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Intellectual disability - microarray and sequencing v5.525 SEPHS1 Arina Puzriakova gene: SEPHS1 was added
gene: SEPHS1 was added to Intellectual disability - microarray and sequencing. Sources: Literature
Q2_24_promote_green tags were added to gene: SEPHS1.
Mode of inheritance for gene: SEPHS1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: SEPHS1 were set to 38531365
Phenotypes for gene: SEPHS1 were set to Neurodevelopmental disorder, MONDO:0700092
Review for gene: SEPHS1 was set to GREEN
Added comment: Mullegama et al. (2024) reported 9 individuals from 8 families with developmental delay, growth and feeding problems, hypotonia, and dysmorphic features, all with heterozygous missense variants in SEPHS1. Eight individuals shared different missense variants at the same p.Arg371 residue in SEPHS1 (p.Arg371Trp, p.Arg371Gln, and p.Arg371Gly); seven of these variants were confirmed as de novo (one unknown). Functional studies showed that variants at the Arg371 residue impact direct protein-protein interactions of SEPSH1 and enhance cell proliferation by modulating ROS homeostasis.
Sources: Literature
Intellectual disability - microarray and sequencing v5.522 FRYL Arina Puzriakova gene: FRYL was added
gene: FRYL was added to Intellectual disability - microarray and sequencing. Sources: Literature
watchlist tags were added to gene: FRYL.
Mode of inheritance for gene: FRYL was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: FRYL were set to 38479391
Phenotypes for gene: FRYL were set to Neurodevelopmental disorder, MONDO:0700092
Review for gene: FRYL was set to AMBER
Added comment: New association linking this gene to disease which is not yet listed in OMIM or Gene2Phenotype. There are no sequence variants in Decipher and ClinVar shows only a single pathogenic frameshift variant (c.1224del, p.Lys409fs) for FRYL-associated neurodevelopmental disorder, amongst multiple SNVs which are mostly missense VUS or B/LB.

Pan et al., 2024 (PMID: 38479391) reported 14 individuals with heterozygous variant in FRYL who presented with DD/ID, dysmorphic features, and other congenital anomalies in multiple systems. Except for DD/ID which was the only universal feature, observed phenotypes were variable and nonspecific.

Variants were confirmed de novo in all except one individual (duo testing excluded paternal inheritance although it was present at low frequency in gnomAD). Variant types include missense (5), fs/stop-gain (8) and canonical splice (1). Modelling 4/5 patient missense variants using flies showed that only one serves as a severe LoF variant, two others behave as partial LoF variants, and one variant had no functional impact (only variant not confirmed as de novo indicating this is a VUS). Four individuals also had P/LP variants in other genes (SF3B4, DHCR7, SLC6A19, SDHA) which could at least partially explain their phenotypes, and a further four harboured additional VUSs.
Sources: Literature
Intellectual disability - microarray and sequencing v5.506 ZFX Tracy Lester reviewed gene: ZFX: Rating: GREEN; Mode of pathogenicity: None; Publications: 38325380; Phenotypes: Intellectual disability, developmental delay, behavioural abnormalities, hypotonia, dysmorphic facies; 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 - microarray and sequencing v5.499 ZFHX3 Sarah Leigh edited their review of gene: ZFHX3: Added comment: Personal communication from Nour Elkhateeb (Clinical Fellow in Genomics, Genomics England): we have data about 12 individuals with nonsense/frameshift/exon deletions in ZFHX3. Five of the variants are located in exon 9/10 or exon 9, which has been shown to harbour the highest density of pathogenic variants (PMID: 38412861). Eleven of these cases presented with developmental delay / intellectual disability and a range of other features, including dysmorphology, seizures and failure to thrive.; Changed publications to: 38412861
Intellectual disability - microarray and sequencing v5.477 INTS1 Arina Puzriakova Phenotypes for gene: INTS1 were changed from Neurodevelopmental disorder with cataracts, poor growth, and dysmorphic facies, 618571; Hypotonia; Global developmental delay; Cataract; Abnormality of the skeletal system to Neurodevelopmental disorder with cataracts, poor growth, and dysmorphic facies, OMIM:618571
Intellectual disability - microarray and sequencing v5.451 MADD Sarah Leigh Phenotypes for gene: MADD were changed from Neurodevelopmental disorder with dysmorphic facies, impaired speech and hypotonia, 619005; DEEAH syndrome, 619004 to DEEAH syndrome, OMIM:619004; deeah syndrome, MONDO:0033561: Neurodevelopmental disorder with dysmorphic facies, impaired speech and hypotonia, OMIM:619005; neurodevelopmental disorder with dysmorphic facies, impaired speech, and hypotonia, MONDO:0033562
Intellectual disability - microarray and sequencing v5.402 ACBD6 Arina Puzriakova edited their review of gene: ACBD6: Added comment: - PMID: 21937992 (2011) - single individuals with a p.G22fs variant in the ACBD6 gene, presenting with mild ID, microcephaly, facial dysmorphism, spasticity. Limited additional information.

- PMID: 32108178 (2020) - two unrelated individuals with neurodevelopmental disorder (moderate ID is noted but otherwise limited clinical information) and carrying homozygous LoF variants in the ACBD6 gene (1 frameshift, 1 canonical splice). One individual also carried an allelic homozygous variant in the PRDX6 gene (unlikely but unknown disease consequence). Skin-derived patient fibroblasts showed reduced ACBD6 expression and N-myristoylation deficiency.

- PMID: 36457943 (2023) - two Thai siblings presenting with profound ID, morbid obesity, pancytopenia with severe recurrent infections, diabetes mellitus, cirrhosis, and renal failure, leading to deaths in their early 30s. Sequencing showed a novel homozygous single bp duplication (c.360dup; p.Leu121Thrfs*27) in the ACBD6 gene. Parents were heterozygous carriers.

- PMID: 37951597 (2023) - 45 previously undiagnosed individuals from 28 families with a neurodevelopmental syndrome including a complex and progressive movement disorder phenotype. Cardinal clinical features include moderate-to-severe GDD/ID (45/45), facial dysmorphism (38/40), HC <2nd percentile (21/31), weight >50th percentile (20/34), mild cerebellar ataxia (35/41), limb spasticity/hypertonia (31/41), gait abnormalities (33/35), dystonia (30/32) and variable epilepsy (13/29).

Homozygous ACBD6 variants were identified by WES in all cases, including 18 predicted LoF, 1 missense and 1 inframe insertion. Knockout studies in zebrafish recapitulate clinical features reported in patients such as movement disorders, seizures, and facial dysmorphology, while inactivation of acbd6 in X. tropicalis predominantly caused embryo death while surviving tadpoles demonstrated microcephaly, reduced movement, eye abnormalities, and brain structure differences.; Changed rating: GREEN; Changed publications to: 21937992, 32108178, 36457943, 37951597; Changed phenotypes to: Neurodevelopmental disorder, MONDO:0700092; Changed mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability - microarray and sequencing v5.362 C20orf24 Arina Puzriakova Added comment: Comment on list classification: New gene added by Hannah Knight. Biallelic LoF variant identified in a patient with craniofacial dysmorphism, skeletal anomalies, and impaired intellectual development syndrome. Authors suggested possible low penetrance due to two relatives with heterozygous variant and cleft lip and/or palate (PMID: 35614220).

Rating Red as only a single family reported to date. In OMIM the relationship between the phenotype and gene is provisional.
Intellectual disability - microarray and sequencing v5.361 C20orf24 Arina Puzriakova Phenotypes for gene: C20orf24 were changed from ?Craniofacial dysmorphism, skeletal anomalies, and impaired intellectual development syndrome 2 to ?Craniofacial dysmorphism, skeletal anomalies, and impaired intellectual development syndrome 2, OMIM:616994
Intellectual disability - microarray and sequencing v5.341 C20orf24 Hannah Knight gene: C20orf24 was added
gene: C20orf24 was added to Intellectual disability - microarray and sequencing. Sources: Literature
Mode of inheritance for gene: C20orf24 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: C20orf24 were set to 35614220
Phenotypes for gene: C20orf24 were set to ?Craniofacial dysmorphism, skeletal anomalies, and impaired intellectual development syndrome 2
Added comment: HGNC Approved Gene Symbol: RAB5IF
PMID: 35614220 (2022) identified a homozygous nonsense variant (p.W25X) in a Turkish boy previously reported by PMID: 24194475 to have bilateral cleft lip, complete cleft palate, moderate to severe intellectual delay and dysmorphic features. FHx of cleft lip/cleft palate as well in relatives who were heterozygous for the reported variant
Sources: Literature
Intellectual disability - microarray and sequencing v5.332 VCP Zornitza Stark gene: VCP was added
gene: VCP was added to Intellectual disability - microarray and sequencing. Sources: Literature
Mode of inheritance for gene: VCP was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: VCP were set to 37883978
Phenotypes for gene: VCP were set to Neurodevelopmental disorder (MONDO: 0700092)
Review for gene: VCP was set to GREEN
Added comment: 13 unrelated individuals with childhood onset ID/DD disorder including macrocephaly, hypotonia and dysmorphic features. Non-specific / mild MRI findings.
12 de novo - 1 inherited
Sources: Literature
Intellectual disability - microarray and sequencing v5.315 MAST4 Zornitza Stark gene: MAST4 was added
gene: MAST4 was added to Intellectual disability - microarray and sequencing. Sources: Literature
Mode of inheritance for gene: MAST4 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: MAST4 were set to 36910266; 33057194
Phenotypes for gene: MAST4 were set to neurodevelopmental disorder MONDO:0700092, MAST4-related
Review for gene: MAST4 was set to GREEN
Added comment: 9 individuals with de novo missense variants and ID reported altogether.

PMID: 36910266 - 4 affecteds from unrelated families, all de novo missense

2x borderline microcephaly (-2SD)
2x gross motor delay
2x dysmorphism
4x ID + seizures
3x abnormal brain MRI findings

PMID: 33057194 - 5x de novos, 4x missense + 1x PTC
Cohort of individuals with severe developmental disorder
individual phenotypic information not provided


Recurrent variants are Thr1471Ile (3x) and Ser1181Phe)
Sources: Literature
Intellectual disability - microarray and sequencing v5.307 SRSF1 Achchuthan Shanmugasundram gene: SRSF1 was added
gene: SRSF1 was added to Intellectual disability - microarray and sequencing. Sources: Literature
Mode of inheritance for gene: SRSF1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: SRSF1 were set to 37071997
Phenotypes for gene: SRSF1 were set to Neurodevelopmental disorder with dysmorphic facies and behavioral abnormalities, OMIM:620489
Review for gene: SRSF1 was set to GREEN
Added comment: There are 17 individuals from 16 different families were reported with 15 different monoallelic variants (mostly de novo) in SRSF1 gene. They were reported with a neurodevelopmental disorder mainly comprising neurological abnormalities such as intellectual disability/ developmental delay, motor delay, speech delay, and behavioural disorders and facial dysmorphisms. Intellectual disability was present in 16 of 17 individuals (3 severe, 2 moderate, 3 mild to moderate, 3 mild, 1 borderline and 4 unknown severity), while the remaining one had learning disability.

Functional testing of a subset of variants in Drosophila supported pathogenicity in most, but 2 missense variants showed no functional effect and were classified VUS.

This gene has already been associated with neurodevelopmental disorder in both OMIM (MIM #620489) and Gene2Phenotype ('limited' rating in the DD panel).
Sources: Literature
Intellectual disability - microarray and sequencing v5.303 UBAP2L Arina Puzriakova Phenotypes for gene: UBAP2L were changed from Delayed speech and language development; Motor delay; Intellectual disability; Autistic behavior; Seizures; Microcephaly; Abnormality of head or neck; Short stature; Abnormality of the skeletal system to Neurodevelopmental disorder with impaired language, behavioral abnormalities, and dysmorphic facies, OMIM:620494
Intellectual disability - microarray and sequencing v5.298 MTSS1L Arina Puzriakova Phenotypes for gene: MTSS1L were changed from Global developmental delay; Intellectual disability; Ophthalmological anomalies; Microcephaly; Mild facial dysmorphisms to Intellectual developmental disorder with ocular anomalies and distinctive facial features, OMIM:620086
Intellectual disability - microarray and sequencing v5.276 NR2F2 Achchuthan Shanmugasundram changed review comment from: This gene is an established gene for congenital heart defects (MIM #615779) and disorder of sexual differentiation (MIM #618901). This gene has been associated with these two phenotypes in both OMIM and Gene2Phenotype.

PMID:29663647 - An 11-month old boy was reported with global developmental delay, dysmorphic features, coarctation of the aorta, and ventricular septal defect and was identified with pathogenic NR2F2 variant.

PMID:37500725 - 16 previously unreported unrelated individuals (and a mildly affected mosaic mother of one of them) with rare heterozygous variants (majority are de novo variants) were reviewed in this publication and they had variable clinical presentations including intrauterine growth restriction (IUGR), CHD, CDH, genital anomalies, DSD, developmental delays, hypotonia, feeding difficulties, failure to thrive, congenital and acquired microcephaly, dysmorphic facial features, renal failure, hearing loss, strabismus, asplenia, and vascular malformations. All 14 for whom data is available had motor delays and 13 had speech delay. One of them had global developmental delay, one had mild intellectual disability and four had learning disabilities.; to: This gene is an established gene for congenital heart defects (MIM #615779) and disorder of sexual differentiation (MIM #618901). This gene has been associated with these two phenotypes in both OMIM and Gene2Phenotype. Some patients with CHD (MIM #615779) are reported with developmental delays in the OMIM record.

PMID:29663647 - An 11-month old boy was reported with global developmental delay, dysmorphic features, coarctation of the aorta, and ventricular septal defect and was identified with pathogenic NR2F2 variant.

PMID:37500725 - 16 previously unreported unrelated individuals (and a mildly affected mosaic mother of one of them) with rare heterozygous variants (majority are de novo variants) were reviewed in this publication and they had variable clinical presentations including intrauterine growth restriction (IUGR), CHD, CDH, genital anomalies, DSD, developmental delays, hypotonia, feeding difficulties, failure to thrive, congenital and acquired microcephaly, dysmorphic facial features, renal failure, hearing loss, strabismus, asplenia, and vascular malformations. All 14 for whom data is available had motor delays and 13 had speech delay. One of them had global developmental delay, one had mild intellectual disability and four had learning disabilities.
Intellectual disability - microarray and sequencing v5.276 NR2F2 Achchuthan Shanmugasundram changed review comment from: This gene is an established gene for congenital heart defects (MIM #615779) and disorder of sexual differentiation (MIM #618901).

PMID:29663647 - An 11-month old boy was reported with global developmental delay, dysmorphic features, coarctation of the aorta, and ventricular septal defect and was identified with pathogenic NR2F2 variant.

PMID:37500725 - 16 previously unreported unrelated individuals (and a mildly affected mosaic mother of one of them) with rare heterozygous variants (majority are de novo variants) were reviewed in this publication and they had variable clinical presentations including intrauterine growth restriction (IUGR), CHD, CDH, genital anomalies, DSD, developmental delays, hypotonia, feeding difficulties, failure to thrive, congenital and acquired microcephaly, dysmorphic facial features, renal failure, hearing loss, strabismus, asplenia, and vascular malformations. All 14 for whom data is available had motor delays and 13 had speech delay. One of them had global developmental delay, one had mild intellectual disability and four had learning disabilities.; to: This gene is an established gene for congenital heart defects (MIM #615779) and disorder of sexual differentiation (MIM #618901). This gene has been associated with these two phenotypes in both OMIM and Gene2Phenotype.

PMID:29663647 - An 11-month old boy was reported with global developmental delay, dysmorphic features, coarctation of the aorta, and ventricular septal defect and was identified with pathogenic NR2F2 variant.

PMID:37500725 - 16 previously unreported unrelated individuals (and a mildly affected mosaic mother of one of them) with rare heterozygous variants (majority are de novo variants) were reviewed in this publication and they had variable clinical presentations including intrauterine growth restriction (IUGR), CHD, CDH, genital anomalies, DSD, developmental delays, hypotonia, feeding difficulties, failure to thrive, congenital and acquired microcephaly, dysmorphic facial features, renal failure, hearing loss, strabismus, asplenia, and vascular malformations. All 14 for whom data is available had motor delays and 13 had speech delay. One of them had global developmental delay, one had mild intellectual disability and four had learning disabilities.
Intellectual disability - microarray and sequencing v5.274 NR2F2 Achchuthan Shanmugasundram commented on gene: NR2F2: This gene is an established gene for congenital heart defects (MIM #615779) and disorder of sexual differentiation (MIM #618901).

PMID:29663647 - An 11-month old boy was reported with global developmental delay, dysmorphic features, coarctation of the aorta, and ventricular septal defect and was identified with pathogenic NR2F2 variant.

PMID:37500725 - 16 previously unreported unrelated individuals (and a mildly affected mosaic mother of one of them) with rare heterozygous variants (majority are de novo variants) were reviewed in this publication and they had variable clinical presentations including intrauterine growth restriction (IUGR), CHD, CDH, genital anomalies, DSD, developmental delays, hypotonia, feeding difficulties, failure to thrive, congenital and acquired microcephaly, dysmorphic facial features, renal failure, hearing loss, strabismus, asplenia, and vascular malformations. All 14 for whom data is available had motor delays and 13 had speech delay. One of them had global developmental delay, one had mild intellectual disability and four had learning disabilities.
Intellectual disability - microarray and sequencing v5.271 NR2F2 Katherine Lachlan reviewed gene: NR2F2: Rating: GREEN; Mode of pathogenicity: None; Publications: PMID: 37500725; Phenotypes: intrauterine growth restriction (IUGR), CHD, CDH, genital anomalies, DSD, developmental delays, hypotonia, feeding difficulties, failure to thrive, congenital and acquired microcephaly, dysmorphic facial features, renal failure, hearing loss, strabismus, asplenia, vascular malformations; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability - microarray and sequencing v5.271 ESAM Julia Baptista gene: ESAM was added
gene: ESAM was added to Intellectual disability - microarray and sequencing. Sources: Literature,Expert Review
Mode of inheritance for gene: ESAM was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: ESAM were set to PMID: 36996813
Phenotypes for gene: ESAM were set to severe ID; seizures, spasticity
Review for gene: ESAM was set to GREEN
Added comment: Lecca et al 2023 reported thirteen patients from eight unrelated families with biallelic loss of function variants (nonsense, frameshift, canonical splice site, all predicted to result in a transcript targeted for nonsense-mediated decay). Protein staining assays in one of the brain fetal samples confirmed loss the loss of protein.
The phenotype reported in this cohort is of a severe neurodevelopmental disorder with brain anomalies (calcifications, hydrocephalus, enlarged ventricles, cerebral atrophy, etc), and dysmorphic features.
Sources: Literature, Expert Review
Intellectual disability - microarray and sequencing v5.268 U2AF2 celia duff changed review comment from: Literature evidence Ref1-5, identification of affected patients in the diagnostic setting (CVA database, 19:55661148:C>T ) and further accounts in open access databases (ClinVar and LOVD), make this gene suitable for clinical review and upgrading to a green gene status on relevant panels. It is associated with a phenotype encompassing dysmorphism, epilepsy, developmental delay, intellectual disability, and brain malformation Ref1-5. There is a recent publication that proposes an extension of this phenotype to include hypomyelination leukodystrophy Ref6. A loss of function mechanism has been suggested, associated with disruption of RNA recognition motifs required for the function of U2AF2 as a pre-mRNA splicing factor Ref4. At least one recurrent pathogenic variant has been identified by this review U2AF2 c.445C>T p.(Arg149Trp). U2AF2 is constrained for missense in gnomAD Z=4.71.
total variants reported
1) De novo U2AF2 (NM_007279.3:c.445C>T p.(Arg149Trp)) recurrent variant; 1x patient in Hiraide (PubMed: 34112922), 1x patient in Kittock (PubMed: 37092751), 2x patients in Kaplanis (Pubmed: 33057194), 7x patients in the Leiden Open Variation Database (LOVD, https://www.lovd.nl/), 1x patient in house BGL and 4x additional on CVA
2) De novo U2AF2 c.603G>T; 1 patient in Wang 2023 (PubMed: 36747105)
3) De novo U2AF2 c.470C>T p.Pro157Leu) in Kuroda (PubMed: 37134193)
4) 9x additional pathogenic or likely pathogenic variants on LOVD
5) 2x additional likely pathogenic variants on ClinVar

References
1.       PubMed: 28135719 McRae (2017)-DDD data
2.       PubMed: 31785789 Turner (2019)-DDD data
3.       PubMed: 34112922 Hiraide (2021) de novo U2AF2 c.445C>T p.R149W
4.       PubMed: 36747105 Wang (2023) de novo U2AF2 c.603G>T, p.163_201del
5.       PubMed: 37092751 Kittock (2023) de novo U2AF2 c.445C>T p.R149W
Possible emerging phenotype of hypomyelinating leukodystrophy
6.       PubMed: 37134193 Kuroda (2023); to: Literature evidence Ref1-5, identification of affected patients in the diagnostic setting (CVA database, 19:55661148:C>T ) and further accounts in open access databases (ClinVar and LOVD), make this gene suitable for clinical review and upgrading to a green gene status on relevant panels. It is associated with a phenotype encompassing dysmorphism, epilepsy, developmental delay, intellectual disability, and brain malformation Ref1-5. There is a recent publication that proposes an extension of this phenotype to include hypomyelination leukodystrophy Ref6. A loss of function mechanism has been suggested, associated with disruption of RNA recognition motifs required for the function of U2AF2 as a pre-mRNA splicing factor Ref4. At least one recurrent pathogenic variant has been identified by this review U2AF2 c.445C>T p.(Arg149Trp). U2AF2 is constrained for missense in gnomAD Z=4.71.
total variants/patients identified
1) De novo U2AF2 (NM_007279.3:c.445C>T p.(Arg149Trp)) recurrent variant; 1x patient in Hiraide (PubMed: 34112922), 1x patient in Kittock (PubMed: 37092751), 2x patients in Kaplanis (Pubmed: 33057194), 7x patients in the Leiden Open Variation Database (LOVD, https://www.lovd.nl/), 1x patient in house BGL and 4x additional on CVA
2) De novo U2AF2 c.603G>T; 1 patient in Wang 2023 (PubMed: 36747105)
3) De novo U2AF2 c.470C>T p.Pro157Leu) in Kuroda (PubMed: 37134193)
4) 9x additional pathogenic or likely pathogenic variants on LOVD
5) 2x additional likely pathogenic variants on ClinVar
6) We are collaborating with a researcher in the USA with a cohort of 40+ cases.


