-name tag was added to gene: HIST1H1E.
Intellectual disability v2.1022 HIST1H1E Louise Daugherty commented on gene: HIST1H1E
Intellectual disability v2.1022 HIST3H3 Louise Daugherty Tag new-gene-name tag was added to gene: HIST3H3.
Intellectual disability v2.1022 HIST3H3 Louise Daugherty commented on gene: HIST3H3: Added new-gene-name tag, new approved HGNC gene symbol for HIST3H3 is H3-4
Intellectual disability v2.1022 KIF1BP Louise Daugherty Tag new-gene-name tag was added to gene: KIF1BP.
Intellectual disability v2.1022 KIF1BP Louise Daugherty commented on gene: KIF1BP: Added new-gene-name tag, new approved HGNC gene symbol for KIF1BP is KIFBP
Intellectual disability v2.1022 VARS Louise Daugherty Tag new-gene-name tag was added to gene: VARS.
Intellectual disability v2.1022 VARS Louise Daugherty commented on gene: VARS
Intellectual disability v2.1022 CARS Louise Daugherty Tag new-gene-name tag was added to gene: CARS.
Intellectual disability v2.1022 CARS Louise Daugherty commented on gene: CARS
Intellectual disability v2.1022 IARS Louise Daugherty commented on gene: IARS: Added new-gene-name tag, new approved HGNC gene symbol for IARS is IARS1
Intellectual disability v2.1022 QARS Louise Daugherty Tag new-gene-name tag was added to gene: QARS.
Intellectual disability v2.1022 QARS Louise Daugherty edited their review of gene: QARS: Added comment: Added new-gene-name tag, new approved HGNC gene symbol for QARS is QARS1; Changed publications: 28620870, 24656866, 25041233, 25471517, 25432320, 24709618; Changed phenotypes: Microcephaly, progressive, seizures, and cerebral and cerebellar atrophy, 615760, Intellectual disability
Intellectual disability v2.1022 KARS Louise Daugherty Tag new-gene-name tag was added to gene: KARS.
Intellectual disability v2.1022 KARS Louise Daugherty commented on gene: KARS: Added new-gene-name tag, new approved HGNC gene symbol for KARS is KARS1
Intellectual disability v2.1022 AARS Louise Daugherty Tag new-gene-name tag was added to gene: AARS.
Intellectual disability v2.1022 AARS Louise Daugherty commented on gene: AARS
Intellectual disability v2.1022 DARS Louise Daugherty Tag new-gene-name tag was added to gene: DARS.
Intellectual disability v2.1022 DARS Louise Daugherty commented on gene: DARS
Intellectual disability v2.1022 DLG4 Louise Daugherty Mode of inheritance for gene: DLG4 was changed from to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.1021 MED25 Konstantinos Varvagiannis changed review comment from: Please consider the 2 additional articles by Nair et al. (2019 - DOI: 10.1159/000494465 - PMID: 30800049 & DOI: 10.1159/000501114 - PMID: NA) reporting on 3 individuals from 2 consanguineous Lebanese families. All affected individuals were homozygous for a MED25 missense variant [NM_030973.3:c.518T>C / p.Ile173Thr], possibly a founder mutation in the Lebanese population. The phenotype presented some similarities with the previously described patients. The variant has a very low AF in gnomAD (0.00003470) and was also absent from the Saudi Variant Database. In silico predictions from PolyPhen2, PROVEAN, MutationTaster were suggestive of a probably damaging effect. The individual from the first report (PMID: 30800049) had an additional homozygous COQ8A variant, with some features fitting with the phenotype of AR primary CoQ10 deficiency type 4 and others negating this diagnosis.

MED25 is included in gene panels for ID offered by several diagnostic laboratories (incl. Radboudumc, Victorian Clinical Genetics and many others). It is not however included in the DD panel of G2P.; to: Please consider the 2 additional articles by Nair et al. (2019 - DOI: 10.1159/000494465 - PMID: 30800049 & DOI: 10.1159/000501114 - PMID: NA) reporting on 3 individuals from 2 consanguineous Lebanese families. All affected individuals were homozygous for a MED25 missense variant [NM_030973.3:c.518T>C / p.Ile173Thr], possibly a founder mutation in the Lebanese population. The phenotype presented some similarities with the previously described patients. The variant has a very low AF in gnomAD (0.00003470) and was also absent from the Saudi Variant Database. In silico predictions from PolyPhen2, PROVEAN, MutationTaster were suggestive of a probably damaging effect. The individual from the first report (PMID: 30800049) had an additional homozygous COQ8A variant, with some features fitting with the phenotype of AR primary CoQ10 deficiency type 4 and others negating this (possibly concurrent) diagnosis.

MED25 is included in gene panels for ID offered by several diagnostic laboratories (incl. Radboudumc, Victorian Clinical Genetics and many others). It is not however included in the DD panel of G2P.
Intellectual disability v2.1021 MED25 Konstantinos Varvagiannis reviewed gene: MED25: Rating: AMBER; Mode of pathogenicity: None; Publications: 30800049, DOI:10.1159/000501114, 25527630, 25792360; Phenotypes: Basel-Vanagait-Smirin-Yosef syndrome (MIM 616449); Mode of inheritance: None; Current diagnostic: yes
Intellectual disability v2.1021 KATNB1 Konstantinos Varvagiannis gene: KATNB1 was added
gene: KATNB1 was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen
Mode of inheritance for gene: KATNB1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: KATNB1 were set to 25521378; 25521379; 26640080
Phenotypes for gene: KATNB1 were set to Lissencephaly 6, with microcephaly (MIM 616212)
Penetrance for gene: KATNB1 were set to Complete
Review for gene: KATNB1 was set to GREEN
gene: KATNB1 was marked as current diagnostic
Added comment: Biallelic pathogenic KATNB1 variants cause Lissencephaly 6, with microcephaly (MIM 616212). At least 13 affected individuals from 9 (mostly consanguineous) families have probably been reported in the following articles:

- Mishra-Gorur et al. (2014 - PMID: 25521378) [7 individuals from 5 unrelated families]
- Hu et al. (2014 - PMID: 25521379) [5 individuals from 3 families]
- Yigit el al. (2016 - PMID: 26640080) [1 subject born to consanguineous parents]

The phenotype appears to be relevant to the current panel. Several different variants have been reported to date. Extensive studies as for the impact of mutations at the cellular level as well as animal models (zebrafish, mouse, drosophila) support involvement of KATNB1. These arguments, provided mainly by the first two studies, are summarized in the respective OMIM entry for the disorder : https://omim.org/entry/616212 (variants and their effect are discussed in the entry for KATNB1 - https://omim.org/entry/602703).

The individual reported by Yigit el al. was a 5 year-old girl with - among others - severely delayed psychomotor development. The child was found to harbor a homozygous splice site variant (removing the acceptor AG signature). Confirmation of the variant and segregation studies were performed with Sanger sequencing. cDNA studies were carried out and demonstrated aberrant splicing.

KATNB1 is not associated with any disorder in G2P.
The gene is included in panels for ID offered by several diagnostic laboratories (incl. Radboudumc).

As a result, this gene can be considered for inclusion in the current panel probably as green (or amber).
Sources: Literature, Radboud University Medical Center, Nijmegen
Intellectual disability v2.1021 MED13 Konstantinos Varvagiannis changed review comment from: Snijders Blok et al. (2018 - PMID: 29740699) report on 13 individuals with MED13 mutations.

Features included DD with speech difficulties (both universal) and motor delay in some. ID was observed in at least 9/13 and in most cases was in the borderline/mild range (moderate ID reported for 1 individual). Other features were ASD (5/13), ADHD, eye/vision abnormalities and in few individuals obstipation or congenital heart anomalies. Some possibly overlapping facial characteristics were also noted.

MED13 and MED13L are mutually exclusive components of the CDK8 kinase module that regulates the activity of the Mediator complex. The Mediator transmits signals from various transcription factors to RNA polymerase II (Pol II). Reversible binding of the CDK8 kinase controls Mediator - Pol II interaction (prevents Pol II recruitment) and thus acts as a molecular switch in Pol II - mediated transcription. DD and ID are features of the MED13L- and CDK8- related disorders.

3 stopgain, 2 frameshift, 6 missense variants and 1 in-frame deletion were reported. In 11 cases, the variants had occurred as de novo events, while 1 individual had inherited a nonsense variant from a similarly affected mother (unknown inheritance in her case).

Effect of a stopgain variant was studied with similar (total) transcript levels between the affected patient and his parents/controls upon qPCR. Sanger sequencing of cDNA amplicons was suggestive of the presence of an aberrant transcript at ~70% levels relative to the normal transcript. Truncated protein was undetectable by Western Blot in mononuclear blood cells from affected subjects. Total MED13 protein levels were not clearly different when comparing an affected individual with his unaffected parent (?).

Missense variants and the inframe deletion clustered either in the N- or the C-terminal domain, with the N-terminal ones all (T326I, T326del, P327S, P327Q / NM_005121.2 - NP_005112.2) affecting positions of a known phosphodegron sequence, important for the protein's ubiquitination and degradation. Another previously studied variant (T326A) had been shown to prevent degradation. As a result, the variants affecting aa 326-327 might lead to altered (increased) levels of MED13.

The remaining missense variants affected the C-terminal portion (Q2060L, A2064V).

As a result the impact of the different subcategories of variants remains unclear/inconclusive.

MED13 is not associated with any phenotype in OMIM. This gene is part of the DD panel of G2P, associated with "MED13 - Neurodevelopment disorder" (dis. confidence : probable / mutation consequence : LoF / GDD, speech/language delay, ID, autistic behavior among the assigned phenotypes).

MED13 is included in gene panels for ID offered by some diagnostic laboratories (incl. Radboudumc).

ID is part of the phenotype of MED13-related disorder, however as the severity in most individuals - when present - was in the borderline/mild range (not relevant for the present panel) and/or the underlying effect of mutations remains unclear, amber rating can probably be considered for this gene.
Sources: Radboud University Medical Center, Nijmegen, Literature; to: Snijders Blok et al. (2018 - PMID: 29740699) report on 13 individuals with MED13 mutations.

Features included DD with speech difficulties (both universal) and motor delay in some. ID was observed in at least 9/13 and in most cases was in the borderline/mild range (moderate ID reported for 1 individual). Other features were ASD (5/13), ADHD, eye/vision abnormalities and in few individuals obstipation or congenital heart anomalies. Some possibly overlapping facial characteristics were also noted.

MED13 and MED13L are mutually exclusive components of the CDK8 kinase module that regulates the activity of the Mediator complex. The Mediator transmits signals from various transcription factors to RNA polymerase II (Pol II). Reversible binding of the CDK8 kinase controls Mediator - Pol II interaction (prevents Pol II recruitment) and thus acts as a molecular switch in Pol II - mediated transcription. DD and ID are features of the MED13L- and CDK8- related disorders.

3 stopgain, 2 frameshift, 6 missense variants and 1 in-frame deletion were reported. In 11 cases, the variants had occurred as de novo events, while 1 individual had inherited a nonsense variant from a similarly affected mother (unknown inheritance in her case).

Effect of a stopgain variant was studied with similar (total) transcript levels between the affected patient and his parents/controls upon qPCR. Sanger sequencing of cDNA amplicons was suggestive of the presence of an aberrant transcript at ~70% levels relative to the normal transcript. Truncated protein was undetectable by Western Blot in mononuclear blood cells from affected subjects. Total MED13 protein levels were not clearly different when comparing an affected individual with his unaffected parent (?).

Missense variants and the inframe deletion clustered either in the N- or the C-terminal domain, with the N-terminal ones all (T326I, T326del, P327S, P327Q / NM_005121.2 - NP_005112.2) affecting positions of a known phosphodegron sequence, important for the protein's ubiquitination and degradation. Another previously studied variant (T326A) had been shown to prevent degradation. As a result, the variants affecting aa 326-327 might lead to altered (increased) levels of MED13.

The remaining missense variants affected the C-terminal portion (Q2060L, A2064V).

As a result the impact of the different subcategories of variants remains unclear/inconclusive.

MED13 is not associated with any phenotype in OMIM. This gene is part of the DD panel of G2P, associated with "MED13 - Neurodevelopment disorder" (dis. confidence : probable / mutation consequence : LoF / GDD, speech/language delay, ID, autistic behavior among the assigned phenotypes).

MED13 is included in gene panels for ID offered by some diagnostic laboratories (incl. Radboudumc).

ID is part of the phenotype of MED13-related disorder. However as the severity in most individuals - when present - was in the borderline/mild range (not relevant for the present panel) and/or the underlying effect of mutations remains unclear, amber rating seems more appropriate.
Sources: Radboud University Medical Center, Nijmegen, Literature
Intellectual disability v2.1021 MED13 Konstantinos Varvagiannis gene: MED13 was added
gene: MED13 was added to Intellectual disability. Sources: Radboud University Medical Center, Nijmegen,Literature
Mode of inheritance for gene: MED13 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: MED13 were set to 29740699
Phenotypes for gene: MED13 were set to Delayed speech and language development; Motor delay; Intellectual disability; Autistic behavior; Attention deficit hyperactivity disorder; Abnormality of the eye; Constipation
Penetrance for gene: MED13 were set to unknown
Review for gene: MED13 was set to AMBER
gene: MED13 was marked as current diagnostic
Added comment: Snijders Blok et al. (2018 - PMID: 29740699) report on 13 individuals with MED13 mutations.

Features included DD with speech difficulties (both universal) and motor delay in some. ID was observed in at least 9/13 and in most cases was in the borderline/mild range (moderate ID reported for 1 individual). Other features were ASD (5/13), ADHD, eye/vision abnormalities and in few individuals obstipation or congenital heart anomalies. Some possibly overlapping facial characteristics were also noted.

MED13 and MED13L are mutually exclusive components of the CDK8 kinase module that regulates the activity of the Mediator complex. The Mediator transmits signals from various transcription factors to RNA polymerase II (Pol II). Reversible binding of the CDK8 kinase controls Mediator - Pol II interaction (prevents Pol II recruitment) and thus acts as a molecular switch in Pol II - mediated transcription. DD and ID are features of the MED13L- and CDK8- related disorders.

3 stopgain, 2 frameshift, 6 missense variants and 1 in-frame deletion were reported. In 11 cases, the variants had occurred as de novo events, while 1 individual had inherited a nonsense variant from a similarly affected mother (unknown inheritance in her case).

Effect of a stopgain variant was studied with similar (total) transcript levels between the affected patient and his parents/controls upon qPCR. Sanger sequencing of cDNA amplicons was suggestive of the presence of an aberrant transcript at ~70% levels relative to the normal transcript. Truncated protein was undetectable by Western Blot in mononuclear blood cells from affected subjects. Total MED13 protein levels were not clearly different when comparing an affected individual with his unaffected parent (?).

Missense variants and the inframe deletion clustered either in the N- or the C-terminal domain, with the N-terminal ones all (T326I, T326del, P327S, P327Q / NM_005121.2 - NP_005112.2) affecting positions of a known phosphodegron sequence, important for the protein's ubiquitination and degradation. Another previously studied variant (T326A) had been shown to prevent degradation. As a result, the variants affecting aa 326-327 might lead to altered (increased) levels of MED13.

The remaining missense variants affected the C-terminal portion (Q2060L, A2064V).

As a result the impact of the different subcategories of variants remains unclear/inconclusive.

MED13 is not associated with any phenotype in OMIM. This gene is part of the DD panel of G2P, associated with "MED13 - Neurodevelopment disorder" (dis. confidence : probable / mutation consequence : LoF / GDD, speech/language delay, ID, autistic behavior among the assigned phenotypes).

MED13 is included in gene panels for ID offered by some diagnostic laboratories (incl. Radboudumc).

ID is part of the phenotype of MED13-related disorder, however as the severity in most individuals - when present - was in the borderline/mild range (not relevant for the present panel) and/or the underlying effect of mutations remains unclear, amber rating can probably be considered for this gene.
Sources: Radboud University Medical Center, Nijmegen, Literature
Intellectual disability v2.1021 PAK1 Konstantinos Varvagiannis changed review comment from: Horn et al. (2019 - doi.org/10.1093/brain/awz264) report on 4 additional individuals with de novo missense PAK1 pathogenic variants. ID, seizures and macrocephaly and walking difficulties were observed in all (4/4). ASD was reported in 3 (but was not among the features in the study by Harms et al).

PAK1 encodes p21 protein-activated kinase 1. The protein has 2 major domains, an autoregulatory and a protein kinase domain. Homodimerization masks the active site of the kinase, leading to autoinhibition (inactive form). PAK1 is activated by dissociation into monomers upon binding of the GTP-bound forms of the Rho GTPases CDC42 and RAC1. TRIO and HACE1 are indirect regulators of PAK1, via RAC1. PAK1 in turn, activates LIMK1 which plays a critical role in dendritic spine morphogenesis and brain function.

CDC42, RAC1, TRIO, HACE1 are all associated with neurodevelopmental disorders. Activation of RAC-PAK1-LIMK1 pathway has been demonstrated for Fragile-X syndrome (sharing ID, macrocephaly and seizures).

Mutations in PAK3, another member of the group I PAK subfamily with similar activation mechanism to PAK1 (by CDC42 / RAC1), cause Mental retardation, X-linked 30/47 (MIM 300558) (Green rating in the current panel).

4 additional missense variants - further to the 2 previously described ones - were found, all as de novo events:
c.397T>C (p.Ser133Pro) / c.361C>T p.(Pro121Ser) / c.328T>A p.(Ser110Thr) / c.1409T>G (p.Leu470Arg) [For the specific variants, cDNA and aa change are the same for both NM_001128620.1 and NM_002576].

The 3 former variants located within the autoinhibitory domain while the latter in the protein kinase domain though - again - close to the autoinhibitory one (in tertiary structure). A gain of function effect by reduced ability of autoinhibition (leading to autophosphorylation) and activation of PAK1 is the suggested mechanism. Gain of function is also supported by the fact that Pak1-/- do not exhibit neurodevelopmental anomalies / abnormal head size. PAK1 is not particularly intolerant to LoF variants as suggested by its pLI of 0.67.

The corresponding phenotype in OMIM is Intellectual developmental disorder with macrocephaly, seizures, and speech delay (MIM 618158). The gene is part of the DD panel of G2P, associated with "Neurodevelopmental Disorder" (monoallelic, activating / disease confidence : probable).

PAK1 is included in the gene panel for ID offered by Radboudumc.; to: Based on a further recent study, PAK1 can probably be upgraded to green in both ID and epilepsy gene panels:

Horn et al. (2019 - doi.org/10.1093/brain/awz264) report on 4 additional individuals with de novo missense PAK1 pathogenic variants. ID, seizures and macrocephaly and walking difficulties were observed in all (4/4). ASD was reported in 3 (but was not among the features in the study by Harms et al).

PAK1 encodes p21 protein-activated kinase 1. The protein has 2 major domains, an autoregulatory and a protein kinase domain. Homodimerization masks the active site of the kinase, leading to autoinhibition (inactive form). PAK1 is activated by dissociation into monomers upon binding of the GTP-bound forms of the Rho GTPases CDC42 and RAC1. TRIO and HACE1 are indirect regulators of PAK1, via RAC1. PAK1 in turn, activates LIMK1 which plays a critical role in dendritic spine morphogenesis and brain function.

CDC42, RAC1, TRIO, HACE1 are all associated with neurodevelopmental disorders. Activation of RAC-PAK1-LIMK1 pathway has been demonstrated for Fragile-X syndrome (sharing ID, macrocephaly and seizures).

Mutations in PAK3, another member of the group I PAK subfamily with similar activation mechanism to PAK1 (by CDC42 / RAC1), cause Mental retardation, X-linked 30/47 (MIM 300558) (Green rating in the current panel).

4 additional missense variants - further to the 2 previously described ones - were found, all as de novo events:
c.397T>C (p.Ser133Pro) / c.361C>T p.(Pro121Ser) / c.328T>A p.(Ser110Thr) / c.1409T>G (p.Leu470Arg) [For the specific variants, cDNA and aa change are the same for both NM_001128620.1 and NM_002576].

The 3 former variants located within the autoinhibitory domain while the latter in the protein kinase domain though - again - close to the autoinhibitory one (in tertiary structure). A gain of function effect by reduced ability of autoinhibition (leading to autophosphorylation) and activation of PAK1 is the suggested mechanism. Gain of function is also supported by the fact that Pak1-/- do not exhibit neurodevelopmental anomalies / abnormal head size. PAK1 is not particularly intolerant to LoF variants as suggested by its pLI of 0.67.

The corresponding phenotype in OMIM is Intellectual developmental disorder with macrocephaly, seizures, and speech delay (MIM 618158). The gene is part of the DD panel of G2P, associated with "Neurodevelopmental Disorder" (monoallelic, activating / disease confidence : probable).

PAK1 is included in the gene panel for ID offered by Radboudumc.

(Previous review below)
Intellectual disability v2.1021 PAK1 Konstantinos Varvagiannis edited their review of gene: PAK1: Added comment: Horn et al. (2019 - doi.org/10.1093/brain/awz264) report on 4 additional individuals with de novo missense PAK1 pathogenic variants. ID, seizures and macrocephaly and walking difficulties were observed in all (4/4). ASD was reported in 3 (but was not among the features in the study by Harms et al).

PAK1 encodes p21 protein-activated kinase 1. The protein has 2 major domains, an autoregulatory and a protein kinase domain. Homodimerization masks the active site of the kinase, leading to autoinhibition (inactive form). PAK1 is activated by dissociation into monomers upon binding of the GTP-bound forms of the Rho GTPases CDC42 and RAC1. TRIO and HACE1 are indirect regulators of PAK1, via RAC1. PAK1 in turn, activates LIMK1 which plays a critical role in dendritic spine morphogenesis and brain function.

CDC42, RAC1, TRIO, HACE1 are all associated with neurodevelopmental disorders. Activation of RAC-PAK1-LIMK1 pathway has been demonstrated for Fragile-X syndrome (sharing ID, macrocephaly and seizures).

Mutations in PAK3, another member of the group I PAK subfamily with similar activation mechanism to PAK1 (by CDC42 / RAC1), cause Mental retardation, X-linked 30/47 (MIM 300558) (Green rating in the current panel).

4 additional missense variants - further to the 2 previously described ones - were found, all as de novo events:
c.397T>C (p.Ser133Pro) / c.361C>T p.(Pro121Ser) / c.328T>A p.(Ser110Thr) / c.1409T>G (p.Leu470Arg) [For the specific variants, cDNA and aa change are the same for both NM_001128620.1 and NM_002576].

The 3 former variants located within the autoinhibitory domain while the latter in the protein kinase domain though - again - close to the autoinhibitory one (in tertiary structure). A gain of function effect by reduced ability of autoinhibition (leading to autophosphorylation) and activation of PAK1 is the suggested mechanism. Gain of function is also supported by the fact that Pak1-/- do not exhibit neurodevelopmental anomalies / abnormal head size. PAK1 is not particularly intolerant to LoF variants as suggested by its pLI of 0.67.

The corresponding phenotype in OMIM is Intellectual developmental disorder with macrocephaly, seizures, and speech delay (MIM 618158). The gene is part of the DD panel of G2P, associated with "Neurodevelopmental Disorder" (monoallelic, activating / disease confidence : probable).