References
1.       PubMed: 28135719 McRae (2017)-DDD data
2.       PubMed: 31785789 Turner (2019)-DDD data
3.       PubMed: 34112922 Hiraide (2021) de novo U2AF2 c.445C>T p.R149W
4.       PubMed: 36747105 Wang (2023) de novo U2AF2 c.603G>T, p.163_201del
5.       PubMed: 37092751 Kittock (2023) de novo U2AF2 c.445C>T p.R149W
Possible emerging phenotype of hypomyelinating leukodystrophy
6.       PubMed: 37134193 Kuroda (2023)
Intellectual disability - microarray and sequencing v5.268 U2AF2 celia duff reviewed gene: U2AF2: Rating: GREEN; Mode of pathogenicity: None; Publications: (PMID: 28135719):(PMID: 31785789):(PMID: 34112922):(PMID: 36747105):(PMID: 37092751):(PMID 37134193); Phenotypes: intellectual disability, global developmental delay, dysmorphism, epilepsy, brain malformation, microcephaly, possible emerging phenotype of hypomyelinating leukodystrophy.; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability - microarray and sequencing v5.256 NEUROG1 Julia Baptista gene: NEUROG1 was added
gene: NEUROG1 was added to Intellectual disability - microarray and sequencing. Sources: Literature
Mode of inheritance for gene: NEUROG1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NEUROG1 were set to 36647078; 33439489; 23419067; 26077850
Phenotypes for gene: NEUROG1 were set to developmental delay; behavioural problems; cranial dysinnervation; absent corneal reflex
Review for gene: NEUROG1 was set to GREEN
Added comment: Five affected individuals from four independently reported families (Middle Eastern, Portuguese, Indian and Turkish backgrounds) with biallelic microdeletion, missense, nonsense or frameshift variants.

Affected individuals present at birth or in early infancy with corneal opacities due to absent blinking, sensorineural deafness associated with hypoplastic or malformed cochlea and hypoplasia or agenesis of CN VIII was reported. Developmental delay, poor speech, autistic behavior and dysmorphic facial features were also present.
Sources: Literature
Intellectual disability - microarray and sequencing v5.255 PABPC1 Sarah Leigh edited their review of gene: PABPC1: Added comment: PABPC1 variants have not been associated with a phenotype in OMIM, Gen2Phen or MONDO. PMID: 35511136 reports four de novo PABPC1 variants in four unrelated cases with a phenotype of global DD, movement coordination disorders,
seizures, behavioral disorders and mild facial dysmorphisms. Intellectual disability ranged in the cases from profound (1/4), IQ: 61 (1/4) and IQ: 79 (2/4). Seizures were apparent in the all of the three cases where it was assessed.
Molecular modeling of the variants suggested that they would result in a reduced binding affinity to the messenger RNA metabolism-related protein - PAIP2. This predicted effect was seen in coimmunoprecipitation assays between variant PABPC1 and PAIP2 (PMID: 35511136). Further functional studies in PMID: 35511136, showed that the proliferation of neural progenitor cells in Pabpc1 knockdown mouse embryo brains were decreased, this effect was rescued by the wild-type Pabpc1, but not by the variants c.1691A>G (p.Glu564Gly) or c.1709T>C (p.Ile570Thr).
Other variants were identified in 3/4 cases in PMID: 35511136, two of these had a ACMG VUS classification (RBBP4: c.845A>G, p.(Asn282Ser), IGF2R: c.1850G>A p.Cys617Tyr), while the third variant was monoallelic, whereas bialleic variants in this gene are associated with disease (KDM5B: c.2265dupA, p.(Tyr755*))(PMID: 35511136, table 1).; Changed rating: GREEN
Intellectual disability - microarray and sequencing v5.249 MKL2 Achchuthan Shanmugasundram Phenotypes for gene: MKL2 were changed from neurodevelopmental phenotype with dysmorphic features to neurodevelopmental disorder, MONDO:0700092
Intellectual disability - microarray and sequencing v5.247 MKL2 Achchuthan Shanmugasundram commented on gene: MKL2: PMID:37013900 - Two unrelated paediatric cases with de novo variants in MKL2 gene (p.Arg103Gly & p.Ala91Pro) were reported with mild dysmorphic features, severe intellectual disability, global developmental delays, speech apraxia, and impulse control issues. Functional studies in a Drosophila model suggest a gain of function disease mechanism.
Intellectual disability - microarray and sequencing v5.222 PIP5K1C Achchuthan Shanmugasundram gene: PIP5K1C was added
gene: PIP5K1C was added to Intellectual disability - microarray and sequencing. Sources: Literature
Mode of inheritance for gene: PIP5K1C was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: PIP5K1C were set to 37451268
Phenotypes for gene: PIP5K1C were set to neurodevelopmental disorder, MONDO:0700092; intellectual disability, MONDO:0001071
Review for gene: PIP5K1C was set to GREEN
Added comment: Three de novo heterozygous missense variants in PIP5K1C (p.Glu146Lys, p.Tyr205Cys & p.Tyr221Cys) were identified in nine unrelated children exhibiting intellectual disability, developmental delay, acquired microcephaly, seizures, visual abnormalities, and dysmorphic features. Intellectual disability was reported in all nine children and seizures were present in seven children, of which three had developmental and epileptic encephalopathy. In addition, there is functional evidence available, which includes an in vivo zebrafish model that recapitulates the human phenotype (developmental defects affecting the forebrain, including the eyes, as well as craniofacial abnormalities) (PMID:37451268).

This gene has been associated with another phenotype (Lethal congenital contractural syndrome 3, MIM #611369) in both OMIM and Gene2Phenotype, but not yet associated with this neurodevelopmental disorders in either databases.
Sources: Literature
Intellectual disability - microarray and sequencing v5.191 MKL2 Dmitrijs Rots gene: MKL2 was added
gene: MKL2 was added to Intellectual disability - microarray and sequencing. Sources: Literature
Mode of inheritance for gene: MKL2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: MKL2 were set to PMID:37013900
Phenotypes for gene: MKL2 were set to neurodevelopmental phenotype with dysmorphic features
Mode of pathogenicity for gene: MKL2 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: MKL2 was set to GREEN
Added comment: 2 cases with de novo missense GoF variants in MRTFB (previously known as MKL2) + functional evidence
Sources: Literature
Intellectual disability - microarray and sequencing v5.163 TCEAL1 Achchuthan Shanmugasundram changed review comment from: PMID:36368327 reported seven unrelated individuals with de novo variants (2 nonsense, 2 frameshift, 2 CNVs & 1 missense variants) in TCEAL1 gene and presenting with an X-linked dominant neurodevelopmental disorder. All these seven individuals had intellectual disability (mild to severe). The other major clinical presentations include hypotonia, abnormal gait, speech impairment, autistic-like behavior, and mildly dysmorphic facial features.

This gene is associated with relevant phenotypes in OMIM (MIM #301094), but not in Gene2Phenotype.
Sources: Literature; to: PMID:36368327 reported seven unrelated individuals with de novo variants (2 nonsense, 2 frameshift, 2 CNVs & 1 missense variants) in TCEAL1 gene and presenting with an X-linked dominant neurodevelopmental disorder. All these seven individuals had intellectual disability (mild to severe). The other major clinical presentations include hypotonia, abnormal gait, speech impairment, autistic-like behaviour, and mildly dysmorphic facial features.

This gene is associated with relevant phenotypes in OMIM (MIM #301094), but not in Gene2Phenotype.
Sources: Literature
Intellectual disability - microarray and sequencing v5.163 TCEAL1 Achchuthan Shanmugasundram gene: TCEAL1 was added
gene: TCEAL1 was added to Intellectual disability - microarray and sequencing. Sources: Literature
Mode of inheritance for gene: TCEAL1 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: TCEAL1 were set to 36368327
Phenotypes for gene: TCEAL1 were set to Neurodevelopmental disorder with gait disturbance, dysmorphic facies and behavioral abnormalities, X-linked, OMIM:301094
Review for gene: TCEAL1 was set to GREEN
Added comment: PMID:36368327 reported seven unrelated individuals with de novo variants (2 nonsense, 2 frameshift, 2 CNVs & 1 missense variants) in TCEAL1 gene and presenting with an X-linked dominant neurodevelopmental disorder. All these seven individuals had intellectual disability (mild to severe). The other major clinical presentations include hypotonia, abnormal gait, speech impairment, autistic-like behavior, and mildly dysmorphic facial features.

This gene is associated with relevant phenotypes in OMIM (MIM #301094), but not in Gene2Phenotype.
Sources: Literature
Intellectual disability - microarray and sequencing v5.50 OTUD7A Achchuthan Shanmugasundram changed review comment from: PMID:31997314 reported a patient presenting with severe global developmental delay, language impairment and epileptic encephalopathy and was identified with homozygous variant in OTUD7A gene (c.697C>T)/ p.Leu233Phe).

PMID:33381903 reported a patient with profound hypotonia, severe intellectual disability, and seizures and identified with biallelic loss-of-function variants in OTUD7A: a 15q13.3 deletion including the OTUD7A locus, and a frameshift OTUD7A variant c.1125del/ p.Glu375Aspfs*11.

PMID:36180924 reported a patient (patient #4) presenting with severe neurodevelopmental diseases and dysmorphic features and identified with hemizygous OTUD7A frameshift variant allele c.2023_2066del/ p.D675Hfs*188 in trans with the recurrent 15q13.3 BP4-BP5 deletion.

OTUD7A knockout mice exhibited reduced body weight, developmental delay, abnormal electroencephalography patterns and seizures, reduced ultrasonic vocalisations, decreased grip strength, impaired motor learning/motor coordination, and reduced acoustic startle (PMID:29395075). The function evidence also suggest that OTUD7A may be the critical “driver gene” in the 15q13.3 deletion syndrome.; to: PMID:31997314 reported a patient presenting with severe global developmental delay, language impairment and epileptic encephalopathy and was identified with homozygous variant in OTUD7A gene (c.697C>T)/ p.Leu233Phe).

PMID:33381903 reported a patient with profound hypotonia, severe intellectual disability, and seizures and identified with biallelic loss-of-function variants in OTUD7A: a 15q13.3 deletion including the OTUD7A locus, and a frameshift OTUD7A variant c.1125del/ p.Glu375Aspfs*11.

PMID:36180924 reported a patient (patient #4) presenting with severe neurodevelopmental diseases and dysmorphic features and identified with hemizygous OTUD7A frameshift variant allele c.2023_2066del/ p.D675Hfs*188 in trans with the recurrent 15q13.3 BP4-BP5 deletion.

OTUD7A knockout mice exhibited reduced body weight, developmental delay, abnormal electroencephalography patterns and seizures, reduced ultrasonic vocalisations, decreased grip strength, impaired motor learning/motor coordination, and reduced acoustic startle (PMID:29395075). The function evidence also suggest that OTUD7A may be the critical “driver gene” in the 15q13.3 deletion syndrome.

This gene has been reported in the DD panel of Gene2Phenotype (with 'limited' rating), but has not yet been associated with phenotypes in OMIM.
Intellectual disability - microarray and sequencing v5.24 KDM5A Achchuthan Shanmugasundram changed review comment from: PMID:21937992 reported a family with recessive missense KDM5A variant presenting with an undefined developmental disorder characterised with intellectual disability and facial dysmorphisms.

PMID:33350388 reported nine patients from seven unrelated families identified with variants in KDM5A, of which three unrelated patients harboured heterozygous variants, while six patients from four unrelated families had homozygous variants. These patients presented with autism spectrum disorder (ASD) and a spectrum of neurodevelopmental phenotypes including intellectual disability, lack of speech, developmental delay and motor impairment.

In addition, loss of KDM5A has resulted in repetitive behaviors, sociability deficits, cognitive dysfunction, and abnormal dendritic morphogenesis in mice.; to: PMID:21937992 reported a family with recessive missense KDM5A variant presenting with an undefined developmental disorder characterised with intellectual disability and facial dysmorphisms.

PMID:33350388 reported nine patients from seven unrelated families identified with variants in KDM5A, of which three unrelated patients harboured heterozygous variants, while six patients from four unrelated families had homozygous variants. These patients presented with autism spectrum disorder (ASD) and a spectrum of neurodevelopmental phenotypes including intellectual disability, lack of speech, developmental delay and motor impairment.

In addition, loss of KDM5A has resulted in repetitive behaviors, sociability deficits, cognitive dysfunction, and abnormal dendritic morphogenesis in mice.

This gene has already been associated with phenotype in Gene2Phenotype (biallelic inheritance with 'limited' rating), but not in OMIM.
Intellectual disability - microarray and sequencing v5.23 KDM5A Achchuthan Shanmugasundram changed review comment from: PMID:21937992 reported a family with recessive missense KDM5A variant presenting with an undefined developmental disorder characterised with intellectual disability and facial dysmorphisms.

PMID:33350388 reported nine patients from seven unrelated families identified with variants in KDM5A, of which three unrelated patients harboured heterozygous variants, while six patients from four unrelated families had homozygous variants. These patients presented with autism spectrum disorder (ASD) and a spectrum of neurodevelopmental phenotypes including intellectual disability, lack of speech, developmental delay and motor impairment.; to: PMID:21937992 reported a family with recessive missense KDM5A variant presenting with an undefined developmental disorder characterised with intellectual disability and facial dysmorphisms.

PMID:33350388 reported nine patients from seven unrelated families identified with variants in KDM5A, of which three unrelated patients harboured heterozygous variants, while six patients from four unrelated families had homozygous variants. These patients presented with autism spectrum disorder (ASD) and a spectrum of neurodevelopmental phenotypes including intellectual disability, lack of speech, developmental delay and motor impairment.

In addition, loss of KDM5A has resulted in repetitive behaviors, sociability deficits, cognitive dysfunction, and abnormal dendritic morphogenesis in mice.
Intellectual disability - microarray and sequencing v5.19 KDM5A Achchuthan Shanmugasundram changed review comment from: PMID:21937992 reported a family with recessive missense KDM5A variant presenting with an undefined developmental disorder characterised with intellectual disability and facial dysmorphisms.

PMID:33350388 reported nine patients from seven unrelated families identified with variants in KDM5A, of which three unrelated patients harboured heterozygous variants, while six patients from four unrelated families had homozygous variants. These patients presented with autism spectrum disorder (ASD) and a spectrum of neurodevelopmental phenotypes including intellectual disability, lack of speech and developmental delay.; to: PMID:21937992 reported a family with recessive missense KDM5A variant presenting with an undefined developmental disorder characterised with intellectual disability and facial dysmorphisms.

PMID:33350388 reported nine patients from seven unrelated families identified with variants in KDM5A, of which three unrelated patients harboured heterozygous variants, while six patients from four unrelated families had homozygous variants. These patients presented with autism spectrum disorder (ASD) and a spectrum of neurodevelopmental phenotypes including intellectual disability, lack of speech, developmental delay and motor impairment.
Intellectual disability - microarray and sequencing v4.112 SUPT16H Achchuthan Shanmugasundram Phenotypes for gene: SUPT16H were changed from Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum to Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum
Intellectual disability - microarray and sequencing v4.112 SUPT16H Achchuthan Shanmugasundram Phenotypes for gene: SUPT16H were changed from Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum to Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum
Intellectual disability - microarray and sequencing v4.112 SUPT16H Achchuthan Shanmugasundram Phenotypes for gene: SUPT16H were changed from Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum to Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum
Intellectual disability - microarray and sequencing v4.111 SUPT16H Achchuthan Shanmugasundram Phenotypes for gene: SUPT16H were changed from Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum to Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum
Intellectual disability - microarray and sequencing v4.111 SUPT16H Achchuthan Shanmugasundram Phenotypes for gene: SUPT16H were changed from Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum to Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum
Intellectual disability - microarray and sequencing v4.111 SUPT16H Achchuthan Shanmugasundram Phenotypes for gene: SUPT16H were changed from Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum to Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum
Intellectual disability - microarray and sequencing v4.111 SUPT16H Achchuthan Shanmugasundram Phenotypes for gene: SUPT16H were changed from Global developmental delay; Intellectual disability; Abnormality of the corpus callosum to Neurodevelopmental disorder with dysmorphic facies and thin corpus callosum, OMIM:619480; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum
Intellectual disability - microarray and sequencing v4.96 CTR9 Achchuthan Shanmugasundram edited their review of gene: CTR9: Added comment: As noted by the reviewer, PMID: 35499524 reported 13 unrelated cases identified with heterozygous variants in CTR9 gene (11 different variants) and they presented with overlapping neurodegenerative phenotypes including intellectual disability, hypotonia, joint hyperlaxity, speech delay, coordination problems, tremor, and autism spectrum disorder. Mild dysmorphism and cardiac anomalies were less frequent. The intellect levels were determined only for 11 patients (the rest are too young) and 8 out of these 11 patients were reported with variable degree of intellectual disability, while other three had impairments in other domains or learning difficulties.

PMID:35717577 reported two additional unrelated cases with non-synonymous heterozygous CTR9 variants (p.Glu15Asp and p.Pro25Arg) and they presented with macrocephaly, motor delay, and intellectual disability. In addition, functional studies in zebrafish also showed that knockout/ over-expression of CTR9 variants caused motor defects and enlargement of telencephalon (homologous to the mammalian cerebrum).

This gene has not yet been associated with relevant phenotypes in OMIM. It has been associated with Wilms tumour in Gene2Phenotype (phenotype not relevant to this panel).; Changed rating: GREEN; Changed publications to: 35499524, 35717577
Intellectual disability - microarray and sequencing v4.95 RBSN Achchuthan Shanmugasundram gene: RBSN was added
gene: RBSN was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: RBSN was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: RBSN were set to 25233840; 29784638; 35652444
Phenotypes for gene: RBSN were set to intellectual disability, MONDO:0001071
Review for gene: RBSN was set to GREEN
Added comment: PMID:25233840 reported a 6.5 year old female patient with a homozygous missense variant c.1273G > A (p.Gly425Arg) and her clinical presentation included intractable seizures, developmental delay, microcephaly, dysostosis, osteopenia, craniofacial dysmorphism, macrocytosis and megaloblastoid erythropoiesis.

PMID:29784638 reported three siblings with homozygous variant c.289G>C (p.Gly97Arg) in RBSN. The proband presented global developmental delay, had complete 46,XY male-to-female sex reversal and died at age 20 months after multiple infections. The other 2 affected siblings underwent unrelated-donor bone marrow or stem cell transplantation at 8 and 6.5 months of age, respectively. Both have severe intellectual disability and are nonambulatory and nonverbal.

PMID:35652444 reported two unrelated families (three siblings from a family of Iranian descent identified with homozygous variant c.547G>A (p.Gly183Arg) and four members from a family of indigenous Cree descent identified with homozygous variant c.538C>G (p.Arg180Gly)) with overlapping phenotypes including developmental delay, intellectual disability, distal motor axonal neuropathy and facial dysmorphism.
Sources: Literature
Intellectual disability - microarray and sequencing v4.93 DPYSL2 Achchuthan Shanmugasundram changed review comment from: This gene should be rated AMBER, as it has been associated with intellectual disability (ID) from two unrelated cases displaying monoallelic variants in DPYSL2/ CRMP2, and supported by functional studies. However, the evidence is not sufficient for green rating as there are variants reported in other (but different) genes in the two patients.

PMID:35861646 reported two cases identified with heterozygous variants (patient1: c.1693C>T (p.Arg565Cys); patient 2: c.42C>A (p.Ser14Arg). These patients had overlapping phenotypes including dysmorphic features, severe global developmental delay and hypoplasia of the corpus callosum. In addition, patient 2 was bed-ridden and could not roll out and had a history of myoclonic seizures and status epilepticus.

It should be noted that patient 1 is compound heterozygous for 2 missense variants in the EFCAB5 gene and was hemizygous for a maternally inherited missense variant in the GPKOW gene and patient 2 had 1 de novo missense variant in the COBLL1 gene and was compound heterozygous for 2 missense variants in the POTEF gene. The severity of the phenotypes between the two cases differs significantly and the additional variants may have possibly contributed to this phenotype.

Brain-specific Crmp2 knockout mice display neuronal development deficits and behavioural impairments associated with hypoplasia of the corpus callosum. In addition, functional studies performed in zebrafish and cell lines that the CRMP2 variants lead to the loss-of-function of CRMP2 protein and can cause intellectual disability.
Sources: Literature; to: This gene should be rated AMBER, as it has been associated with intellectual disability (ID) from two unrelated cases displaying monoallelic variants in DPYSL2/ CRMP2, and supported by functional studies. However, the evidence is not sufficient for green rating as there are variants reported in other (but different) genes in the two patients.

PMID:35861646 reported two cases identified with heterozygous variants (patient1: c.1693C>T (p.Arg565Cys); patient 2: c.42C>A (p.Ser14Arg). These patients had overlapping phenotypes including dysmorphic features, severe global developmental delay and hypoplasia of the corpus callosum. In addition, patient 2 was bed-ridden and could not roll out and had a history of myoclonic seizures and status epilepticus.

It should be noted that patient 1 is compound heterozygous for 2 missense variants in the EFCAB5 gene and was hemizygous for a maternally inherited missense variant in the GPKOW gene and patient 2 had 1 de novo missense variant in the COBLL1 gene and was compound heterozygous for 2 missense variants in the POTEF gene. The severity of the phenotypes between the two cases differs significantly and the additional variants may have possibly contributed to this phenotype.

Brain-specific Crmp2 knockout mice display neuronal development deficits and behavioural impairments associated with hypoplasia of the corpus callosum. In addition, functional studies performed in zebrafish and cell lines that the CRMP2 variants lead to the loss-of-function of CRMP2 protein and can cause intellectual disability.

This gene has not yet been associated with relevant phenotypes either in OMIM or in Gene2Phenotype.
Sources: Literature
Intellectual disability - microarray and sequencing v4.93 DPYSL2 Achchuthan Shanmugasundram gene: DPYSL2 was added
gene: DPYSL2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DPYSL2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: DPYSL2 were set to 27249678; 35861646
Phenotypes for gene: DPYSL2 were set to intellectual disability, MONDO:0001071; Aplasia/Hypoplasia of the corpus callosum, HP:0007370
Review for gene: DPYSL2 was set to AMBER
Added comment: This gene should be rated AMBER, as it has been associated with intellectual disability (ID) from two unrelated cases displaying monoallelic variants in DPYSL2/ CRMP2, and supported by functional studies. However, the evidence is not sufficient for green rating as there are variants reported in other (but different) genes in the two patients.

PMID:35861646 reported two cases identified with heterozygous variants (patient1: c.1693C>T (p.Arg565Cys); patient 2: c.42C>A (p.Ser14Arg). These patients had overlapping phenotypes including dysmorphic features, severe global developmental delay and hypoplasia of the corpus callosum. In addition, patient 2 was bed-ridden and could not roll out and had a history of myoclonic seizures and status epilepticus.

It should be noted that patient 1 is compound heterozygous for 2 missense variants in the EFCAB5 gene and was hemizygous for a maternally inherited missense variant in the GPKOW gene and patient 2 had 1 de novo missense variant in the COBLL1 gene and was compound heterozygous for 2 missense variants in the POTEF gene. The severity of the phenotypes between the two cases differs significantly and the additional variants may have possibly contributed to this phenotype.

Brain-specific Crmp2 knockout mice display neuronal development deficits and behavioural impairments associated with hypoplasia of the corpus callosum. In addition, functional studies performed in zebrafish and cell lines that the CRMP2 variants lead to the loss-of-function of CRMP2 protein and can cause intellectual disability.
Sources: Literature
Intellectual disability - microarray and sequencing v4.92 NUP214 Eleanor Williams changed review comment from: Associated with {Encephalopathy, acute, infection-induced, susceptibility to, 9} 618426 in OMIM and Gene2Phenotype (probable).

PMID: 31178128 - Fichtman et al 2019 - report on two families one of Palestinian decent, the other Northern European (not Finnish descent). Each had two affected siblings in which neurological decline was seen after febrile events. The older son in family A, exhibited minor developmental delay from infancy. A homozygous missense variant was identified in NUP214 (p.Arg38Cys) in family A and segregated with the disease in available family members. In family B affected sisters were compound heterozygous for a frameshift and a missense variant in NUP214 (p.Pro387Ser and p.Pro525Leufs∗6). Functional studies with fibroblasts from one patient in family A showed a decrease in NUP214 and NUP88 levels compared to controls,

PMID: 30758658 - Shamseldin et al 2019 - describe a multiplex consanguineous family in which four affected members presented with severe neonatal hypotonia, profound global developmental delay, progressive microcephaly and early death (<2 year old). Whole exome sequencing revealed the presence of a novel homozygous missense variant in NUP214, p.D154G.

PMID: 29483668 - Egloff et al 2018 - report a 4-year-old girl presenting with developmental delay, growth retardation and facial dysmorphism. She was found to have a 9q deletion inherited from her healthy mother and a hemizygous one-base pair deletion in the NUP214 gene inherited from her father. From patient leukocytes it was found that the expression level of the NUP214 transcript was significantly decreased and close to zero in the patient compared to the controls. ; to: Associated with {Encephalopathy, acute, infection-induced, susceptibility to, 9} 618426 in OMIM and Gene2Phenotype (probable).

PMID: 31178128 - Fichtman et al 2019 - report on two families one of Palestinian decent, the other Northern European (not Finnish descent). Each had two affected family members in which neurological decline was seen after febrile events. The older son in family A, exhibited minor developmental delay from infancy. A homozygous missense variant was identified in NUP214 (p.Arg38Cys) in family A and segregated with the disease in available family members. In family B affected sisters were compound heterozygous for a frameshift and a missense variant in NUP214 (p.Pro387Ser and p.Pro525Leufs∗6). Functional studies with fibroblasts from one patient in family A showed a decrease in NUP214 and NUP88 levels compared to controls,

PMID: 30758658 - Shamseldin et al 2019 - describe a multiplex consanguineous family in which four affected members presented with severe neonatal hypotonia, profound global developmental delay, progressive microcephaly and early death (<2 year old). Whole exome sequencing revealed the presence of a novel homozygous missense variant in NUP214, p.D154G.

PMID: 29483668 - Egloff et al 2018 - report a 4-year-old girl presenting with developmental delay, growth retardation and facial dysmorphism. She was found to have a 9q deletion inherited from her healthy mother and a hemizygous one-base pair deletion in the NUP214 gene inherited from her father. From patient leukocytes it was found that the expression level of the NUP214 transcript was significantly decreased and close to zero in the patient compared to the controls.
Intellectual disability - microarray and sequencing v4.81 TASP1 Achchuthan Shanmugasundram Phenotypes for gene: TASP1 were changed from Developmental delay; microcephaly; dysmorphic features; congenital abnormalities to Suleiman-El-Hattab syndrome, OMIM:618950
Intellectual disability - microarray and sequencing v4.68 CHAMP1 Achchuthan Shanmugasundram Phenotypes for gene: CHAMP1 were changed from Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579 to Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579
Intellectual disability - microarray and sequencing v4.68 CHAMP1 Achchuthan Shanmugasundram Phenotypes for gene: CHAMP1 were changed from Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579 to Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579
Intellectual disability - microarray and sequencing v4.68 CHAMP1 Achchuthan Shanmugasundram Phenotypes for gene: CHAMP1 were changed from Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579 to Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579
Intellectual disability - microarray and sequencing v4.68 CHAMP1 Achchuthan Shanmugasundram Phenotypes for gene: CHAMP1 were changed from Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579 to Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579
Intellectual disability - microarray and sequencing v4.67 CHAMP1 Achchuthan Shanmugasundram Phenotypes for gene: CHAMP1 were changed from Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579 to Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579
Intellectual disability - microarray and sequencing v4.67 CHAMP1 Achchuthan Shanmugasundram Phenotypes for gene: CHAMP1 were changed from Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579 to Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579
Intellectual disability - microarray and sequencing v4.67 CHAMP1 Achchuthan Shanmugasundram Phenotypes for gene: CHAMP1 were changed from INTELLECTUAL DISABILITY to Neurodevelopmental disorder with hypotonia, impaired language, and dysmorphic features, OMIM:616579
Intellectual disability - microarray and sequencing v4.62 TRPM3 Eleanor Williams Phenotypes for gene: TRPM3 were changed from Generalized hypotonia; Global developmental delay; Intellectual disability; Seizures; Autistic behavior to Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skeletal anomalies, with or without seizures, OMIM:620224
Intellectual disability - microarray and sequencing v4.61 PGM2L1 Achchuthan Shanmugasundram Phenotypes for gene: PGM2L1 were changed from Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191 to Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191
Intellectual disability - microarray and sequencing v4.60 PGM2L1 Achchuthan Shanmugasundram Phenotypes for gene: PGM2L1 were changed from Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191 to Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191
Intellectual disability - microarray and sequencing v4.61 PGM2L1 Achchuthan Shanmugasundram Phenotypes for gene: PGM2L1 were changed from Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191 to Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191
Intellectual disability - microarray and sequencing v4.60 PGM2L1 Achchuthan Shanmugasundram Phenotypes for gene: PGM2L1 were changed from Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191 to Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191
Intellectual disability - microarray and sequencing v4.60 PGM2L1 Achchuthan Shanmugasundram Phenotypes for gene: PGM2L1 were changed from Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191 to Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191
Intellectual disability - microarray and sequencing v4.60 PGM2L1 Achchuthan Shanmugasundram Phenotypes for gene: PGM2L1 were changed from Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191 to Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191
Intellectual disability - microarray and sequencing v4.60 PGM2L1 Achchuthan Shanmugasundram Phenotypes for gene: PGM2L1 were changed from Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191 to Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191
Intellectual disability - microarray and sequencing v4.60 PGM2L1 Achchuthan Shanmugasundram Phenotypes for gene: PGM2L1 were changed from Neurodevelopmental disorder to Neurodevelopmental disorder with hypotonia, dysmorphic facies, and skin abnormalities, OMIM:620191
Intellectual disability - microarray and sequencing v4.56 ISCA-37420-Loss Arina Puzriakova Phenotypes for Region: ISCA-37420-Loss were changed from PMID: 18628315 developmental delay, hypotonia, facial dysmorphisms including a long face, a tubular or pear-shaped nose and a bulbous nasal tip, and a friendly/amiable behaviour, other clinically important features include epilepsy, heart defects and kidney/urologic anomalies; 610443; PMID: 25217958; Koolen-De Vries syndrome 610443 to Koolen-De Vries syndrome, OMIM:610443; Developmental delay/intellectual disability, hypotonia, distinctive facial features, congenital malformations, and behavioural feature
Intellectual disability - microarray and sequencing v4.55 ISCA-37420-Loss Arina Puzriakova commented on Region: ISCA-37420-Loss: Previously in phenotypes field:

PMID: 18628315 developmental delay, hypotonia, facial dysmorphisms including a long face, a tubular or pear-shaped nose and a bulbous nasal tip, and a friendly/amiable behaviour, other clinically important features include epilepsy, heart defects and kidney/urologic anomalies; 610443; PMID: 25217958; Koolen-De Vries syndrome 610443
Intellectual disability - microarray and sequencing v4.55 ISCA-37408-Loss Arina Puzriakova Phenotypes for Region: ISCA-37408-Loss were changed from PMID: 16963482 idiopathic intellectual disability including moderate to severe intellectual disability, autism/autistic features, microcephaly, structural brain anomalies including cortical dysplasia/pachygyria, renal anomalies (multicystic kidney, hydronephrosis), digital camptodactyly, visual impairment, strabismus, neuromotor deficits, communication and attention impairments, and a distinctive pattern of craniofacial features. Dysmorphic craniofacial features include progressive microcephaly, flat occiput, widened inner canthal distance, small palpebral fissures, ptosis, long and straight eyelashes, broad and high nasal root extending to a widened, prominent nasal tip with elongated, smooth philtrum, rounding of the upper vermillion border and everted lower lips. PMID: 18245392 A 32-year-old, mentally retarded male was referred to our centre for further clinical genetic analysis. He was born to non-consanguineous parents after 42 weeks gestation with a birth weight of 3500 g. He had a healthy older brother. In the neonatal period he was hypotonic and at 8 weeks of age he underwent surgery because of an inguinal hernia with removal of an atrophic right testis. His motor development was severely delayed with sitting at 3.5 years and walking at 5 years of age. Speech was poorly developed, characterised by the usage of only a few words. During infancy an optic nerve hypoplasia was diagnosed, and during childhood he frequently suffered from luxations of the patellae, which required surgery. At the age of 32 years his height is 163 cm (_3 SDS) and head circumference 52.5 cm (_2.5 SDS). He has a narrow receding forehead, widened inner canthal distance of 3.5 cm (90th centile), normal outer canthal distance of 8.5 cm (25th centile), telecanthus, short and down slanting palpebral fissures, epicanthal folds, ptosis, long, straight eyelashes, high nasal bridge, low set large ears, flat philtrum, small mouth with high, narrow palate and retrognathia. The thorax is broad with increased internipple distance and slight gynaecomastia. A recent renal ultrasound revealed multiple cysts in the left, dystrophic kidney and two uncomplicated cysts in the enlarged, right kidney. The patient has a normally sized phallus with absent right testis and small left testis. His hands show a simian crease right and tapering fingers with broad proximal interphalangeal joints. He shows sandal gaps on both flat feet with clinodactyly of the fourth and fifth toes (and more); 612513; PMID: 22579565 severe developmental delay, congenital microcephaly, intractable epilepsy, and renal anomalies, as well as a congenital choledochal cyst which has not been previously reported in other patients with this cytogenetic defect to Dysmorphic features, moderate to severe intellectual disability, microcephaly and renal anomalies
Intellectual disability - microarray and sequencing v4.46 BAP1 Mafalda Gomes commented on gene: BAP1: Kry et al. (2022) performed trio-WES in a cohort with a rare syndromic NDD and identified de novo missense variants in 11 unrelated individuals. All individuals had DD or ID characterised notably by speech (11/11) and motor delay (6/11). Additional common characteristics were hypotonia, (7/11), seizures (6/11), and abnormal behaviour (8/10), including ASD, ADHD, and hypersensitivity. Almost all individuals showed dysmorphic facial features (10/11), and more than half (6/11) had skeletal malformations involving the hands, feet, or spine. Functional analysis showed that most of the variants cannot rescue the consequences of BAP1 inactivation, suggesting a loss-of-function mechanism. In T cells isolated from two affected children, H2A deubiquitination was impaired. In summary, this gene should be promoted to GREEN in this panel, with autosomal dominant mode of inheritance.
Intellectual disability - microarray and sequencing v4.43 TMEM147 Sarah Leigh gene: TMEM147 was added
gene: TMEM147 was added to Intellectual disability. Sources: Literature
Q1_23_promote_green tags were added to gene: TMEM147.
Mode of inheritance for gene: TMEM147 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TMEM147 were set to 36044892
Phenotypes for gene: TMEM147 were set to Neurodevelopmental disorder with facial dysmorphism, absent language, and pseudo-Pelger-Huet anomaly, OMIM:620075
Review for gene: TMEM147 was set to GREEN
Added comment: Associated with relevant phenotype in OMIM and as strong Gen2Phen gene. PMID: 36044892 reports 12 variants in at least 15 unrelated derived from GeneMatcher. Supportive functional evidence is also presented.
Sources: Literature
Intellectual disability - microarray and sequencing v4.21 SOX4 Arina Puzriakova Phenotypes for gene: SOX4 were changed from Coffin-Siris syndrome 10, 618506; Syndromic intellectual disability; Global developmental delay; Intellectual disability; Growth delay; Clinodactyly of the 5th finger; facial dysmorphism to Coffin-Siris syndrome 10, OMIM:618506; Syndromic intellectual disability; Global developmental delay; Intellectual disability; Growth delay; Clinodactyly of the 5th finger; facial dysmorphism
Intellectual disability - microarray and sequencing v4.18 KLHL20 Arina Puzriakova Added comment: Comment on list classification: There is sufficient evidence to promote this gene to Green at the next GMS panel review.
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Sleyp et al. 2022 (PMID: 36214804) reported on 14 patients with de novo missense variants who all presented with mild to severe ID, seizures, ASD, hyperactivity, and dysmorphic facial features. One variant (c.1069G>A, p.Gly357Arg) was recurrent in 11/14 cases but all variants clustered in the Kelch-type β-propeller domain (substrate binding surface) of the KLHL20 protein. No functional studies were performed but given the overlap in clinical presentation observed in patients with the same recurrent variant but also multiple different variants, its worth including as diagnostic-grade.
Intellectual disability - microarray and sequencing v4.15 RPL10 Dmitrijs Rots reviewed gene: RPL10: 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: 35876338; Phenotypes: ID, dysmorphic features, progressive postnatal microcephaly, and retinal anomalies; Mode of inheritance: X-LINKED: hemizygous mutation in males, biallelic mutations in females
Intellectual disability - microarray and sequencing v3.1769 JARID2 Eleanor Williams Phenotypes for gene: JARID2 were changed from Intellectual disability; Neurodevelopmental syndrome to Intellectual disability; Neurodevelopmental syndrome; Developmental delay with variable intellectual disability and dysmorphic facies, OMIM:620098
Intellectual disability - microarray and sequencing v3.1768 HNRNPR Eleanor Williams Phenotypes for gene: HNRNPR were changed from Global developmental delay; Intellectual disability; Seizures; Postnatal microcephaly; Short digit to Global developmental delay; Intellectual disability; Seizures; Postnatal microcephaly; Short digit; Neurodevelopmental disorder with dysmorphic facies and skeletal and brain abnormalities, OMIM:620073
Intellectual disability - microarray and sequencing v3.1767 HNRNPH1 Eleanor Williams Phenotypes for gene: HNRNPH1 were changed from HNRNPH1‐related syndromic intellectual disability to HNRNPH1‐related syndromic intellectual disability; Neurodevelopmental disorder with craniofacial dysmorphism and skeletal defects, OMIM:620083
Intellectual disability - microarray and sequencing v3.1733 MTSS1L Arina Puzriakova gene: MTSS1L was added
gene: MTSS1L was added to Intellectual disability. Sources: Literature
new-gene-name, Q4_22_rating tags were added to gene: MTSS1L.
Mode of inheritance for gene: MTSS1L was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: MTSS1L were set to 36067766
Phenotypes for gene: MTSS1L were set to Global developmental delay; Intellectual disability; Ophthalmological anomalies; Microcephaly; Mild facial dysmorphisms
Review for gene: MTSS1L was set to GREEN
Added comment: Huang et al. 2022 (PMID: 36067766) reported five unrelated individuals with the same heterozygous de novo variant (c.2011C>T; p.Arg671Trp) in MTSS2 (formally known as MTSS1L). Linkage analysis was not performed but given the variants arose de novo and the mixed ethnicity of the affected individuals (4 European, 1 Chinese) a founder effect can be ruled out.

Subjects displayed a shared phenotype of GDD and/or ID, ophthalmological anomalies (most commonly nystagmus), microcephaly (primary in 2, relative in 3) and shared mild facial dysmorphisms. The single adult patient also presented with seizures and optic atrophy.

Functional studies showed the variant leads to a decrease in mRNA level but does not impact protein levels of MTSS2. However, a Drosophila model demonstrated that loss of the fly ortholog results in defects in locomotor and visual functions which were rescued by human MTSS2 and only partially rescued by the MTSS2 c.2011C>T variant. Overexpression of the c.2011C>T variant caused similar phenotypes as the LoF mutant indicating a possible dominant-negative effect.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1701 UBAP2L Konstantinos Varvagiannis gene: UBAP2L was added
gene: UBAP2L was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: UBAP2L was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: UBAP2L were set to 35977029
Phenotypes for gene: UBAP2L were set to Delayed speech and language development; Motor delay; Intellectual disability; Autistic behavior; Seizures; Microcephaly; Abnormality of head or neck; Short stature; Abnormality of the skeletal system
Penetrance for gene: UBAP2L were set to unknown
Review for gene: UBAP2L was set to GREEN
Added comment: Based on Jia et al (2022 - PMID: 35977029) speech, motor delay as well as ID are observed in individuals harboring de novo pLoF variants in UBAP2L. The gene encodes a regulator of the stress granule (SG) assembly. Extensive evidence is provided on the effect of variants as well as the role of UBAP2L and other genes for components and/or regulation of SG in pathogenesis of NDDs. Among others a Ubap2l htz deletion mouse model (behavioral and cognitive impairment, abnormal cortical development due to impaired SG assembly, etc). Data from 26 previous studies, aggregating 40,853 probands with NDDs (mostly DD/ID, also ASD) suggest enrichment for DNMs in UBAP2L or other genes previously known and further shown to be important for SG formation (incl. G3BP1/G3BP2, CAPRIN1).

Details provided below.

Not associated with any phenotype in OMIM, G2P or SysNDD.

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Jia et al (2022 - PMID: 35977029) describe 12 affected individuals with heterozygous de novo pLoF variants in UBAP2L.

Phenotype: Features included hypotonia, speech (11/11) and motor delay (8/12), ID (8/10 with formal evaluation), variable behavioral concerns (ADHD 5/11, ASD in 4/10, etc). Seizures were reported in 7/12 with 3/10 having a formal diagnosis of epilepsy. Few had microcephaly (3/10). Facial dysmorphisms were common (9/9) and included abnormal palpebral fissures, deep prominent concha, high broad forehead, hypertelorism, thin upper lip and mild synophrys (each in 4 or less individuals). Short stature or skeletal alterations were described in some (4/10 each).

Role of the gene: UBAP2L encodes an essential regulator of stress granule assembly. Stress granules are membraneless cytoplasmic compartments in eukaryotic cells, induced upon a variety of stressors and playing a role in regulation of gene expression.

Variants identified : 9 nonsense/frameshift UBAP2L variants and 3 splicing ones were reported, in all cases as de novo events, upon trio/quad exome sequencing. All were absent from gnomAD. There were no other causative variants.