PAK1 is included in the gene panel for ID offered by Radboudumc.; Changed rating: GREEN; Changed publications: 30290153, doi.org/10.1093/brain/awz264; Set current diagnostic: yes
Intellectual disability v2.1021 GABBR2 Rebecca Foulger commented on gene: GABBR2: Added missense tag: only missense variants (A707T and A567T) reported so far in the literature.
Intellectual disability v2.1021 GABBR2 Rebecca Foulger Tag missense tag was added to gene: GABBR2.
Intellectual disability v2.1021 GABBR2 Rebecca Foulger Classified gene: GABBR2 as Green List (high evidence)
Intellectual disability v2.1021 GABBR2 Rebecca Foulger Added comment: Comment on list classification: Updated gene from Amber to Green: As noted by Konstantinos Varvagiannis, an additional 2018 study has been published associating a new GABBR2 variant (A707T) with a RETT-like phenotype including intellectual impairment (PMID:29369404). This adds to the previous papers documenting the recurring p.Ala567Thr variant in RETT-like patients from Portugal (PMID:26740508) and Korea (PMID:28856709). Plus OMIM has been updated since the Dec 2017 curation to include neurodevelopmental disorder MIM:617904. Thirdly, email correspondence from J. Evans notes a patient with a relevant phenotype and a previously-published pathogenic variant in GABBR2. Therefore sufficient unrelated cases to support a Green rating.
Intellectual disability v2.1021 GABBR2 Rebecca Foulger Gene: gabbr2 has been classified as Green List (High Evidence).
Intellectual disability v2.1020 GABBR2 Rebecca Foulger commented on gene: GABBR2
Intellectual disability v2.1020 GABBR2 Rebecca Foulger Phenotypes for gene: GABBR2 were changed from EPILEPTIC ENCEPHALOPATHY; Rett syndrome to EPILEPTIC ENCEPHALOPATHY; Rett syndrome; Neurodevelopmental disorder with poor language and loss of hand skills, 617903
Intellectual disability v2.1019 GABBR2 Rebecca Foulger Publications for gene: GABBR2 were set to 29100083; 28061363; 28135719; 28856709
Intellectual disability v2.1018 GOT2 Catherine Snow Tag treatable tag was added to gene: GOT2.
Tag watchlist tag was added to gene: GOT2.
Intellectual disability v2.1018 GOT2 Catherine Snow Classified gene: GOT2 as Amber List (moderate evidence)
Intellectual disability v2.1018 GOT2 Catherine Snow Gene: got2 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1017 GOT2 Catherine Snow reviewed gene: GOT2: Rating: AMBER; Mode of pathogenicity: None; Publications: 31422819; Phenotypes: Global developmental delay, Intellectual disability, Seizures; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.1017 GEMIN4 Ivone Leong Classified gene: GEMIN4 as Amber List (moderate evidence)
Intellectual disability v2.1017 GEMIN4 Ivone Leong Added comment: Comment on list classification: Promoted from red to amber based on new evidence. PMID: 27878435 reported on different variant found in a patient with cataracts, global developmental delay and ataxia.
Intellectual disability v2.1017 GEMIN4 Ivone Leong Gene: gemin4 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1016 GEMIN4 Ivone Leong Publications for gene: GEMIN4 were set to 25558065
Intellectual disability v2.1015 HNRNPR Konstantinos Varvagiannis changed review comment from: Duijkers et al. (2019 - PMID: 31079900) report on the phenotype of 4 individuals with de novo HNRNPR variants and provide additional information on a previously published case (Helbig et al, 2016 - PMID: 26795593). All 5 were unrelated.

The phenotype consisted of DD (5/5 - moderate to severe in 4 for which this has been commented on), postnatal microcephaly, seizures, brachydactyly, with additional (cardiac, urogenital, etc) anomalies observed in few. Some partially overlapping facial features were also noted.

3 truncating variants as well as a missense one, all localizing within the last exon of the gene (NM_001102398.2 used as ref. although this exon is shared by all transcripts).

HNRNPR encodes heterogeneous nuclear ribonucleoprotein R, which is part of the spliceosome C. The latter functions in the nucleus to process and transport mRNA. Apart from splicing hnRNPs are also involved in other levels of gene regulation (PMID: 27215579). Some hnRNPs have been found in the cytoplasm in stress granules, aggregations of protein, RNAs and stalled initiation complexes that are formed as stress response upon oxidative insult and dissipate upon cessation of this insult.

Western blot in LCLs from affected individuals demonstrated the presence of the truncated protein as well as the full-length and short isoform (as expected by the variant localization).
As the C-terminal part has features of a "prion-like domain" (PrLD), critical for the formation of stress granules in the case of hnRNP-related disorders, comparison of fibroblasts from affected and healthy individuals revealed abnormal persistence of these granules in affected individuals following a recovery period, despite similar formation either at basal levels or under conditions of stress.

In line with a role of hnRNPs in splicing and gene regulation, RNA-Sequencing in fibroblasts from 2 affected individuals revealed abnormal splicing of some genes (eg. HOXA5, HOXB3, LHX9) and significant dysregulation of genes important for the development (upregulation of FOXG1, TBX1, several members of the HOX family and downregulation of LHX9, IRX3, etc) possibly contributing to the patient features.

Helbig et al. provide details on animal studies incl.expression in neural tissues (cerebrum and cerebellum), higher levels of expression early in the development (of both R1/R2 isoforms), etc (extensive discussion in the supplement with several articles cited).

HNRNPR is not associated with any phenotype in OMIM/G2P.

As a result this gene can be considered for inclusion as amber (developmental outcome not commented on sufficiently despite moderate/severe DD in most).
Sources: Literature; to: Duijkers et al. (2019 - PMID: 31079900) report on the phenotype of 4 individuals with de novo HNRNPR variants and provide additional information on a previously published case (Helbig et al, 2016 - PMID: 26795593). All 5 were unrelated.

The phenotype consisted of DD (5/5 - moderate to severe in 4 for which this has been commented on), postnatal microcephaly, seizures, brachydactyly, with additional (cardiac, urogenital, etc) anomalies observed in few. Some partially overlapping facial features were also noted.

3 truncating variants as well as a missense one, all localizing within the last exon of the gene (NM_001102398.2 used as ref. although this exon is shared by all transcripts).

HNRNPR encodes heterogeneous nuclear ribonucleoprotein R, which is part of the spliceosome C. The latter functions in the nucleus to process and transport mRNA. Apart from splicing hnRNPs are also involved in other levels of gene regulation (PMID: 27215579). Some hnRNPs have been found in the cytoplasm in stress granules, aggregations of protein, RNAs and stalled initiation complexes that are formed as stress response upon oxidative insult and dissipate upon cessation of this insult.

Western blot in LCLs from affected individuals demonstrated the presence of the truncated protein as well as the full-length and short isoform (as expected by the variant localization).
As the C-terminal part has features of a "prion-like domain" (PrLD), critical for the formation of stress granules in the case of hnRNP-related disorders, comparison of fibroblasts from affected and healthy individuals revealed abnormal persistence of these granules in affected individuals following a recovery period, despite similar formation either at basal levels or under conditions of stress.

In line with a role of hnRNPs in splicing and gene regulation, RNA-Sequencing in fibroblasts from 2 affected individuals revealed abnormal splicing of some genes (eg. HOXA5, HOXB3, LHX9) and significant dysregulation of genes important for the development (upregulation of FOXG1, TBX1, several members of the HOX family and downregulation of LHX9, IRX3, etc) possibly contributing to the patient features.

Helbig et al. provide details on animal studies incl.expression in neural tissues (cerebrum and cerebellum), higher levels of expression early in the development (of both R1/R2 isoforms), etc (extensive discussion in the supplement with several articles cited).

HNRNPR is not associated with any phenotype in OMIM/G2P.

As a result this gene can be considered for inclusion as amber (developmental outcome not commented on sufficiently despite moderate/severe DD in most) or green.
Sources: Literature
Intellectual disability v2.1015 HNRNPR Konstantinos Varvagiannis gene: HNRNPR was added
gene: HNRNPR was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HNRNPR was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: HNRNPR were set to 31079900; 26795593
Phenotypes for gene: HNRNPR were set to Global developmental delay; Intellectual disability; Seizures; Postnatal microcephaly; Short digit
Penetrance for gene: HNRNPR were set to unknown
Review for gene: HNRNPR was set to GREEN
Added comment: Duijkers et al. (2019 - PMID: 31079900) report on the phenotype of 4 individuals with de novo HNRNPR variants and provide additional information on a previously published case (Helbig et al, 2016 - PMID: 26795593). All 5 were unrelated.

The phenotype consisted of DD (5/5 - moderate to severe in 4 for which this has been commented on), postnatal microcephaly, seizures, brachydactyly, with additional (cardiac, urogenital, etc) anomalies observed in few. Some partially overlapping facial features were also noted.

3 truncating variants as well as a missense one, all localizing within the last exon of the gene (NM_001102398.2 used as ref. although this exon is shared by all transcripts).

HNRNPR encodes heterogeneous nuclear ribonucleoprotein R, which is part of the spliceosome C. The latter functions in the nucleus to process and transport mRNA. Apart from splicing hnRNPs are also involved in other levels of gene regulation (PMID: 27215579). Some hnRNPs have been found in the cytoplasm in stress granules, aggregations of protein, RNAs and stalled initiation complexes that are formed as stress response upon oxidative insult and dissipate upon cessation of this insult.

Western blot in LCLs from affected individuals demonstrated the presence of the truncated protein as well as the full-length and short isoform (as expected by the variant localization).
As the C-terminal part has features of a "prion-like domain" (PrLD), critical for the formation of stress granules in the case of hnRNP-related disorders, comparison of fibroblasts from affected and healthy individuals revealed abnormal persistence of these granules in affected individuals following a recovery period, despite similar formation either at basal levels or under conditions of stress.

In line with a role of hnRNPs in splicing and gene regulation, RNA-Sequencing in fibroblasts from 2 affected individuals revealed abnormal splicing of some genes (eg. HOXA5, HOXB3, LHX9) and significant dysregulation of genes important for the development (upregulation of FOXG1, TBX1, several members of the HOX family and downregulation of LHX9, IRX3, etc) possibly contributing to the patient features.

Helbig et al. provide details on animal studies incl.expression in neural tissues (cerebrum and cerebellum), higher levels of expression early in the development (of both R1/R2 isoforms), etc (extensive discussion in the supplement with several articles cited).

HNRNPR is not associated with any phenotype in OMIM/G2P.

As a result this gene can be considered for inclusion as amber (developmental outcome not commented on sufficiently despite moderate/severe DD in most).
Sources: Literature
Intellectual disability v2.1015 FBXW11 Konstantinos Varvagiannis gene: FBXW11 was added
gene: FBXW11 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: FBXW11 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: FBXW11 were set to 31402090
Phenotypes for gene: FBXW11 were set to Global developmental delay; Intellectual disability; Abnormality of the eye; Abnormality of the head; Abnormality of digit
Penetrance for gene: FBXW11 were set to unknown
Review for gene: FBXW11 was set to GREEN
Added comment: Holt et al. (2019 - PMID: 31402090) report on 7 unrelated individuals with de novo FBXW11 variants.

Features included DD (6/7), ID (6/7 - severity relevant to the current panel in most cases), eye, digital, jaw anomalies, etc. There was some overlap with the phenotype of a 1.24-Mb 5q35.1 microduplication spanning FBXW11 and 6 additional genes (Koolen et al, 2006 - PMID: 16865294).

FBXW11 encodes an F-box protein part of the Skp1-cullin-F-box (SCF) ubiquitin ligase complex, involved in ubiquitination and proteasomal degratation. The SCF complex functions as a regulator of Wnt/β-catenin, Hh (and possibly RAS) signalling pathways.

Each individual harbored a private missense variant as a de novo event. Alternative diagnoses (eg. Noonan syndrome in the case of a suggestive phenotype) were ruled out to the extent possible.

All 7 variants localized in regions depleted for nonsynonymous variation (constrained coding regions) at the tips of loops of the WD repeat domains and were presumed to lead to destabilization of the protein and/or its interactions. Given the clustering a gain-of-function or dominant-negative effect of these variants might be suggested. [In gnomAD FBXW11 has a Z score = 3.96 for missense variants / pLI = 0.98].

In situ hybridization on human embryo sections demonstrated expression in the developping eye, hand, brain and mandibular process.

Relevant expression patterns were also observed for the 2 zebrafish orthologs of FBXW11, fbxw11a/b. Generated zebrafish homozygous for a frameshift fbxw11b frameshift variant demonstrated relevant phenotypes upon additional injection of a fbxw11a morpholino (abnormal pectoral fins, heart edema, smaller eyes, abnormal jaw development).

FBXW11 is not associated with any phenotype in OMIM/G2P.

As a result, this gene can be considered for inclusion in the ID panel as green (sufficient cases, expression, phenotype in zebrafish model, etc.) or amber.
Sources: Literature
Intellectual disability v2.1015 GOT2 Konstantinos Varvagiannis gene: GOT2 was added
gene: GOT2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: GOT2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: GOT2 were set to 31422819
Phenotypes for gene: GOT2 were set to Global developmental delay; Intellectual disability; Seizures; Increased serum lactate; Hyperammonemia; Microcephaly; Failure to thrive; Feeding difficulties; Abnormality of nervous system morphology
Penetrance for gene: GOT2 were set to Complete
Review for gene: GOT2 was set to GREEN
Added comment: van Karnebeek et al. (2019 - PMID: 31422819) report on 4 individuals from 3 families, with biallelic GOT2 pathogenic variants (3 missense SNVs and 1 in-frame deletion).

The phenotype corresponded to a metabolic encephalopathy with onset of epilepsy in the first year of life (4/4) with DD and ID (4/4). Additional features included postnatal microcephaly, failure to thrive/feeding difficulties and cerebral anomalies (atrophy and white matter). All subjects had high blood lactate and hyperammonemia. Plasma serine was low in one case (alternative causes were ruled out).

Administration of serine and pyridoxine led to clinical improvement (cessation / better control of seizures) in 2 subjects suggesting that GOT2 deficiency may be amenable to therapeutic intervention. [Treatment could not be started in the 2 further affected individuals].

GOT2 encodes the mitochondrial glutamate oxaloacetate transaminase, a component of the malate-aspartate shuttle (MAS). The latter is important for intracellular NAD(H) redox homeostasis.

The authors provide several lines of evidence that GOT2 deficiency explains the patients' phenotype and metabolic defects incl. :
- Reduced GOT2 protein levels (due to lower expression/impaired stability) and diminished activity in patient fibroblasts (lower activity was also shown for carriers). Rescue of the GOT enzymatic activity was observed upon transduction of patient fibroblasts using lentiviral particles with wt GOT2.
- Impairment of de novo serine biosynthesis in patient (and to a lesser extent in carrier) fibroblasts compared to controls. This was similar in GOT2-knockout HEK293 cells. Serine biosynthesis in these cells was restored by pyruvate supplementation.
- CRISPR/Cas9 Got2-knockout mice resulted in early lethality (during pregnancy). Heterozygous mice were viable and healthy.
- Morpholino knockdown of got2a in zebrafish was shown to perturb embryonic development (smaller head, slow circulation, bend body, brain developmental defects, etc). Pyridoxine and serine in embryo water resulted in milder phenotypes/improved morphant survival. Zebrafish got2a morphants had seizure-like spikes upon EEG that were rescued by treatment with pyridoxine.

GOT2 is not associated with any phenotype in OMIM/G2P.

As a result, this gene can be considered for inclusion in both epilepsy and ID gene panels probably as green (3 families, relevant phenotypes and severity, evidence from cell and animal studies) or amber.

[Please consider inclusion in other relevant panels eg. mitochondrial disorders, metabolic disorders and/or addition of the 'treatable' tag].
Sources: Literature
Intellectual disability v2.1015 DDX6 Konstantinos Varvagiannis gene: DDX6 was added
gene: DDX6 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DDX6 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: DDX6 were set to 31422817
Phenotypes for gene: DDX6 were set to Generalized hypotonia; Global developmental delay; Intellectual disability; Unsteady gait; Abnormality of the cardiovascular system; Abnormality of the genitourinary system; Abnormality of limbs
Penetrance for gene: DDX6 were set to unknown
Review for gene: DDX6 was set to GREEN
Added comment: Balak et al. (2019 - PMID: 31422817) report on 5 individuals with de novo likely pathogenic DDX6 variants.

Clinical details are provided for 4. Frequent features included hypotonia, DD, ID (4/4), gait instability, cardiac, genitourinary as well anomalies of the extremities.

DDX6 belongs to the DEAD box family of RNA helicases. This helicase is an essential component of processing bodies (P-bodies / PBs), which are mebrane-less organelles involved in storage of mRNAs and proteins related to mRNA decay thus playing an important role in translational repression/post-transcriptional regulation (PMID: 29381060).

All 5 variants had occurred as de novo events, clustered in exon 11 (NM_004397.5) and affected residues 372-373 of the QxxR motif (c.1115A>G or p.His372Arg / c.1118G>A or p.Arg373Gln) or 390-391 of the V motif (c.1168T>C or p.Cys390Arg / c.1171A>C or p.Thr391Pro / c.1172C>T or p.Thr391Ile). The specific motifs (and RecA-2 domain) are involved in RNA binding, helicase activity and protein-partner binding.

Fibroblasts from 2 individuals were studied. Patient cells contained fewer PBs compared to cells from relatives/control-subjects, despite similar amounts of DDX6 protein upon immunobloting. Additional studies suggested that DDX6 variants caused impaired binding of other DDX6 protein partners involved in PB formation / translation repression (eg. LSM14A, 4E-T, etc) thus resulting in defective PB assembly.

Transcriptome analysis in fibroblasts from one affected individual revealed (significant) differential expression of >1000 genes, enriched for genes related to protein translation, ribosome and RNA processing.

As the authors discuss, given the residual PB assembly, haploinsufficiency is favored over a dominant-negative effect which would result in complete suppression of PBs (as sugested by a previous study of a dominant-negative DDX6 variant - PMID cited: 19297524). [In gnomAD, DDX6 has a Z-score for missense variants of 3.78 and a pLI of 1].

DDX6 is not associated with any phenotype in OMIM.
In G2P it is associated with ID (disease confidence : probable / mutations : all missense/in frame).

As a result, this gene can be considered for inclusion in the ID panel as green (sufficient cases, relevant phenotype, functional studies) or amber.
Sources: Literature
Intellectual disability v2.1015 TRAPPC6B Konstantinos Varvagiannis reviewed gene: TRAPPC6B: Rating: GREEN; Mode of pathogenicity: None; Publications: 28626029, 28397838, DOI 10.1055/s-0039-1693664; Phenotypes: ; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v2.1015 KCNMA1 Konstantinos Varvagiannis reviewed gene: KCNMA1: Rating: AMBER; Mode of pathogenicity: None; Publications: 31427379, 31152168, 27567911; Phenotypes: ; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability v2.1015 SOX4 Louise Daugherty Added comment: Comment on phenotypes: added OMIM MIM id
Intellectual disability v2.1015 SOX4 Louise Daugherty Phenotypes for gene: SOX4 were changed from Syndromic intellectual disability; Global developmental delay; Intellectual disability; Growth delay; Clinodactyly of the 5th finger; facial dysmorphism to Coffin-Siris syndrome 10, 618506; Syndromic intellectual disability; Global developmental delay; Intellectual disability; Growth delay; Clinodactyly of the 5th finger; facial dysmorphism
Intellectual disability v2.1014 KMT2E Louise Daugherty Added comment: Comment on phenotypes: added OMIM MIM id
Intellectual disability v2.1014 KMT2E Louise Daugherty Phenotypes for gene: KMT2E were changed from Global developmental delay; Intellectual disability; Autism; Seizures; Abnormality of skull size to O'Donnell-Luria-Rodan syndrome, 618512; Global developmental delay; Intellectual disability; Autism; Seizures; Abnormality of skull size
Intellectual disability v2.1013 CNOT1 Louise Daugherty Added comment: Comment on phenotypes: added OMIM MIM id
Intellectual disability v2.1013 CNOT1 Louise Daugherty Phenotypes for gene: CNOT1 were changed from global developmental delay to Holoprosencephaly 12, with or without pancreatic agenesis, 618500; global developmental delay
Intellectual disability v2.1012 CACNA1B Louise Daugherty Added comment: Comment on phenotypes: added OMIM MIM id
Intellectual disability v2.1012 CACNA1B Louise Daugherty Phenotypes for gene: CACNA1B were changed from Progressive Epilepsy-Dyskinesia; Seizures; Abnormality of movement; Intellectual disability; Developmental regression; Global developmental delay to Neurodevelopmental disorder with seizures and nonepileptic hyperkinetic movements, 618497; Progressive Epilepsy-Dyskinesia; Seizures; Abnormality of movement; Intellectual disability; Developmental regression; Global developmental delay
Intellectual disability v2.1011 PUF60 Rebecca Foulger Phenotypes for gene: PUF60 were changed from Verheij syndrome, 615583; VRJS; Chromosome 8q24.3 deletion syndrome; PUF60 syndrome; Intellectual disability to Syndromic intellectual disability; Verheij syndrome, 615583; VRJS; Chromosome 8q24.3 deletion syndrome; PUF60 syndrome; Intellectual disability
Intellectual disability v2.1010 COLEC10 Rebecca Foulger commented on gene: COLEC10
Intellectual disability v2.1010 COLEC10 Rebecca Foulger Phenotypes for gene: COLEC10 were changed from to 3MC syndrome 3, 248340
Intellectual disability v2.1009 COLEC10 Rebecca Foulger Publications for gene: COLEC10 were set to
Intellectual disability v2.1008 FRMPD4 Rebecca Foulger Classified gene: FRMPD4 as Green List (high evidence)
Intellectual disability v2.1008 FRMPD4 Rebecca Foulger Added comment: Comment on list classification: Updated rating from Amber to Green on advice of Genomics England clinical team: four families with a relevant phenotype meets the criteria for a Green rating.
Intellectual disability v2.1008 FRMPD4 Rebecca Foulger Gene: frmpd4 has been classified as Green List (High Evidence).
Intellectual disability v2.1007 FRMPD4 Rebecca Foulger Added comment: Comment on mode of inheritance: MOI set to X-linked dominant on advice of Genomics England clinical team, in view of the single reported female heterozygote with a relevant phenotype.
Intellectual disability v2.1007 FRMPD4 Rebecca Foulger Mode of inheritance for gene: FRMPD4 was changed from X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) to X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Intellectual disability v2.1006 GRIA2 Rebecca Foulger commented on gene: GRIA2
Intellectual disability v2.1006 POLR2A Rebecca Foulger Classified gene: POLR2A as Green List (high evidence)
Intellectual disability v2.1006 POLR2A Rebecca Foulger Gene: polr2a has been classified as Green List (High Evidence).
Intellectual disability v2.1005 POLR2A Rebecca Foulger Phenotypes for gene: POLR2A were changed from Generalized hypotonia; Global developmental delay; Feeding difficulties to Global developmental delay; Generalized hypotonia; Feeding difficulties
Intellectual disability v2.1004 POLR2A Rebecca Foulger commented on gene: POLR2A
Intellectual disability v2.1004 AFF3 Rebecca Foulger changed review comment from: As noted by Konstantinos Varvagiannis, Voisin et al., 2019 (not yet in PubMed) describe de novo missense variants in the degron of AFF3 (a region required for its degradation) in 10 unrelated individuals with symptoms including ID. 4 different missense variants were identified (p.A258S, p.A258T, p.A258V and p.V260G). Although there are sufficient cases with a relevant phenotype, I have rated as Amber pending publication of the 2019 article: as OMIM note in their correspondance on AFF3, information changes from the initial bioRxiv upload to peer-reviewed publication. Therefore updated rating of AFF3 from Red to Amber, added 'watchlist' tag (in addition to missense tag), and will re-curate when the paper is published.; to: As noted by Konstantinos Varvagiannis, Voisin et al., 2019 (not yet in PubMed) describe de novo missense variants in the degron of AFF3 (a region required for its degradation) in 10 unrelated individuals with symptoms including ID. 4 different missense variants were identified (p.A258S, p.A258T, p.A258V and p.V260G). Although there are sufficient cases with a relevant phenotype (plus the individual reported in PMID:18616733), I have rated as Amber pending publication of the Voisin 2019 article: as OMIM note in their correspondance on AFF3, information changes from the initial bioRxiv upload to peer-reviewed publication. Therefore updated rating of AFF3 from Red to Amber, added 'watchlist' tag and 'missense' tag, and will re-curate when the paper is published.
Intellectual disability v2.1004 AFF3 Rebecca Foulger Publications for gene: AFF3 were set to
Intellectual disability v2.1003 AFF3 Rebecca Foulger Phenotypes for gene: AFF3 were changed from to Intellectual disability; Seizures
Intellectual disability v2.1002 AFF3 Rebecca Foulger Mode of inheritance for gene: AFF3 was changed from to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.1001 AFF3 Rebecca Foulger Mode of pathogenicity for gene: AFF3 was changed from to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Intellectual disability v2.1001 AFF3 Rebecca Foulger Classified gene: AFF3 as Amber List (moderate evidence)
Intellectual disability v2.1001 AFF3 Rebecca Foulger Gene: aff3 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.1000 AFF3 Rebecca Foulger Tag watchlist tag was added to gene: AFF3.
Intellectual disability v2.1000 AFF3 Rebecca Foulger Tag missense tag was added to gene: AFF3.
Intellectual disability v2.1000 AFF3 Rebecca Foulger commented on gene: AFF3
Intellectual disability v2.1000 WDR37 Rebecca Foulger commented on gene: WDR37: Added missense tag: only missense variants reported so far (PMID:31327510 and PMID:31327508).
Intellectual disability v2.1000 WDR37 Rebecca Foulger Classified gene: WDR37 as Green List (high evidence)
Intellectual disability v2.1000 WDR37 Rebecca Foulger Gene: wdr37 has been classified as Green List (High Evidence).
Intellectual disability v2.1000 WDR37 Rebecca Foulger Mode of pathogenicity for gene: WDR37 was changed from None to Other
Intellectual disability v2.999 WDR37 Rebecca Foulger commented on gene: WDR37: WDR37 was added to the ID panel and rated Green by Konstantinos Varvagiannis. Although WDR37 is not yet associated with a disorder in OMIM or Gene2Phenotype, there are sufficient unrelated cases in two recent papers (PMID:31327510 and PMID:31327508) with a severe ID/DD phenotype for inclusion on the panel. Plus it was agreed at the Webex call on Thurs 8th August with members of the GMS Neurology Specialist Test Group that WDR37 should be rated Green on the epilepsy panel (402). Therefore updated rating from Grey to Green.
Intellectual disability v2.999 WDR37 Rebecca Foulger Tag missense tag was added to gene: WDR37.
Intellectual disability v2.999 WDR37 Rebecca Foulger commented on gene: WDR37
Intellectual disability v2.999 PIGU Rebecca Foulger Classified gene: PIGU as Green List (high evidence)
Intellectual disability v2.999 PIGU Rebecca Foulger Gene: pigu has been classified as Green List (High Evidence).
Intellectual disability v2.998 PIGU Rebecca Foulger commented on gene: PIGU: PIGU (together with other PIGx genes) were discussed with members of the GMS Neurology Specialist Test Group on the Webex call Thursday 8th August 2019 to discuss R59 Early onset or syndromic epilepsy. Agreed that there is enough evidence to rate PIGU Green on the 'Genetic epilepsy syndromes' panel (402). Therefore applied Green rating to the ID panel also: although PIGU is not yet associated with a disorder in OMIM or Gene2Phenotype, there are sufficient unrelated cases described in PMID:31353022.
Intellectual disability v2.998 PIGU Rebecca Foulger commented on gene: PIGU: Added 'missense' tag as missense variants only reported so far (PMID:31353022).
Intellectual disability v2.998 PIGU Rebecca Foulger Tag missense tag was added to gene: PIGU.
Intellectual disability v2.998 PIGU Rebecca Foulger commented on gene: PIGU: PMID:31353022 (Knaus et al. 2019) report two homozygous missense mutations (c.209T>A [p.Ile70Lys] and c.1149C>A [p.Asn383Lys]) in 5 individuals from 3 unrelated families. All individuals presented with global DD severe-to-profound ID, muscular hypotonia, seizures, brain anomalies, scoliosis, and mild facial dysmorphism. Sequencing confirmed that all parents were healthy carriers. c.209T>A has not been observed in gnomAD while c.1149C>A has been observed only in the heterozygous state (7/277194).
Intellectual disability v2.998 PIGU Rebecca Foulger commented on gene: PIGU
Intellectual disability v2.998 NFASC Sarah Leigh Classified gene: NFASC as Green List (high evidence)
Intellectual disability v2.998 NFASC Sarah Leigh Added comment: Comment on list classification: Associated with phenotype in OMIM and not in Gen2Phen. At least 3 variants identified in unrelated cases.
Intellectual disability v2.998 NFASC Sarah Leigh Gene: nfasc has been classified as Green List (High Evidence).
Intellectual disability v2.997 NFASC Sarah Leigh gene: NFASC was added
gene: NFASC was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: NFASC was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NFASC were set to 28940097; 30124836; 30850329
Phenotypes for gene: NFASC were set to Neurodevelopmental disorder with central and peripheral motor dysfunction 618356
Review for gene: NFASC was set to GREEN
Added comment: Sources: Literature
Intellectual disability v2.996 POLR2A Konstantinos Varvagiannis gene: POLR2A was added
gene: POLR2A was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: POLR2A was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: POLR2A were set to 31353023
Phenotypes for gene: POLR2A were set to Generalized hypotonia; Global developmental delay; Feeding difficulties
Penetrance for gene: POLR2A were set to unknown
Review for gene: POLR2A was set to GREEN
gene: POLR2A was marked as current diagnostic
Added comment: Haijes et al. (2019 - PMID: 31353023) report on 16 individuals with heterozygous de novo POLR2A variants.