Variant effect/studies (NM_014847.4 / NP_055662.3) :
- Minigene assays revealed that the 3 splice variants all resulted in out-of-frame exon skipping.
- In patient fibroblasts one of these splice variants was demonstrated to result to reduced protein levels.
- 8 of the 9 nonsense/frameshift variants were predicted to result to NMD.
- 1 nonsense variant (c.88C>T/p.Q30*) was shown to result to decreased protein expression in patient fibroblasts, with detection of the protein using an antibody for the C terminus but not the N terminus. Protein N-terminal sequencing confirmed that the protein lacked the N terminus, with utilization of an alternative start site (11 codons downstream).
- Generation of HeLa UBAP2L KO cell lines resulted in significant reduction of SG numbers which was also the case for 4 variants studied, under stress conditions.
- The protein has a DUF domain (aa 495-526) known to mediate interaction of UBAP2L with G3BP1 (a stress granule marker) with deletions of this domain leading to shuttling of UBAP2L from the cytoplasm to the nucleus. Truncating variants upstream of the DUF domain were shown to result in nuclear localization.

Mouse model :
- The authors generated Ubap2l KO model with hmz deletion of Ubap2l resulting in a lethal phenotype (2.6% survived) and htz deletion leading to behavioral issues (low preference for social novelty, anxious-like behaviors) and cognitive impairment.
- Ubap2l haploinsufficiency resulted in abnormal cortical development and lamination with reduction of neural progenitor proliferation.
- Ubap2l deficiency was shown to impair SG assembly during cortical development both under physiological stress conditions or upon utilization of an oxidative stress inducer.

Additional evidence of UBAP2L and SG overall in pathogenesis of NDDs:
- Based on DNMs from 40,853 individuals with NDDs from 26 studies (9,228 with ASD, 31,625 with DD/ID) the authors demonstrate significant excess of DNM in 31 genes encoding SG components, regulators or both, the latter being the case for UBAP2L and 2 further genes (G3BP1 and G3BP2 - both with crucial roles in SG assembly).
- Excess dn splice-site (N=3) and missense (N=5) variants in G3BP1 were observed in the above cohort [c.95+1G>A, c.353+1G>T, c.539+1G>A / p.S208C, R320C, V366M].
- Excess dn missense (N=7) variants in G3BP2 were observed in the above cohort [p.R13W, D151N, E158K, L209P, E399D, K408E, R438C].
- Generation of G3BP1 or G3BP2 KO HeLa cell lines and immunofluorescence upon use of oxidative stress inducer revealed significant reduction of stress granules.
- Generation of HeLa cell lines for 5 G3BP1 mutants (R78C*, R132I*, S208C*, R320C*, V366M) and 7 G3BP2 mutants (p.R13W*, D151N*, E158K, L209P*, E399D, K408E, R438C) revealed that several (those in asterisk) resulted in significantly fewer SG formation under oxidative stress compared to WT while the subcellular distribution of the proteins under stress was identical to WT.
- Among the identified genes for SG enriched for DNMs, CAPRIN1 was implicated in previous publications as a NDD risk gene with 3 dn missense SNVs reported (p.I373K, p.Q446H, p.L484P). CAPRIN1 binding to G3BP1/2 has been shown to promote SG formation. Significant reduction of SG was observed in CAPRIN1 KO HeLa lines. p.I373K abolished interaction with G3BP1/2 and disrupted SG formation.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1687 NRCAM Sarah Leigh edited their review of gene: NRCAM: Added comment: Associated with relevant phenotype in OMIM and as moderate Gen2Phen gene for NRCAM neurodevelopmental disorder with dysmorphic features, hypotonia and spasticity. At least 12 variants have been reported in PMID: 35108495 in 8 unrelated cases (table 1). Global developmental delay / intellectual disabilty was evident in 5/7 unrelated cases (individual 1 was not considered as they also had homozygous loss-of-function variant in CD55 (OMIM: 125240)(PMID: 35108495).; Changed rating: GREEN
Intellectual disability - microarray and sequencing v3.1662 TAF4 Eleanor Williams commented on gene: TAF4: Not associated with a phenotype in OMIM or Gene2Phenotype.

PMID: 33875846 - Bertoli-Avella et al 2021 - identified two de novo LoF variants (splicing and nonsense) in two unrelated patients with dysmorphic features and one with intellectual disability and one with delayed speech and language development with global developmental delay.

PMID: 28191890 - Kosmicki et al 2017 - report a child with autism with an indel in TAF4 leading to a frameshift. No phenotypic details provided.

PMID: 27026076 - Langer et al 2016 - Taf4a−/− (gene encoding Taf4) mouse embryos survive until E9.5, but show severe growth retardation and specific defects in anterior and ventral patterning and morphogenesis.
Intellectual disability - microarray and sequencing v3.1624 GNB2 Arina Puzriakova Phenotypes for gene: GNB2 were changed from Intellectual disability to Neurodevelopmental disorder with hypotonia and dysmorphic facies, OMIM:619503
Intellectual disability - microarray and sequencing v3.1606 ATP6V0A1 Mike Spiller changed review comment from: Bott et al 2021 PMID: 34909687

17 individuals from 14 unrelated families

12 individuals with de novo variants in ATP6V0A1.
Associated with severe intellectual disability and refractory seizures following initial normal development.
1 stillborn; other 11 all have intellectual disability and slowing of developmental progression. 10 have epilepsy, microcephaly also common and MRI abnormalities in some.
Dysmorphic features less common.

7/12 have recurrent hotspot variant NM_001130021.3 c.2219G>A R740Q.

Biallelic inheritance also suggested - 2 separate families (apparently unrelated by IBD analysis) with affected individuals compound heterozygous for c.445delG p.(Glu149fs) and c.1483C>T p.(Arg495Trp).
Phenotype of ID, epilepsy, but with ataxia and cerebellar anomalies.

Gene involved in proton transport into organelles. Cell lines stably expressing R740Q show reduced endolysosome acidification consistent with reduced transporter function.
Supported by data showing impaired maturation of Cathepsin D (requires acidic pH).
Also refer to studies of yeast homologue showing that R735 (corresponds to human R740) is essential for proton transport function (Kawasaki-Nishi et al 2001 PMID: 11592980).

Strong evidence that pathogenic missense variants in this gene cause severe ID/epilepsy, Less certain for biallelic inheritance.
Recommend upgrade to Green for ID and epilepsy.; to: Bott et al 2021 PMID: 34909687

17 individuals from 14 unrelated families

12 individuals with de novo variants in ATP6V0A1.
Associated with severe intellectual disability and refractory seizures following initial normal development.
1 stillborn; other 11 all have intellectual disability and slowing of developmental progression. 10 have epilepsy, microcephaly also common and MRI abnormalities in some.
Dysmorphic features less common.

7/12 have recurrent hotspot variant NM_001130021.3 c.2219G>A R740Q.

Biallelic inheritance also suggested - 2 separate families (apparently unrelated by IBD analysis) with affected individuals compound heterozygous for c.445delG p.(Glu149fs) and c.1483C>T p.(Arg495Trp).
Phenotype of ID, epilepsy, but with ataxia and cerebellar anomalies.

Gene involved in proton transport into organelles. Cell lines stably expressing R740Q show reduced endolysosome acidification consistent with reduced transporter function.
Supported by data showing impaired maturation of Cathepsin D (requires acidic pH).
Also refer to studies of yeast homologue showing that R735 (corresponds to human R740) is essential for proton transport function (Kawasaki-Nishi et al 2001 PMID: 11592980).

Strong evidence that heterozygous pathogenic missense variants in this gene cause severe ID/epilepsy, Less certain for biallelic inheritance.
Recommend upgrade to Green for ID and epilepsy.
Intellectual disability - microarray and sequencing v3.1606 HIST1H4J Arina Puzriakova Phenotypes for gene: HIST1H4J were changed from microcephaly; intellectual disability; dysmorphic features to ?Tessadori-van Haaften neurodevelopmental syndrome 2 , OMIM:619759
Intellectual disability - microarray and sequencing v3.1593 ALKBH8 Konstantinos Varvagiannis edited their review of gene: ALKBH8: Added comment: Please consider upgrade to green rating.

2 additional relevant families reported in literature, as summarized below. While affected individuals from 3 (of the 4 total) families with the disorder were homozygous for truncating variants in the last exon (potentially corresponding to hypomorphic / incomplete LoF rather than null alleles), a more recent publication describes 2 sibs homozygous for a missense SNV with demonstrated loss-of-function in the context of normal protein levels.

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Saad et al (2020 - PMID: 33544954) report 2 sibs, born to consanguineous parents from Egypt homozygous for an ALKBH8 frameshift variant. Both exhibited global DD and ID (proband IQ of 51 / Stanford Binet test, sib: 42 using Weschler scale). There was no history of seizures. Family based exome sequencing of both sibs and parents revealed homozygosity for NM_001301010.1:c.1684delC [p.(Arg562Alafs*56))] within a region of AOH. As the authors note this variant also occurred in the last exon of the gene, likely escaping NMD and based on previous evidence from Monnies et al, hypothesize that truncating variants in the last exon represent hypomorphic alleles encoding for a partially functional protein, while protein truncating variants in earlier exons may be null alleles.

Maddirevula et al (2021 - PMID: 34757492) describe the phenotype of 2 sibs, homozygous for a missense variant. Features included severe DD and ID, microcephaly, facial dysmorphism and epilepsy (the latter limited to the elder one). Exome with autozygome analysis identified homozygosity for a missense variant (NM_138775.2:c.1874G>A / p.Arg625His) with Sanger for confirmation / segregation studies.LC-MS/MS using tRNA isolated from LCLs from the affected individual, a carrier parent and controls revealed complete loss of ALKBH8-dependent tRNA posttranscriptional modifications, the results being suggestive of abrogation of the catalytic activities of both MT and Ox domains. The protein was detected at low levels in LCLs from control and patient samples, a finding that was also supported by immunoblot analysis suggesting that the observed loss-of-function is not mediated by loss of the protein.; Changed rating: GREEN; Changed publications to: 33544954, 34757492
Intellectual disability - microarray and sequencing v3.1580 SRRM2 Konstantinos Varvagiannis changed review comment from: Recent report of 22 unrelated individuals with nonsense / frameshift variants or microdeletions of SRRM2 reported. DD was a universal feature, with ID present in some (16/20 - in all cases mild). Note possible 'overlap' with the study by Kaplanis et al / DDD study cited in the previous review by Prof. Z. Stark.

The gene is not intolerant to missense variation (z-score of -6.28) and eventual contribution of missense variants is not known. While SRRM2 is known to encode a splicing factor promoting interaction between mRNA and the spliceosome catalytic machinery (discussed below) molecular and functional studies are required to characterize the pathogenesis of the disorder.

There is currently no SRRM2-related phenotype in OMIM. SRRM2 is included in the DD panel of G2P [confidence : definitive, SRRM2-related developmental disorder (monoallelic), cited : Kaplanis et al / DDD]. In PanelApp Australia SRRM2 has amber rating in the ID panel (based on the study by Kaplanis et al / DDD).

Consider inclusion with green rating (several individuals/families/variants - rather consistent phenotype) or amber rating (as for pathogenesis / also DD universal feature, ID observed in most but not all affected individuals, when present always mild).

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Cuinat et al. (2022 - PMID: 35567594) report on 22 individuals with LoF variants in SRRM2.

All subjects had DD (22/22) predominantly affecting language acquisition (16/19) while motor delay was less common. ID was present in 16/20 (in all cases mild) of the individuals with available neurocognitive evaluation. Some individuals displayed autistic features (9/22) although others had a friendly - in some cases excessively - sociable personality (8/22). Other features included hypotonia in some, growth abnormalities (12/22 overweight, 7/22 with obesity, 4/22 tall stature). Morphological features incl. facial (20/22 - e.g. deep-set eyes, bulbous nasal tip or smooth philtrum) or small hands and feet (6/22) were also reported. Visceral / skeletal abnormalities were uncommon.

SRRM2 encodes serine/arginine repetitive matrix protein 2 (or SRm300), a nuclear ubiquitous protein forming a complex with the protein encoded by SRRM1 (SRm160). As the authors summarize this complex is one of the main catalytic components of the spliceosome having a role in pre-mRNA maturation.

12 subjects harbored frameshift variants, 8 nonsense while 2 further ones had microdeletions (66-270kb) spanning - but not limited to - SRRM2 (other genes not predicted to be haploinsufficient). The gene has a pLI in gnomAD of 1 (o/e = 0.06) while it appears to be tolerant to missense variation (z-score of -6.28 / o/e = 1.43). With the exception of the 2 subjects harboring a microdeletion, all were investigated with singleton/trio ES with no other candidate variants.

Variants occurred de novo in 19/22. Mosaicism (in an asymptomatic parent) was suspected based on the reads in one case. One individual had inherited the variant (parent with DD). Segregation analyses was not possible in one case.

While one variant lied in ex2 (of 15) all others were in the large ex11 (encoding ~2000 of the 2752 total residues based on the schema provided / NM_016333.4), all predicted to lead to NMD.

There are no studies for pathogenesis of the disorder or the underlying effect of variants. Animal models not discussed.

The authors do a comparison with other 'spliceosomopathies', e.g. due to variants in SF3B4 or EFTUD2, where DD/ID can be a feature although these disorders have also prominent skeletal features.

Previously, as the authors note, the study by Kaplanis et al (2020 - PMID: 33057194) integrating exome sequence data from ~31,000 parent-offspring trios of individuals with developmental disorders had identified SRRM2 among 28 genes significantly enriched in LoF variants. [ The present study possibly includes individuals from the aforementioned cohort, e.g. from Radboudumc ].; to: Recent report of 22 unrelated individuals with nonsense / frameshift variants or microdeletions of SRRM2. DD was a universal feature, with ID present in some affected individuals (16/20 - in all cases mild). Note possible 'overlap' with the study by Kaplanis et al / DDD study cited in the previous review by Prof. Z. Stark.

The gene is not intolerant to missense variation (z-score of -6.28) and eventual contribution of missense variants is not known. While SRRM2 is known to encode a splicing factor promoting interaction between mRNA and the spliceosome catalytic machinery (discussed below) molecular and functional studies are required to characterize the pathogenesis of the disorder.

There is currently no SRRM2-related phenotype in OMIM. SRRM2 is included in the DD panel of G2P [confidence : definitive, SRRM2-related developmental disorder (monoallelic), cited : Kaplanis et al / DDD]. In PanelApp Australia SRRM2 has amber rating in the ID panel (based on the study by Kaplanis et al / DDD).

Consider inclusion with green rating (several individuals/families/variants - rather consistent phenotype) or amber rating (as for pathogenesis / also DD universal feature, ID observed in most but not all affected individuals, when present always mild).

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Cuinat et al. (2022 - PMID: 35567594) report on 22 individuals with LoF variants in SRRM2.

All subjects had DD (22/22) predominantly affecting language acquisition (16/19) while motor delay was less common. ID was present in 16/20 (in all cases mild) of the individuals with available neurocognitive evaluation. Some individuals displayed autistic features (9/22) although others had a friendly - in some cases excessively - sociable personality (8/22). Other features included hypotonia in some, growth abnormalities (12/22 overweight, 7/22 with obesity, 4/22 tall stature). Morphological features incl. facial (20/22 - e.g. deep-set eyes, bulbous nasal tip or smooth philtrum) or small hands and feet (6/22) were also reported. Visceral / skeletal abnormalities were uncommon.

SRRM2 encodes serine/arginine repetitive matrix protein 2 (or SRm300), a nuclear ubiquitous protein forming a complex with the protein encoded by SRRM1 (SRm160). As the authors summarize this complex is one of the main catalytic components of the spliceosome having a role in pre-mRNA maturation.

12 subjects harbored frameshift variants, 8 nonsense while 2 further ones had microdeletions (66-270kb) spanning - but not limited to - SRRM2 (other genes not predicted to be haploinsufficient). The gene has a pLI in gnomAD of 1 (o/e = 0.06) while it appears to be tolerant to missense variation (z-score of -6.28 / o/e = 1.43). With the exception of the 2 subjects harboring a microdeletion, all were investigated with singleton/trio ES with no other candidate variants.

Variants occurred de novo in 19/22. Mosaicism (in an asymptomatic parent) was suspected based on the reads in one case. One individual had inherited the variant (parent with DD). Segregation analyses was not possible in one case.

While one variant lied in ex2 (of 15) all others were in the large ex11 (encoding ~2000 of the 2752 total residues based on the schema provided / NM_016333.4), all predicted to lead to NMD.

There are no studies for pathogenesis of the disorder or the underlying effect of variants. Animal models not discussed.

The authors do a comparison with other 'spliceosomopathies', e.g. due to variants in SF3B4 or EFTUD2, where DD/ID can be a feature although these disorders have also prominent skeletal features.

Previously, as the authors note, the study by Kaplanis et al (2020 - PMID: 33057194) integrating exome sequence data from ~31,000 parent-offspring trios of individuals with developmental disorders had identified SRRM2 among 28 genes significantly enriched in LoF variants. [ The present study possibly includes individuals from the aforementioned cohort, e.g. from Radboudumc ].
Intellectual disability - microarray and sequencing v3.1564 ADD1 Konstantinos Varvagiannis gene: ADD1 was added
gene: ADD1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: ADD1 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: ADD1 were set to 34906466
Phenotypes for gene: ADD1 were set to Global developmental delay; Intellectual disability; Seizures; Ventriculomegaly; Abnormality of the corpus callosum
Penetrance for gene: ADD1 were set to unknown
Review for gene: ADD1 was set to AMBER
Added comment: A recent study suggests an ADD1-related phenotype (3 subjects with monoallelic de novo variants/1 with biallelic variants) with DD/ID and ventriculomegaly or corpus callosum dysgenesis and possibly seizures among the features.

There is currently no associated phenotype in other databases (OMIM, G2P, SysID, PanelApp Australia).

Consider inclusion in the current panel with amber / green rating (3 subjects/variants/families, role of the gene and mouse models recapitulating ventriculomegaly/CC abnormalities, relevant expression, variant studies demonstrating abn. protein levels and/or disruption of adducin heterodimer formation || monoallelic vs bi-allelic variants).

Please consider inclusion in other possibly relevant gene panels (e.g. for corpus callosum / ventriculomegaly) [ Not added ].

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Qi et al (2022 - PMID: 34906466) describe the phenotype of 3 unrelated individuals with monoallelic de novo ADD1 pathogenic variants as well as of a fourth homozygous for a missense SNV.

Overall, the authors propose a common phenotype consisting of morphological brain abnormalities (incl. ventriculomegaly and corpus callosum dysgenesis) and neurological symptoms such as DD and/or ID and attention deficit.

All individuals were investigated with singleton/trio ES.

De novo variants - phenotype:
One individual investigated for hypotonia, DD & ID, partial ACC, well controlled seizures (on ketogenic diet) and proportional short stature harbored a de novo stopgain variant (NM_014189.3:c.1418G>A / p.Trp473*) absent from gnomAD.
Another affected subject with hypotonia, FTT/feeding difficulties, mild motor delays complete ACC, a seizure (2y11m), staring spells without EEG correlate, and fatigue (with low coenz. Q10, and complex I & IV deficiency in muscle biopsy) had a de novo fs variant (NM_001119:c.2029_2039del / p.Glu680Argfs*7 - gnomAD:0) and a VUS in a gene not associated with phenotype to date.
A 3rd subject investigated for seizures (onset:1y), speech delay, mild ID, ADHD, without MRI abnormalities harbored a de novo missense SNV (NM_001119:c.670C>T / p.His224Tyr - gnomAD:0) and with cmp htz for 2 missense SPTBN2 SNV not fitting the phenotype (no ataxia).

Biallelic variants - phenotype:
One individual with ID, and ACC, abnormal sulcation, enlarged lateral and 3rd ventricles, abnormal of white matter and hypoplastic vermis upon MRI was reported to harbor in homozygosity a missense SNV (NM_001119:c.169A>T / p.Arg57Trp). There was an additional variant in a gene without associated phenotype to date and not expressed in brain.

Role of the encoded protein:
ADD1 encodes adducin 1/alpha (similar to ADD2, ADD3 encoding other adducins). As the authors note, adducins are cytoskeleton proteins critical for osmotic rigidity and cell shape. In neurons they have been reported to form membrane associated periodic ring-like structures with actin and β-spectrin. Deletion of Add1 in mice results in increased MPS ring diameter and axonal degeneration (several refs provided).

ADD1/2/3 form heterodimers which in turn form heterotetramers. ADD1 is expressed in most tissues.

Mouse model:
Previous mouse models have demonstrated that Add1 null mice have also undetectable ADD2/3 (suggesting a role for stabilization of the latter) and exhibit growth delay, anemia and develop lethal hydrocephalus and ventriculomegaly with 50% penetrance (cited PMIDs: 27068466, 18723693). Here the authors demonstrated that surviving mice had ventriculomegaly and thinning of corpus callosum thus recapitulating the respective human phenotypes. Htz mice also presented thinner CC, though not to a statistically significant extent.

ADD1 expression and isoforms:
- Performing mRNA studies and W.Blot in (developing - GW15-17) human or mouse brain (E12.5-P40) the authors demonstrated dynamic expression of ADD1 with differentially expressed isoforms, notably alternative splicing of ex10 and ex15 with NM_176801 (extended ex10, inclusion of ex15) corresponding to a neuronal isoform and NM_001119 (shorter ex10, exclusion of ex15) corresponding to a neural progenitor cell (NPC) isoform.
- Variants here reported appear to affect both isoforms with the exception of NM_001119:c.2029_2039del / p.Glu680Argfs*7 affecting only the longer NPC one.
- PTBP1 is an RNA binding protein expressed in NPCs known to suppress neuronal exon insertion. The authors demonstrated in mouse Neuro2A cells, through shRNA targeting of Ptbp1, that the latter suppresses the neuronal Add1 isoform.