DD in all domains was observed in all individuals, ranging from mild to severe (in 8/16 moderate or more severe). The developmental scores were stable over time (as for eventual catch-up/decline) supporting relevance to the current panel.

POLR2A encodes RPB1, the largest subunit of RNA polymerase II (pol II). Pol II is responsible for the transcription of all protein coding genes as well as several long/short non-coding RNA genes.

Missense, in-frame deletions as well as truncating mutations were observed. POLR2A has a pLI of 1 and a Z-score for missense variants of 7.13 (one of the highest ones). The reported variants did not cluster in specific domains of the protein although many were in regions relatively depleted in benign variants in gnomAD (stretches of desert Z-scores). Measures such as the CADD scores did not discriminate between deleterious ones and those in gnomAD.

Different layers of structural analyses, functional analyses (impaired growth in S. cerevisiae in genetic background lacking transcr. factors Dst1 / Sub1 - suggesting reduced transcriptional fidelity / reduced HeLa cell viability) or phenotypic overlap were used to classify variants in probably disease causing (11), possibly disease causing (4 - only based on phenotypic overlap) or of unknown effect (1 variant - due to unavailable/incomplete phenotype).

Some variants were predicted to act by haploinsufficiency while others (missense ones) by a dominant-negative mechanism, the latter being more likely to result in severe phenotypes.

Mutations in genes encoding subunits of pol III (responsible for tRNA synthesis) are associated with leukodystrophy phenotypes with some limited overlap with POLR2A (delayed myelination/white-matter loss/tooth misalignment). Mutations in genes encoding other subunits of pol II (other than RPB1 encoded by POLR2A) have not been implicated in disease though.

POLR2A is not associated with any phenotype in OMIM/G2P. This gene is included in panels for ID offered by some diagnostic laboratories [eg. Utrecht UMC - affiliation of many co-authors of this study or GeneDx].

As a result, this gene can be considered for inclusion in the ID panel probably as green, or amber.
Sources: Literature
Intellectual disability v2.996 AFF3 Konstantinos Varvagiannis changed review comment from: Voisin et al. (2019 - https://doi.org/10.1101/693937) report on 10 individuals with de novo missense AFF3 variants affecting a 9-amino-acid sequence (degron) important for the protein's degradation and summarize the phenotype of an additional individual previously described by Steichen-Gersdorf et al. (2008 - PMID: 18616733) with a 500 kb affecting only AFF3 (LAF4) and removing also this sequence.

The phenotype of missense variants consisted of kidney anomalies, mesomelic dysplasia, seizures, hypertrichosis, intellectual disability and pulmonary problems and was overlapping with that of the deletion. [10 of 11 subjects exhibited severe developmental epileptic encephalopathy].

9 probands harbored missense variants affecting the codon 258 while one individual had a variant affecting codon 260 [c.772G>T or p.Ala258Ser (x2), c.772G>A or p.Ala258Thr (x6), c.773C>T or p.Ala258Val (x1) and c.779T>G or p.(Val260Gly) (x1) - NM_001025108.1 / NP_001020279.1]. The deletion removed exons 4-13.

AFF1-4 are ALF transcription factor paralogs, components of the transcriptional super elongation complex regulating expression of genes involved in neurogenesis and development.

Using HEK293T cells expressing FLAG-tagged AFF3 (and AFF4) wt or mutants, accumulation of mutated forms was shown upon immunoblot.

Aff3+/- and/or -/- mice exhibit skeletal defects. These were more pronounced in homozygous mice which demonstrated also some elements in favor of kidney dysfunction and/or metabolic deregulation and possible neurological dysfunction (signs of impaired hearing and diminished grip strength). Homozygous mice had CNS anomalies (enlarged lateral ventricles and decreased corpus callosum size) similar to some affected individuals, although these were not observed in another Aff3-/- model. Knock-in mice modeling the microdeletion and the Ala258Thr variant displayed lower mesomelic limb deformities and early lethality respectively [cited PMIDs : 21677750, 25660031, knock-in model was part of the present study].

Accumulation of the protein in zebrafish (by overexpression of the human wt AFF3 mRNA), led to morphological defects.

Reanalysis of transcriptome data from previously generated HEK293T cell lines knocked down for AFF2, AFF3 and AFF4 by shRNAs (study) suggested that these transcription factors are not redundant.

Finally, CHOPS syndrome (#616368) due to mutations of AFF4 also leading to increased protein stability presents a partially overlapping phenotype (incl. cognitive impairment) to that of AFF3.
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In G2P, AFF3 is associated with Skeletal dysplasia with severe neurological disease (disease confidence : probable / ID and seizures among the assigned phenotypes). There is no associated phenotype in OMIM.
Some diagnostic laboratories include AFF3 in their ID panel (eg. among the many co-authors' affiliations GeneDx and Victorian Clinical Genetics - which was already listed as source for AFF3 in the current panel).
----
As a result this gene can be considered for upgrade to green (relevant phenotype and severity, sufficient cases, evidence for accumulation similar to AFF4, animal models, etc) or amber (pending publication of the article).; to: Voisin et al. (2019 - https://doi.org/10.1101/693937) report on 10 individuals with de novo missense AFF3 variants affecting a 9-amino-acid sequence (degron) important for the protein's degradation and summarize the phenotype of an additional individual previously described by Steichen-Gersdorf et al. (2008 - PMID: 18616733) with a 500 kb affecting only AFF3 (LAF4) and removing also this sequence.

The phenotype of missense variants consisted of kidney anomalies, mesomelic dysplasia, seizures, hypertrichosis, intellectual disability and pulmonary problems and was overlapping with that of the deletion. [10 of 11 subjects exhibited severe developmental epileptic encephalopathy].

9 probands harbored missense variants affecting the codon 258 while one individual had a variant affecting codon 260 [c.772G>T or p.Ala258Ser (x2), c.772G>A or p.Ala258Thr (x6), c.773C>T or p.Ala258Val (x1) and c.779T>G or p.(Val260Gly) (x1) - NM_001025108.1 / NP_001020279.1]. The deletion removed exons 4-13.

AFF1-4 are ALF transcription factor paralogs, components of the transcriptional super elongation complex regulating expression of genes involved in neurogenesis and development.

Using HEK293T cells expressing FLAG-tagged AFF3 (and AFF4) wt or mutants, accumulation of mutated forms was shown upon immunoblot.

Aff3+/- and/or -/- mice exhibit skeletal defects. These were more pronounced in homozygous mice which demonstrated also some elements in favor of kidney dysfunction and/or metabolic deregulation and possible neurological dysfunction (signs of impaired hearing and diminished grip strength). Homozygous mice had CNS anomalies (enlarged lateral ventricles and decreased corpus callosum size) similar to some affected individuals, although these were not observed in another Aff3-/- model. Knock-in mice modeling the microdeletion and the Ala258Thr variant displayed lower mesomelic limb deformities and early lethality respectively [cited PMIDs : 21677750, 25660031, knock-in model was part of the present study].

Accumulation of the protein in zebrafish (by overexpression of the human wt AFF3 mRNA), led to morphological defects.

Reanalysis of transcriptome data from previously generated HEK293T cell lines knocked down for AFF2, AFF3 and AFF4 by shRNAs (study) suggested that these transcription factors are not redundant.

Finally, CHOPS syndrome (#616368) due to mutations of AFF4 also leading to increased protein stability presents a partially overlapping phenotype (incl. cognitive impairment) to that of AFF3.
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Shimizu et al. (8/2019 - PMID: 31388108) describe an additional individual with de novo AFF3 missense variant. The phenotype overlaps with that summarized by Voisin et al. incl. mesomelic dysplasia with additional skeletal anomalies, bilateral kidney hypoplasia and severe DD at the age of 2.5 years. Seizures and pulmonary problems were not observed. Although a different RefSeq is used the variant is among those also reported by Voisin et al. [NM_002285.2:c.697G>A (p.Ala233Thr) corresponding to NM_001025108.1:c.772G>A (p.Ala258Thr)].
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In G2P, AFF3 is associated with Skeletal dysplasia with severe neurological disease (disease confidence : probable / ID and seizures among the assigned phenotypes). There is no associated phenotype in OMIM.
Some diagnostic laboratories include AFF3 in their ID panel (eg. among the many co-authors' affiliations GeneDx and Victorian Clinical Genetics - which was already listed as source for AFF3 in the current panel).
----
As a result this gene can be considered for upgrade to green (relevant phenotype and severity, sufficient cases, evidence for accumulation similar to AFF4, animal models, etc) or amber (pending publication of the article).

[Review modified to add additional reference/case report]
Intellectual disability v2.996 GRIA2 Konstantinos Varvagiannis reviewed gene: GRIA2: Rating: GREEN; Mode of pathogenicity: None; Publications: 31300657; Phenotypes: ; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.996 AFF3 Konstantinos Varvagiannis reviewed gene: AFF3: Rating: GREEN; Mode of pathogenicity: Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments; Publications: https://doi.org/10.1101/693937, 18616733; Phenotypes: Intellectual disability, Seizures, Abnormality of skeletal morphology, Abnormality of the urinary system, Hypertrichosis, Abnormality of the respiratory system; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown; Current diagnostic: yes
Intellectual disability v2.996 PIGU Konstantinos Varvagiannis gene: PIGU was added
gene: PIGU was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: PIGU was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PIGU were set to 31353022
Phenotypes for gene: PIGU were set to Global developmental delay; Intellectual disability; Seizures; Cerebral atrophy; Cerebellar hypoplasia; Scoliosis
Penetrance for gene: PIGU were set to Complete
Review for gene: PIGU was set to GREEN
Added comment: Knaus et al. (2019 - PMID: 31353022) report on 5 affected individuals (from 3 unrelated families) with biallelic pathogenic PIGU variants.

Common features included tone abnormalities, global DD, ID, seizures, CNS anomalies (cerebral atrophy and/or cerebellar hypoplasia), scoliosis. Affected individuals presented also with facial similarities. DD/ID were universal features and their severity appears to be relevant to the panel. Seizures were also reported in all individuals (myoclonic in 3, for whom this was specified). ALP was normal in all.

Three individuals from 2 non-consanguineous families (one from Norway, the other not specified) were homozygous for a missense variant NM_080476.4:c.1149C>A (or p.Asn383Lys) present with an AF of 7/277197 in Europeans. Two individuals born to consanguineous parents from Turkey were homozygous for another missense variant (c.209T>A or p.Ile70Lys - same RefSeq).

Segregation analyses in parents and unaffected sibs were carried out.

PIGU encodes a subunit of the GPI transaminidase, a heteropentameric complex (other subunits encoded by PIGK, PIGS, PIGT and GPAA1) that mediates attachment in the endoplasmic reticulum of glycosylphosphatidylinositol (GPI) to the C-termini of proteins which are subsequently anchored to the cell surface.

Pathogenic variants in 18 of 29 genes implicated in biosynthesis of the GPI anchor have been identified as a cause of GPI biosynthesis disorders, with ID and seizures as principal features. Mutations in other genes encoding components of the GPI transaminidase complex (GPAA1, PIGT and PIGS) lead to neurodevelopmental disorders.

Functional impairment of PIGU was supported by flow-cytometric analysis showing significant reduction of cell surface expression of GPI anchored proteins (mainly FLAER, CD16 and CD24) on granulocytes from affected individuals. In addition accumulation of free GPI anchors on the cell surface of B cells from affected individuals further suggested deficiency of the GPI transaminidase.

Transient expression of mutant (Asn383Lys) protein failed to rescue expression of GPI-APs to the same extent as wt in a CHO cell line deficient for PIGU.

Feature analysis demonstrated similarities among individuals with mutations in other genes of the GPI transamidase complex (GPAA1 and PIGT) as well as with GPI biosynthesis disorders. Facial analysis was also suggestive of facial similarities between individuals with GPAA1 and PIGU mutations.

PIGU is not associated with any phenotype in OMIM or G2P.

As a result this gene can be considered for inclusion in the ID and epilepsy panels probably as green (3 families, ID of relevant severity and seizures in all affected individuals, known group of disorders and supportive evidence) or amber.
Sources: Literature
Intellectual disability v2.996 WDR37 Konstantinos Varvagiannis reviewed gene: WDR37: Rating: GREEN; Mode of pathogenicity: Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments; Publications: 31327510, 31327508; Phenotypes: Global developmental delay, Intellectual disability, Seizures, Abnormality of the eye, Abnormality of nervous system morphology, Hearing abnormality, Abnormality of the cardiovascular system, Abnormality of the skeletal system, Abnormality of the genitourinary system; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.996 WDR37 Konstantinos Varvagiannis Deleted their review
Intellectual disability v2.996 WDR37 Konstantinos Varvagiannis gene: WDR37 was added
gene: WDR37 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: WDR37 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: WDR37 were set to 31327510; 31327508
Phenotypes for gene: WDR37 were set to Global developmental delay; Intellectual disability; Seizures; Abnormality of the eye; Abnormality of nervous system morphology; Hearing abnormality; Abnormality of the cardiovascular system; Abnormality of the skeletal system; Abnormality of the genitourinary system
Penetrance for gene: WDR37 were set to unknown
Review for gene: WDR37 was set to GREEN
Added comment: Two concurrent publications by Reis et al. and Kanca et al. (2019 - PMIDs: 31327510, 31327508) report on the phenotype of individuals with de novo WDR37 mutations.

The study by Reis et al. provides clinical details on 4 affected individuals, while 5 further are described by Kanca et al.

4 different de novo variants were reported in these individuals who appear to be unrelated in (and between) the 2 studies [NM_014023.3]:
- c.356C>T (p.Ser119Phe) [Reis indiv. 1 - 3y, Kanca proband 3 - 5m2w]
- c.389C>T (p.Thr130Ile) [Reis indiv. 2 - 22m , Kanca proband 5 - 6w]
- c.374C>T (p.Thr125Ile) [Reis indiv. 3 - 8y , Kanca proband 1 - 7y]
- c.386C>G (p.Ser129Cys) [Reis indiv. 4 - unkn age, Kanca probands 2 and 4, 6.5y and 19y]

Common features included DD/ID (severity relevant for the current panel), seizures (9/9), ocular anomalies (corneal opacity/Peters anomaly, coloboma, microphthalmia etc.) and variable brain, hearing, cardiovascular, skeletal and genitourinary anomalies. Some facial and/or other dysmorphic features (incl. excess nuchal skin / webbed neck) were also frequent among affected individuals. Feeding difficulties and growth deficiency were also among the features observed.

The function of WDR37 is not known. Variants demonstrated comparable protein levels and cellular localization compared to wt.

Reis et al. provide evidence using CRISPR-Cas9 mediated genome editing in zebrafish, to introduce the Ser129Cys variant observed in affected individuals as well as novel missense and frameshift variants. Poor growth (similar to the human phenotype) and larval lethality were noted for missense variants. Head size was proportionately small. Ocular (coloboma/corneal) or craniofacial anomalies were not observed. Zebrafish heterozygous for LoF variants survived to adulthood.

Based on these a dominant-negative mechanism was postulated for missense alleles.

RNA-seq analysis in zebrafish showed upregulation of cholesterol biosynthesis pathways (among the most dysregulated ones).

Previous data in mice, suggest a broad expression pattern for Wdr37 with enrichment in ocular and brain tissues, significant associations in homozygous mutant mice for decreased body weight, grip strength, skeletal anomalies and possible increase (p =< 0.05) in ocular (lens/corneal) and other anomalies [BioGPS and International Mouse Phenotyping Consortium cited].

CG12333 loss (the Drosophila WDR37 ortholog) causes increased bang sensitivity in flies (analogous to the human epilepsy phenotype), defects in copulation and grip strength, phenotypes that were rescued by human reference but not variant cDNAs.

As discussed by Kanca et al. based on data from Drosophila and mice, limited phenotypic similarity of CNVs spanning WDR37 and adjacent genes with the reported individuals and the presence of LoF variants in control populations haploinsufficiency appears unlikely. Gain-of-function is also unlikely, as expression of human variants in flies did not exacerbate the observed phenotypes. A dominant-negative effect is again proposed.

WDR37 is not associated with any phenotype in OMIM/G2P.