Variant studies demonstrated that effect of variants was mediated by decreased protein levels and/or disruption of adducin complex formation (ADD1-ADD2 dimer formation known to be mediated by N- and C- terminal ADD1 domains):
- Expression of Arg57Trp (found in hmz in one individual) NPC and neuronal isoforms in Neuro2a cells showed that while protein levels were not significantly affected, there were (also) truncated protein products for both isoforms suggesting that aberrant splicing or protein translation/cleavage may apply.
- The authors generated HEK293FT cells for the truncating variants demonstrating decreased protein levels (using N-/C- terminal antibodies).
- Reduced (HA-tagged)-ADD1-(V5-tagged)-ADD2 protein interaction was shown to apply for the Arg57Trp and Arg473* in HEK293FT cells. Similarly in Neuro2a cells, reduced ADD1-ADD2 interaction was shown for His224Tyr.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1562 CTR9 Konstantinos Varvagiannis gene: CTR9 was added
gene: CTR9 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CTR9 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CTR9 were set to 35499524; 2815719; 25363760; 27479843; 25099282; 29292210
Phenotypes for gene: CTR9 were set to Delayed speech and language development; Motor delay; Intellectual disability; Behavioral abnormality; Autistic behavior; Failure to thrive; Feeding difficulties; Abnormality of the cardiovascular system
Penetrance for gene: CTR9 were set to unknown
Mode of pathogenicity for gene: CTR9 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: CTR9 was set to AMBER
Added comment: Meuwissen, Verstraeten, Ranza et al (2022 - PMID: 35499524) describe the phenotype of 13 unrelated individuals harboring heterozygous - predominantly de novo - CTR9 missense variants.

Overlapping features included delayed speech and/or motor development (each in 9 cases) with the latter complicated by hypotonia or hyperlaxity in some cases. Balance or coordination problems were also reported in some. Variable degrees of ID ranging from mild to severe were observed in all individuals of relevant age except for 3 who however experienced impairment in other domains and/or learning difficulties (8/11 - 2 individuals were too young for evaluation). Few had evidence of regression. Other features included behavioral abnormalities (incl. ASD in 4), FTT/feeding problems (in 5), cardiovascular findings (in 4 - incl. infantile thoracic aortic aneurysm, VSD, pulm. valve stenosis, SVAS). The authors reported variable/nonspecific dysmorphic features.

WES revealed heterozygous CTR9 missense variants in all cases (NM_014633.5 as RefSeq). The variants occurred de novo in most (11/13) individuals with a one proband having inherited the variant from his affected parent. For one case, a single parental sample was available. Most SNVs were absent from gnomAD with the exception of c.1364A>G/p.Asn455Ser and c.2633G>A/p.Arg878Gln present once in the database (Z-score for CTR9: 4.3 / pLI : 1). The variants affected highly conserved residues with in silico predictions mostly in favor of a deleterious effect.

CTR9 encodes a subunit of the PAF1 complex (PAF1C) with the other subunits encoded by PAF1, LEO1, CDC73, RTF1 and WDR61/SKI8. The complex acts as a transcriptional regulator with CTR9 binding RNA polymerase II. The complex influences gene expression by promoting H2BK123 ubiquitylation, H3K4 and H3K36 methylation. In yeast, Paf1 and Ctr9 appear to mediate involvement of Paf1C in induction of mitophagy (several Refs provided).

In silico modeling: a group of N-terminal variants likely destabilize structure, another group possibly perturbs CTR9-PAF1 interactions and a 3rd class influences interactions with other subunits. p.Glu15Lys did not appear to influence protein stability.

Functional studies: H3K4/H3K36 methylation analysis, mitochondrial quality assessment and RNA-seq studies in fibroblasts did not provide conclusive evidence for downstream consequences of the variants (albeit a brain-specific effect - as demonstrated for other disorders – cannot be excluded).

Animal models: In zebrafish, the Paf1C complex has been shown to play a role in cardiac specification and heart morphogenesis with ctr9 mutants showing severe defects in morphogenesis of primitive heart tube (cited PMID: 21338598). This supports a role of the CTR9 variants in the cardiac abnormalities observed in 4 individuals. Although Paf1C zebrafish homologues are required for Notch-regulated transcription (cited PMID: 17721442), there was no supporting evidence from RNA-seq analyses performed by the authors. In Drosophila, Ctr9 has a key role at multiple stages of nervous system development in Drosophila (cited PMID: 27520958). In rat, Ctr9 is expressed in dopaminergic neurons, with its expression not restricted to the nucleus, regulating dopamine transporter activity (cited PMID: 26048990).

As commented, de novo CTR9 variants have been identified in indivdiduals with developmental disorders in larger cohorts, though without phenotypic details (DDD study - PMID:2815719, De Rubeis et al, 2014 - PMID: 25363760, Lelieveld et al PMID: 27479843) [ https://denovo-db.gs.washington.edu/denovo-db/QueryVariantServlet?searchBy=Gene&target=CTR9 ]

Two previous studies (Hanks et al, 2014 - PMID: 25099282, Martins et al 2018, PMID: 29292210) have identified individuals with pLoF variants [in almost all cases leading to skipping of ex9 e.g. NM_014633.4:c.958-9A>G or (RefSeq not provided) c.1194+2T>C, c.1194+3A>C, the single exception being c.106C>T/p.Q36*] in individuals and families with Wilms tumor after exclusion of other genetic causes. Analyses of tumor samples revealed in several of these cases either LOH (most commonly) or truncating variants as second hits. These individuals did not display neurodevelopmental phenotypes (despite detailed clinical information provided in the 2 studies). CTR9 is included in the gene panels for WT and Tumor predisposition - childhood onset with green rating. [In addition few individuals with hyperparathyroidism jaw tumor syndrome due to heterozygous variants in CDC73 - another subunit of the PAF1 complex - have been reported with WT].

Given these reports, commenting on the embryonic lethality of Ctr9 homozygous ko mice (MGI) and the observation of only missense variants in their cohort Meuwissen, Verstraeten, Ranza et al presume that a dominant-negative effect may apply for the variants they report.

Consider inclusion in the current panel with amber (variant effect/underlying mechanism unknown) or green rating (>3 individuals/families/variants, multiple reports, some supporting evidence from animal models).
Sources: Literature
Intellectual disability - microarray and sequencing v3.1561 DALRD3 Konstantinos Varvagiannis changed review comment from: Biallelic pathogenic DALRD3 variants cause ?Developmental and epileptic encephalopathy 86 (# 618910).

Lentini et al (2020 - PMID: 32427860) report 2 sibs born to first cousin parents, homozygous for a DALRD3 pathogenic variant.

Both exhibited hypotonia, severe global DD and epilepsy (onset of seizures at the age 6-7m, poorly controlled by AEDs in one) corresponding overall to an developmental and epileptic encephalopathy. The authors reported subtle dysmorphic features. Other findings included GI concerns (in both) with microcephaly, CHD or renal anomalies in the younger.

WES guided by autozygome analysis revealed homozygosity for a DALRD3 stopgain variant (NM_001009996.3:c.1251C>A/pTyr417*) with Sanger sequencing confirming status of the children and carrier state of the parents.

DALRD3 encodes DALR anticodon-binding domain-containing protein 3. A DALR

It's DALR anticodon-binding domain is similar to those found in arginyl-tRNA synthetases RARS1/2.

As the authors demonstrate, and (better) summarized in OMIM, its product is a tRNA-binding protein that interacts with METTL2 to facilitate 3-methylcytosine (m3C) modification - by METTL2 - at position 32 of the anticodon loop in specific arginine tRNAs, namely tRNA-Arg-UCU and tRNA-Arg-CCU. In particular, DALRD3 seems to serve as discrimination factor required for recognition of these specific tRNAs.

In addition to DALRD3, a DALR anticodon-binding domain is also found in arginyl-tRNA synthetases (the cytoplasmic RARS1, and mitochondrial RARS2).

Given the variant type observed, predicting truncation of the protein and/or NMD, in LCLs from the 2 sibs (and comparison with controls) the authors demonstrated that the levels of full-length DALRD3 were decreased in cell lysates, with severe reduction (/loss) of m3C modification of the specific arginine tRNAs, which was not observed for other tRNAs (eg. tRNA-Ser-UGA) or controls. These findings were suggestive of c.1251C>A / pTyr417* being a partial LoF allele.

As the authors discuss, defects in tRNA modification have been associated with numerous human - among others neurological and neurodevelopmental - disorders (cited PMID: 30529455, table 1 of this review summarizing these incl. ADAT3-, PUS3-, TRMT1- related NDDs, etc).

Consider inclusion in the current panel with amber rating.
Sources: Literature; to: Biallelic pathogenic DALRD3 variants cause ?Developmental and epileptic encephalopathy 86 (# 618910).

Lentini et al (2020 - PMID: 32427860) report 2 sibs born to first cousin parents, homozygous for a DALRD3 pathogenic variant.

Both exhibited hypotonia, severe global DD and epilepsy (onset of seizures at the age 6-7m, poorly controlled by AEDs in one) corresponding overall to an developmental and epileptic encephalopathy. The authors reported subtle dysmorphic features. Other findings included GI concerns (in both) with microcephaly, CHD or renal anomalies in the younger.

WES in both followed by autozygome analysis revealed homozygosity for a DALRD3 stopgain variant (NM_001009996.3:c.1251C>A/pTyr417*) with Sanger sequencing confirming status of the children and carrier state of the parents.

DALRD3 encodes DALR anticodon-binding domain-containing protein 3. A DALR

As the authors demonstrate, and (better) summarized in OMIM, its product is a tRNA-binding protein that interacts with METTL2 to facilitate 3-methylcytosine (m3C) modification - by METTL2 - at position 32 of the anticodon loop in specific arginine tRNAs, namely tRNA-Arg-UCU and tRNA-Arg-CCU. In particular, DALRD3 seems to serve as discrimination factor required for recognition of these specific tRNAs.

In addition to DALRD3, a DALR anticodon-binding domain is also found in arginyl-tRNA synthetases (the cytoplasmic RARS1, and mitochondrial RARS2).

Given the variant type observed, predicting truncation of the protein and/or NMD, in LCLs from the 2 sibs (and comparison with controls) the authors demonstrated that the levels of full-length DALRD3 were decreased in cell lysates, with severe reduction (/loss) of m3C modification of the specific arginine tRNAs, which was not observed for other tRNAs (eg. tRNA-Ser-UGA) or controls. These findings were suggestive of c.1251C>A / pTyr417* being a partial LoF allele.

As the authors discuss, defects in tRNA modification have been associated with numerous human - among others neurological and neurodevelopmental - disorders (cited PMID: 30529455, table 1 of this review summarizing these incl. ADAT3-, PUS3-, TRMT1- related NDDs, etc).

Consider inclusion in the current panel with amber rating.

Sources: Literature
Intellectual disability - microarray and sequencing v3.1561 DALRD3 Konstantinos Varvagiannis gene: DALRD3 was added
gene: DALRD3 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DALRD3 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: DALRD3 were set to 32427860
Phenotypes for gene: DALRD3 were set to ?Developmental and epileptic encephalopathy 86, # 618910
Penetrance for gene: DALRD3 were set to Complete
Review for gene: DALRD3 was set to AMBER
Added comment: Biallelic pathogenic DALRD3 variants cause ?Developmental and epileptic encephalopathy 86 (# 618910).

Lentini et al (2020 - PMID: 32427860) report 2 sibs born to first cousin parents, homozygous for a DALRD3 pathogenic variant.

Both exhibited hypotonia, severe global DD and epilepsy (onset of seizures at the age 6-7m, poorly controlled by AEDs in one) corresponding overall to an developmental and epileptic encephalopathy. The authors reported subtle dysmorphic features. Other findings included GI concerns (in both) with microcephaly, CHD or renal anomalies in the younger.

WES guided by autozygome analysis revealed homozygosity for a DALRD3 stopgain variant (NM_001009996.3:c.1251C>A/pTyr417*) with Sanger sequencing confirming status of the children and carrier state of the parents.

DALRD3 encodes DALR anticodon-binding domain-containing protein 3. A DALR

It's DALR anticodon-binding domain is similar to those found in arginyl-tRNA synthetases RARS1/2.

As the authors demonstrate, and (better) summarized in OMIM, its product is a tRNA-binding protein that interacts with METTL2 to facilitate 3-methylcytosine (m3C) modification - by METTL2 - at position 32 of the anticodon loop in specific arginine tRNAs, namely tRNA-Arg-UCU and tRNA-Arg-CCU. In particular, DALRD3 seems to serve as discrimination factor required for recognition of these specific tRNAs.

In addition to DALRD3, a DALR anticodon-binding domain is also found in arginyl-tRNA synthetases (the cytoplasmic RARS1, and mitochondrial RARS2).

Given the variant type observed, predicting truncation of the protein and/or NMD, in LCLs from the 2 sibs (and comparison with controls) the authors demonstrated that the levels of full-length DALRD3 were decreased in cell lysates, with severe reduction (/loss) of m3C modification of the specific arginine tRNAs, which was not observed for other tRNAs (eg. tRNA-Ser-UGA) or controls. These findings were suggestive of c.1251C>A / pTyr417* being a partial LoF allele.

As the authors discuss, defects in tRNA modification have been associated with numerous human - among others neurological and neurodevelopmental - disorders (cited PMID: 30529455, table 1 of this review summarizing these incl. ADAT3-, PUS3-, TRMT1- related NDDs, etc).

Consider inclusion in the current panel with amber rating.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1561 DPH5 Konstantinos Varvagiannis gene: DPH5 was added
gene: DPH5 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DPH5 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: DPH5 were set to 35482014
Phenotypes for gene: DPH5 were set to Abnormality of prenatal development or birth; Neonatal hypotonia; Global developmental delay; Intellectual disability; Seizures; Abnormality of the cardiovascular system; Abnormality of the globe; Feeding difficulties; Short stature; Abnormality of head or neck
Penetrance for gene: DPH5 were set to unknown
Review for gene: DPH5 was set to AMBER
Added comment: Shankar et al (2022 - PMID: 35482014) present evidence for a diphthamide-deficiency syndrome due to biallelic DPH5 pathogenic variants.

As the authors summarize, DPH5 encodes a methyltransferase critical to the biosynthesis of diphthamide. Diphthamide is a post translationally modified histidine residue found in eukaryotic elongation factor 2 (eEF2). eEF2 is essential for mRNA translation and protein synthesis. The role of diphthamide is not clear, although it serves as a target for ADP-ribosylation, the latter resulting in inactivation of the eEF2 (inhibition of its translocation activity) and arrest of protein synthesis. Biosynthesis of diphthamide is complex involving multiple components (DPH1-DPH7) and the methylating co-factor S-adenosyl methionine, with 2 diphthamide-deficiency disorders due to biallelic DPH1 or DPH2 pathogenic variants and a NDD phenotype reported to date.

The authors describe a phenotypic spectrum associated with biallelic DPH5 variants ranging from a prenatally lethal presentation to profound neurodevelopmental disorder. Details are provided on 5 individuals from 3 unrelated families. While one subject died at the age of few days due to multisystem complications, the phenotype appeared to be relatively consistent with prenatal findings (decreased fetal movements in 2 from 2 families, polyhydramnios in 2 from 2 families), hypotonia, global DD and ID (4/4 from 2 families - profound in 3), seizures (3/5 from 2 families - abnormal EEG in 4/4), cardiovascular findings (5/5, MVP and regurgitation in 2 from Fam1 || aortic dilatation in 2 sibs from Fam2 || VSD, ASD and hypopl. PA, pericardial effusion in 5th), GI issues (5/5, poor feeding in 4), short stature (4/4). Ocular findings were reported in 3/4 (gray sclerae in 2, ocular melanocytosis in 2). The authors describe some common craniofacial findings incl. broad/prominent forehead (5/5), sparse eyebrows (4/5), downturned corners of mouth or triangular chin (each in 3/5).

WES/WGS revealed biallelic DPH5 variants in all affected individuals, namely: homozygosity for a missense variant in 2 sibs (NM_001077394.2:c.779A>G/p.His260Arg). Homozygosity for c.521dupA/p.Asn174LysTer10 for the individual deceased in the neonatal period (for this family there was significant history of spontaneous miscarriages/stillbirth/neonatal death). Two sibs born to non-consanguineous parents were compound htz for a stopgain and a missense SNV (c.619C>T/p.Arg207*, c.329A>G/p.Asn110Ser).

In silico modeling revealed that the pLoF variants, not predicted to lead to NMD, likely remove the domain for interaction with eEF2 while the missense ones also affected interaction with eEF2.

In recombinant MCF7 breast cancer cell line-derived DPH5-knockouts, transfected with recombinant expr. plasmids encoding wt or the 4 variants, the 2 truncating variants were shown to affect ADP-ribosylation of eEF2's diphthamide (total lack / minimal enzymatic activity for Arg207* and Asn174Lysfs respectively). Asn110Ser and His260Arg had residual activities which was thought to be explained by high expression levels compensating partial inactivation (given the multicopy plasmid-driven expression).

ADP-ribosylation assays in S. cerevisiae demonstrated loss of function for the 2 truncating variants. Although the 2 missense variants retained sufficient activity to produce diphthamide (assayed through toxin induced ADP-ribosylation of eEF2), more sensitive assays indicated that diphthamide synthesis was also partially compromised for both variants.

Generation of a knockin mouse model for His260Arg, appeared to recapitulate the human phenotypes with craniofacial, ophthalmologic, cardiac and visceral abnormalities and hmz mice being subviable. A single homozygous liveborn mouse had low birthweight, FTT, craniofacial dysmorphology, polydactyly, abnormal grooming behavior and early death. Few heterozygous embryos had craniofacial features, decreased body weight, reduced neuromuscular function without other abnormalities, either due to their inbred background or in the context of milder phenotype of heterozygosity in mice.

DPH5 is ubiquitously expressed in all human tissues. The gene has a pLI of 0 and LOEUF score of 0.77 (0.48-1.27) in gnomAD. The authors refer to unpublished data, noting that complete absence of DPH5 is incompatible with life with embryonic lethality of a Dph5(ko/ko) line.

The phenotype bears similarities to DPH1- and DPH2- related NDDs (both AR / green and amber respectively in ID panel) and appears to be more severe compared to the phenotype of de novo EEF2 variants (cited PMID: 33355653).

Please consider inclusion in the ID panel with amber (4 individuals from 2 families with ID) / green rating (rather consistent phenotype in 3 families probably representing a continuous spectrum, variant studies, mouse model, similarities with diphthamide-deficiency syndromes). Also consider amber rating in the epilepsy panel (3 individuals from 2 families reported). The gene may be also relevant in other gene panels e.g. for congenital heart disease, short stature, etc (not added).
Sources: Literature
Intellectual disability - microarray and sequencing v3.1561 CCDC82 Konstantinos Varvagiannis gene: CCDC82 was added
gene: CCDC82 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CCDC82 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CCDC82 were set to 27457812; 28397838; 35118659; 35373332
Phenotypes for gene: CCDC82 were set to Global developmental delay; Intellectual disability; Spastic paraparesis
Penetrance for gene: CCDC82 were set to Complete
Review for gene: CCDC82 was set to AMBER
Added comment: The phenotype of individuals with biallelic CCDC82 variants has been reported - in most cases briefly - in the following reports (each summarizing the findings of previous ones):

Riazzudin et al (2017 - PMID: 27457812) in a large consanguineous pedigree from Pakistan (PKMR206) identified 4 individuals homozygous for a fs variant [NM_024725.3:c.373delG / p.(Asp125Ilefs*6)] (V3,V4,V5,V10). There was no other variant segregating with the phenotype of ID (Delayed CMS, moderate ID and speech delay probably common to all, V3,4,5 had also mild hypotonia and motor weakness). There was one unaffected sib tested (homozygous for ref. alelle). 2 further affected males (V1, V2) with similar phenotype were not tested.

Harripaul et al (2018 - PMID: 28397838) reported 2 sibs with nonsyndromic ID belonging to a consanguineous family (AS17) from the Middle-East. Both were homozygous for NM_024725.3:c.535C>T / p.Arg179*. The variant was confirmed with Sanger sequencing and parents were heterozygous carriers. Two additional affected sibs were probably not tested.

Yahia et al (2022 - PMID: 35118659) described 2 sibs belonging to a consanguineous family from Sudan. These presented global DD (last evaluation at 4y and 9m) and spasticity. There was a common history of infantile spasms with the elder developing GTC convulsions with spontaneous resolution. Additionaly, both presented microcephaly (<-2 and <-3SD). Exome sequencing revealed homozygosity for c.535C>T / p.Arg179* (previously reported by Harripaul et al). Sanger sequencing was used for confirmation and demonstration of carrier state of parents. Two similarly affected sibs were not available for testing.

Bauer et al (2022 - PMID: 35373332) reported a 21 y.o. male born to consanguineous parents from Pakistan. Features included short stature, ID, spastic paraparesis (at the age of 3y). Gelastic seizures were suspected but not confirmed (repeated normal EEGs). WES revealed homozygosity for a fs CCDC82 variant [NM_001318736.1:c.183del / p.(Phe61Leufs*27)] with Sanger confirmation in proband and heterozygous parents. There was another hmz variant, albeit classified as VUS and not thought to fit the clinical presentation.

As proposed by Bauer et al. overlapping features include spastic paraparesis, DD and dysmorphic features. As commented, CCDC82 encodes coiled-coil domain protein 82, a protein with unknown function.