As a result WDR37 can be considered for inclusion in the ID and epilepsy panels with green (relevant phenotype, sufficient cases, animal models) or amber rating.
Sources: Literature
Intellectual disability v2.996 POU3F3 Catherine Snow Classified gene: POU3F3 as Green List (high evidence)
Intellectual disability v2.996 POU3F3 Catherine Snow Gene: pou3f3 has been classified as Green List (High Evidence).
Intellectual disability v2.995 POU3F3 Catherine Snow reviewed gene: POU3F3: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.995 IARS Sarah Leigh commented on gene: IARS
Intellectual disability v2.995 IARS Sarah Leigh Tag new-gene-name tag was added to gene: IARS.
Intellectual disability v2.995 POU3F3 Catherine Snow Publications for gene: POU3F3 were set to https://doi.org/10.1016/j.ajhg.2019.06.007; 24550763
Intellectual disability v2.994 SHANK1 Catherine Snow Classified gene: SHANK1 as Red List (low evidence)
Intellectual disability v2.994 SHANK1 Catherine Snow Gene: shank1 has been classified as Red List (Low Evidence).
Intellectual disability v2.993 SHANK1 Catherine Snow reviewed gene: SHANK1: Rating: RED; Mode of pathogenicity: None; Publications: 30053575, 20868654; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.993 PIGB Catherine Snow Classified gene: PIGB as Green List (high evidence)
Intellectual disability v2.993 PIGB Catherine Snow Gene: pigb has been classified as Green List (High Evidence).
Intellectual disability v2.993 PIGB Catherine Snow Classified gene: PIGB as Green List (high evidence)
Intellectual disability v2.993 PIGB Catherine Snow Gene: pigb has been classified as Green List (High Evidence).
Intellectual disability v2.992 PIGB Catherine Snow reviewed gene: PIGB: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.992 DLG4 Catherine Snow Classified gene: DLG4 as Green List (high evidence)
Intellectual disability v2.992 DLG4 Catherine Snow Gene: dlg4 has been classified as Green List (High Evidence).
Intellectual disability v2.991 CTBP1 Rebecca Foulger Tag missense tag was added to gene: CTBP1.
Intellectual disability v2.991 AP2M1 Catherine Snow Tag missense tag was added to gene: AP2M1.
Intellectual disability v2.991 CYP27A1 Catherine Snow Tag watchlist tag was added to gene: CYP27A1.
Intellectual disability v2.991 CYP27A1 Catherine Snow commented on gene: CYP27A1: Advice from clinical team "the phenotypic relevance is borderline. I would opt for amber in view of the small number of cases of school age, or earlier, intellectual impairment. This phenotype is the mainstay of this panel, but not clearly the common presentation for this disorder. Therefore I would prefer to opt to await further cases with a relevant phenotype before reviewing this".
CYP27A1 will therefore remain Amber on the panel and the watchlist tag been added.
Intellectual disability v2.991 PHF21A Catherine Snow Classified gene: PHF21A as Green List (high evidence)
Intellectual disability v2.991 PHF21A Catherine Snow Gene: phf21a has been classified as Green List (High Evidence).
Intellectual disability v2.990 PHF21A Catherine Snow changed review comment from: Potocki-Shaffer syndrome thought to caused by a deletion of 11p11.2, the minimum deleted region contains at least five genes, including PHF21A.
Hamanaka et al in PMID: 30487643 reported on three individuals who all underwent trio WES to have de novo, variants in PHF21A. All individuals had DD and ID although mild in one case.
PHF21A is not currently associated with any phenotypes in OMIM but is classed probable and associated with Disease: POTOCKI-SHAFFER SYNDROME in Gene2Phenotype.
Combined with the functional evidence and two expert reviews, there is now enough evidence for PHF21A to be classed as Green.; to: Potocki-Shaffer syndrome thought to caused by a deletion of 11p11.2, the minimum deleted region contains at least five genes, including PHF21A.
Hamanaka et al in PMID: 30487643 reported on three individuals who all underwent trio WES to have de novo, variants in PHF21A. All individuals had DD and ID although mild in one case. This is the first reporting of LOF variants solely in PHF21A.
PHF21A is not currently associated with any phenotypes in OMIM but is classed probable and associated with Disease: POTOCKI-SHAFFER SYNDROME in Gene2Phenotype.
Combined with the functional evidence and two expert reviews, there is now enough evidence for PHF21A to be classed as Green.
Intellectual disability v2.990 PHF21A Catherine Snow reviewed gene: PHF21A: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.990 GTF3C3 Catherine Snow Classified gene: GTF3C3 as Amber List (moderate evidence)
Intellectual disability v2.990 GTF3C3 Catherine Snow Gene: gtf3c3 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.989 GTF3C3 Catherine Snow reviewed gene: GTF3C3: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.989 PPP1R21 Catherine Snow Phenotypes for gene: PPP1R21 were changed from Hepatosplenomegaly; Abnormality of the respiratory system; Generalized hypotonia, Feeding difficulties, Profound global developmental delay, Abnormality of the face, Abnormality of vision, Abnormal heart morphology, Abnormality of the respiratory system to Hepatosplenomegaly; Abnormality of the respiratory system; Generalized hypotonia, Feeding difficulties, Profound global developmental delay, Abnormality of the face, Abnormality of vision, Abnormal heart morphology
Intellectual disability v2.988 PPP1R21 Catherine Snow Phenotypes for gene: PPP1R21 were changed from Hepatosplenomegaly; Abnormality of the respiratory system; Generalized hypotonia, Feeding difficulties, Profound global developmental delay, Abnormality of the face, Abnormality of vision, Abnormal heart morphology, Abnormality of the respiratory system, Hepatosplenomegaly; Profound global developmental delay; Abnormal heart morphology; Generalized hypotonia; Feeding difficulties; Abnormality of the face; Abnormality of vision to Hepatosplenomegaly; Abnormality of the respiratory system; Generalized hypotonia, Feeding difficulties, Profound global developmental delay, Abnormality of the face, Abnormality of vision, Abnormal heart morphology, Abnormality of the respiratory system
Intellectual disability v2.987 GTF3C3 Catherine Snow Tag watchlist tag was added to gene: GTF3C3.
Intellectual disability v2.987 GTF3C3 Catherine Snow Phenotypes for gene: GTF3C3 were changed from to Global developmental delay; Intellectual disability; Seizures
Intellectual disability v2.987 GTF3C3 Catherine Snow Publications for gene: GTF3C3 were set to 28940097, 28097321
Intellectual disability v2.986 KMT2B Catherine Snow Publications for gene: KMT2B were set to 25529582; 27839873; 27992417; 29276005; 25405613; 29289525; 31216378
Intellectual disability v2.985 MTO1 Catherine Snow Publications for gene: MTO1 were set to
Intellectual disability v2.984 PHF21A Catherine Snow Publications for gene: PHF21A were set to 22770980; 26333423; 8456828; 8882796; 14872200; 9489802; 11017806; 11903336; 15852040; 23239541; 28127865
Intellectual disability v2.983 MTO1 Catherine Snow Classified gene: MTO1 as Green List (high evidence)
Intellectual disability v2.983 MTO1 Catherine Snow Gene: mto1 has been classified as Green List (High Evidence).
Intellectual disability v2.982 MTO1 Catherine Snow reviewed gene: MTO1: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.982 KMT2B Catherine Snow commented on gene: KMT2B
Intellectual disability v2.982 KMT2B Catherine Snow Publications for gene: KMT2B were set to 25529582; 27839873; 27992417; 29276005; 25405613; 29289525
Intellectual disability v2.981 ZBTB11 Catherine Snow Tag watchlist tag was added to gene: ZBTB11.
Intellectual disability v2.981 VPS11 Catherine Snow Tag watchlist tag was added to gene: VPS11.
Intellectual disability v2.981 TKT Catherine Snow Tag watchlist tag was added to gene: TKT.
Intellectual disability v2.981 SUFU Catherine Snow Tag watchlist tag was added to gene: SUFU.
Intellectual disability v2.981 SRP54 Catherine Snow Tag watchlist tag was added to gene: SRP54.
Intellectual disability v2.981 SMG9 Catherine Snow Tag watchlist tag was added to gene: SMG9.
Intellectual disability v2.981 SLC5A7 Catherine Snow Tag watchlist tag was added to gene: SLC5A7.
Intellectual disability v2.981 SCYL1 Catherine Snow Tag watchlist tag was added to gene: SCYL1.
Intellectual disability v2.981 RSPRY1 Catherine Snow Tag watchlist tag was added to gene: RSPRY1.
Intellectual disability v2.981 RNF13 Catherine Snow Tag watchlist tag was added to gene: RNF13.
Intellectual disability v2.981 RAB11A Catherine Snow Tag watchlist tag was added to gene: RAB11A.
Intellectual disability v2.981 PTRHD1 Catherine Snow Tag watchlist tag was added to gene: PTRHD1.
Intellectual disability v2.981 PTRH2 Catherine Snow Tag watchlist tag was added to gene: PTRH2.
Intellectual disability v2.981 PLEKHG2 Catherine Snow Tag watchlist tag was added to gene: PLEKHG2.
Intellectual disability v2.981 LSS Catherine Snow Tag watchlist tag was added to gene: LSS.
Intellectual disability v2.981 LIPT2 Catherine Snow Tag watchlist tag was added to gene: LIPT2.
Intellectual disability v2.981 GTF2E2 Catherine Snow Tag watchlist tag was added to gene: GTF2E2.
Intellectual disability v2.981 FUK Catherine Snow Tag watchlist tag was added to gene: FUK.
Intellectual disability v2.981 EMG1 Catherine Snow Tag watchlist tag was added to gene: EMG1.
Intellectual disability v2.981 DYNC1I2 Catherine Snow Tag watchlist tag was added to gene: DYNC1I2.
Intellectual disability v2.981 DONSON Catherine Snow Tag watchlist tag was added to gene: DONSON.
Intellectual disability v2.981 GMNN Catherine Snow Tag watchlist tag was added to gene: GMNN.
Intellectual disability v2.981 UFM1 Catherine Snow Tag de novo tag was added to gene: UFM1.
Intellectual disability v2.980 CTBP1 Rebecca Foulger Classified gene: CTBP1 as Green List (high evidence)
Intellectual disability v2.980 CTBP1 Rebecca Foulger Added comment: Comment on list classification: Gene added to panel and rated Green by Chris Buxton. Changed rating to Green after agreement from Genomics England clinical team- sufficient cases and relevant phenotype. Have added missense tag, because only one missense tag reported so far.
Intellectual disability v2.980 CTBP1 Rebecca Foulger Gene: ctbp1 has been classified as Green List (High Evidence).
Intellectual disability v2.979 CTBP1 Rebecca Foulger commented on gene: CTBP1
Intellectual disability v2.979 MAP3K7 Catherine Snow Mode of inheritance for gene MAP3K7 was changed from to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.979 TKT Catherine Snow Mode of inheritance for gene TKT was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.979 SUFU Catherine Snow Mode of inheritance for gene SUFU was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.979 SRP54 Catherine Snow Mode of inheritance for gene SRP54 was changed from to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.979 SMG9 Catherine Snow Mode of inheritance for gene SMG9 was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.979 SLC5A7 Catherine Snow Mode of inheritance for gene SLC5A7 was changed from to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v2.979 SCYL1 Catherine Snow Mode of inheritance for gene SCYL1 was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.979 RSPRY1 Catherine Snow Mode of inheritance for gene RSPRY1 was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.979 LIPT2 Catherine Snow Mode of inheritance for gene LIPT2 was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.979 LIAS Catherine Snow Mode of inheritance for gene LIAS was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.979 GTF2E2 Catherine Snow Mode of inheritance for gene GTF2E2 was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.979 GMNN Catherine Snow Mode of inheritance for gene GMNN was changed from to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.979 EMG1 Catherine Snow Mode of inheritance for gene EMG1 was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.979 TRAIP Catherine Snow Mode of inheritance for gene TRAIP was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.979 PRR12 Catherine Snow Mode of inheritance for gene PRR12 was changed from MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v2.979 MRPS34 Catherine Snow Mode of inheritance for gene MRPS34 was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.979 EMC1 Catherine Snow Mode of inheritance for gene EMC1 was changed from BOTH monoallelic and biallelic (but BIALLELIC mutations cause a more SEVERE disease form), autosomal or pseudoautosomal to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.978 MAP3K7 Catherine Snow gene: MAP3K7 was added
gene: MAP3K7 was added to Intellectual disability. Sources: Literature,Expert Review Red
Mode of inheritance for gene: MAP3K7 was set to
Publications for gene: MAP3K7 were set to 27426733; 30914295
Phenotypes for gene: MAP3K7 were set to Frontometaphyseal dysplasia 2, 617137
Intellectual disability v2.978 ZBTB11 Catherine Snow Source Expert Review was added to ZBTB11.
Source Expert Review Amber was added to ZBTB11.
Added phenotypes Intellectual developmental disorder, autosomal recessive 69, 618383 for gene: ZBTB11
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 VPS11 Catherine Snow Source Expert Review was added to VPS11.
Source Expert Review Amber was added to VPS11.
Added phenotypes Leukodystrophy, hypomyelinating, 12, 616683 for gene: VPS11
Publications for gene VPS11 were changed from 27120463; 26307567; 27473128 to 27473128; 26307567; 27120463
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 UFC1 Catherine Snow Added phenotypes Neurodevelopmental disorder with spasticity and poor growth, 618076 for gene: UFC1
Publications for gene UFC1 were changed from 29868776; 27431290; 30237576 to 30914295
Intellectual disability v2.978 TSEN15 Catherine Snow Added phenotypes Pontocerebellar hypoplasia, type 2F, 617026 for gene: TSEN15
Publications for gene TSEN15 were changed from 27392077; 25558065 to 27392077; 30914295; 25558065
Intellectual disability v2.978 TKT Catherine Snow gene: TKT was added
gene: TKT was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: TKT was set to
Publications for gene: TKT were set to 27259054; 30914295
Phenotypes for gene: TKT were set to Short stature, developmental delay, and congenital heart defects, 617044
Intellectual disability v2.978 SUFU Catherine Snow gene: SUFU was added
gene: SUFU was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: SUFU was set to
Publications for gene: SUFU were set to 28965847; 30914295
Phenotypes for gene: SUFU were set to Joubert syndrome 32, 617757
Intellectual disability v2.978 SRP54 Catherine Snow gene: SRP54 was added
gene: SRP54 was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: SRP54 was set to
Publications for gene: SRP54 were set to 28972538; 30914295
Phenotypes for gene: SRP54 were set to Syndromic neutropenia with Shwachman-Diamond-like features
Intellectual disability v2.978 SMG9 Catherine Snow gene: SMG9 was added
gene: SMG9 was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: SMG9 was set to
Publications for gene: SMG9 were set to 27018474; 30914295
Phenotypes for gene: SMG9 were set to Heart and brain malformation syndrome, 616920
Intellectual disability v2.978 SLC5A7 Catherine Snow gene: SLC5A7 was added
gene: SLC5A7 was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: SLC5A7 was set to
Publications for gene: SLC5A7 were set to 30914295; 27569547
Phenotypes for gene: SLC5A7 were set to Myasthenic syndrome, congenital, 20, presynaptic,CMS20, 617143
Intellectual disability v2.978 SCYL1 Catherine Snow gene: SCYL1 was added
gene: SCYL1 was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: SCYL1 was set to
Publications for gene: SCYL1 were set to 26581903; 30914295
Phenotypes for gene: SCYL1 were set to Spinocerebellar ataxia, autosomal recessive 21, 616719
Intellectual disability v2.978 RSPRY1 Catherine Snow gene: RSPRY1 was added
gene: RSPRY1 was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: RSPRY1 was set to
Publications for gene: RSPRY1 were set to 26365341; 30914295
Phenotypes for gene: RSPRY1 were set to Spondyloepimetaphyseal dysplasia, Faden-Alkuraya type, 616585
Intellectual disability v2.978 RNF13 Catherine Snow Source Expert Review was added to RNF13.
Source Expert Review Amber was added to RNF13.
Added phenotypes Epileptic encephalopathy, early infantile, 73, 618379 for gene: RNF13
Publications for gene RNF13 were changed from to 30595371
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 RAB11A Catherine Snow Source Expert Review was added to RAB11A.
Source Expert Review Amber was added to RAB11A.
Added phenotypes Global developmental delay, Intellectual disability for gene: RAB11A
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 PTRHD1 Catherine Snow Source Expert Review was added to PTRHD1.
Source Expert Review Amber was added to PTRHD1.
Added phenotypes Parkinsonism, Intellectual disability for gene: PTRHD1
Publications for gene PTRHD1 were changed from 30398675; 27134041; 29143421; 27753167 to 30398675; 27134041; 27753167; 29143421
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 PTRH2 Catherine Snow Source Expert Review was added to PTRH2.
Source Expert Review Amber was added to PTRH2.
Added phenotypes Infantile-onset multisystem neurologic, endocrine, and pancreatic disease, 616263 for gene: PTRH2
Publications for gene PTRH2 were changed from 25574476; 27129381; 25558065; 28328138; 28175314 to 25574476; 28175314; 28328138; 25558065; 27129381
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 PLEKHG2 Catherine Snow Source Expert Review was added to PLEKHG2.
Source Expert Review Amber was added to PLEKHG2.
Added phenotypes Leukodystrophy and acquired microcephaly with or without dystonia, 616763 for gene: PLEKHG2
Publications for gene PLEKHG2 were changed from 26539891; 26573021; 24001768 to 26539891; 24001768; 26573021
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 LSS Catherine Snow Source Expert Review was added to LSS.
Source Expert Review Amber was added to LSS.
Added phenotypes Cataract 44, Hypotrichosis 14, 616509, 618275 for gene: LSS
Publications for gene LSS were changed from 30723320; 30401459 to 30723320; 26200341; 30401459; 29016354
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 LIPT2 Catherine Snow gene: LIPT2 was added
gene: LIPT2 was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: LIPT2 was set to
Publications for gene: LIPT2 were set to 28628643; 30914295
Phenotypes for gene: LIPT2 were set to Encephalopathy, neonatal severe, with lactic acidosis and brain abnormalities, 617668
Intellectual disability v2.978 LIAS Catherine Snow gene: LIAS was added
gene: LIAS was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: LIAS was set to
Publications for gene: LIAS were set to 22152680; 26108146; 24334290; 30914295
Phenotypes for gene: LIAS were set to Hyperglycinemia, lactic acidosis, and seizures, 614462
Intellectual disability v2.978 GTF2E2 Catherine Snow gene: GTF2E2 was added
gene: GTF2E2 was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: GTF2E2 was set to
Publications for gene: GTF2E2 were set to 30914295; 26996949
Phenotypes for gene: GTF2E2 were set to Trichothiodystrophy 6, nonphotosensitive, 616943
Intellectual disability v2.978 GMNN Catherine Snow gene: GMNN was added
gene: GMNN was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: GMNN was set to
Publications for gene: GMNN were set to 26637980; 30914295
Phenotypes for gene: GMNN were set to Meier-Gorlin syndrome 6, 616835
Intellectual disability v2.978 FUK Catherine Snow Source Expert Review was added to FUK.
Source Expert Review Amber was added to FUK.
Added phenotypes Congenital disorder of glycosylation with defective fucosylation 2, 618324 for gene: FUK
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 FRRS1L Catherine Snow Source Expert Review Amber was added to FRRS1L.
Added phenotypes Epileptic encephalopathy, early infantile, 37, 616981 for gene: FRRS1L
Publications for gene FRRS1L were changed from 27236917; 27239025; 21147040; 29276473 to 29276473; 27239025; 21147040; 27236917; 30914295
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 EMG1 Catherine Snow gene: EMG1 was added
gene: EMG1 was added to Intellectual disability. Sources: Literature,Expert Review Amber
Mode of inheritance for gene: EMG1 was set to
Publications for gene: EMG1 were set to 30914295
Phenotypes for gene: EMG1 were set to Bowen-Conradi syndrome, 211180
Intellectual disability v2.978 DYNC1I2 Catherine Snow Source Expert Review was added to DYNC1I2.
Source Expert Review Amber was added to DYNC1I2.
Added phenotypes Abnormality of head or neck; Microcephaly; Abnormality of nervous system morphology; Intellectual disability for gene: DYNC1I2
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 DONSON Catherine Snow Source Expert Review was added to DONSON.
Source Expert Review Amber was added to DONSON.
Added phenotypes Microcephaly, short stature, and limb abnormalities 617604; Microcephaly-micromelia syndrome 251230 for gene: DONSON
Rating Changed from No List (delete) to Amber List (moderate evidence)
Intellectual disability v2.978 ZNF462 Catherine Snow Source Expert Review Green was added to ZNF462.
Source Expert Review was added to ZNF462.
Added phenotypes Ptosis, Prominent metopic ridge, Craniosynostosis, Global developmental delay, Intellectual disability, Autistic behavior for gene: ZNF462
Publications for gene ZNF462 were changed from 28513610; 29427787; 14564155; 12825074 to 28513610; 12825074; 29427787; 14564155
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 ZNF142 Catherine Snow Source Expert Review Green was added to ZNF142.
Source Expert Review was added to ZNF142.
Added phenotypes Neurodevelopmental disorder with impaired speech and hyperkinetic movements, 618425 for gene: ZNF142
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 ZMIZ1 Catherine Snow Source Expert Review Green was added to ZMIZ1.
Source Expert Review was added to ZMIZ1.
Added phenotypes Global developmental delay, Intellectual disability, Feeding difficulties, Growth abnormality, Microcephaly, Abnormality of the skeletal system, Abnormality of the urinary system, Abnormality of the cardiovascular system, Abnormality of head or neck for gene: ZMIZ1
Publications for gene ZMIZ1 were changed from 29754769; 18053775; 17967885; 26163108; 27479843 to 29754769; 18053775; 17967885; 30639322; 26163108; 27479843
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 WARS2 Catherine Snow Source Expert Review Green was added to WARS2.
Source Expert Review was added to WARS2.
Added phenotypes Neurodevelopmental disorder, mitochondrial, with abnormal movements and lactic acidosis, with or without seizures, 617710 for gene: WARS2
Publications for gene WARS2 were changed from 28236339; 28650581; 28905505; 29783990; 29120065 to 29783990; 28236339; 29120065; 28650581; 28905505
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 VARS Catherine Snow Source Expert Review Green was added to VARS.
Added phenotypes Neurodevelopmental disorder with microcephaly, seizures, and cortical atrophy, 617802 for gene: VARS
Publications for gene VARS were changed from 26539891; 29691655; 30275004 to 26539891; 30275004; 29691655
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 VAMP2 Catherine Snow Source Expert Review Green was added to VAMP2.
Source Expert Review was added to VAMP2.
Added phenotypes Generalized hypotonia, Global developmental delay, Intellectual disability, Autistic behavior, Stereotypic behavior, Seizures, Abnormality of movement, Cortical visual impairment for gene: VAMP2
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 UFM1 Catherine Snow Source Expert Review Green was added to UFM1.
Added phenotypes Leukodystrophy, hypomyelinating, 14, 617899 for gene: UFM1
Publications for gene UFM1 were changed from 28931644; 29868776; 30237576 to 28931644; 29868776; 30914295
Rating Changed from Amber List (moderate evidence) to Green List (high evidence)
Intellectual disability v2.978 TRRAP Catherine Snow Source Expert Review Green was added to TRRAP.
Source Expert Review was added to TRRAP.
Added phenotypes Developmental delay with or without dysmorphic facies and autism, 603015 for gene: TRRAP
Publications for gene TRRAP were changed from 30827496 to 30827496; 30424743
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 TRAIP Catherine Snow gene: TRAIP was added
gene: TRAIP was added to Intellectual disability. Sources: Expert Review Green,Literature
Mode of inheritance for gene: TRAIP was set to
Publications for gene: TRAIP were set to 26595769; 30914295
Phenotypes for gene: TRAIP were set to Seckel syndrome 9, 616777
Intellectual disability v2.978 SNAP25 Catherine Snow Source Expert Review Green was added to SNAP25.
Added phenotypes ?Myasthenic syndrome, congenital, 18, 616330 for gene: SNAP25
Publications for gene SNAP25 were changed from 29491473; 28135719; 29100083; 25381298; 25003006 to 29100083; 28135719; 25003006; 29491473; 25381298; 30914295
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 RPIA Catherine Snow Source Expert Review Green was added to RPIA.
Source Expert Review was added to RPIA.
Added phenotypes ?Ribose 5-phosphate isomerase deficiency, 608611 for gene: RPIA
Publications for gene RPIA were changed from 14988808; 20499043; 28801340; 30088433 to 20499043; 31056085; 14988808; 30088433; 28801340
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 RALA Catherine Snow Source Expert Review Green was added to RALA.
Source Expert Review was added to RALA.
Added phenotypes Global developmental delay, Intellectual disability, Seizures, Abnormality of nervous system morphology for gene: RALA
Publications for gene RALA were changed from to 30500825
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 RAC3 Catherine Snow Source Expert Review Green was added to RAC3.
Source Expert Review was added to RAC3.
Added phenotypes Abnormality of brain morphology, Abnormal muscle tone, Neurodevelopmental delay, Intellectual disability for gene: RAC3
Publications for gene RAC3 were changed from 30293988; 29276006 to 29276006; 30293988
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 PUS7 Catherine Snow Source Expert Review Green was added to PUS7.
Source Expert Review was added to PUS7.
Added phenotypes Intellectual developmental disorder with abnormal behavior, microcephaly, and short stature, 618342 for gene: PUS7
Publications for gene PUS7 were changed from to 30778726; 30526862
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 PUS3 Catherine Snow Source Expert Review Green was added to PUS3.
Source Expert Review was added to PUS3.
Added phenotypes Mental retardation, autosomal recessive 55, 617051 for gene: PUS3
Publications for gene PUS3 were changed from 27055666; 30308082 to 30697592; 30308082; 27055666
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 PRR12 Catherine Snow Source Expert Review Green was added to PRR12.
Source Expert Review was added to PRR12.
Added phenotypes Global developmental delay, Intellectual disability, Abnormality of the iris, Abnormality of vision, Behavioral abnormality for gene: PRR12
Publications for gene PRR12 were changed from 29556724; 26163108 to 28135719; 26163108; 29556724
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 PPP2CA Catherine Snow Source Expert Review Green was added to PPP2CA.
Source Expert Review was added to PPP2CA.
Added phenotypes Neurodevelopmental disorder and language delay with or without structural brain abnormalities, 618354 for gene: PPP2CA
Publications for gene PPP2CA were changed from 29274472; 30030003 to 29274472; 30030003; 30595372
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 PPP1R21 Catherine Snow Source Expert Review Green was added to PPP1R21.
Source Expert Review was added to PPP1R21.
Added phenotypes Generalized hypotonia, Feeding difficulties, Profound global developmental delay, Abnormality of the face, Abnormality of vision, Abnormal heart morphology, Abnormality of the respiratory system, Hepatosplenomegaly for gene: PPP1R21
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 PITRM1 Catherine Snow Source Expert Review Green was added to PITRM1.
Source Expert Review was added to PITRM1.
Added phenotypes Ataxia; Intellectual disability for gene: PITRM1
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 PIGG Catherine Snow Source Expert Review Green was added to PIGG.
Added phenotypes Mental retardation, autosomal recessive 53, 616917 for gene: PIGG
Publications for gene PIGG were changed from 26996948; 28581210 to 28581210; 26996948; 30914295
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 P4HTM Catherine Snow Source Expert Review Green was added to P4HTM.
Source Expert Review was added to P4HTM.
Added phenotypes Central hypotonia, Muscular hypotonia, Global developmental delay, Intellectual disability, Seizures, Abnormality of the eye, Hypoventilation, Sleep apnea, Dysautonomia for gene: P4HTM
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 MRPS34 Catherine Snow gene: MRPS34 was added
gene: MRPS34 was added to Intellectual disability. Sources: Expert Review Green,Literature
Mode of inheritance for gene: MRPS34 was set to
Publications for gene: MRPS34 were set to 30914295; 28777931
Phenotypes for gene: MRPS34 were set to Combined oxidativephosphorylation deficiency 32, 617664
Intellectual disability v2.978 GPT2 Catherine Snow Source Expert Review Green was added to GPT2.
Source Expert Review was added to GPT2.
Added phenotypes Mental retardation, autosomal recessive 49, 138210 for gene: GPT2
Publications for gene GPT2 were changed from PMID: 25758935; 27601654; 28130718; 29226631 to 27601654; 28130718; 29226631; 25758935
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 GNB5 Catherine Snow Source Expert Review Green was added to GNB5.
Added phenotypes Language delay and ADHD/cognitive impairment with or without cardiac arrhythmia, 617182; Intellectual developmental disorder with cardiac arrhythmia, 617173 for gene: GNB5
Publications for gene GNB5 were changed from 27523599; 27677260; 28697420; 29368331 to 27677260; 28697420; 29368331; 30914295; 27523599
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 FBXL3 Catherine Snow Source Expert Review Green was added to FBXL3.
Added phenotypes Intellectual developmental disorder with short stature, facial anomalies, and speech defects, 606220 for gene: FBXL3
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 FARS2 Catherine Snow Source Expert Review Green was added to FARS2.
Source Expert Review was added to FARS2.
Added phenotypes Spastic paraplegia 77, autosomal recessive, 617046; Combined oxidative phosphorylation deficiency 14, 614946 for gene: FARS2
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 EMC1 Catherine Snow Source Expert Review Green was added to EMC1.
Added phenotypes Cerebellar atrophy, visual impairment, and psychomotor retardation, 616875 for gene: EMC1
Publications for gene EMC1 were changed from 26942288; 29271071 to 29271071; 26942288; 30914295
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 DPH1 Catherine Snow Source Expert Review Green was added to DPH1.
Added phenotypes Developmental delay with short stature, dysmorphic features, and sparse hair, 616901 for gene: DPH1
Publications for gene DPH1 were changed from 25558065; 26220823; 29362492; 29410513 to 29362492; 29410513; 26220823; 25558065
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 DHPS Catherine Snow Source Expert Review Green was added to DHPS.
Source Expert Review was added to DHPS.
Added phenotypes Abnormal muscle tone, Global developmental delay, Intellectual disability, Seizures, EEG abnormality, Behavioral abnormality, Abnormality of head or neck for gene: DHPS
Publications for gene DHPS were changed from 21389784; 21850436 to 21389784; 30661771; 21850436
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 DDX59 Catherine Snow Source Expert Review Green was added to DDX59.
Added phenotypes Orofaciodigital syndrome V, 174300 for gene: DDX59
Publications for gene DDX59 were changed from 23972372; 28711741; 29127725 to 28711741; 29127725; 23972372; 30914295
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 DCPS Catherine Snow Source Expert Review Green was added to DCPS.
Added phenotypes Al-Raqad syndrome, 616459 for gene: DCPS
Publications for gene DCPS were changed from 25712129; 25701870; 30289615 to 25701870; 30289615; 25712129
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 CYFIP2 Catherine Snow Source Expert Review Green was added to CYFIP2.
Source Expert Review was added to CYFIP2.
Added phenotypes Epileptic encephalopathy, early infantile, 65, 618008 for gene: CYFIP2
Publications for gene CYFIP2 were changed from 29534297; 29667327; 30664714; 25432536; 27524794; 12818175; 20537992 to 12818175; 30664714; 20537992; 29534297; 25432536; 27524794; 29667327
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 CUX1 Catherine Snow Source Expert Review Green was added to CUX1.
Source Expert Review was added to CUX1.
Added phenotypes Global developmental delay with or without impaired intellectual development, 618330 for gene: CUX1
Publications for gene CUX1 were changed from 30014507; 20510857; 25059644 to 25059644; 20510857; 30014507
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 CARS Catherine Snow Source Expert Review Green was added to CARS.
Source Expert Review was added to CARS.
Added phenotypes Brittle hair; Fragile nails; Microcephaly; Neurodevelopmental delay for gene: CARS
Publications for gene CARS were changed from to 30824121
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 CAD Catherine Snow Source Expert Review Green was added to CAD.
Added phenotypes Epileptic encephalopathy, early infantile, 50 - MIM 616457 for gene: CAD
Publications for gene CAD were changed from 25678555; 28007989 to 25678555; 28007989; 30914295
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 CACNA1B Catherine Snow Source Expert Review was added to CACNA1B.
Added phenotypes Global developmental delay; Seizures; Intellectual disability; Abnormality of movement; Developmental regression for gene: CACNA1B
Publications for gene CACNA1B were changed from 30982612; 25296916 to 26157024; 30982612
Intellectual disability v2.978 BRSK2 Catherine Snow Source Expert Review Green was added to BRSK2.
Source Expert Review was added to BRSK2.
Added phenotypes Global developmental delay, Intellectual disability, Autism, Behavioral abnormality for gene: BRSK2
Publications for gene BRSK2 were changed from https://doi.org/10.1016/j.ajhg.2019.02.002 to 15705853; 23715323; 30879638; 25363768; 28135719
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 AP2M1 Catherine Snow Source Expert Review Green was added to AP2M1.
Source Expert Review was added to AP2M1.
Added phenotypes Seizures; Ataxia; Generalized hypotonia; Intellectual disability; Global developmental delay; Autistic behavior for gene: AP2M1
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.978 ALKBH8 Catherine Snow Source Expert Review Green was added to ALKBH8.
Source Expert Review was added to ALKBH8.
Added phenotypes Global developmental delay; Seizures; Intellectual disability for gene: ALKBH8
Publications for gene ALKBH8 were changed from 31079898 to 31130284; 31079898
Rating Changed from No List (delete) to Green List (high evidence)
Intellectual disability v2.977 FRMPD4 Catherine Snow changed review comment from: Further paper identified to indicated FRMPD4 is relevant to ID. PMID: 29267967 provides details of four unrelated families, two families, family 1 and 4 had already been identified and reported in PMID:25644381.
Family 2, two brothers, had a micro deletion of exon 2, their mother was heterozygous for the same micro deletion.
Family 3, two half-siblings (p.Arg286Ter) Their unaffected mother was heterozygous for the same deletion, a hetrozygous sister was mildly disabled.
No further segregation information for the two families was reported.
Some functional work performed but only for the frameshift variant that was reported in family 1.
Requesting support from clinical team as limited information on the extended families and the female affected in family 3 is the only hetrozygous carrier who displays ID features.; to: Further paper identified to indicated FRMPD4 is relevant to ID. PMID: 29267967 provides details of four unrelated families, two families, family 1 and 4 had already been identified and reported in PMID:25644381.
Family 2, two brothers, had a micro deletion of exon 2, their mother was heterozygous for the same micro deletion.
Family 3, two half-siblings (p.Arg286Ter) Their unaffected mother was heterozygous for the same deletion, a hetrozygous sister was mildly disabled.
No further segregation information for the two families was reported.
Some functional work performed but only for the frameshift variant that was reported in family 1.
Requesting support from clinical team as limited information on the extended families and the female affected in family 3 is the only heterozygous carrier who displays ID features.
Intellectual disability v2.977 FRMPD4 Catherine Snow changed review comment from: Further paper identified to indicated FRMPD4 is relevant to ID. PMID: 29267967 provides details of four unrelated families, two families, family 1 and 4 had already been identified and reported in PMID:25644381.
Family 2, two brothers, had a micro deletion of exon 2, their mother was hetrozygous for the same micro deletion.
Family 3, two half-siblings, p.Arg286Ter . Their unaffected mother was heterozygous for the same deletion, a hetrozygous sister was mildly disabled.
No further segregation information for the two families was reported
Some functional work on mice performed.
Requesting support from clinical team as limited information on the extended families and the female affected in family 3 is the only hetrozygous carrier who displays ID features.; to: Further paper identified to indicated FRMPD4 is relevant to ID. PMID: 29267967 provides details of four unrelated families, two families, family 1 and 4 had already been identified and reported in PMID:25644381.
Family 2, two brothers, had a micro deletion of exon 2, their mother was heterozygous for the same micro deletion.
Family 3, two half-siblings (p.Arg286Ter) Their unaffected mother was heterozygous for the same deletion, a hetrozygous sister was mildly disabled.
No further segregation information for the two families was reported.
Some functional work performed but only for the frameshift variant that was reported in family 1.
Requesting support from clinical team as limited information on the extended families and the female affected in family 3 is the only hetrozygous carrier who displays ID features.
Intellectual disability v2.977 FRMPD4 Catherine Snow changed review comment from: Further paper identified to indicated FRMPD4 is relevant to ID. PMID: 29267967 provides details of four unrelated families, two families, family 1 and 4 had already been identified and reported in PMID:25644381.
Family 2, two brothers, had a micro deletion of exon 2, their mother was hetrozygous for the same micro deletion
Family 3, two half-siblings, p.Arg286Ter . Their unaffected mother was heterozygous for the same deletion, a hetrozygous sister was mildly disabled.
No further segregation information for the two families was reported
Some functional work on mice performed.
Requesting support from clinical team as limited information on the extended families and the female affected in family 3 is the only hetrozygous carrier who displays ID features.; to: Further paper identified to indicated FRMPD4 is relevant to ID. PMID: 29267967 provides details of four unrelated families, two families, family 1 and 4 had already been identified and reported in PMID:25644381.
Family 2, two brothers, had a micro deletion of exon 2, their mother was hetrozygous for the same micro deletion.
Family 3, two half-siblings, p.Arg286Ter . Their unaffected mother was heterozygous for the same deletion, a hetrozygous sister was mildly disabled.
No further segregation information for the two families was reported
Some functional work on mice performed.
Requesting support from clinical team as limited information on the extended families and the female affected in family 3 is the only hetrozygous carrier who displays ID features.
Intellectual disability v2.977 FRMPD4 Catherine Snow changed review comment from: PMID: 29267967 provides details of four unrelated families, two families, family 1 and 4 had already been identified and reported in PMID:25644381.
Family 2, two brothers, had a micro deletion of exon 2, their mother was hetrozygous for the same micro deletion
Family 3, two half-siblings, p.Arg286Ter . Their unaffected mother was heterozygous for the same deletion, a hetrozygous sister was mildly disabled.
No further segregation information for the two families was reported
Some functional work on mice performed.
Requesting support from clinical team as limited information on the extended families and the female affected in family 3 is the only hetrozygous carrier who displays ID features.; to: Further paper identified to indicated FRMPD4 is relevant to ID. PMID: 29267967 provides details of four unrelated families, two families, family 1 and 4 had already been identified and reported in PMID:25644381.
Family 2, two brothers, had a micro deletion of exon 2, their mother was hetrozygous for the same micro deletion
Family 3, two half-siblings, p.Arg286Ter . Their unaffected mother was heterozygous for the same deletion, a hetrozygous sister was mildly disabled.
No further segregation information for the two families was reported
Some functional work on mice performed.
Requesting support from clinical team as limited information on the extended families and the female affected in family 3 is the only hetrozygous carrier who displays ID features.
Intellectual disability v2.977 FRMPD4 Catherine Snow reviewed gene: FRMPD4: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.977 KIF2A Catherine Snow changed review comment from: Three further cases identified in the literature.
PMID:27747449 (Cavallin et al 2017) detected two de novo p.Ser317Asn and p.His321Pro mutations in KIF2A in two patients with lissencephaly and microcephaly. Case 1 had DD, no epilepsy but was only 9 months old at last reporting. Case 2 had neonatal seizures and severe DD.
PMID:27896282 (Tian et al 2016) report a patient with lissencephaly, developmental delay, and infantile spasms, due to de novo heterozygous variant in KIF2A (p.Thr320Ile).