Consider inclusion probably with amber rating (>3 individuals/families/variants, role of the gene not known, variant studies not performed to date, animal models not discussed).
Sources: Literature
Intellectual disability - microarray and sequencing v3.1539 RAC3 Arina Puzriakova Phenotypes for gene: RAC3 were changed from 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 to Neurodevelopmental disorder with structural brain anomalies and dysmorphic facies, OMIM:618577
Intellectual disability - microarray and sequencing v3.1534 ZBTB7A Konstantinos Varvagiannis gene: ZBTB7A was added
gene: ZBTB7A was added to Intellectual disability. Sources: Literature,Other
Mode of inheritance for gene: ZBTB7A was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: ZBTB7A were set to 31645653; 34515416
Phenotypes for gene: ZBTB7A were set to Global developmental delay; Intellectual disability; Macrocephaly; Abnormality of the lymphatic system; Sleep apnea; Increased body weight; Autism; Persistence of hemoglobin F; Abnormal leukocyte count; Recurrent infections; Umbilical hernia
Penetrance for gene: ZBTB7A were set to unknown
Review for gene: ZBTB7A was set to AMBER
Added comment: Monoallelic pathogenic ZBTB7A variants cause Macrocephaly, neurodevelopmental delay, lymphoid hyperplasia, and persistent fetal hemoglobin (#619769).
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Ohishi et al (2020 - PMID: 31645653) described the phenotype of a 6y5m-old male harboring a heterozygous, de novo ZBTB7A missense variant. Features included macrocephaly, mild intellectual disability (tIQ 65) and sleep apnea. Available hemoglobin levels (in the 1st month) supported high Hb and HbF levels. Other features included PDA and an umbilical hernia.

Initial investigations incl. karyotype and CMA were normal.

The ZBTB7A variant (NM_015898.3:c.1152C>G / p.Cys384Tyr) was identified following trio WES with a list of additional findings (in suppl.) not explaining the phenotype. This SNV, confirmed by Sanger sequencing, was absent from public db with several in silico predictions in favor of a deleterious effect.

ZBTB7A on 19p encodes zinc finger- and BTB domain-containing protein 7 (or Pokemon).

The authors performed a review of 19p13.3 microdeletion cases supporting a minimum region of overlap spanning PIAS4, ZBTB7A and MAP2K2 and common features of DD and ID, macrocephaly with prominent forehead, sleep apnea. The authors argue that loss of ZBTB7A explains part of - but probably not all - features of 19p13.3 microdeletions.

ZBTB7A is known to repress expression of HBG1 and HBG2 (γ-globin), with the few available HbF patient measurements in line with this role.

Based on the structure of the protein, Cys384 (along with 3 other residues) forms a coordinate bond with the Zn+2 ion, this bond predicted to be disrupted by Tyr. Further they favor a dominant negative effect given that ZBTB7A protein is known to form dimer via interaction at the BTB domain [hetero (variant+wt) and homodimers (variant+variant) having compromised function]. To support this notion, 3 previously reported somatic variants within the zinc-finger domain have been shown to exert a dominant-negative effect (PMID cited: 26455326).
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In a collaborative study, von der Lippe et al (2022 - PMID: 34515416) identified 12 additional individuals (from 10 families) harboring monoallelic ZBTB7A missense/pLoF variants most commonly as de novo events.

The authors describe a consistent phenotype with motor (9/11) and speech delay (9/12), cognitive impairment/ID (12/12 - commonly mild, ranged from specific learning difficulties to severe ID), macrocephaly (>90%le in 11/12, >97% in 7/12), lymphoid hypertrophy of pharyngeal tissue/adenoid overgrowth (12/12), sleep apnea (9/12). Autistic features were observed in 7/12. Other phenotypes included frequent upper airway infections (10/11), weight above 97th percentile (7/11). HbF levels were elevated in 4/5 individuals with available measurements (range: 2.2% to 11.2% - ref. for subjects above 6m of age : <2% ). Other hematological issues were observed in few individuals (abn. monocyte/neutrophil counts in 3-4). Cardiovascular issues were reported in 4 (2 fam). 3 subjects had umbilical hernia. There was no common dysmorphic feature.

Various initial investigations were normal or did not appear to explain the NDD phenotype and incl. standard karyotype, CMA, targeted testing for genes/disorders previously considered (PTEN, FMR1, NSD1, BWS and PWS methylation studies, CFTR, etc). One male had a maternally inherited chrX dup not thought to explain his complex phenotype, while another had a concurrent diagnosis of thalassemia.

Individuals were investigated with singleton (or trio) WES. Of note some individuals were DDD study participants.

8 had de novo ZBTB7A variants, incl. one who harbored 2 de novo missense SNVs several residues apart. 2 sibs had inherited a fs variant from their affected parent. For the latter as well as for another subject parental samples were unavailable.

There were no other variants of interest upon exome analysis.

5 different missense, 2 nonsense and 3 fs variants were identified with pLoF all predicted to lead to NMD.

All variants were absent from gnomAD (pLI of 0.96, LOEUF 0.33 and missense Z-score of 4.04) which lists one individual with htz LoF, likely not an artifact.

Given this individual (and the familial case) the authors discuss on the mild phenotype and/or eventual reduced penetrance or underdiagnosis of the disorder.

There was no difference in severity between those with missense/truncating variants.

ZBTB7A transcription factor (or pokemon or lymphoma/leukemia-related factor) is widely expressed. It is involved in several activities being among others required to block Notch signaling which in turn drives T-cell at the expense of B-cell development. Notch pathway activation has been demonstrated in Zbtba7 ko mouse models. Finally, the authors discuss the role of notch signaling in thymus and the nervous system, as well as that ZBTB7A up/down-regulation known to repress/increase respectively HbF expression (several refs in text).
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MGI (1335091) for Zbtb7a : "Mice homozygous for a knock-out allele die around E16.5 due to anemia and exhibit a cell autonomous defect in early B cell development". (Phenotypes from nervous system not commented on).
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Apart from OMIM (#619769), ZBTB7A is included in the DD panel of G2P (ZBTB7A-associated developmental disorder / monoallelic_autosomal / absent gene product / confidence limited) as well as among the primary ID genes in SysID. In PanelApp Australia the gene is incl. with green rating in the ID and Macrocephaly gene panels.
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Consider inclusion with amber or green rating (several individuals/families/variants, highly consistent phenotype, overlap with 19p microdeletions || variant effect not studied, animal models supporting contribution of the gene to the phenotype though no data on associated NDD ones).

Please also consider inclusion in other relevant panels (macrocephaly, lymphatic disorders, ASD, etc).
Sources: Literature, Other
Intellectual disability - microarray and sequencing v3.1530 MAN2C1 Konstantinos Varvagiannis gene: MAN2C1 was added
gene: MAN2C1 was added to Intellectual disability. Sources: Literature,Other
Mode of inheritance for gene: MAN2C1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: MAN2C1 were set to 35045343
Phenotypes for gene: MAN2C1 were set to Global developmental delay; Intellectual disability; Abnormality of nervous system morphology; Abnormality of the corpus callosum; Ventriculomegaly; Polymicrogyria; Abnormality of the face; Macrocephaly
Penetrance for gene: MAN2C1 were set to unknown
Review for gene: MAN2C1 was set to GREEN
Added comment: Biallelic pathogenic MAN2C1 variants cause Congenital disorder of deglycosylation 2 (# 619775). Mild to moderate impairment of intellectual development is a feature in most patients as in the OMIM's clinical synopsis for this disorder.
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Specifically, Maia et al (2022 - PMID: 35045343) report the clinical features based of 6 relevant individuals (4/6 aged 4-18years and 2/6 fetuses) from 4 families. These individuals had non-specific dysmorphic features (micro/retrognathia being the most common in 5/6), different congenital anomalies, variable degrees of ID (3/4), as well as brain MRI abnormalities (PMG in 3/6 from 3 fam, ventriculomegaly in 3/6 from 2 fam, callosal anomalies in 4/6 from 3 fam, cerebellar hypoplasia 2/6 - 2 fam, vermis hypoplasia 4/6 - 3 fam etc). Macrocephaly was reported for 2/6 individuals (2 fam).

While ID was observed in 3/4 individuals of relevant age (mild in 1/4, moderate in 1/4, unk in 1/4), delayed motor and language development was reported for all (4/4).

All individuals harbored biallelic MAN2C1 variants following exome sequencing (previous investigations not reported), and Sanger sequencing was used for validation and segregation (parents/sibs).

There were no putative pathogenic variants in known disease genes.

MAN2C1 encodes mannosidase, alpha, class 2c, member 1, an enzyme playing a role in deglycosylation of free oligosaccharides (fOSs). The latter are generated and released in the cytoplasm or the ER lumen during N-glycosylation of proteins. fOSs are generated from two different pathways (ERAD and LLO) with a defect in an enzyme of the NGLY1 already described to cause a NDD due to defect of deglycosylation. In a later step oligossaccharides are trimmed by the action of ENGase to form fOS containing one GlcNAc (N-Acetylglucosamine) residue (fOSGn1) at the reducing end. Processing of these fOSs by the cytosolic α-mannosidase (MAN2C1) converts Man7-9Gn1 to Man5Gn1 subsequently transported to lysosomes for degradation.

Variants incl. 3 missense SNVs incl. c.2612G>C/p.Cys871Ser, c.2303G>A/p.Arg768Gln, c.607G>A/p.Gly203Arg, one splice variant (c.601-2A>G/p.Gly201Profs*10) and one indel (c.2733_2734del/p.His911Glnfs*67). [RefSeq NM_006715.3]

Most were present in gnomAD with low AF ranging from 0.013% to 0.11% while c.2303G>A/p.Arg768 has an AF of 0.33% with 5 homozygotes(*) in the database. Conservation and in silico predictions supported their effect.

For the variant affecting the splicing acceptor site (c.601-2A>G) studies in patient fibroblasts confirmed skipping of ex6. Fibroblasts from 2 sibs cmp htz for Arg768Gln and c.601-2A>G (Gly201Profs*10) were studied for protein levels, demonstrating 90% reduction in the amount of MAN2C1. There was no truncated protein observed upon immunoblot. Protein abundance was not affected in fibroblasts from the individual who was homozygous for Gly203Arg.

Mannosidase activities were studied upon overexpression in a HEK293 model, with Gly203Arg presenting similar activity to WT and Arg768Gln exhibiting only a tiny residual activity. Cys871Ser showed increased activity compared to WT.

Using fibroblasts from controls and the same individuals as above, the authors showed that pathogenic MAN2C1 variants caused defects in fOS processing (delayed processing of high oligomannose species, reduced production of M5Gn1 with M8 and M9Gn1/2 species remaining at high levels) supporting a total/partial loss of mannosidase activity for Arg768Gln and Gly203Arg.

In MAN2C1-KO HAP1 cell lines, M7-M9Gn1 species accumulated while M5Gn1 - the product of MAN2C1 - were absent. Complementation of KO HAP1 cells with Gly203Arg, Arg768Gln and Cys871Ser suggested impaired fOS processing for Gly203Arg and Arg768Gln (with significant amounts of M7-M9Gn1 species). Cells complemented with Cys871Ser did not exhibit fOS processing defects.

The authors speculate that Cys871Ser could affect a non-mannosidase function of the enzyme relevant to brain development or that it might lead to abnormal inter-subunit interactions or tetramer formation.

Finally, Maia et al summarize findings in previously described Man2c1-KO mice (cited PMID: 24550399). These appeared normal, did not exhibit differences in growth or lifespan and did not present behavioral alterations. Man2c1-KO mice had CNS involvement with histological analyses in favor of neuronal and glial degeneration with multiple vacuoles in deep neocortical layers and telencephalic white matter tracts. Vacuolization was not observed upon brain histology for the 2 fetuses studied which Maia et al speculate may occur at a later stage. In KO mice there was considerable accumulation of Man8–9GlcNAc oligosaccharides.
----
G2P includes MAN2C1 in it's DD panel (confidence: strong, MAN2C1-associated neurodevelopmental disorder with cerebral malformations). In PanelApp Australia, this gene is rated green in the ID, polymicrogyria, cerebellar hypoplasia and fetal anomalies gene panels.

Consider inclusion in the current panel with green (3 individuals/families/variants, role of the gene, NDD phenotype also reported for NGLY1-related disorder of deglycosylation, variant studies) or amber rating (ID not a universal feature, still DD observed in all affected individuals).

Please consider adding this gene in other relevant panels (as in PanelApp Australia, also for corpus callosum abnormalities, metabolic disorders, etc).
Sources: Literature, Other
Intellectual disability - microarray and sequencing v3.1528 ADAT3 Arina Puzriakova Phenotypes for gene: ADAT3 were changed from Mental retardation, autosomal recessive 36, 615286; MRT36 to Neurodevelopmental disorder with brain abnormalities, poor growth, and dysmorphic facies, OMIM:615286
Intellectual disability - microarray and sequencing v3.1520 PAN2 Konstantinos Varvagiannis gene: PAN2 was added
gene: PAN2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: PAN2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PAN2 were set to 29620724; https://doi.org/10.1038/s41431-022-01077-y
Phenotypes for gene: PAN2 were set to Global developmental delay; Intellectual disability; Sensorineural hearing impairment; Abnormality of the genitourinary system; Abnormality of the cardiovascular system; Abnormality of blood and blood-forming tissues; EEG abnormality; Seizures; Anorectal anomaly; Abnormality of the skeletal system; Abnormality of the eye; Abnormality of head or neck
Penetrance for gene: PAN2 were set to Complete
Review for gene: PAN2 was set to AMBER
Added comment: 1.
Maddirevula et al (2018 - PMID: 29620724) first reported on the phenotype associated with biallelic pathogenic variants in PAN2.

This concerned a male (15DG2222) born to consanguineous parents and exhibiting MCA, dysmorphic features and global DD (age of 34 m). Features incl. imperforate anus, metopic craniosynostosis, scoliosis, CHD (PFO, PDA, VSD), renal anomalies (duplicated collecting system) and abnormalities of the eye (posterior embryotoxon, maculopathy).

As the other 411 individuals from the cohort, the child had 1st-tier testing genetic testing using a dysmorphology/skeletal dysplasia panel of 296 genes.

Subsequent autozygome analysis (Axiom genotyping platform) was used to identify ROH (authors state "segregating within the family", in pedigree the proband was the single affected person and single child).

WES revealed a PAN2 indel. [NM_001166279.1:c.3162delC / p.(Ser1055Profs*4)].

There were no additional studies.

Role of PAN2 and animal models discussed as below.
---
2.
Reuter et al. (2022 - https://doi.org/10.1038/s41431-022-01077-y) describe the phenotype of 5 additional individuals - from 3 unrelated families (2 consanguineous) - harboring biallelic PAN2 variants. The authors review the phenotype of the previously described case.

Features included DD (6/6), ID (4/5 with relevant age in the mild-moderate range, 1/5 had borderline IF), sensorineural hearing loss (5/6) and incompletely penetrant congenital anomalies of the heart (4/6 - TOF, septal defects, Ao root dilat), urinary malformations (4/6 - hypoplasia/agenesis, anovesical fistula), ophthalmological anomalies (2/6 - Rieger, posterior embryotoxon, etc). EEG anomalies or seizures were noted in 4/6. Craniofacial feat. in >=2/6 included cleft palate/bifid uvula, ptosis, hypertelorism, abn. of the nose, low-set ears, short neck. There was no comprehensive evaluation for skeletal dysplasia despite short stature/skeletal anomalies in multiple individuals. Hematological anomalies were reported in 2, possibly explained by another concurrent diagnosis (of GSD) in one individual.

WGS was performed for 1 individual, and WES for 4 members of the 2nd family and the proband in the 3rd. ROH identified in all 3 families (1 non-consanguineous but from the same region of Italy) are mentioned in the suppl. Sanger sequencing for parents and affected/unaffected sibs was mentioned for the 2 families with solo WGS/WES. One individual had a dual - previously established - diagnosis (of SLC37A4-related GSD) not related to his NDD. There were no other candidate variants except for VUS or variants in 'genes of uncertain significance'.

The majority of mammalian mature mRNAs have polyA tails, added during RNA processing. PAN2 encodes a subunit of the Pan2-Pan3 deadenylation complex which shortens mRNA 3' polyA tails, regulating mRNA stability/translation efficiency.

Specifically Pan2 is the catalytic subunit, while the interaction with Pan3 mediates efficient mRNA binding. Deadenylation in cytoplasm is mostly carried out by the Pan2-Pan3 or Ccr4-Not compexes. While perturbations of mRNA metabolism/decay are established causes of NDD and ID. In particular, monoallelic variants in genes of Ccr4-Not complex (inc. CNOT1/2/3) already causative of NDDs.

All affected individuals were homozygous for pLoF PAN2 variants, namely (NM_001166279.2): c.2335G>T / p.(Glu779*) [Fam1], c.3408dupT / p.(Glu1137*) [Fam2], c.574-2A>G / p.? [Fam3].

Variants were absent from gnomAD (where PAN2 has a pLI:0.94, o/e:0.19).

There were no variant studies performed. The splicing variant is predicted in silico to abolish the splice-acceptor site, with in-frame skippling of ex5 which codes a repeat within the WD40 domain. Previous studies in yeast have shown that this domain is important for sensing the length of the polyA tail, with absence of this domain resulting in impaired deadenylation of 90A tails (similarly to complete Pan2 del) [cited PMID: 31104843].

Overall PAN2 loss-of-function is thought to be the underlying disease mechanism.

Partial functional redundancy of Pan2/Pan3 (initiation of deadenylation) and Ccr4-Not complexes (further shortening of polyA) is speculated to mitigate consequences of PAN2 LoF in humans.

In yeast Pan2Δ, Ccr4Δ and Pan2Δ/Ccr4Δ have been studied with more severe phenotypes in double mutants where ability to shorten mRNA polyA tails was abolished [cited PMID:11239395]. In yeast extracts lacking Pan2p and Pan3p, transcripts were polyadenylated to >90-200 adenosines [cited PMID: 9774670]

Mouse mutants (MGI:1918984) had increased heart weight, increased eosinophil cell number while homozygosity for a stopgain allele (by ENU mutagenesis) was shown to result in embyonic lethality.

Finally, given the presence of thrombocytopenia and anemia in 3 individuals (2 families) as well as the link between mRNA deadenylation and telomere disease, telomere length analyses from WGS data were performed (TelSeq/Expansion Hunter dn), but there was no evidence for telomeric shortening.
---
Currently, there is no PAN2-related phenotype in OMIM/G2P/SysID/PanelApp Australia.
---
Consider inclusion in the ID panel with amber rating [>3 individuals/families/variants, though variant studies not performed (NMD/splicing) and authors of 2nd study recognize possibility of additional/concurrent diagnoses in individuals from consanguineous families, possibility of missed dn variants due to singleton WGS/WES in 2 fam. Also the presumed deadenylation defect not studied to date].

Please consider adding this gene to other panels - eg. for sens. hearing loss (5/6 - 3 fam), urinary tract anomalies (4/6 - 4 fam), congenital (4/6 - 3fam), anorectal malformations (2/6 - 2 families, incl. fistula or imperforate anus), clefting (2/6 - 1 fam), hematological disorders, etc.

For the time being, not added in epilepsy panel as some individuals had only EEG anomalies, few had also clinical seizures not necessarily requiring treatment.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1520 HIST1H4D Konstantinos Varvagiannis gene: HIST1H4D was added
gene: HIST1H4D was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HIST1H4D was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: HIST1H4D were set to 35202563
Phenotypes for gene: HIST1H4D were set to Global developmental delay; Intellectual disability; Microcephaly; Growth abnormality; Abnormality of the face
Penetrance for gene: HIST1H4D were set to Complete
Mode of pathogenicity for gene: HIST1H4D 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: HIST1H4D was set to AMBER
Added comment: Histone H4 is a core component of the nucleosome, the basic repeating unit of eukaryotic chromatin. Each nucleosome consists of ~150 bp of DNA wrapped around a histone octamer. Each histone octamer is composed of 2 copies of each of the histones H2A, H2B, H3, H4. This organization is important for DNA replication, transcription and repair.

There are 14 canonical histone H4 genes in the human genome, which despite being different at the nucleotide level encode an identical protein. These cluster in 3 genomic loci. Their transcription is independently regulated with differing expression during brain development and in human tissues.

Histone H4 forms a dimer with H3 (which however has variant isoforms linked to specific cellular processes).

Pathogenic variants in genes encoding H4 have been reported in several individuals. Irrrespective of the gene for H4 involved, all patients presented with highly overlapping features, DD and ID being universal. Available reports to date concern :
- H4C3/HIST1H4C (9 subjects - PMID: 28920961, 35202563),
- H4C11/HIST1H4J (1 subject - PMID: 31804630, 35202563),
- H4C4/HIST1H4D (1 subject - PMID:35202563),
- H4C5/HIST1H4E (17 subjects - PMID: 35202563),
- H4C6/HIST1H4F (1 subject - PMID: 35202563),
- H4C9/HIST1H4I (3 subjects - PMID: 35202563).

Variants in all cases were missense SNVs, occurring (in almost all cases) as dn variants and affecting the same residue in the same and/or different H4 genes (details for clusters below). Eg. Arg45Cys was a recurrent variant for H4C5 (>=7 subjects), while variants affecting Arg40 have been reported in H4C4, H4C5, H4C9, H4C11 (7 subjects overall).

Zebrafish studies for all genes reported have included most - if not all - patient variants and recapitulate features observed in affected individuals (head size/structure and growth).

Additional studies specificaly for H4C3/HIST1H4C have been performed in patient fibroblasts (demonstrating among others transcriptional dysregulation) and zebrafish (accumulation of DSBs, increased apoptosis in head/tail, abn. cell cycle progression).