Therefore upgrading rating from Amber to Green as now sufficient (>3) unrelated cases.; to: Three further cases identified in the literature.
PMID:27747449 (Cavallin et al 2017) detected two de novo p.Ser317Asn and p.His321Pro mutations in KIF2A in two patients with lissencephaly and microcephaly. Case 1 had DD, no epilepsy but was only 9 months old at last reporting. Case 2 had neonatal seizures and severe DD.
PMID:27896282 (Tian et al 2016) report a patient with lissencephaly, developmental delay, and infantile spasms, due to de novo heterozygous variant in KIF2A (p.Thr320Ile).
Most cases identified have epilepsy first however as one individual did not have seizures KIF2A is relevant for the ID panel.
Therefore upgrading rating from Amber to Green as now sufficient (>3) unrelated cases.
Intellectual disability v2.977 DLG4 Catherine Snow Publications for gene: DLG4 were set to 27479843; 25123844; 19617690; 29460436; 23020937; 28135719
Intellectual disability v2.976 DLG4 Catherine Snow Phenotypes for gene: DLG4 were changed from to Intellectual disability; Marfanoid habitus
Intellectual disability v2.976 DLG4 Catherine Snow Publications for gene: DLG4 were set to 27479843; 25123844; 19617690; 29460436; 23020937; 28135719
Intellectual disability v2.976 DLG4 Catherine Snow Publications for gene: DLG4 were set to 27479843; 25123844; 19617690
Intellectual disability v2.975 DLG4 Catherine Snow reviewed gene: DLG4: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.975 KIF2A Catherine Snow Classified gene: KIF2A as Green List (high evidence)
Intellectual disability v2.975 KIF2A Catherine Snow Gene: kif2a has been classified as Green List (High Evidence).
Intellectual disability v2.974 KIF2A Catherine Snow commented on gene: KIF2A
Intellectual disability v2.974 KIF2A Catherine Snow Phenotypes for gene: KIF2A were changed from Cortical dysplasia, complex, with other brain malformations 3, 615411 to Cortical dysplasia, complex, with other brain malformations 3, 615411
Intellectual disability v2.973 KIF2A Catherine Snow Phenotypes for gene: KIF2A were changed from Cortical dysplasia, complex, with other brain malformations 3, 615411 to Cortical dysplasia, complex, with other brain malformations 3, 615411
Intellectual disability v2.973 KIF2A Catherine Snow Phenotypes for gene: KIF2A were changed from MALFORMATIONS OF CORTICAL DEVELOPMENT AND MICROCEPHALY. to Cortical dysplasia, complex, with other brain malformations 3, 615411
Intellectual disability v2.972 KIF2A Catherine Snow Publications for gene: KIF2A were set to 23603762; 21594994; 27747449; 27896282
Intellectual disability v2.971 KIF2A Catherine Snow Publications for gene: KIF2A were set to 23603762; 21594994; 27747449; 27896282
Intellectual disability v2.971 KIF2A Catherine Snow Publications for gene: KIF2A were set to 23603762; 21594994
Intellectual disability v2.970 CYP27A1 Catherine Snow reviewed gene: CYP27A1: Rating: AMBER; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.970 CYP27A1 Catherine Snow Publications for gene: CYP27A1 were set to 24442603; 29484516
Intellectual disability v2.970 CYP27A1 Catherine Snow Publications for gene: CYP27A1 were set to
Intellectual disability v2.969 GRIA2 Catherine Snow changed review comment from: GRIA2 has been associated with ID in PMID: 31300657. The authors identified 28 unrelated individuals who had heterozygous de novo GRIA2 mutations. All individuals had experienced DD and moderate to severe ID, except 2 who had died at a young age. Epilepsy was identified in at least 10 individuals.
Multiple de-novo intragenic variants including missense (n = 15), splice-site (n = 2), in-frame deletion (n = 1), stop-gain (n = 1) and frameshift (n = 2) variants were reported. In all patients with intragenic variants they were first identified by WES, WGS or massively parallel targeted sequencing and confirmed as de-novo by trio Sanger sequencing. Also a further three patients were identified with a microdeletion involving GRIA2 using micro array analysis.

GRIA2 is currently not associated with a disease in OMIM or Gene2Phenotype and this is the first time that GRIA2 has been reported to be associated with ID but other AMPA receptors, GRIA3, and GRIA4 are Green on the ID panel.
Therefore there is not sufficient number of unrelated individuals and evidence to make GRIA2 Green.; to: GRIA2 has been associated with ID in PMID: 31300657. The authors identified 28 unrelated individuals who had heterozygous de novo GRIA2 mutations. All individuals had experienced DD and moderate to severe ID, except 2 who had died at a young age. Epilepsy was identified in at least 10 individuals.
Multiple de-novo intragenic variants including missense (n = 15), splice-site (n = 2), in-frame deletion (n = 1), stop-gain (n = 1) and frameshift (n = 2) variants were reported. In all patients with intragenic variants they were first identified by WES, WGS or massively parallel targeted sequencing and confirmed as de-novo by trio Sanger sequencing. Also a further three patients were identified with a microdeletion involving GRIA2 using micro array analysis.

GRIA2 is currently not associated with a disease in OMIM or Gene2Phenotype and this is the first time that GRIA2 has been reported to be associated with ID but other AMPA receptors, GRIA3, and GRIA4 are Green on the ID panel.
Therefore there is now sufficient number of unrelated individuals and evidence to make GRIA2 Green.
Intellectual disability v2.969 GRIA2 Catherine Snow Classified gene: GRIA2 as Green List (high evidence)
Intellectual disability v2.969 GRIA2 Catherine Snow Gene: gria2 has been classified as Green List (High Evidence).
Intellectual disability v2.968 GRIA2 Catherine Snow reviewed gene: GRIA2: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.968 GRIA2 Catherine Snow Publications for gene: GRIA2 were set to 28725178; 26350204; 24896178; 22669415; 28630856
Intellectual disability v2.967 SHANK1 Chris Buxton commented on gene: SHANK1
Intellectual disability v2.967 DEGS1 Rebecca Foulger Phenotypes for gene: DEGS1 were changed from Leukodystrophy hypomyelinating 18, MIM 618404) to Leukodystrophy hypomyelinating 18, MIM 618404); developmental delay
Intellectual disability v2.966 DEGS1 Rebecca Foulger Classified gene: DEGS1 as Green List (high evidence)
Intellectual disability v2.966 DEGS1 Rebecca Foulger Added comment: Comment on list classification: DEGS1 was added to the panel and rated Green by Konstantinos Varvagiannis. Developmental delay and/or ID is a common phenotype (and initial presentation) of the Leukodystrophy. Sufficient cases from multiple papers (PMIDs:30620338,30620337,31186544) to support inclusion on the panel.
Intellectual disability v2.966 DEGS1 Rebecca Foulger Gene: degs1 has been classified as Green List (High Evidence).
Intellectual disability v2.965 DEGS1 Rebecca Foulger commented on gene: DEGS1: PMID:30620338: Karsai et al., 2019 identified a homozygous p.Ala280Val variant in DEGS1 in a Turkish patient of consanguineous parents. Both parents and healthy siblings were heterozygous carriers of the variant. Leading symptoms were early-onset developmental delay, movement disorder, progressive spasticity, and epilepsy.
Intellectual disability v2.965 DEGS1 Rebecca Foulger commented on gene: DEGS1: PMID:31186544: Dolgin et al., 2019 describe four individuals from a consanguineous family. All four had mild to severe ID, spastic quadriplegia, scoliosis and epilepsy in most. WES identified a homozygous missense variant in DEGS1 (in isoforms N219S, N255S).
Intellectual disability v2.965 DEGS1 Rebecca Foulger commented on gene: DEGS1
Intellectual disability v2.965 ATN1 Catherine Snow Phenotypes for gene: ATN1 were changed from Generalized hypotonia; Global developmental delay; Intellectual disability; Seizures; Feeding difficulties; Abnormality of the cardiovascular system; Cleft palate; Abnormality of the kidney to Generalized hypotonia; Global developmental delay; Intellectual disability; Seizures; Feeding difficulties; Abnormality of the cardiovascular system; Cleft palate; Abnormality of the kidney
Intellectual disability v2.965 ATN1 Catherine Snow Phenotypes for gene: ATN1 were changed from Dentatorubro-pallidoluysian atrophy 125370 to Generalized hypotonia; Global developmental delay; Intellectual disability; Seizures; Feeding difficulties; Abnormality of the cardiovascular system; Cleft palate; Abnormality of the kidney
Intellectual disability v2.964 ATN1 Catherine Snow Publications for gene: ATN1 were set to 24972706; 30827498
Intellectual disability v2.964 ATN1 Catherine Snow Publications for gene: ATN1 were set to 24972706
Intellectual disability v2.963 ATN1 Catherine Snow changed review comment from: As reviewed on the Genetic epilepsy syndromes (Version 1.178). Advice from the clinical team was that as phenotype is relevant it can be rated as Green.

Konstantinos Varvagiannis reviewed Palmer et al. (2019 - PMID: 30827498) who describes 8 individuals all with de novo variants in a specific and highly evolutionary conserved histidine-rich 16 amino acid motif encoded by exon 7 of ATN1. The pedigree analysis showed that all individuals are unrelated with different ancestry, all except one had undergone trio sequencing.

All individuals have DD/ID and 5/8 have seizures therefore making it applicable to the epilepsy panel. ATN1 is in OMIM but is associated with the STR, it is in Gene2Phenotype as probable based on this paper.

ATN1_CAG STR is Green in a large number of panels and there are a number of publications associated with the STR. This is the first publication where variants within the gene and not the STR have been associated with this phenotype; to: As reviewed on the Genetic epilepsy syndromes (Version 1.178). Advice from the clinical team was that as phenotype is relevant it can be rated as Green.

Konstantinos Varvagiannis reviewed Palmer et al. (2019 - PMID: 30827498) who describes 8 individuals all with de novo variants in a specific and highly evolutionary conserved histidine-rich 16 amino acid motif encoded by exon 7 of ATN1. The pedigree analysis showed that all individuals are unrelated with different ancestry, all except one had undergone trio sequencing.

All individuals have DD/ID. ATN1 is in OMIM but is associated with the STR, it is in Gene2Phenotype as probable based on this paper.