Note that the nomenclature for variants - at the protein level - used in literature commonly takes into consideration cleavage of Met1, thus the numbering may not correspond to the HGVS one.

Relevant entries exist in OMIM, G2P and SysID only for H4C3/HIST1H4C (Tessadori-van Haaften neurodevelopmental syndrome 1, #619758) and H4C11/HIST1H4J (?Tessadori-van Haaften neurodevelopmental syndrome 2, #619759) but not for other genes.

Rating in PanelApp Australia - ID Panel : HIST1H4C Green, H4J Amber, H4D Amber, H4E Green, H4F Amber, H4I Green.

Please consider inclusion in other possibly relevant panels (microcephaly, short stature/FTT, etc).

------
Initial work from Tessadori et al (incl. DDD study, 2017 - PMID:28920961) identified monoallelic missense SNVs affecting the same residue of H4C3 (HIST1H4C), in 3 individuals from 2 families. [c.274A>C/ HGVS p.(Lys92Gln) dn in 1 subject and c.275A>C/ HGVS p.(Lys92Arg) inherited from unaffected mosaic parent].

Individuals from both families having relevant age had intellectual disability (2/2 - 2 families). Other features incl. growth delay (3/3) and microcephaly (3/3).

Expression of the variants in zebrafish severely affected structural development recapitulating the patient phenotypes (microcephaly and short stature).

RNA sequencing in fibroblasts from 2 unrelated patients and a control, revealed that expression of H4C3 variants was similar to wt. The authors estimated that ~8% of H4 cDNA molecules contained the variant. LC-MS/MS analysis suggested that the mutant protein was present in nucleosomes at a level of 1-2% while RNA-seq identified 115 differential expressed genes, with enrichment for relevant procedures (chr. organization, histone binding, DNA packaging, nucleosomal organization, cell cycle).

Post-translational modifications of Lys92 (H4K91) are highly conserved and have been previously associated with processes from chromatin assembly , DNA damage sensitivity, etc. Post-translational marks on Lys92 (K91) were absent in patient derived cells as a result of each variant.

Zebrafish models for both variants were suggestive for accumulation of double strand breaks (DSBs) more visible in heads and tails of larvae. Embryos expressing mutants displayed increased apoptosis in head and tail. Additional studies in larvae were suggestive of abnormal cell cycle progression (rel. increase in cellls in S/G2/M phase, increased occurrence of activated CHK2 with p53 stabilization) applying to both variants studied.

------
In a subsequent publication, Tessadori et al. (2020 - PMID: 31804630) described the phenotype of a 14 y.o. boy harboring a dn heterozygous missense H4C11 (HIST1H4J) variant following trio-ES [c.274A>G / HGVS p.(Lys92Glu)]. Features incl. profound ID, microcephaly, short stature with some dysmorphic features (uplsanting p-f, hypertelorism, etc). Previous work-up was normal/non-diagnostic and incl. FMR1, MECP2 and a CMA showing an inherited 207 kb CNV involving KCNV1. Upon mRNA microinjection in zebrafish embryos - either for wt or for Lys92Glu HIST1H4J - effect for wt was very mild. Lys92Glu expression led to defective development of head structures (brain, eyes), faulty body axis growth and dysmorphic tail reproducing the microcephaly and short stature phenotype. This was similar to previous zebrafish studies for HIS1H4C variants (above).

------
Tessadori et al. (2022 - PMID: 35202563) describe 29 *additional individuals with de novo missense variants in genes encoding H4, namely:
- H4C3 (HIST1H4C/N=6 subjects),
- H4C11 (HIST1H4J/N=1),
- H4C4 (HIST1H4D/N=1),
- H4C5 (HIST1H4E/N=17),
- H4C6 (HIST1H4F/N=1),
- H4C9 (HIST1H4I/N=3).

All individuals, exhibited DD and ID (29/29). Other features incl. hypotonia (10/29), seizures (5/29), autism (5/29), ataxia (4/29). Abnormal growth incl. progressive microcephaly (2/19 prenatal, 20/29 postnatal onset), short stature/FTT (each 11/29). Few had skeletal features (craniosynostosis 2/29, abn. digits 4/29, vertebral 4/29). Some had visual (17/28) or hearing impairment (7/29). Facial features incl. hypertelorism (5/29), upslanting p-f (3/29), broad nasal tip (11/29), thin upper lip (4/29) and teeth anomalies (6/29 - notably gap between central incisors).

The authors state that the cohort was collected with trio WES but also after data sharing via Genematcher / DECIPHER.

Identified variants were in all cases missense and de novo, the latter either by trio WES or Sanger sequencing of parents.

Previous work-up or presence of additional variants are not discussed.

At the protein level 10 aa were affected, 6 of which recurrently within the same gene (Arg45, His75, Lys91, Tyr98) as well among several genes for H4 (Pro32, Arg40). Variants lied within two clusters, one corresponding to the α-helix of H4 (reported variants affected Lys31 - Arg45) important for DNA contacts, interactions with H3 and histone chaperones. The other within the core of nucleosome (reported patient variants : His75-Tyr98) with important strucural contact between H3-H4 dimer and histone chaperones.

There were no detectable genotype-phenotype patterns separating individual H4 genes or protein regions. Of note, variability was observed even among 7 individuals with the same dn H4C5 variant (Arg45Cys).

All variants were absent from control databases incl. gnomAD and affected residues conserved through to S. cerevisiae. Substitutions affecting Arg45 and Gly94 and His75 have been studied previously with effect in growth/fitness/chromatin remodeling/DNA damage repair depending on variant (5 studies cited).

Zebrafish embryos at the 1 cell stage were injected with mRNA encoding either wt or identified variants, the latter inducing significant developmental defects with the exception of Pro32Ala (H4C3) and Arg40Cys (H4C5, H4C11).

For Pro32Ala and Arg40Cys however, the strong recurrence in this cohort supports pathogenicity. A dosage dependent effect was observed for 2 variants.

H4 genes appear to be tolerant to both missense and loss-of-function variation (the latter even in homozygous form) suggesting a dominant effect of the variants.

------
[RefSeqs : H4C3/HIST1H4C - NM_0035242.4 | H4C4/HIST1H4D - NM_003539.4 | H4C5/HIST1H4E - NM_003545.3 | H4C6/HIST1H4F - NM_003540.4 | H4C9/HIST1H4I - NM_003495.2 | H4C11/HIST1H4J - NM_021968.4 // Variants at the protein level above are according to the HGVS nomenclature. However as the N-terminal methionine is cleaved, numbering relative to the mature peptide has also been used in publications eg. p.Pro33Ala HGVS corresponding to Pro32Ala]
Sources: Literature
Intellectual disability - microarray and sequencing v3.1520 HIST1H4E Konstantinos Varvagiannis gene: HIST1H4E was added
gene: HIST1H4E was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HIST1H4E was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: HIST1H4E were set to 35202563
Phenotypes for gene: HIST1H4E were set to Global developmental delay; Intellectual disability; Microcephaly; Growth abnormality; Abnormality of the face
Penetrance for gene: HIST1H4E were set to unknown
Mode of pathogenicity for gene: HIST1H4E 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: HIST1H4E was set to GREEN
Added comment: Histone H4 is a core component of the nucleosome, the basic repeating unit of eukaryotic chromatin. Each nucleosome consists of ~150 bp of DNA wrapped around a histone octamer. Each histone octamer is composed of 2 copies of each of the histones H2A, H2B, H3, H4. This organization is important for DNA replication, transcription and repair.

There are 14 canonical histone H4 genes in the human genome, which despite being different at the nucleotide level encode an identical protein. These cluster in 3 genomic loci. Their transcription is independently regulated with differing expression during brain development and in human tissues.

Histone H4 forms a dimer with H3 (which however has variant isoforms linked to specific cellular processes).

Pathogenic variants in genes encoding H4 have been reported in several individuals. Irrrespective of the gene for H4 involved, all patients presented with highly overlapping features, DD and ID being universal. Available reports to date concern :
- H4C3/HIST1H4C (9 subjects - PMID: 28920961, 35202563),
- H4C11/HIST1H4J (1 subject - PMID: 31804630, 35202563),
- H4C4/HIST1H4D (1 subject - PMID:35202563),
- H4C5/HIST1H4E (17 subjects - PMID: 35202563),
- H4C6/HIST1H4F (1 subject - PMID: 35202563),
- H4C9/HIST1H4I (3 subjects - PMID: 35202563).

Variants in all cases were missense SNVs, occurring (in almost all cases) as dn variants and affecting the same residue in the same and/or different H4 genes (details for clusters below). Eg. Arg45Cys was a recurrent variant for H4C5 (>=7 subjects), while variants affecting Arg40 have been reported in H4C4, H4C5, H4C9, H4C11 (7 subjects overall).

Zebrafish studies for all genes reported have included most - if not all - patient variants and recapitulate features observed in affected individuals (head size/structure and growth).

Additional studies specificaly for H4C3/HIST1H4C have been performed in patient fibroblasts (demonstrating among others transcriptional dysregulation) and zebrafish (accumulation of DSBs, increased apoptosis in head/tail, abn. cell cycle progression).

Note that the nomenclature for variants - at the protein level - used in literature commonly takes into consideration cleavage of Met1, thus the numbering may not correspond to the HGVS one.

Relevant entries exist in OMIM, G2P and SysID only for H4C3/HIST1H4C (Tessadori-van Haaften neurodevelopmental syndrome 1, #619758) and H4C11/HIST1H4J (?Tessadori-van Haaften neurodevelopmental syndrome 2, #619759) but not for other genes.

Rating in PanelApp Australia - ID Panel : HIST1H4C Green, H4J Amber, H4D Amber, H4E Green, H4F Amber, H4I Green.

Please consider inclusion in other possibly relevant panels (microcephaly, short stature/FTT, etc).

------
Initial work from Tessadori et al (incl. DDD study, 2017 - PMID:28920961) identified monoallelic missense SNVs affecting the same residue of H4C3 (HIST1H4C), in 3 individuals from 2 families. [c.274A>C/ HGVS p.(Lys92Gln) dn in 1 subject and c.275A>C/ HGVS p.(Lys92Arg) inherited from unaffected mosaic parent].

Individuals from both families having relevant age had intellectual disability (2/2 - 2 families). Other features incl. growth delay (3/3) and microcephaly (3/3).

Expression of the variants in zebrafish severely affected structural development recapitulating the patient phenotypes (microcephaly and short stature).

RNA sequencing in fibroblasts from 2 unrelated patients and a control, revealed that expression of H4C3 variants was similar to wt. The authors estimated that ~8% of H4 cDNA molecules contained the variant. LC-MS/MS analysis suggested that the mutant protein was present in nucleosomes at a level of 1-2% while RNA-seq identified 115 differential expressed genes, with enrichment for relevant procedures (chr. organization, histone binding, DNA packaging, nucleosomal organization, cell cycle).

Post-translational modifications of Lys92 (H4K91) are highly conserved and have been previously associated with processes from chromatin assembly , DNA damage sensitivity, etc. Post-translational marks on Lys92 (K91) were absent in patient derived cells as a result of each variant.

Zebrafish models for both variants were suggestive for accumulation of double strand breaks (DSBs) more visible in heads and tails of larvae. Embryos expressing mutants displayed increased apoptosis in head and tail. Additional studies in larvae were suggestive of abnormal cell cycle progression (rel. increase in cellls in S/G2/M phase, increased occurrence of activated CHK2 with p53 stabilization) applying to both variants studied.

------
In a subsequent publication, Tessadori et al. (2020 - PMID: 31804630) described the phenotype of a 14 y.o. boy harboring a dn heterozygous missense H4C11 (HIST1H4J) variant following trio-ES [c.274A>G / HGVS p.(Lys92Glu)]. Features incl. profound ID, microcephaly, short stature with some dysmorphic features (uplsanting p-f, hypertelorism, etc). Previous work-up was normal/non-diagnostic and incl. FMR1, MECP2 and a CMA showing an inherited 207 kb CNV involving KCNV1. Upon mRNA microinjection in zebrafish embryos - either for wt or for Lys92Glu HIST1H4J - effect for wt was very mild. Lys92Glu expression led to defective development of head structures (brain, eyes), faulty body axis growth and dysmorphic tail reproducing the microcephaly and short stature phenotype. This was similar to previous zebrafish studies for HIS1H4C variants (above).

------
Tessadori et al. (2022 - PMID: 35202563) describe 29 *additional individuals with de novo missense variants in genes encoding H4, namely:
- H4C3 (HIST1H4C/N=6 subjects),
- H4C11 (HIST1H4J/N=1),
- H4C4 (HIST1H4D/N=1),
- H4C5 (HIST1H4E/N=17),
- H4C6 (HIST1H4F/N=1),
- H4C9 (HIST1H4I/N=3).

All individuals, exhibited DD and ID (29/29). Other features incl. hypotonia (10/29), seizures (5/29), autism (5/29), ataxia (4/29). Abnormal growth incl. progressive microcephaly (2/19 prenatal, 20/29 postnatal onset), short stature/FTT (each 11/29). Few had skeletal features (craniosynostosis 2/29, abn. digits 4/29, vertebral 4/29). Some had visual (17/28) or hearing impairment (7/29). Facial features incl. hypertelorism (5/29), upslanting p-f (3/29), broad nasal tip (11/29), thin upper lip (4/29) and teeth anomalies (6/29 - notably gap between central incisors).

The authors state that the cohort was collected with trio WES but also after data sharing via Genematcher / DECIPHER.

Identified variants were in all cases missense and de novo, the latter either by trio WES or Sanger sequencing of parents.

Previous work-up or presence of additional variants are not discussed.

At the protein level 10 aa were affected, 6 of which recurrently within the same gene (Arg45, His75, Lys91, Tyr98) as well among several genes for H4 (Pro32, Arg40). Variants lied within two clusters, one corresponding to the α-helix of H4 (reported variants affected Lys31 - Arg45) important for DNA contacts, interactions with H3 and histone chaperones. The other within the core of nucleosome (reported patient variants : His75-Tyr98) with important strucural contact between H3-H4 dimer and histone chaperones.

There were no detectable genotype-phenotype patterns separating individual H4 genes or protein regions. Of note, variability was observed even among 7 individuals with the same dn H4C5 variant (Arg45Cys).

All variants were absent from control databases incl. gnomAD and affected residues conserved through to S. cerevisiae. Substitutions affecting Arg45 and Gly94 and His75 have been studied previously with effect in growth/fitness/chromatin remodeling/DNA damage repair depending on variant (5 studies cited).

Zebrafish embryos at the 1 cell stage were injected with mRNA encoding either wt or identified variants, the latter inducing significant developmental defects with the exception of Pro32Ala (H4C3) and Arg40Cys (H4C5, H4C11).

For Pro32Ala and Arg40Cys however, the strong recurrence in this cohort supports pathogenicity. A dosage dependent effect was observed for 2 variants.

H4 genes appear to be tolerant to both missense and loss-of-function variation (the latter even in homozygous form) suggesting a dominant effect of the variants.

------
[RefSeqs : H4C3/HIST1H4C - NM_0035242.4 | H4C4/HIST1H4D - NM_003539.4 | H4C5/HIST1H4E - NM_003545.3 | H4C6/HIST1H4F - NM_003540.4 | H4C9/HIST1H4I - NM_003495.2 | H4C11/HIST1H4J - NM_021968.4 // Variants at the protein level above are according to the HGVS nomenclature. However as the N-terminal methionine is cleaved, numbering relative to the mature peptide has also been used in publications eg. p.Pro33Ala HGVS corresponding to Pro32Ala]
Sources: Literature
Intellectual disability - microarray and sequencing v3.1520 HIST1H4F Konstantinos Varvagiannis gene: HIST1H4F was added
gene: HIST1H4F was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HIST1H4F was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: HIST1H4F were set to 35202563
Phenotypes for gene: HIST1H4F were set to Global developmental delay; Intellectual disability; Microcephaly; Growth abnormality; Abnormality of the face
Penetrance for gene: HIST1H4F were set to unknown
Mode of pathogenicity for gene: HIST1H4F 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: HIST1H4F was set to AMBER
Added comment: Histone H4 is a core component of the nucleosome, the basic repeating unit of eukaryotic chromatin. Each nucleosome consists of ~150 bp of DNA wrapped around a histone octamer. Each histone octamer is composed of 2 copies of each of the histones H2A, H2B, H3, H4. This organization is important for DNA replication, transcription and repair.

There are 14 canonical histone H4 genes in the human genome, which despite being different at the nucleotide level encode an identical protein. These cluster in 3 genomic loci. Their transcription is independently regulated with differing expression during brain development and in human tissues.

Histone H4 forms a dimer with H3 (which however has variant isoforms linked to specific cellular processes).

Pathogenic variants in genes encoding H4 have been reported in several individuals. Irrrespective of the gene for H4 involved, all patients presented with highly overlapping features, DD and ID being universal. Available reports to date concern :
- H4C3/HIST1H4C (9 subjects - PMID: 28920961, 35202563),
- H4C11/HIST1H4J (1 subject - PMID: 31804630, 35202563),
- H4C4/HIST1H4D (1 subject - PMID:35202563),
- H4C5/HIST1H4E (17 subjects - PMID: 35202563),
- H4C6/HIST1H4F (1 subject - PMID: 35202563),
- H4C9/HIST1H4I (3 subjects - PMID: 35202563).

Variants in all cases were missense SNVs, occurring (in almost all cases) as dn variants and affecting the same residue in the same and/or different H4 genes (details for clusters below). Eg. Arg45Cys was a recurrent variant for H4C5 (>=7 subjects), while variants affecting Arg40 have been reported in H4C4, H4C5, H4C9, H4C11 (7 subjects overall).

Zebrafish studies for all genes reported have included most - if not all - patient variants and recapitulate features observed in affected individuals (head size/structure and growth).

Additional studies specificaly for H4C3/HIST1H4C have been performed in patient fibroblasts (demonstrating among others transcriptional dysregulation) and zebrafish (accumulation of DSBs, increased apoptosis in head/tail, abn. cell cycle progression).

Note that the nomenclature for variants - at the protein level - used in literature commonly takes into consideration cleavage of Met1, thus the numbering may not correspond to the HGVS one.

Relevant entries exist in OMIM, G2P and SysID only for H4C3/HIST1H4C (Tessadori-van Haaften neurodevelopmental syndrome 1, #619758) and H4C11/HIST1H4J (?Tessadori-van Haaften neurodevelopmental syndrome 2, #619759) but not for other genes.

Rating in PanelApp Australia - ID Panel : HIST1H4C Green, H4J Amber, H4D Amber, H4E Green, H4F Amber, H4I Green.

Please consider inclusion in other possibly relevant panels (microcephaly, short stature/FTT, etc).

------
Initial work from Tessadori et al (incl. DDD study, 2017 - PMID:28920961) identified monoallelic missense SNVs affecting the same residue of H4C3 (HIST1H4C), in 3 individuals from 2 families. [c.274A>C/ HGVS p.(Lys92Gln) dn in 1 subject and c.275A>C/ HGVS p.(Lys92Arg) inherited from unaffected mosaic parent].

Individuals from both families having relevant age had intellectual disability (2/2 - 2 families). Other features incl. growth delay (3/3) and microcephaly (3/3).

Expression of the variants in zebrafish severely affected structural development recapitulating the patient phenotypes (microcephaly and short stature).

RNA sequencing in fibroblasts from 2 unrelated patients and a control, revealed that expression of H4C3 variants was similar to wt. The authors estimated that ~8% of H4 cDNA molecules contained the variant. LC-MS/MS analysis suggested that the mutant protein was present in nucleosomes at a level of 1-2% while RNA-seq identified 115 differential expressed genes, with enrichment for relevant procedures (chr. organization, histone binding, DNA packaging, nucleosomal organization, cell cycle).

Post-translational modifications of Lys92 (H4K91) are highly conserved and have been previously associated with processes from chromatin assembly , DNA damage sensitivity, etc. Post-translational marks on Lys92 (K91) were absent in patient derived cells as a result of each variant.

Zebrafish models for both variants were suggestive for accumulation of double strand breaks (DSBs) more visible in heads and tails of larvae. Embryos expressing mutants displayed increased apoptosis in head and tail. Additional studies in larvae were suggestive of abnormal cell cycle progression (rel. increase in cellls in S/G2/M phase, increased occurrence of activated CHK2 with p53 stabilization) applying to both variants studied.

------
In a subsequent publication, Tessadori et al. (2020 - PMID: 31804630) described the phenotype of a 14 y.o. boy harboring a dn heterozygous missense H4C11 (HIST1H4J) variant following trio-ES [c.274A>G / HGVS p.(Lys92Glu)]. Features incl. profound ID, microcephaly, short stature with some dysmorphic features (uplsanting p-f, hypertelorism, etc). Previous work-up was normal/non-diagnostic and incl. FMR1, MECP2 and a CMA showing an inherited 207 kb CNV involving KCNV1. Upon mRNA microinjection in zebrafish embryos - either for wt or for Lys92Glu HIST1H4J - effect for wt was very mild. Lys92Glu expression led to defective development of head structures (brain, eyes), faulty body axis growth and dysmorphic tail reproducing the microcephaly and short stature phenotype. This was similar to previous zebrafish studies for HIS1H4C variants (above).

------
Tessadori et al. (2022 - PMID: 35202563) describe 29 *additional individuals with de novo missense variants in genes encoding H4, namely:
- H4C3 (HIST1H4C/N=6 subjects),
- H4C11 (HIST1H4J/N=1),
- H4C4 (HIST1H4D/N=1),
- H4C5 (HIST1H4E/N=17),
- H4C6 (HIST1H4F/N=1),
- H4C9 (HIST1H4I/N=3).