ATN1_CAG STR is Green in a large number of panels and there are a number of publications associated with the STR. This is the first publication where variants within the gene and not the STR have been associated with this phenotype
Intellectual disability v2.963 ATN1 Catherine Snow Mode of pathogenicity for gene: ATN1 was changed from to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Intellectual disability v2.962 ATN1 Catherine Snow Classified gene: ATN1 as Green List (high evidence)
Intellectual disability v2.962 ATN1 Catherine Snow Gene: atn1 has been classified as Green List (High Evidence).
Intellectual disability v2.962 ATN1 Catherine Snow Classified gene: ATN1 as Green List (high evidence)
Intellectual disability v2.962 ATN1 Catherine Snow Gene: atn1 has been classified as Green List (High Evidence).
Intellectual disability v2.961 ATN1 Catherine Snow reviewed gene: ATN1: Rating: GREEN; Mode of pathogenicity: None; Publications: ; Phenotypes: ; Mode of inheritance: None
Intellectual disability v2.961 KCNJ11 Rebecca Foulger Publications for gene: KCNJ11 were set to
Intellectual disability v2.960 KCNJ11 Rebecca Foulger Added comment: Comment on mode of inheritance: Changed MOI from BIALLELIC to BOTH monoallelic and biallelic, based on most papers in the literature reporting heterozygous activating variants in KCNJ11 with DD/ID as features: (e.g. PMIDs 25678012, 16670688, 27681997, 28943513).
Intellectual disability v2.960 KCNJ11 Rebecca Foulger Mode of inheritance for gene: KCNJ11 was changed from BIALLELIC, autosomal or pseudoautosomal to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v2.959 ATRX Rebecca Foulger Added comment: Comment on mode of inheritance: Changed Mode of inheritance from XLR to XLD: Alpha-thalassemia/mental retardation syndrome, 301040 is listed as XLD in OMIM (in addition to Mental retardation-hypotonic facies syndrome, X-linked, 309580 listed as XLR). Although PMID:17503331 report that nearly all female carriers of ATRX syndrome have highly skewed X-chromosome inactivation in favour of cells expressing the normal ATRX allele and are essentially phenotypically normal, PMID:16955409 report a female carrier where the chromosome carrying the mutant allele was active and she therefore showed a phenotype.
Intellectual disability v2.959 ATRX Rebecca Foulger Mode of inheritance for gene: ATRX was changed from X-LINKED: hemizygous mutation in males, biallelic mutations in females to X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Intellectual disability v2.958 ATRX Rebecca Foulger Publications for gene: ATRX were set to 25529582; 24896178; 26860117; 26997013; 10995512; 7697714; 12116232; 15565397; 8644709; 9244431; 9598720
Intellectual disability v2.957 ATRX Rebecca Foulger commented on gene: ATRX: PMID:16955409: Badens et al. 2006 report a 4 year old female with a heterozygous R246C variant in ATRX and a skewed pattern of X-inactivation where her maternally-inherited X chromosome that carried the de novo variant remained active. Clinical features included severed DD.
Intellectual disability v2.957 ATRX Rebecca Foulger commented on gene: ATRX
Intellectual disability v2.957 ATRX Rebecca Foulger Phenotypes for gene: ATRX were changed from Alpha-thalassemia/mental retardation syndrome, 301040Alpha-thalassemia myelodysplasia syndrome, somatic, 300448Mental retardation-hypotonic facies syndrome, X-linked, 309580; MENTAL RETARDATION SYNDROMIC X-LINKED WITH HYPOTONIC FACIES SYNDROME TYPE 1 (MRXSHF1) to Alpha-thalassemia/mental retardation syndrome, 301040; Mental retardation-hypotonic facies syndrome, X-linked, 309580
Intellectual disability v2.956 ATRX Rebecca Foulger Publications for gene: ATRX were set to
Intellectual disability v2.955 SLC9A6 Rebecca Foulger Publications for gene: SLC9A6 were set to
Intellectual disability v2.954 SLC9A6 Rebecca Foulger changed review comment from: Comment on mode of inheritance: Changed the MOI from XLR to XLD based on Pescosolido et al., 2014 (PMID:25044251) who report mild to moderate ID in heterozygous female carriers.; to: Comment on mode of inheritance: Changed the MOI from XLR to XLD based on Pescosolido et al., 2014 (PMID:25044251) who report mild to moderate ID in heterozygous female carriers. Note that NHE6 is an alias for SLC9A6.
Intellectual disability v2.954 SLC9A6 Rebecca Foulger Added comment: Comment on mode of inheritance: Changed the MOI from XLR to XLD based on Pescosolido et al., 2014 (PMID:25044251) who report mild to moderate ID in heterozygous female carriers.
Intellectual disability v2.954 SLC9A6 Rebecca Foulger Mode of inheritance for gene: SLC9A6 was changed from X-LINKED: hemizygous mutation in males, biallelic mutations in females to X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Intellectual disability v2.953 CTBP1 Chris Buxton reviewed gene: CTBP1: Rating: GREEN; Mode of pathogenicity: Other; Publications: 27094857, 31041561; Phenotypes: intellectual disability, ataxia, hypotonia, tooth enamel defect; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability v2.953 DEGS1 Konstantinos Varvagiannis gene: DEGS1 was added
gene: DEGS1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DEGS1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: DEGS1 were set to 30620337; 30620338; 31186544
Phenotypes for gene: DEGS1 were set to Leukodystrophy hypomyelinating 18, MIM 618404)
Penetrance for gene: DEGS1 were set to Complete
Review for gene: DEGS1 was set to GREEN
Added comment: Several individuals with biallelic pathogenic DEGS1 variants have been reported to date, in the following studies :
[1] Pant et al. 2019 (PMID: 30620337) : 19 patients from 13 unrelated families
[2] Karsai et al. 2019 (PMID: 30620338) : 1 individual
[3] Dolgin et al. 2019 (PMID: 31186544) : 4 individuals belonging to a large consanguineous kindred

As summarized in the first article and OMIM, affected individuals may have very poor psychomotor development, dystonia, spasticity, seizures with hypomyelinating leukodystrophy upon brain imaging and/or progressive atrophy of corpus callosum, thalami and cerebellum. Although a severe form overall was reported for many individuals in the first study, variable severity (eg. mild to severe ID) was reported among individuals belonging to the same kindred in the report by Dolgin et al.

DEGS1 encodes Δ4-dehydroceramide desaturase which catalyzes conversion of dihydroceramide (DhCer) to ceramide (Cer) in the de novo ceramide biosynthetic pathway. Ceramide is the central unit of all sphingolipids, which are components of cellular membranes and play key roles in several processes incl. cell differentiation, neuronal signaling and myelin sheath formation.

Sphingolipid balance is important for the CNS as demonstrated in the case of lysosomal disorders (eg. Gaucher, Niemann Pick, Farber) one enzymatic step away from DEGS1.

Variants of all types (missense, stopgain, frameshift) have been reported with the majority/almost all located in the fatty acid desaturase (FAD) domain.

Extensive studies have been carried out and demonstrated:
- impaired DEGS1 activity in patients' fibroblasts and muscle suggested by increased DhCer/Cer ratio and compatible broader biochemical effects (higher levels of dihydrosphingosine, dihydrosphingomyelins, etc. and lower levels of sphingosine, monohexosylceramides, etc).
- increased ROS production in patient fibroblasts (similar to a Drosophila model of excess DhCer),
- high expression of the gene in child and adult CNS tissues from control individuals (evaluated by RT-qPCR in Ref. 1). A previous study has suggested that DEGS1 expression is upregulated during the 4-9th week of human embryogenesis (PMID cited: 20430792) which may suggest an important role for neural system development.
- decreased expression for some variants either evaluated at the mRNA (RT-qPCR) / protein level (by Western Blot)
- In zebrafish loss of Degs1 resulted in increased DhCer/Cer ratio, locomotor disability and impaired myelination similar to the patients' phenotype. Fingolimod, a sphingosine analog inhibiting Cer synthase (one step prior to DEGS1 in the de novo ceramide biosynthesis pathway, and converting sphingosine to ceramide in the salvage pathway) reduced the DhCer/Cer imbalance, ameliorated the locomotor phenotype and increased the number of myelinating oligodendrocytes in zebrafish, while it reduced the ROS levels in patient fibroblasts.

Previous animal models:
Apart from the zebrafish model (Pant et al.), higher DhCer/Cer ratios have been shown in homozygous Degs1 -/- mice similar to what is also observed in D. melanogaster. As summarized in MGI (and the previous studies as well) "mice homozygous for a knock-out allele exhibit premature death, decreased to absent ceramide levels, decreased body weight, scaly skin, sparse hair, tremors, hematological and blood chemistry abnormalities, decreased bone mineral content and density and decreased liver function." (PMIDs cited: 17339025, 28507162).
----
The respective OMIM entry is Leukodystrophy, hypomyelinating, 18 (#618404). DEGS1 is not associated with any phenotype in G2P.
----
As a result, DEGS1 can be considered for inclusion in the ID and epilepsy panels probably as green (relevant phenotype, sufficient number of individuals, supportive expression and biochemical studies, animal models, etc).
Sources: Literature
Intellectual disability v2.953 PIGB Konstantinos Varvagiannis gene: PIGB was added
gene: PIGB was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: PIGB was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PIGB were set to 31256876
Phenotypes for gene: PIGB were set to Generalized hypotonia; Global developmental delay; Intellectual disability; Seizures; Hearing abnormality; Abnormality of vision; Elevated alkaline phosphatase; Abnormality of the head; Abnormality of the hand; Abnormality of the foot
Penetrance for gene: PIGB were set to Complete
Review for gene: PIGB was set to GREEN
Added comment: Murakami et al. (2019 - PMID: 31256876) provide detailed information on 14 individuals from 10 families (4 of which consanguineous) with biallelic pathogenic PIGB variants.

Overlapping features included DD/ID (13/13), epilepsy (14/14), deafness (7/14), ophthalmological or brain anomalies, hand and feet anomalies as well as presence of dysmorphic features. ID was common, in those individuals with appropriate age. Some had a previous diagnosis of DOORS syndrome (deafness/onychodystrophy/osteodystrophy,retardation, seizures) and few showed 2-oxoglutatic aciduria which can also be seen in DOORS s.

PIGB encodes phosphatidylinositol glycan anchor biosynthesis class B protein.

Overall the phenotype was similar to other inherited glycosylphosphatidylinositol (GPI) deficiencies (IGDs). As happens to be the case in some other GPI deficiencies alkaline phosphatase was also elevated in those tested (8/9).

8 missense, 1 stopgain as well as an intronic SNV are reported. All variants were either absent or ultra-rare and with no homozygotes in gnomAD.

Affected individuals from 4 families, harbored an intronic SNV in the homozygous state. For this variant - with MAF of 0.0001592 or 6.51x10-5 in ExAC and gnomAD - activation of an aberrant splice acceptor site was shown [NM_004855.4:c.847-10A>G or p.Gln282_Trp283insArgCysGln].

Flow cytometric analysis of blood cells or fibroblasts showed decreased levels for various GPI-AP (GPI-anchored protein) markers in affected individuals. These levels were rescued upon transduction with a PIGB-encoding-Lx304 lentiviral vector of fibroblasts from one affected individual, suggesting that the PIGB defect was responsible.

The effect of the variants was evaluated using PIGB-deficient CHO cells, transfected with wt or mutant PIGB cDNAs. FACS analysis and immunoblotting demonstrated that variants were able to restore only slightly/partially - if at all - the surface presence of GPI-APs in the case of variants while the levels of mutant protein were reduced.

PIGB is not associated with any phenotype in OMIM/G2P. This gene is not commonly included in gene panels for ID offered by diagnostic laboratories.

As a result, this gene can be considered for inclusion in the ID and epilepsy panels probably as green (or amber).
Sources: Literature
Intellectual disability v2.953 DEAF1 Rebecca Foulger Phenotypes for gene: DEAF1 were changed from MENTAL RETARDATION, AUTOSOMAL DOMINANT 24 to MENTAL RETARDATION, AUTOSOMAL DOMINANT 24; ?Dyskinesia, seizures, and intellectual developmental disorder, 617171; Mental retardation, autosomal dominant 24, 615828
Intellectual disability v2.952 DEAF1 Rebecca Foulger Added comment: Comment on mode of inheritance: Changed the MOI from 'MONOALLELIC' to 'BOTH monoallelic and biallelic' based on PMID:30923367. Nabais et al., 2019 investigated AD and AR DEAF1 variants in a cohort of 23 patients. With the exception of microcephaly, most phenotypes (including ID, DD and seizures) were reported in patients with biallelic and pathogenic de novo DEAF1 variants.
Intellectual disability v2.952 DEAF1 Rebecca Foulger Mode of inheritance for gene: DEAF1 was changed from MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Intellectual disability v2.951 POU3F3 Konstantinos Varvagiannis gene: POU3F3 was added
gene: POU3F3 was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen
Mode of inheritance for gene: POU3F3 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: POU3F3 were set to https://doi.org/10.1016/j.ajhg.2019.06.007; 24550763
Phenotypes for gene: POU3F3 were set to Generalized hypotonia; Delayed speech and language development; Global developmental delay; Intellectual disability; Autistic behavior
Penetrance for gene: POU3F3 were set to unknown
Review for gene: POU3F3 was set to GREEN
gene: POU3F3 was marked as current diagnostic
Added comment: Snijders Blok et al. (2019, DOI: https://doi.org/10.1016/j.ajhg.2019.06.007) report on 19 individuals with heterozygous POU3F3 variants.

Features included hypotonia in some, DD/ID (19/19) with impairment in speech and language skills, and autism-like symptoms with formal ASD diagnosis in 7(/19). Epilepsy was reported for 2 individuals. Overlapping facial features were noted among these individuals.

POU3F3 encodes a member of the class III POU family of transcription factors expressed in the central nervous system (Sumiyama et al. 1996, PMID: 8703082 cited in OMIM) and as the authors comment holds a role in regulation of key processes, eg. cortical neuronal migration, upper-layer specification and production and neurogenesis (PMIDs cited: 11859196, 12130536, 22892427, 17141158).

In almost all subjects (17/19) the variant had occurred as a de novo event, while one individual had inherited the variant from a similarly affected parent.

In total 12 nonsense/frameshift variants, 5 missense ones as well as 1 in-frame deletion were identified following (mostly) trio exome sequencing. All variants were absent from gnomAD, with in silico predictions in favour of pathogenicity.

The few missense variants and the in-frame deletion were found either in the POU-specific (NM_006236.2:c.1085G>T / p.Arg362Leu found in 2 subjects) or the POU-homeobox domain (where 2 variants affected the same residue, namely p.Arg407Gly/Leu, the other variant was p.Asn456Ser).

POU3F3 is an intronless gene and as a result truncating variants are not subject to NMD. The gene appears to be intolerant to LoF variants (pLI of 0.89 in gnomAD).

Western blot analysis of YFP-tagged POU3F3 variants (in HEK293 cell lysates) showed that the YFP-fusion proteins were expressed and had the expected molecular weights.

For several truncating variants tested as well as the in-frame deletion, aberrant subcellular localization pattern was demonstrated although this was not the case for 4 missense variants.

In vitro studies were carried out and suggested that POU3F3, as is known to be the case for POU3F2, is able to activate an intronic binding site in FOXP2. Using a luciferase assay, transcriptional activation was severely impaired for truncating variants tested, significantly lower for many missense ones with the exception of those affecting Arg407 in which case luciferase expression was either similar to wt (for Arg407Gly) or even increased in the case of Arg407Leu.

As the authors comment, both loss- and gain- of function mechanisms may underly pathogenicity of variants.

The ability of mutant proteins to form dimers either with wt or themselves was tested. Dimerization capacity was intact for most missense variants but was lost/decreased for truncating variants. The in-frame deletion resulted in impaired dimerization with wt, although homo-dimerization was found to be normal.
---
Dheedene et al. (2014 - PMID: 24550763) had previously reported on a boy with ID. aCGH had demonstrated a de novo 360-kb deletion of 2q12.1 spanning only POU3F3 and MRPS9 the latter encoding a mitochondrial ribosomal protein (which would be most compatible with a - yet undescribed - recessive inheritance pattern / disorder).
---
POU3F3 is not associated with any phenotype in OMIM/G2P.
The gene is included in gene panels for ID offered by some diagnostic laboratories (incl. Radboudumc, among the principal authors of the study).
---
As a result POU3F3 seems to fulfill criteria for inclusion in the current panel probably as green [DD/ID was a universal feature - severity of ID was relevant in 5/10 individuals for whom details were available, functional evidence provided] or amber.
Sources: Literature, Radboud University Medical Center, Nijmegen
Intellectual disability v2.951 NEXMIF Rebecca Foulger Publications for gene: NEXMIF were set to
Intellectual disability v2.950 NEXMIF Rebecca Foulger Added comment: Comment on mode of inheritance: Changed MOI from XLR to XLD to match the XLD recorded for 'Mental retardation, X-linked 98' in OMIM (MIM:300912) and Gene2Phenotype, which records X-linked dominant inheritance for 'Intellectual disability and epilepsy' in addition to hemizgyous inheritance for 'KIAA2022'. An XLD inheritance is supported by PMID:27358180 which reports 14 female patients who carry a heterozygous de novo NEXMIF (KIAA2022) variant and share a phenotype characterised by intellectual disability and epilepsy.
Intellectual disability v2.950 NEXMIF Rebecca Foulger Mode of inheritance for gene: NEXMIF was changed from X-LINKED: hemizygous mutation in males, biallelic mutations in females to X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males)
Intellectual disability v2.949 HK1 Ivone Leong Classified gene: HK1 as Green List (high evidence)
Intellectual disability v2.949 HK1 Ivone Leong Added comment: Comment on list classification: Promoted from red to green. This gene is associated with a phenotype in OMIM but not in Gene2Phenotype. There are sufficient cases for this gene to be promote to green status. Variants on the 5' end of the gene have been associated with neuropathy, hereditary motor and sensory, Russe type.
Intellectual disability v2.949 HK1 Ivone Leong Gene: hk1 has been classified as Green List (High Evidence).
Intellectual disability v2.948 HK1 Ivone Leong Added comment: Comment on mode of pathogenicity: A gain of function effect is presumed to cause disease.
Intellectual disability v2.948 HK1 Ivone Leong Mode of pathogenicity for gene: HK1 was changed from to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Intellectual disability v2.947 HK1 Ivone Leong Phenotypes for gene: HK1 were changed from Hemolytic anemia due to hexokinase deficiency, 235700; Neuropathy, hereditary motor and sensory, Russe type, 605285 to Hemolytic anemia due to hexokinase deficiency, 235700; Neuropathy, hereditary motor and sensory, Russe type, 605285; Abnormal muscle tone; Global developmental delay; Intellectual disability; Visual impairment; Neurological speech impairment; Ataxia
Intellectual disability v2.946 HK1 Ivone Leong Publications for gene: HK1 were set to
Intellectual disability v2.945 HK1 Ivone Leong Tag missense tag was added to gene: HK1.
Intellectual disability v2.945 NDUFAF5 Ivone Leong Classified gene: NDUFAF5 as Amber List (moderate evidence)
Intellectual disability v2.945 NDUFAF5 Ivone Leong Added comment: Comment on list classification: Promoted from red to amber. This gene is associated with a relevant phenotype in OMIM but not in Gene2Phenotype. After discussion with the Genomics England Clinical Team it was decided that there is currently not enough evidence to promote this gene to green. The clinical presentations reported in the papers are not classical for an ID cohort (except perhaps patient 1 in the Ashkenzi Jewish families). Therefore, this gene has been promoted to amber until further evidence emerges.
Intellectual disability v2.945 NDUFAF5 Ivone Leong Gene: ndufaf5 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.944 SMARCD1 Ivone Leong Classified gene: SMARCD1 as Green List (high evidence)
Intellectual disability v2.944 SMARCD1 Ivone Leong Added comment: Comment on list classification: Promoted from red to green. SMARCD1 is not associated with any phenotype in OMIM or Gene2Phenotype. After consulting with the Genomics England Clinical Team and based on the submitted expert review, it was decided that there is enough evidence to promote this gene to green status.
Intellectual disability v2.944 SMARCD1 Ivone Leong Gene: smarcd1 has been classified as Green List (High Evidence).
Intellectual disability v2.943 SMARCD1 Ivone Leong Mode of inheritance for gene: SMARCD1 was changed from to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.942 SMARCD1 Ivone Leong Phenotypes for gene: SMARCD1 were changed from to Generalized hypotonia; Feeding difficulties; Global developmental delay; Intellectual disability; Abnormality of the hand; Abnormality of the foot
Intellectual disability v2.941 CTBP1 Rebecca Foulger Phenotypes for gene: CTBP1 were changed from Generalized hypotonia; Global developmental delay; Intellectual disability; Ataxia; Abnormality of dental enamel to Hypotonia, ataxia, developmental delay, and tooth enamel defect syndrome, 617915
Intellectual disability v2.940 TRPM3 Rebecca Foulger Classified gene: TRPM3 as Amber List (moderate evidence)
Intellectual disability v2.940 TRPM3 Rebecca Foulger Added comment: Comment on list classification: TRPM3 was added to the panel and rated Green by Konstantinos Varvagiannis based on PMID:31278393 (Dyment et al 2019). Although 8 probands were reported, 1 proband carries a VUS and an additional splice variant in DDB1. Therefore only variant is pathogenic, and this is missense, and de novo in all cases. The authors also note that heterozygous LOF variants in TRPM3 are observed in the general population. Not yet associated with a disorder in Gene2Phenotype or OMIM. Therefore have rated Amber and added 'watchlist' tag awaiting further cases or additional functional studies.
Intellectual disability v2.940 TRPM3 Rebecca Foulger Gene: trpm3 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.939 TRPM3 Rebecca Foulger Tag missense tag was added to gene: TRPM3.
Tag watchlist tag was added to gene: TRPM3.
Intellectual disability v2.939 TRPM3 Rebecca Foulger Publications for gene: TRPM3 were set to doi.org/10.1038/s41431-019-0462-x
Intellectual disability v2.938 TRPM3 Rebecca Foulger commented on gene: TRPM3
Intellectual disability v2.938 CTBP1 Konstantinos Varvagiannis changed review comment from: 12 individuals with a recurrent missense variant in CTBP1 have been reported, all summarized in the last article:
- Beck et al. 2016 (PMID: 27094857) : 4 individuals
- Sommerville et al. 2017 (PMID: 28955726) : 1 subject
- Beck et al. 2019 (PMID: 31041561) : 7 further individuals

Features included hypotonia, DD/ID, ataxia and tooth enamel defects. The degree of ID - when present - appeared to be highly variable based at least on the first two reports (3 individuals with severe ID, 1 with borderline-normal intellectual functioning, 1 did not exhibit ID) where this feature was further commented on.

A recurrent missense variant was found in all 12 affected individuals [NM_001328.2:c.1024C>T - p.(Arg342Trp) or NM_001012614.1:c.991C>T - p.(Arg331Trp)]. De novo occurrence this SNV was shown for (almost) all individuals, although in one case maternal sequencing reads were compatible with low-level somatic mosaicism (4/75 reads) not detected by Sanger sequencing. The mother of this individual was phenotypically normal. The variant is absent from gnomAD. Several in silico predictions (SIFT, PolyPhen2, MutationTaster, etc) suggest a deleterious effect.

Given recurrence of this specific variant, and presence of LoF ones in healthy individuals (pLI of 0.98 though in gnomAD) Beck et al. suggested a dominant negative or a gain-of-function effect rather than a loss of function mechanism.

Exclusion of alternative causes: was mainly discussed for the subject reported by Sommerville et al., due to the primary suspicion of a mitochondrial disorder (sequencing and research for mtDNA rearrangements, additional analysis of nuclear genes for mitochondrial disorders).

Expression: CTBP1 encodes C-terminal binding protein 1, with expression among others in brain and cerebellum (https://gtexportal.org/home/gene/CTBP1).

Role and Functional studies:
- The major nuclear isoform of CTBP1 (corresponding to NM_001328.2) and of its paralog CTBP2 function as transcriptional regulators (corepressors). The PLDLS(Pro-Leu-Asp-Leu-Ser)-binding cleft domain where this variant lies, acts as a high-affinity protein-binding interface to recruit DNA-binding repressors and chromatin modifying enzymes (PMID: 17967884).
- In a human glioblastoma cell line interaction of various cofactors with (Flag-tagged) CTBP1 was studied by immunoprecitipation with the Flag antibody and subsequent proteomic (LC-MS) analysis. This demonstrated reduced interaction in the case of R342W (compared to wt) with Zn-finger transcription factors, histone deacetylases, histone methyltransferases, histone H3-K4 demethylase etc. Western blot analyses also revealed reduced interaction of the R342W with several CTBP cofactors.
- RNA-seq analysis in glioblastoma cell line revealed similar overall transcriptional profiles between wt and R342W though multiple RNA species showed significant differences (eg. genes involved in the biological processes of mitotic nuclear division, DNA repair, transcription and regulation of transcription among those that were most upregulated and genes involved in brain development among the most downregulated).
- Patient fibroblasts under conditions of glucose deprivation exhibited strikingly more cell death compared to control fibroblasts. Study of mRNA levels of pro-apoptotic genes by q-RT-PCR revealed that Noxa expression under glucose deprivation vs under normal glucose was 8 to 10-fold enhanced for control fibroblasts, but more than 30-fold enhanced in the case patient fibroblasts. Western blot analyses were also in line with this.
- Mitochondrial dysfunction (probably secondary) with evidence of decreased complex I (and complex IV) activities in skeletal muscle was the case for 2 individuals among multiple patients who had muscle biopsies.

Animal models:
- Beck et al. discuss previously published mouse models where Ctbp1/2 both play overlapping transcriptional roles during development. Homozygous deletion of Ctbp2 is embryonically lethal (>E10.5). Homozygous deletion of Ctbp1 results in viable mice with reduced size and lifespan (Cited: Hildebrand et al. 2002 - PMID: 12101226)
- As commented on by Sommerville et al., Ctbp1 knockout in mouse embryonic fibroblasts resulted in elongated mitochondria, abnormal mitochondrial cristae, diminished ATP and O2 consumption and mitochondrial membrane potential.

----
CTBP1 is associated with Hypotonia, ataxia, developmental delay, and tooth enamel defect syndrome (617915) in OMIM. It is not associated with any phenotype in G2P.
Some diagnostic laboratories (eg. GeneDx participating in the first study and others) include this gene in panels for intellectual disability.
----

As a result, CTBP1 can be added in the current panel probably as green.; to: 12 individuals with a recurrent missense variant in CTBP1 have been reported, all summarized in the last article:
- Beck et al. 2016 (PMID: 27094857) : 4 individuals
- Sommerville et al. 2017 (PMID: 28955726) : 1 subject
- Beck et al. 2019 (PMID: 31041561) : 7 further individuals

Features included hypotonia, DD/ID, ataxia and tooth enamel defects. The degree of ID - when present - appeared to be highly variable based at least on the first two reports (3 individuals with severe ID, 1 with borderline-normal intellectual functioning, 1 did not exhibit ID) where this feature was further commented on.

A recurrent missense variant was found in all 12 affected individuals [NM_001328.2:c.1024C>T - p.(Arg342Trp) or NM_001012614.1:c.991C>T - p.(Arg331Trp)]. De novo occurrence this SNV was shown for (almost) all individuals, although in one case maternal sequencing reads were compatible with low-level somatic mosaicism (4/75 reads) not detected by Sanger sequencing. The mother of this individual was phenotypically normal. The variant is absent from gnomAD. Several in silico predictions (SIFT, PolyPhen2, MutationTaster, etc) suggest a deleterious effect.

Given recurrence of this specific variant, and presence of LoF ones in healthy individuals (pLI of 0.98 though in gnomAD) Beck et al. suggested a dominant negative or a gain-of-function effect rather than a loss of function mechanism.

Exclusion of alternative causes: was mainly discussed for the subject reported by Sommerville et al., due to the primary suspicion of a mitochondrial disorder (sequencing and research for mtDNA rearrangements, additional analysis of nuclear genes for mitochondrial disorders).

Expression: CTBP1 encodes C-terminal binding protein 1, with expression among others in brain and cerebellum (https://gtexportal.org/home/gene/CTBP1).

Role and Functional studies:
- The major nuclear isoform of CTBP1 (corresponding to NM_001328.2) and of its paralog CTBP2 function as transcriptional regulators (corepressors). The PLDLS(Pro-Leu-Asp-Leu-Ser)-binding cleft domain where this variant lies, acts as a high-affinity protein-binding interface to recruit DNA-binding repressors and chromatin modifying enzymes (PMID: 17967884).
- In a human glioblastoma cell line interaction of various cofactors with (Flag-tagged) CTBP1 was studied by immunoprecitipation with the Flag antibody and subsequent proteomic (LC-MS) analysis. This demonstrated reduced interaction in the case of R342W (compared to wt) with Zn-finger transcription factors, histone deacetylases, histone methyltransferases, histone H3-K4 demethylase etc. Western blot analyses also revealed reduced interaction of the R342W with several CTBP cofactors.
- RNA-seq analysis in glioblastoma cell line revealed similar overall transcriptional profiles between wt and R342W though multiple RNA species showed significant differences (eg. genes involved in the biological processes of mitotic nuclear division, DNA repair, transcription and regulation of transcription among those that were most upregulated and genes involved in brain development among the most downregulated).
- Patient fibroblasts under conditions of glucose deprivation exhibited strikingly more cell death compared to control fibroblasts. Study of mRNA levels of pro-apoptotic genes by q-RT-PCR revealed that Noxa expression under glucose deprivation vs under normal glucose was 8 to 10-fold enhanced for control fibroblasts, but more than 30-fold enhanced in the case patient fibroblasts. Western blot analyses were also in line with this.
- Mitochondrial dysfunction (probably secondary) with evidence of decreased complex I (and complex IV) activities in skeletal muscle was the case for 2 individuals among multiple patients who had muscle biopsies.

Animal models:
- Beck et al. discuss previously published mouse models where Ctbp1/2 both play overlapping transcriptional roles during development. Homozygous deletion of Ctbp2 is embryonically lethal (>E10.5). Homozygous deletion of Ctbp1 results in viable mice with reduced size and lifespan (Cited: Hildebrand et al. 2002 - PMID: 12101226)
- As commented on by Sommerville et al., Ctbp1 knockout in mouse embryonic fibroblasts resulted in elongated mitochondria, abnormal mitochondrial cristae, diminished ATP and O2 consumption and mitochondrial membrane potential (Cited: Kim and Youn 2009 - PMID: 19136938).

----
CTBP1 is associated with Hypotonia, ataxia, developmental delay, and tooth enamel defect syndrome (617915) in OMIM. It is not associated with any phenotype in G2P.
Some diagnostic laboratories (eg. GeneDx participating in the first study and others) include this gene in panels for intellectual disability.
----

As a result, CTBP1 can be added in the current panel probably as green.
Intellectual disability v2.938 CTBP1 Konstantinos Varvagiannis reviewed gene: CTBP1: Rating: GREEN; Mode of pathogenicity: Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments; Publications: 27094857, 28955726, 31041561; Phenotypes: Hypotonia, ataxia, developmental delay, and tooth enamel defect syndrome (MIM 617915); Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown; Current diagnostic: yes
Intellectual disability v2.938 CTBP1 Konstantinos Varvagiannis Deleted their review
Intellectual disability v2.938 CTBP1 Konstantinos Varvagiannis changed review comment from: 12 individuals with a recurrent missense variant in CTBP1 have been reported, all summarized in the last article:
- Beck et al. 2016 (PMID: 27094857) : 4 individuals
- Sommerville et al. 2017 (PMID: 28955726) : 1 subject
- Beck et al. 2019 (PMID: 31041561) : 7 further individuals

Features included hypotonia, DD/ID, ataxia and tooth enamel defects. The degree of ID - when present - appeared to be highly variable based at least on the first two reports (3 individuals with severe ID, 1 with borderline-normal intellectual functioning, 1 did not exhibit ID) where this feature was further commented on.

A recurrent missense variant was found in all 12 affected individuals [NM_001328.2:c.1024C>T - p.(Arg342Trp) or NM_001012614.1:c.991C>T - p.(Arg331Trp)]. De novo occurrence this SNV was shown for (almost) all individuals, although in one case maternal sequencing reads were compatible with low-level somatic mosaicism (4/75 reads) not detected by Sanger sequencing. The mother of this individual was phenotypically normal. The variant is absent from gnomAD. Several in silico predictions (SIFT, PolyPhen2, MutationTaster, etc) suggest a deleterious effect.

Given recurrence of this specific variant, and presence of LoF ones in healthy individuals (pLI of 0.98 though in gnomAD) Beck et al. suggested a dominant negative or a gain-of-function effect rather than a loss of function mechanism.

Exclusion of alternative causes: was mainly discussed for the subject reported by Sommerville et al., due to the primary suspicion of a mitochondrial disorder (sequencing and research for mtDNA rearrangements, additional analysis of nuclear genes for mitochondrial disorders).

Expression: CTBP1 encodes C-terminal binding protein 1, with expression among others in brain and cerebellum (https://gtexportal.org/home/gene/CTBP1 ).

Role and Functional studies:
- The major nuclear isoform of CTBP1 (corresponding to NM_001328.2) and of its paralog CTBP2 function as transcriptional regulators (corepressors). The PLDLS(Pro-Leu-Asp-Leu-Ser)-binding cleft domain where this variant lies, acts as a high-affinity protein-binding interface to recruit DNA-binding repressors and chromatin modifying enzymes (PMID: 17967884).
- In a human glioblastoma cell line interaction of various cofactors with (Flag-tagged) CTBP1 was studied by immunoprecitipation with the Flag antibody and subsequent proteomic (LC-MS) analysis. This demonstrated reduced interaction in the case of R342W (compared to wt) with Zn-finger transcription factors, histone deacetylases, histone methyltransferases, histone H3-K4 demethylase etc. Western blot analyses also revealed reduced interaction of the R342W with several CTBP cofactors.
- RNA-seq analysis in glioblastoma cell line revealed similar overall transcriptional profiles between wt and R342W though multiple RNA species showed significant differences (eg. genes involved in the biological processes of mitotic nuclear division, DNA repair, transcription and regulation of transcription among those that were most upregulated and genes involved in brain development among the most downregulated).
- Patient fibroblasts under conditions of glucose deprivation exhibited strikingly more cell death compared to control fibroblasts. Study of mRNA levels of pro-apoptotic genes by q-RT-PCR revealed that Noxa expression under glucose deprivation vs under normal glucose was 8 to 10-fold enhanced for control fibroblasts, but more than 30-fold enhanced in the case patient fibroblasts. Western blot analyses were also in line with this.
- Mitochondrial dysfunction (probably secondary) with evidence of decreased complex I (and complex IV) activities in skeletal muscle was the case for 2 individuals among multiple patients who had muscle biopsies.

Animal models:
- Beck et al. discuss previously published mouse models where Ctbp1/2 both play overlapping transcriptional roles during development. Homozygous deletion of Ctbp2 is embryonically lethal (>E10.5). Homozygous deletion of Ctbp1 results in viable mice with reduced size and lifespan (Cited: Hildebrand et al. 2002 - PMID: 12101226)
- As commented on by Sommerville et al., Ctbp1 knockout in mouse embryonic fibroblasts resulted in elongated mitochondria, abnormal mitochondrial cristae, diminished ATP and O2 consumption and mitochondrial membrane potential.

----
CTBP1 is associated with Hypotonia, ataxia, developmental delay, and tooth enamel defect syndrome (617915) in OMIM. It is not associated with any phenotype in G2P.
Some diagnostic laboratories (eg. GeneDx participating in the first study and others) include this gene in panels for intellectual disability.
----

As a result, CTBP1 can be added in the current panel probably as green.
Sources: Literature; to: 12 individuals with a recurrent missense variant in CTBP1 have been reported, all summarized in the last article:
- Beck et al. 2016 (PMID: 27094857) : 4 individuals
- Sommerville et al. 2017 (PMID: 28955726) : 1 subject
- Beck et al. 2019 (PMID: 31041561) : 7 further individuals

Features included hypotonia, DD/ID, ataxia and tooth enamel defects. The degree of ID - when present - appeared to be highly variable based at least on the first two reports (3 individuals with severe ID, 1 with borderline-normal intellectual functioning, 1 did not exhibit ID) where this feature was further commented on.

A recurrent missense variant was found in all 12 affected individuals [NM_001328.2:c.1024C>T - p.(Arg342Trp) or NM_001012614.1:c.991C>T - p.(Arg331Trp)]. De novo occurrence this SNV was shown for (almost) all individuals, although in one case maternal sequencing reads were compatible with low-level somatic mosaicism (4/75 reads) not detected by Sanger sequencing. The mother of this individual was phenotypically normal. The variant is absent from gnomAD. Several in silico predictions (SIFT, PolyPhen2, MutationTaster, etc) suggest a deleterious effect.

Given recurrence of this specific variant, and presence of LoF ones in healthy individuals (pLI of 0.98 though in gnomAD) Beck et al. suggested a dominant negative or a gain-of-function effect rather than a loss of function mechanism.

Exclusion of alternative causes: was mainly discussed for the subject reported by Sommerville et al., due to the primary suspicion of a mitochondrial disorder (sequencing and research for mtDNA rearrangements, additional analysis of nuclear genes for mitochondrial disorders).

Expression: CTBP1 encodes C-terminal binding protein 1, with expression among others in brain and cerebellum (https://gtexportal.org/home/gene/CTBP1).

Role and Functional studies:
- The major nuclear isoform of CTBP1 (corresponding to NM_001328.2) and of its paralog CTBP2 function as transcriptional regulators (corepressors). The PLDLS(Pro-Leu-Asp-Leu-Ser)-binding cleft domain where this variant lies, acts as a high-affinity protein-binding interface to recruit DNA-binding repressors and chromatin modifying enzymes (PMID: 17967884).
- In a human glioblastoma cell line interaction of various cofactors with (Flag-tagged) CTBP1 was studied by immunoprecitipation with the Flag antibody and subsequent proteomic (LC-MS) analysis. This demonstrated reduced interaction in the case of R342W (compared to wt) with Zn-finger transcription factors, histone deacetylases, histone methyltransferases, histone H3-K4 demethylase etc. Western blot analyses also revealed reduced interaction of the R342W with several CTBP cofactors.
- RNA-seq analysis in glioblastoma cell line revealed similar overall transcriptional profiles between wt and R342W though multiple RNA species showed significant differences (eg. genes involved in the biological processes of mitotic nuclear division, DNA repair, transcription and regulation of transcription among those that were most upregulated and genes involved in brain development among the most downregulated).
- Patient fibroblasts under conditions of glucose deprivation exhibited strikingly more cell death compared to control fibroblasts. Study of mRNA levels of pro-apoptotic genes by q-RT-PCR revealed that Noxa expression under glucose deprivation vs under normal glucose was 8 to 10-fold enhanced for control fibroblasts, but more than 30-fold enhanced in the case patient fibroblasts. Western blot analyses were also in line with this.
- Mitochondrial dysfunction (probably secondary) with evidence of decreased complex I (and complex IV) activities in skeletal muscle was the case for 2 individuals among multiple patients who had muscle biopsies.

Animal models:
- Beck et al. discuss previously published mouse models where Ctbp1/2 both play overlapping transcriptional roles during development. Homozygous deletion of Ctbp2 is embryonically lethal (>E10.5). Homozygous deletion of Ctbp1 results in viable mice with reduced size and lifespan (Cited: Hildebrand et al. 2002 - PMID: 12101226)
- As commented on by Sommerville et al., Ctbp1 knockout in mouse embryonic fibroblasts resulted in elongated mitochondria, abnormal mitochondrial cristae, diminished ATP and O2 consumption and mitochondrial membrane potential.

----
CTBP1 is associated with Hypotonia, ataxia, developmental delay, and tooth enamel defect syndrome (617915) in OMIM. It is not associated with any phenotype in G2P.
Some diagnostic laboratories (eg. GeneDx participating in the first study and others) include this gene in panels for intellectual disability.
----

As a result, CTBP1 can be added in the current panel probably as green.
Sources: Literature
Intellectual disability v2.938 CTBP1 Konstantinos Varvagiannis gene: CTBP1 was added
gene: CTBP1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CTBP1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: CTBP1 were set to 27094857; 28955726; 31041561
Phenotypes for gene: CTBP1 were set to Generalized hypotonia; Global developmental delay; Intellectual disability; Ataxia; Abnormality of dental enamel
Penetrance for gene: CTBP1 were set to unknown
Mode of pathogenicity for gene: CTBP1 was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: CTBP1 was set to GREEN
gene: CTBP1 was marked as current diagnostic
Added comment: 12 individuals with a recurrent missense variant in CTBP1 have been reported, all summarized in the last article:
- Beck et al. 2016 (PMID: 27094857) : 4 individuals
- Sommerville et al. 2017 (PMID: 28955726) : 1 subject
- Beck et al. 2019 (PMID: 31041561) : 7 further individuals

Features included hypotonia, DD/ID, ataxia and tooth enamel defects. The degree of ID - when present - appeared to be highly variable based at least on the first two reports (3 individuals with severe ID, 1 with borderline-normal intellectual functioning, 1 did not exhibit ID) where this feature was further commented on.

A recurrent missense variant was found in all 12 affected individuals [NM_001328.2:c.1024C>T - p.(Arg342Trp) or NM_001012614.1:c.991C>T - p.(Arg331Trp)]. De novo occurrence this SNV was shown for (almost) all individuals, although in one case maternal sequencing reads were compatible with low-level somatic mosaicism (4/75 reads) not detected by Sanger sequencing. The mother of this individual was phenotypically normal. The variant is absent from gnomAD. Several in silico predictions (SIFT, PolyPhen2, MutationTaster, etc) suggest a deleterious effect.

Given recurrence of this specific variant, and presence of LoF ones in healthy individuals (pLI of 0.98 though in gnomAD) Beck et al. suggested a dominant negative or a gain-of-function effect rather than a loss of function mechanism.

Exclusion of alternative causes: was mainly discussed for the subject reported by Sommerville et al., due to the primary suspicion of a mitochondrial disorder (sequencing and research for mtDNA rearrangements, additional analysis of nuclear genes for mitochondrial disorders).

Expression: CTBP1 encodes C-terminal binding protein 1, with expression among others in brain and cerebellum (https://gtexportal.org/home/gene/CTBP1 ).

Role and Functional studies:
- The major nuclear isoform of CTBP1 (corresponding to NM_001328.2) and of its paralog CTBP2 function as transcriptional regulators (corepressors). The PLDLS(Pro-Leu-Asp-Leu-Ser)-binding cleft domain where this variant lies, acts as a high-affinity protein-binding interface to recruit DNA-binding repressors and chromatin modifying enzymes (PMID: 17967884).
- In a human glioblastoma cell line interaction of various cofactors with (Flag-tagged) CTBP1 was studied by immunoprecitipation with the Flag antibody and subsequent proteomic (LC-MS) analysis. This demonstrated reduced interaction in the case of R342W (compared to wt) with Zn-finger transcription factors, histone deacetylases, histone methyltransferases, histone H3-K4 demethylase etc. Western blot analyses also revealed reduced interaction of the R342W with several CTBP cofactors.
- RNA-seq analysis in glioblastoma cell line revealed similar overall transcriptional profiles between wt and R342W though multiple RNA species showed significant differences (eg. genes involved in the biological processes of mitotic nuclear division, DNA repair, transcription and regulation of transcription among those that were most upregulated and genes involved in brain development among the most downregulated).
- Patient fibroblasts under conditions of glucose deprivation exhibited strikingly more cell death compared to control fibroblasts. Study of mRNA levels of pro-apoptotic genes by q-RT-PCR revealed that Noxa expression under glucose deprivation vs under normal glucose was 8 to 10-fold enhanced for control fibroblasts, but more than 30-fold enhanced in the case patient fibroblasts. Western blot analyses were also in line with this.
- Mitochondrial dysfunction (probably secondary) with evidence of decreased complex I (and complex IV) activities in skeletal muscle was the case for 2 individuals among multiple patients who had muscle biopsies.

Animal models:
- Beck et al. discuss previously published mouse models where Ctbp1/2 both play overlapping transcriptional roles during development. Homozygous deletion of Ctbp2 is embryonically lethal (>E10.5). Homozygous deletion of Ctbp1 results in viable mice with reduced size and lifespan (Cited: Hildebrand et al. 2002 - PMID: 12101226)
- As commented on by Sommerville et al., Ctbp1 knockout in mouse embryonic fibroblasts resulted in elongated mitochondria, abnormal mitochondrial cristae, diminished ATP and O2 consumption and mitochondrial membrane potential.

----
CTBP1 is associated with Hypotonia, ataxia, developmental delay, and tooth enamel defect syndrome (617915) in OMIM. It is not associated with any phenotype in G2P.
Some diagnostic laboratories (eg. GeneDx participating in the first study and others) include this gene in panels for intellectual disability.
----

As a result, CTBP1 can be added in the current panel probably as green.
Sources: Literature
Intellectual disability v2.938 TRPM3 Konstantinos Varvagiannis changed review comment from: Dyment et al. (2019 - https://doi.org/10.1038/s41431-019-0462-x) report on 7 unrelated individuals with a recurrent de novo TRPM3 missense variant [NM_020952.4:c.2509G>A - NP_066003.3:p.(Val837Met)] as well as an additional individual with a further de novo missense variant [c.2810C>A or p.(Pro937Gln) - same ref. sequences].

Overlapping features included hypotonia (7/8 - in one case mixed tone abnormality), DD/ID (8/8 - all individuals at appropriate age - degree relevant), EEG-confirmed epilepsy (7/8). Autism-like features were observed in 4 (out of 6 for whom this information was reported). Other features were noted in a minority (or were private to certain) of these individuals.

Different clinical types of seizures were reported incl. absence, generalized-toni-clonic, infantile spasms as well as subclinical ones. Onset was in infancy or early childhood.

In all individuals the variant was found following trio exome sequencing.

The first variant fulfilled ACMG criteria to be classified as pathogenic due to it's de novo occurrence, prevalence in affected individuals (>=6 affected individuals and in the same time) absence from population databases, in silico predictions in favour of pathogenicity (PS2, PS4_Moderate, PM2, PP3).

The Pro937Gln variant is however classified as a VUS. The subject harboring this variant had an additional de novo variant in another gene (DDB1) not associated with any phenotype, to date.

Several other genetic causes had previously been ruled out for most individuals by other investigations : aCGH was normal in all, FMR1 testing in 6 subjects, genes (PHF6, MECP2, MCT8) or smaller panels for ID (the latter in 3 subjects), mtDNA or testing of nuclear genes for mitochondrial disorders, etc.

TRPM3 encodes transient receptor potential (TRP) cation channel, subfamily M, member 3. TRP channels are a superfamily of gated cation channels sensitive to various physical or chemical stimuli (Clapham 2003 - PMID: 14654832 cited) eg. temperature or pain.

The gene is highly expressed in the brain in humans and other vertebrates (Grimm et al. 2003 - PMID : 12672799 and GTEx - https://gtexportal.org/home/gene/TRPM3).

Animal models : In rat brain, expression is initially restricted to neurons but later - as myelination progresses - shifts to oligodendrocytes (cited : Hoffmann et al. 2010 - PMID: 20163522). Most subjects had normal brain MRI appart from one individual with nonspecific white matter hyperintensities and another with possible mild cerebral volume loss. Trpm3 -/- mice show attenuated nocifensive behavior after heat or dermal injection of pregnenolone sulfate. Heat or pain insensitivity was reported only for 2 individuals.

Functional studies were not carried out, although some hypotheses are proposed following in silico modeling of the TRPM3 variants using an available structure for TRPM7.

As discussed by Dyment et al., happloinsufficiency appears to be unlikely given the presence of LoF variants in ExAC/gnomAD (pLI of 0), some intragenic copy number variants in DGV. In addition, pathogenicity of deletions spanning only TRPM3 or additional proximal genes was not evident in 2 cases:
- In the first case a exon 1-9 deletion was found in 2 brothers with Becker muscular dystrophy due to DMD intragenic duplication and autism/cognitive impairment though the TRPM3 deletion was found also in unaffected family members. The deletion was also found in unaffected relatives. A multiple hit hypothesis was hypothesized for this family. [Pagnamenta et al. 2011 - PMID: 21484199]
- Kuniba et al. [2009 - PMID: 19343044] reported a 1.27-Mb deletion spanning TRPM3, KLF9, SMC5 and MAMDC2 in a patient with Kabuki syndrome working diagnosis. Segregation studies were however not possible. At the time, the molecular etiology of Kabuki syndrome (KMT2D/KDM6A) was not known.
-----
TRPM3 is not associated with any phenotype in OMIM or G2P.
This gene is included in panels for ID offered by some diagnostic laboratories (eg. GeneDx participating in the above study).
-----
As a result, TRPM3 seems to fulfill criteria for inclusion in the ID/epilepsy panels probably as green (# of individuals, degree of ID relevant, EEG-confirmed epilepsy) or amber (if further functional evidence would be required).

[Please consider eligibility for inclusion in other possibly relevant panels eg. autism, etc].
Sources: Literature; to: Dyment et al. (2019 - https://doi.org/10.1038/s41431-019-0462-x) report on 7 unrelated individuals with a recurrent de novo TRPM3 missense variant [NM_020952.4:c.2509G>A - NP_066003.3:p.(Val837Met)] as well as an additional individual with a further de novo missense variant [c.2810C>A or p.(Pro937Gln) - same ref. sequences].

Overlapping features included hypotonia (7/8 - in one case mixed tone abnormality), DD/ID (8/8 - all individuals at appropriate age - degree relevant), EEG-confirmed epilepsy (7/8). Autism-like features were observed in 4 (out of 6 for whom this information was reported). Other features were noted in a minority (or were private to certain) of these individuals.

Different clinical types of seizures were reported incl. absence, generalized-toni-clonic, infantile spasms as well as subclinical ones. Onset was in infancy or early childhood.

In all individuals the variant was found following trio exome sequencing.

The first variant fulfilled ACMG criteria to be classified as pathogenic due to it's de novo occurrence, prevalence in affected individuals (>=6 affected individuals and in the same time) absence from population databases, in silico predictions in favour of pathogenicity (PS2, PS4_Moderate, PM2, PP3).

The Pro937Gln variant is however also present once in gnomAD (1/251370 alleles or AF:3.98e-6) and is classified as VUS according to the ACMG criteria. The subject harboring this variant had an additional de novo variant in another gene (DDB1) not associated with any phenotype, to date.

Several other genetic causes had previously been ruled out for most individuals by other investigations : aCGH was normal in all, FMR1 testing in 6 subjects, genes (PHF6, MECP2, MCT8) or smaller panels for ID (the latter in 3 subjects), mtDNA or testing of nuclear genes for mitochondrial disorders, etc.

TRPM3 encodes transient receptor potential (TRP) cation channel, subfamily M, member 3. TRP channels are a superfamily of gated cation channels sensitive to various physical or chemical stimuli (Clapham 2003 - PMID: 14654832 cited) eg. temperature or pain.

The gene is highly expressed in the brain in humans and other vertebrates (Grimm et al. 2003 - PMID : 12672799 and GTEx - https://gtexportal.org/home/gene/TRPM3).

Animal models : In rat brain, expression is initially restricted to neurons but later - as myelination progresses - shifts to oligodendrocytes (cited : Hoffmann et al. 2010 - PMID: 20163522). Most subjects had normal brain MRI appart from one individual with nonspecific white matter hyperintensities and another with possible mild cerebral volume loss. Trpm3 -/- mice show attenuated nocifensive behavior after heat or dermal injection of pregnenolone sulfate. Heat or pain insensitivity was reported only for 2 individuals.

Functional studies were not carried out, although some hypotheses are proposed following in silico modeling of the TRPM3 variants using an available structure for TRPM7.

As discussed by Dyment et al., happloinsufficiency appears to be unlikely given the presence of LoF variants in ExAC/gnomAD (pLI of 0), some intragenic copy number variants in DGV. In addition, pathogenicity of deletions spanning only TRPM3 or additional proximal genes was not evident in 2 cases:
- In the first case a exon 1-9 deletion was found in 2 brothers with Becker muscular dystrophy due to DMD intragenic duplication and autism/cognitive impairment though the TRPM3 deletion was found also in unaffected family members. The deletion was also found in unaffected relatives. A multiple hit hypothesis was hypothesized for this family. [Pagnamenta et al. 2011 - PMID: 21484199]
- Kuniba et al. [2009 - PMID: 19343044] reported a 1.27-Mb deletion spanning TRPM3, KLF9, SMC5 and MAMDC2 in a patient with Kabuki syndrome working diagnosis. Segregation studies were however not possible. At the time, the molecular etiology of Kabuki syndrome (KMT2D/KDM6A) was not known.
-----
TRPM3 is not associated with any phenotype in OMIM or G2P.
This gene is included in panels for ID offered by some diagnostic laboratories (eg. GeneDx participating in the above study).
-----
As a result, TRPM3 seems to fulfill criteria for inclusion in the ID/epilepsy panels probably as green (# of individuals, degree of ID relevant, EEG-confirmed epilepsy) or amber (if further functional evidence would be required).

[Please consider eligibility for inclusion in other possibly relevant panels eg. autism, etc].
Sources: Literature
Intellectual disability v2.938 TRPM3 Konstantinos Varvagiannis gene: TRPM3 was added
gene: TRPM3 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: TRPM3 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: TRPM3 were set to doi.org/10.1038/s41431-019-0462-x
Phenotypes for gene: TRPM3 were set to Generalized hypotonia; Global developmental delay; Intellectual disability; Seizures; Autistic behavior
Penetrance for gene: TRPM3 were set to unknown
Mode of pathogenicity for gene: TRPM3 was set to Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Review for gene: TRPM3 was set to GREEN
gene: TRPM3 was marked as current diagnostic
Added comment: Dyment et al. (2019 - https://doi.org/10.1038/s41431-019-0462-x) report on 7 unrelated individuals with a recurrent de novo TRPM3 missense variant [NM_020952.4:c.2509G>A - NP_066003.3:p.(Val837Met)] as well as an additional individual with a further de novo missense variant [c.2810C>A or p.(Pro937Gln) - same ref. sequences].

Overlapping features included hypotonia (7/8 - in one case mixed tone abnormality), DD/ID (8/8 - all individuals at appropriate age - degree relevant), EEG-confirmed epilepsy (7/8). Autism-like features were observed in 4 (out of 6 for whom this information was reported). Other features were noted in a minority (or were private to certain) of these individuals.

Different clinical types of seizures were reported incl. absence, generalized-toni-clonic, infantile spasms as well as subclinical ones. Onset was in infancy or early childhood.

In all individuals the variant was found following trio exome sequencing.

The first variant fulfilled ACMG criteria to be classified as pathogenic due to it's de novo occurrence, prevalence in affected individuals (>=6 affected individuals and in the same time) absence from population databases, in silico predictions in favour of pathogenicity (PS2, PS4_Moderate, PM2, PP3).

The Pro937Gln variant is however classified as a VUS. The subject harboring this variant had an additional de novo variant in another gene (DDB1) not associated with any phenotype, to date.

Several other genetic causes had previously been ruled out for most individuals by other investigations : aCGH was normal in all, FMR1 testing in 6 subjects, genes (PHF6, MECP2, MCT8) or smaller panels for ID (the latter in 3 subjects), mtDNA or testing of nuclear genes for mitochondrial disorders, etc.

TRPM3 encodes transient receptor potential (TRP) cation channel, subfamily M, member 3. TRP channels are a superfamily of gated cation channels sensitive to various physical or chemical stimuli (Clapham 2003 - PMID: 14654832 cited) eg. temperature or pain.

The gene is highly expressed in the brain in humans and other vertebrates (Grimm et al. 2003 - PMID : 12672799 and GTEx - https://gtexportal.org/home/gene/TRPM3).

Animal models : In rat brain, expression is initially restricted to neurons but later - as myelination progresses - shifts to oligodendrocytes (cited : Hoffmann et al. 2010 - PMID: 20163522). Most subjects had normal brain MRI appart from one individual with nonspecific white matter hyperintensities and another with possible mild cerebral volume loss. Trpm3 -/- mice show attenuated nocifensive behavior after heat or dermal injection of pregnenolone sulfate. Heat or pain insensitivity was reported only for 2 individuals.

Functional studies were not carried out, although some hypotheses are proposed following in silico modeling of the TRPM3 variants using an available structure for TRPM7.

As discussed by Dyment et al., happloinsufficiency appears to be unlikely given the presence of LoF variants in ExAC/gnomAD (pLI of 0), some intragenic copy number variants in DGV. In addition, pathogenicity of deletions spanning only TRPM3 or additional proximal genes was not evident in 2 cases:
- In the first case a exon 1-9 deletion was found in 2 brothers with Becker muscular dystrophy due to DMD intragenic duplication and autism/cognitive impairment though the TRPM3 deletion was found also in unaffected family members. The deletion was also found in unaffected relatives. A multiple hit hypothesis was hypothesized for this family. [Pagnamenta et al. 2011 - PMID: 21484199]
- Kuniba et al. [2009 - PMID: 19343044] reported a 1.27-Mb deletion spanning TRPM3, KLF9, SMC5 and MAMDC2 in a patient with Kabuki syndrome working diagnosis. Segregation studies were however not possible. At the time, the molecular etiology of Kabuki syndrome (KMT2D/KDM6A) was not known.
-----
TRPM3 is not associated with any phenotype in OMIM or G2P.
This gene is included in panels for ID offered by some diagnostic laboratories (eg. GeneDx participating in the above study).
-----
As a result, TRPM3 seems to fulfill criteria for inclusion in the ID/epilepsy panels probably as green (# of individuals, degree of ID relevant, EEG-confirmed epilepsy) or amber (if further functional evidence would be required).

[Please consider eligibility for inclusion in other possibly relevant panels eg. autism, etc].
Sources: Literature
Intellectual disability v2.938 DBT Rebecca Foulger commented on gene: DBT
Intellectual disability v2.938 DBT Rebecca Foulger Publications for gene: DBT were set to
Intellectual disability v2.937 TRAPPC12 Louise Daugherty commented on gene: TRAPPC12: Did not upgrade gene on the Genetic Epilepsy Syndromes panel as there was no phenotype of epilepsy in the third case.
Intellectual disability v2.937 USP7 Rebecca Foulger Phenotypes for gene: USP7 were changed from to Intellectual disability, autism, epilepsy, aggressive behaviour, hypotonia, and hypogonadism
Intellectual disability v2.936 USP7 Rebecca Foulger Classified gene: USP7 as Amber List (moderate evidence)
Intellectual disability v2.936 USP7 Rebecca Foulger Gene: usp7 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.935 USP7 Rebecca Foulger Classified gene: USP7 as Red List (low evidence)
Intellectual disability v2.935 USP7 Rebecca Foulger Added comment: Comment on list classification: USP7 was rated Green by Konstantinos Varvagiannis. Not currently associated with a disorder in OMIM, but has a 'possible' Disease confidence in Gene2Phenotype for the disorder: Intellectual disability, autism, epilepsy, aggressive behaviour, hypotonia, and hypogonadism (based on PMID:26365382). There is now a 2019 paper in addition to PMID:26365382 (PMID:30679821). In total, 22/23 individuals have an ID/DD phenotype, and 23/23 have speech delay. However, the Tyr143Ter variant described by both PMID:26365382 and PMID:30679821 is a VUS, and the microdeletions in other patients cover additional genes (PMID:26365382, Figure 5). Plus three patients in PMID:30679821 harbour variants in additional genes. Therefore although the phenotype is relevant, I have updated the rating from Red to Amber until there is more evidence that USP7 variants are causative.
Intellectual disability v2.935 USP7 Rebecca Foulger Gene: usp7 has been classified as Red List (Low Evidence).
Intellectual disability v2.934 USP7 Rebecca Foulger Mode of inheritance for gene: USP7 was changed from to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability v2.933 USP7 Rebecca Foulger commented on gene: USP7: PMID:30679821: Fountain et al., 2019 report on the clinical and genetic spectrum of 16 new and 7 previously reported (by PMID:26365382) individuals with USP7 heterozygous de novo variants.
The variants include 2 deletions, 3 nonsense, 3 splice site variants and 8 missense variants. Speech delay was seen in 23/23 patients, and ID/DD was seen in 22/23 patients. Note that Patients 18 and 20 harbor additional variants in TMEM106B and SLC2A1, Patient 19 also has a de novo heterozygous 102.5-kb mosaic loss of uncertain significance at 10q21.1.
Intellectual disability v2.933 USP7 Rebecca Foulger commented on gene: USP7
Intellectual disability v2.933 TRAF7 Rebecca Foulger Classified gene: TRAF7 as Green List (high evidence)
Intellectual disability v2.933 TRAF7 Rebecca Foulger Added comment: Comment on list classification: Updated rating from Amber to Green following advice from the Genomics England clinical team that the combination of motor and speech delay would be regarded by many clinicians as equivalent to global developmental delay.
Intellectual disability v2.933 TRAF7 Rebecca Foulger Gene: traf7 has been classified as Green List (High Evidence).
Intellectual disability v2.932 TRAF7 Rebecca Foulger Publications for gene: TRAF7 were set to 29961569; 27479843; 28135719
Intellectual disability v2.931 PIGC Rebecca Foulger Classified gene: PIGC as Amber List (moderate evidence)
Intellectual disability v2.931 PIGC Rebecca Foulger Added comment: Comment on list classification: Updated rating from Red to Amber following external review by Zornitza Stark. Not yet associated with a disorder in OMIM, and two cases in the current literature (PMID:27694521).
Intellectual disability v2.931 PIGC Rebecca Foulger Gene: pigc has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.930 PIGC Rebecca Foulger commented on gene: PIGC
Intellectual disability v2.930 CACNA1B Louise Daugherty Classified gene: CACNA1B as Green List (high evidence)
Intellectual disability v2.930 CACNA1B Louise Daugherty Added comment: Comment on list classification: New gene added by external expert and reviewed by curation team: appropriate phenotype, sufficient cases and external expert review all support gene-disease association and relevance to this panel to rate gene to Green.
Intellectual disability v2.930 CACNA1B Louise Daugherty Gene: cacna1b has been classified as Green List (High Evidence).
Intellectual disability v2.930 PIGC Rebecca Foulger Phenotypes for gene: PIGC were changed from Glycosylphosphatidylinositol biosynthesis defect 16 to Glycosylphosphatidylinositol biosynthesis defect 16, 617816
Intellectual disability v2.929 CACNA1B Louise Daugherty Added comment: Comment on phenotypes: added Progressive Epilepsy-Dyskinesia from PMID:30982612. gene-phenotype currently not listed in OMIM
Intellectual disability v2.929 CACNA1B Louise Daugherty Phenotypes for gene: CACNA1B were changed from Global developmental delay; Developmental regression; Seizures; Intellectual disability; Abnormality of movement to Global developmental delay; Developmental regression; Seizures; Intellectual disability; Abnormality of movement; Progressive Epilepsy-Dyskinesia
Intellectual disability v2.928 CACNA1B Louise Daugherty Added comment: Comment on publications: added publication to support gene-disease association
Intellectual disability v2.928 CACNA1B Louise Daugherty Publications for gene: CACNA1B were set to
Intellectual disability v2.927 ISCA2 Ivone Leong Classified gene: ISCA2 as Amber List (moderate evidence)
Intellectual disability v2.927 ISCA2 Ivone Leong Added comment: Comment on list classification: After consulting with the Genomics England Clinical team it was decided to only promote this gene to amber as the clinical picture is more of a mitochondrial phenotype and is likely to be investigated that way.
Intellectual disability v2.927 ISCA2 Ivone Leong Gene: isca2 has been classified as Amber List (Moderate Evidence).
Intellectual disability v2.926 CWC27 Ivone Leong Classified gene: CWC27 as Green List (high evidence)
Intellectual disability v2.926 CWC27 Ivone Leong Added comment: Comment on list classification: Promoted from red to green. CWC27 is associated with a phenotype in OMIM and Gene2Phenotype. PMID: 28285769 reported on 7 unrelated families (10 affected individuals) with variants in this gene. 8/10 had neurological problems, which include ID, delayed walking, delayed speech or psychomotor retardation. Two cases (same family) are specified as moderate ID and they have indicated severe psychomotor retardation in others. After consulting the Genomics England Clinical Team, it was decided that there is enough evidence to promote this to green status.
Intellectual disability v2.926 CWC27 Ivone Leong Gene: cwc27 has been classified as Green List (High Evidence).
Intellectual disability v2.925 TRAPPC12 Louise Daugherty changed review comment from: Comment on list classification: Appropriate phenotype, sufficient cases due to on unpublished report all support gene-disease association and relevance to this panel to rate gene to Green.; to: Comment on list classification: Appropriate phenotype, sufficient cases due to an unpublished report that supports gene-disease association and relevance to this panel to rate gene from Red to Green.
Intellectual disability v2.925 SMARCD1 Ivone Leong Publications for gene: SMARCD1 were set to 26350204
Intellectual disability v2.924 TRAPPC12 Louise Daugherty Classified gene: TRAPPC12 as Green List (high evidence)
Intellectual disability v2.924 TRAPPC12 Louise Daugherty Added comment: Comment on list classification: Appropriate phenotype, sufficient cases due to on unpublished report all support gene-disease association and relevance to this panel to rate gene to Green.
Intellectual disability v2.924 TRAPPC12 Louise Daugherty Gene: trappc12 has been classified as Green List (High Evidence).
Intellectual disability v2.923 TRAPPC12 Louise Daugherty Phenotypes for gene: TRAPPC12 were changed from Encephalopathy, progressive, early-onset, with brain atrophy and spasticity, 617669 to Encephalopathy, progressive, early-onset, with brain atrophy and spasticity, 617669; Developmental delay
Intellectual disability v2.922 TRAPPC12 Louise Daugherty Publications for gene: TRAPPC12 were set to 28777934
Intellectual disability v2.922 TRAPPC12 Louise Daugherty Phenotypes for gene: TRAPPC12 were changed from to Encephalopathy, progressive, early-onset, with brain atrophy and spasticity, 617669
Intellectual disability v2.921 TRAPPC12 Louise Daugherty Publications for gene: TRAPPC12 were set to
Intellectual disability v2.921 TRAPPC12 Louise Daugherty Mode of inheritance for gene: TRAPPC12 was changed from to BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.920 TRAPPC12 Louise Daugherty reviewed gene: TRAPPC12: Rating: GREEN; Mode of pathogenicity: None; Publications: 28777934; Phenotypes: Encephalopathy, progressive, early-onset, with brain atrophy and spasticity, 617669; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability v2.920 PPP3CA Ivone Leong Classified gene: PPP3CA as Green List (high evidence)
Intellectual disability v2.920 PPP3CA Ivone Leong Added comment: Comment on list classification: Promoted from red to green. PPP3CA is associated with Epileptic encephalopathy, infantile or early childhood, 1 in OMIM and is probably associated with Severe Neurodevelopmental Disease with Seizures
Page navigation in Gene2Phenotype. PMID: 28942967 reported on 6 unrelated individuals from different ethnic backgrounds who have different PPP3CA variants (missense and nonsense) who have severe ID. Therefore, there is enough evidence to promote this gene to green status.
Intellectual disability v2.920 PPP3CA Ivone Leong Gene: ppp3ca has been classified as Green List (High Evidence).
Intellectual disability v2.919 PPP3CA Ivone Leong Phenotypes for gene: PPP3CA were changed from Epileptic encephalopathy, infantile or early childhood, 1 to Epileptic encephalopathy, infantile or early childhood, 1, 617711
Intellectual disability v2.918 PPP1R15B Ivone Leong Classified gene: PPP1R15B as Green List (high evidence)
Intellectual disability v2.918 PPP1R15B Ivone Leong Added comment: Comment on list classification: Promoted from red to green. PPP1R15B is associated with a phenotype in OMIM and possibly associated with a phenotype in Gene2Phenotype. PMID: 26159176, 26307080 reported on 2 unrelated patients (Canadian, Algerian) who have the same missense variant in the PPP1R15B gene. Both patients have ID. PMID:27640355 reported on another case where the patient was compound heterozygous for 2 different variants (1 frameshift and 1 nonsense). The patient also had ID. Therefore, there is enough evidence to promote this gene to green status.
Intellectual disability v2.918 PPP1R15B Ivone Leong Gene: ppp1r15b has been classified as Green List (High Evidence).
Intellectual disability v2.917 PPP1R15B Ivone Leong Phenotypes for gene: PPP1R15B were changed from Microcephaly, short stature, and impaired glucose metabolism 2 to Microcephaly, short stature, and impaired glucose metabolism 2, 616817
Intellectual disability v2.916 PPP1R15B Ivone Leong Publications for gene: PPP1R15B were set to 26159176, 26307080, 27640355
Intellectual disability v2.915 PIGW Ivone Leong Classified gene: PIGW as Green List (high evidence)
Intellectual disability v2.915 PIGW Ivone Leong Added comment: Comment on list classification: Promoted from red to green, based the expert reviews and the evidence that was provided.
Intellectual disability v2.915 PIGW Ivone Leong Gene: pigw has been classified as Green List (High Evidence).
Intellectual disability v2.914 PIGW Ivone Leong Phenotypes for gene: PIGW were changed from Glycosylphosphatidylinositol biosynthesis defect 11 to Glycosylphosphatidylinositol biosynthesis defect 11, 616025
Intellectual disability v2.913 PIGW Ivone Leong Publications for gene: PIGW were set to 24367057, 27626616, 27626616
Intellectual disability v2.912 NDUFAF5 Ivone Leong Phenotypes for gene: NDUFAF5 were changed from Mitochondrial complex 1 deficiency to Mitochondrial complex 1 deficiency, 618238
Intellectual disability v2.911 MTFMT Ivone Leong Phenotypes for gene: MTFMT were changed from Combined oxidative phosphorylation deficiency 15 to Combined oxidative phosphorylation deficiency 15, 614947
Intellectual disability v2.910 NDUFAF5 Ivone Leong Publications for gene: NDUFAF5 were set to 19542079, 21607760, 18940309
Intellectual disability v2.909 MTFMT Ivone Leong Classified gene: MTFMT as Green List (high evidence)
Intellectual disability v2.909 MTFMT Ivone Leong Added comment: Comment on list classification: Promoted from red to green. MTFMT is associated with a phenotype in OMIM but not in Gene2Phenotype. There are >3 unrelated cases of patients who have different variants in this gene who have ID or developmental delay. Therefore, there is enough evidence to promote this gene to green status.
Intellectual disability v2.909 MTFMT Ivone Leong Gene: mtfmt has been classified as Green List (High Evidence).
Intellectual disability v2.908 MTFMT Ivone Leong Publications for gene: MTFMT were set to 24461907; 23499752
Intellectual disability v2.907 MTFMT Ivone Leong Publications for gene: MTFMT were set to 24461907; 23499752; 24461907
Intellectual disability v2.906 MTFMT Ivone Leong Publications for gene: MTFMT were set to 24461907, 23499752, 24461907
Intellectual disability v2.905 KMT5B Ivone Leong Publications for gene: KMT5B were set to 29276005, 28191889, 25363768