All individuals, exhibited DD and ID (29/29). Other features incl. hypotonia (10/29), seizures (5/29), autism (5/29), ataxia (4/29). Abnormal growth incl. progressive microcephaly (2/19 prenatal, 20/29 postnatal onset), short stature/FTT (each 11/29). Few had skeletal features (craniosynostosis 2/29, abn. digits 4/29, vertebral 4/29). Some had visual (17/28) or hearing impairment (7/29). Facial features incl. hypertelorism (5/29), upslanting p-f (3/29), broad nasal tip (11/29), thin upper lip (4/29) and teeth anomalies (6/29 - notably gap between central incisors).

The authors state that the cohort was collected with trio WES but also after data sharing via Genematcher / DECIPHER.

Identified variants were in all cases missense and de novo, the latter either by trio WES or Sanger sequencing of parents.

Previous work-up or presence of additional variants are not discussed.

At the protein level 10 aa were affected, 6 of which recurrently within the same gene (Arg45, His75, Lys91, Tyr98) as well among several genes for H4 (Pro32, Arg40). Variants lied within two clusters, one corresponding to the α-helix of H4 (reported variants affected Lys31 - Arg45) important for DNA contacts, interactions with H3 and histone chaperones. The other within the core of nucleosome (reported patient variants : His75-Tyr98) with important strucural contact between H3-H4 dimer and histone chaperones.

There were no detectable genotype-phenotype patterns separating individual H4 genes or protein regions. Of note, variability was observed even among 7 individuals with the same dn H4C5 variant (Arg45Cys).

All variants were absent from control databases incl. gnomAD and affected residues conserved through to S. cerevisiae. Substitutions affecting Arg45 and Gly94 and His75 have been studied previously with effect in growth/fitness/chromatin remodeling/DNA damage repair depending on variant (5 studies cited).

Zebrafish embryos at the 1 cell stage were injected with mRNA encoding either wt or identified variants, the latter inducing significant developmental defects with the exception of Pro32Ala (H4C3) and Arg40Cys (H4C5, H4C11).

For Pro32Ala and Arg40Cys however, the strong recurrence in this cohort supports pathogenicity. A dosage dependent effect was observed for 2 variants.

H4 genes appear to be tolerant to both missense and loss-of-function variation (the latter even in homozygous form) suggesting a dominant effect of the variants.

------
[RefSeqs : H4C3/HIST1H4C - NM_0035242.4 | H4C4/HIST1H4D - NM_003539.4 | H4C5/HIST1H4E - NM_003545.3 | H4C6/HIST1H4F - NM_003540.4 | H4C9/HIST1H4I - NM_003495.2 | H4C11/HIST1H4J - NM_021968.4 // Variants at the protein level above are according to the HGVS nomenclature. However as the N-terminal methionine is cleaved, numbering relative to the mature peptide has also been used in publications eg. p.Pro33Ala HGVS corresponding to Pro32Ala]
Sources: Literature
Intellectual disability - microarray and sequencing v3.1520 HIST1H4I Konstantinos Varvagiannis gene: HIST1H4I was added
gene: HIST1H4I was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HIST1H4I was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: HIST1H4I were set to 35202563
Phenotypes for gene: HIST1H4I were set to Global developmental delay; Intellectual disability; Microcephaly; Growth abnormality; Abnormality of the face
Penetrance for gene: HIST1H4I were set to unknown
Mode of pathogenicity for gene: HIST1H4I 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: HIST1H4I was set to GREEN
Added comment: Histone H4 is a core component of the nucleosome, the basic repeating unit of eukaryotic chromatin. Each nucleosome consists of ~150 bp of DNA wrapped around a histone octamer. Each histone octamer is composed of 2 copies of each of the histones H2A, H2B, H3, H4. This organization is important for DNA replication, transcription and repair.

There are 14 canonical histone H4 genes in the human genome, which despite being different at the nucleotide level encode an identical protein. These cluster in 3 genomic loci. Their transcription is independently regulated with differing expression during brain development and in human tissues.

Histone H4 forms a dimer with H3 (which however has variant isoforms linked to specific cellular processes).

Pathogenic variants in genes encoding H4 have been reported in several individuals. Irrrespective of the gene for H4 involved, all patients presented with highly overlapping features, DD and ID being universal. Available reports to date concern :
- H4C3/HIST1H4C (9 subjects - PMID: 28920961, 35202563),
- H4C11/HIST1H4J (1 subject - PMID: 31804630, 35202563),
- H4C4/HIST1H4D (1 subject - PMID:35202563),
- H4C5/HIST1H4E (17 subjects - PMID: 35202563),
- H4C6/HIST1H4F (1 subject - PMID: 35202563),
- H4C9/HIST1H4I (3 subjects - PMID: 35202563).

Variants in all cases were missense SNVs, occurring (in almost all cases) as dn variants and affecting the same residue in the same and/or different H4 genes (details for clusters below). Eg. Arg45Cys was a recurrent variant for H4C5 (>=7 subjects), while variants affecting Arg40 have been reported in H4C4, H4C5, H4C9, H4C11 (7 subjects overall).

Zebrafish studies for all genes reported have included most - if not all - patient variants and recapitulate features observed in affected individuals (head size/structure and growth).

Additional studies specificaly for H4C3/HIST1H4C have been performed in patient fibroblasts (demonstrating among others transcriptional dysregulation) and zebrafish (accumulation of DSBs, increased apoptosis in head/tail, abn. cell cycle progression).

Note that the nomenclature for variants - at the protein level - used in literature commonly takes into consideration cleavage of Met1, thus the numbering may not correspond to the HGVS one.

Relevant entries exist in OMIM, G2P and SysID only for H4C3/HIST1H4C (Tessadori-van Haaften neurodevelopmental syndrome 1, #619758) and H4C11/HIST1H4J (?Tessadori-van Haaften neurodevelopmental syndrome 2, #619759) but not for other genes.

Rating in PanelApp Australia - ID Panel : HIST1H4C Green, H4J Amber, H4D Amber, H4E Green, H4F Amber, H4I Green.

Please consider inclusion in other possibly relevant panels (microcephaly, short stature/FTT, etc).

------
Initial work from Tessadori et al (incl. DDD study, 2017 - PMID:28920961) identified monoallelic missense SNVs affecting the same residue of H4C3 (HIST1H4C), in 3 individuals from 2 families. [c.274A>C/ HGVS p.(Lys92Gln) dn in 1 subject and c.275A>C/ HGVS p.(Lys92Arg) inherited from unaffected mosaic parent].

Individuals from both families having relevant age had intellectual disability (2/2 - 2 families). Other features incl. growth delay (3/3) and microcephaly (3/3).

Expression of the variants in zebrafish severely affected structural development recapitulating the patient phenotypes (microcephaly and short stature).

RNA sequencing in fibroblasts from 2 unrelated patients and a control, revealed that expression of H4C3 variants was similar to wt. The authors estimated that ~8% of H4 cDNA molecules contained the variant. LC-MS/MS analysis suggested that the mutant protein was present in nucleosomes at a level of 1-2% while RNA-seq identified 115 differential expressed genes, with enrichment for relevant procedures (chr. organization, histone binding, DNA packaging, nucleosomal organization, cell cycle).

Post-translational modifications of Lys92 (H4K91) are highly conserved and have been previously associated with processes from chromatin assembly , DNA damage sensitivity, etc. Post-translational marks on Lys92 (K91) were absent in patient derived cells as a result of each variant.

Zebrafish models for both variants were suggestive for accumulation of double strand breaks (DSBs) more visible in heads and tails of larvae. Embryos expressing mutants displayed increased apoptosis in head and tail. Additional studies in larvae were suggestive of abnormal cell cycle progression (rel. increase in cellls in S/G2/M phase, increased occurrence of activated CHK2 with p53 stabilization) applying to both variants studied.

------
In a subsequent publication, Tessadori et al. (2020 - PMID: 31804630) described the phenotype of a 14 y.o. boy harboring a dn heterozygous missense H4C11 (HIST1H4J) variant following trio-ES [c.274A>G / HGVS p.(Lys92Glu)]. Features incl. profound ID, microcephaly, short stature with some dysmorphic features (uplsanting p-f, hypertelorism, etc). Previous work-up was normal/non-diagnostic and incl. FMR1, MECP2 and a CMA showing an inherited 207 kb CNV involving KCNV1. Upon mRNA microinjection in zebrafish embryos - either for wt or for Lys92Glu HIST1H4J - effect for wt was very mild. Lys92Glu expression led to defective development of head structures (brain, eyes), faulty body axis growth and dysmorphic tail reproducing the microcephaly and short stature phenotype. This was similar to previous zebrafish studies for HIS1H4C variants (above).

------
Tessadori et al. (2022 - PMID: 35202563) describe 29 *additional individuals with de novo missense variants in genes encoding H4, namely:
- H4C3 (HIST1H4C/N=6 subjects),
- H4C11 (HIST1H4J/N=1),
- H4C4 (HIST1H4D/N=1),
- H4C5 (HIST1H4E/N=17),
- H4C6 (HIST1H4F/N=1),
- H4C9 (HIST1H4I/N=3).

All individuals, exhibited DD and ID (29/29). Other features incl. hypotonia (10/29), seizures (5/29), autism (5/29), ataxia (4/29). Abnormal growth incl. progressive microcephaly (2/19 prenatal, 20/29 postnatal onset), short stature/FTT (each 11/29). Few had skeletal features (craniosynostosis 2/29, abn. digits 4/29, vertebral 4/29). Some had visual (17/28) or hearing impairment (7/29). Facial features incl. hypertelorism (5/29), upslanting p-f (3/29), broad nasal tip (11/29), thin upper lip (4/29) and teeth anomalies (6/29 - notably gap between central incisors).

The authors state that the cohort was collected with trio WES but also after data sharing via Genematcher / DECIPHER.

Identified variants were in all cases missense and de novo, the latter either by trio WES or Sanger sequencing of parents.

Previous work-up or presence of additional variants are not discussed.

At the protein level 10 aa were affected, 6 of which recurrently within the same gene (Arg45, His75, Lys91, Tyr98) as well among several genes for H4 (Pro32, Arg40). Variants lied within two clusters, one corresponding to the α-helix of H4 (reported variants affected Lys31 - Arg45) important for DNA contacts, interactions with H3 and histone chaperones. The other within the core of nucleosome (reported patient variants : His75-Tyr98) with important strucural contact between H3-H4 dimer and histone chaperones.

There were no detectable genotype-phenotype patterns separating individual H4 genes or protein regions. Of note, variability was observed even among 7 individuals with the same dn H4C5 variant (Arg45Cys).

All variants were absent from control databases incl. gnomAD and affected residues conserved through to S. cerevisiae. Substitutions affecting Arg45 and Gly94 and His75 have been studied previously with effect in growth/fitness/chromatin remodeling/DNA damage repair depending on variant (5 studies cited).

Zebrafish embryos at the 1 cell stage were injected with mRNA encoding either wt or identified variants, the latter inducing significant developmental defects with the exception of Pro32Ala (H4C3) and Arg40Cys (H4C5, H4C11).

For Pro32Ala and Arg40Cys however, the strong recurrence in this cohort supports pathogenicity. A dosage dependent effect was observed for 2 variants.

H4 genes appear to be tolerant to both missense and loss-of-function variation (the latter even in homozygous form) suggesting a dominant effect of the variants.

------
[RefSeqs : H4C3/HIST1H4C - NM_0035242.4 | H4C4/HIST1H4D - NM_003539.4 | H4C5/HIST1H4E - NM_003545.3 | H4C6/HIST1H4F - NM_003540.4 | H4C9/HIST1H4I - NM_003495.2 | H4C11/HIST1H4J - NM_021968.4 // Variants at the protein level above are according to the HGVS nomenclature. However as the N-terminal methionine is cleaved, numbering relative to the mature peptide has also been used in publications eg. p.Pro33Ala HGVS corresponding to Pro32Ala]
Sources: Literature
Intellectual disability - microarray and sequencing v3.1501 NALCN Arina Puzriakova Phenotypes for gene: NALCN were changed from ?Neuroaxonal neurodegeneration, infantile, with facial dysmophism, 615419; CONGENITAL CONTRACTURES OF THE LIMBS AND FACE, HYPOTONIA, AND DEVELOPMENTAL DELAY to Congenital contractures of the limbs and face, hypotonia, and developmental delay, OMIM:616266; Hypotonia, infantile, with psychomotor retardation and characteristic facies 1, OMIM:615419
Intellectual disability - microarray and sequencing v3.1478 FOXR1 Zornitza Stark gene: FOXR1 was added
gene: FOXR1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: FOXR1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: FOXR1 were set to 34723967
Phenotypes for gene: FOXR1 were set to Postnatal microcephaly, progressive brain atrophy and global developmental delay
Review for gene: FOXR1 was set to AMBER
Added comment: 1 patient described with a de novo missense variant. Phenotypes include: postnatal microcephaly, progressive brain atrophy, skeletal abnormalities, brain abnormalities, ophthalmic abnormalities, neuromuscular abnormalities, and dysmorphic features. A variant in ATP1A3 was considered to have contributed to the final phenotype.

In vitro functional evidence is supportive of pathogenicity (variant causes protein instability and abnormal nuclear aggregation).

A mouse knockout has comparable phenotypes, and a severe survival deficit.

Rated amber (1 patient, functional evidence, mouse model).
Sources: Literature
Intellectual disability - microarray and sequencing v3.1405 NUP85 Eleanor Williams changed review comment from: PMID: 34170319 - Ravindran et al 2021 report two pedigrees with an MCPH-SCKS phenotype spectrum without SRNS. In the first family, a 9 yo female, with consanguineous parents, is reported to have a missense variant in NUP85 (c.932G > A; p.R311Q). Intrauterine growth restriction was noticed. At birth microcephaly was observed (OFC < 3rd centile, < −3.6 SD) as well as hypotrophy [weight −2.8 SD), length 45 cm (−2.7 SD), both <3rd centile], facial dysmorphism, syndactyly, long and thin fingers, and bilateral pes adductus. She has severe developmental delay with strongly delayed motor milestones and absent speech. Drug-resistant, genetic epilepsy with focal-onset seizures started in the first year of life. She had no clinical, laboratory or radiological findings indicative of kidney dysfunction

In the second family, compound heterozygous missense variants in NUP85 were detected
(c.1109A > G, c.1589 T > C;p.N370S, p.M530T ) in a fetus. MRI of the fetal brain at 24 + 2 GW indicated complete agenesis of the corpus callosum, abnormal sulcation in the left frontal lobe, nodularity of the frontal horn and trigone with focal puckering of the left lateral ventricle.

PMID: 30179222 - Braun et al 2018 - 2 individuals from the 1 of the families reported with steroid-resistant nephrotic syndrome were also reported to have intellectual disability but showed no structural brain defects. The degree of intellectual disability is not stated. They were found to have 2 compound heterozygous alleles (c.405+1G>A and c.1741G>C, p.Ala581Pro), which segregated from the maternal and the paternal side.
Sources: Literature; to: PMID: 34170319 - Ravindran et al 2021 report two pedigrees with an MCPH-SCKS phenotype spectrum without SRNS. In the first family, a 9 yo female, with consanguineous parents, is reported to have a missense variant in NUP85 (c.932G > A; p.R311Q). Intrauterine growth restriction was noticed. At birth microcephaly was observed (OFC < 3rd centile, < −3.6 SD) as well as hypotrophy [weight −2.8 SD), length 45 cm (−2.7 SD), both <3rd centile], facial dysmorphism, syndactyly, long and thin fingers, and bilateral pes adductus. She has severe developmental delay with strongly delayed motor milestones and absent speech. Drug-resistant, genetic epilepsy with focal-onset seizures started in the first year of life. She had no clinical, laboratory or radiological findings indicative of kidney dysfunction.

In the second family, compound heterozygous missense variants in NUP85 were detected
(c.1109A > G, c.1589 T > C;p.N370S, p.M530T ) in a fetus. MRI of the fetal brain at 24 + 2 GW indicated complete agenesis of the corpus callosum, abnormal sulcation in the left frontal lobe, nodularity of the frontal horn and trigone with focal puckering of the left lateral ventricle.

PMID: 30179222 - Braun et al 2018 - 2 individuals from 1 of the families reported with steroid-resistant nephrotic syndrome were also reported to have intellectual disability but showed no structural brain defects. The degree of intellectual disability is not stated. They were found to have 2 compound heterozygous alleles (c.405+1G>A and c.1741G>C, p.Ala581Pro) in NUP85.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1405 NUP85 Eleanor Williams gene: NUP85 was added
gene: NUP85 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: NUP85 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NUP85 were set to 34170319
Phenotypes for gene: NUP85 were set to Primary autosomal recessive microcephaly and Seckel syndrome spectrum disorders (MCPH-SCKS)
Review for gene: NUP85 was set to AMBER
Added comment: PMID: 34170319 - Ravindran et al 2021 report two pedigrees with an MCPH-SCKS phenotype spectrum without SRNS. In the first family, a 9 yo female, with consanguineous parents, is reported to have a missense variant in NUP85 (c.932G > A; p.R311Q). Intrauterine growth restriction was noticed. At birth microcephaly was observed (OFC < 3rd centile, < −3.6 SD) as well as hypotrophy [weight −2.8 SD), length 45 cm (−2.7 SD), both <3rd centile], facial dysmorphism, syndactyly, long and thin fingers, and bilateral pes adductus. She has severe developmental delay with strongly delayed motor milestones and absent speech. Drug-resistant, genetic epilepsy with focal-onset seizures started in the first year of life. She had no clinical, laboratory or radiological findings indicative of kidney dysfunction

In the second family, compound heterozygous missense variants in NUP85 were detected
(c.1109A > G, c.1589 T > C;p.N370S, p.M530T ) in a fetus. MRI of the fetal brain at 24 + 2 GW indicated complete agenesis of the corpus callosum, abnormal sulcation in the left frontal lobe, nodularity of the frontal horn and trigone with focal puckering of the left lateral ventricle.

PMID: 30179222 - Braun et al 2018 - 2 individuals from the 1 of the families reported with steroid-resistant nephrotic syndrome were also reported to have intellectual disability but showed no structural brain defects. The degree of intellectual disability is not stated. They were found to have 2 compound heterozygous alleles (c.405+1G>A and c.1741G>C, p.Ala581Pro), which segregated from the maternal and the paternal side.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1399 EIF5A Arina Puzriakova Phenotypes for gene: EIF5A were changed from Intellectual disability; microcephaly; dysmorphism to Faundes-Banka syndrome, OMIM:619376
Intellectual disability - microarray and sequencing v3.1352 SNIP1 Sarah Leigh Added comment: Comment on list classification: Associated with relevant phenotype in OMIM and as possible Gen2Phen gene. A single (founder) variant NM_024700.4:c.1097A>G, p.(Glu366Gly) has been reported in over 30 cases of Psychomotor retardation, epilepsy, and craniofacial dysmorphism OMIM:614501 in the Amish community (PMIDs: 22279524; 34570759). Cases are homozygous for this variant and unaffected members of the families are heterozygous or wt. Overexpression of the equivalent mouse variant in mouse inner medullary collecting duct cells, resulted in a more aggregated appearance in the nucleus compared to wildtype. The variant protein maybe unstable as Western blots showed reduced levels of the variant protein (PMID: 22279524). Whole transcriptomic analysis of patient blood was performed in PMID: 34570759. This revealed 11 upregulated and 32 downregulated genes, of which 24 had previously been associated with neurological disease.
Intellectual disability - microarray and sequencing v3.1350 SNIP1 Sarah Leigh Phenotypes for gene: SNIP1 were changed from Psychomotor retardation, epilepsy, and craniofacial dysmorphism, 614501; severe developmental delay to Psychomotor retardation, epilepsy, and craniofacial dysmorphism OMIM:614501; psychomotor retardation, epilepsy, and craniofacial dysmorphism MONDO:0013787
Intellectual disability - microarray and sequencing v3.1332 DDX23 Zornitza Stark edited their review of gene: DDX23: Added comment: PMID 34050707: 9 unrelated individuals (gathered through GeneMatcher) with de novo missense alterations in DDX23. Clinical features include: tone abnormalities, global developmental delay, facial dysmorphism, autism spectrum disorder, and seizures. Additionally, there were a variety of other findings in the skeletal, renal, ocular, and cardiac systems. The missense alterations all occurred within a highly conserved RecA-like domain of the protein, and are located within or proximal to the DEAD box sequence. The gene is ubiquitously expressed and functions in RNA splicing, maintenance of genome stability, and the sensing of double-stranded RNA.; Changed rating: GREEN; Changed publications to: 33057194, 34050707
Intellectual disability - microarray and sequencing v3.1332 HMGB1 Zornitza Stark gene: HMGB1 was added
gene: HMGB1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HMGB1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: HMGB1 were set to 34164801
Phenotypes for gene: HMGB1 were set to Developmental delay and microcephaly
Review for gene: HMGB1 was set to GREEN
gene: HMGB1 was marked as current diagnostic
Added comment: 13q12.3 microdeletion syndrome is a rare cause of syndromic ID. Previous studies identified four genes within the ~300 Kb minimal critical region including two candidate protein coding genes: KATNAL1 and HMGB1.

Uguen et al. (2021) report 6 patients with LOF variants involving HMGB1 with features similar to 13q12.3 microdeletion syndrome (i.e. developmental delay, language delay, microcephaly, obesity and dysmorphic features). In silico analyses suggest that HMGB1 is likely to be intolerant to LOF, and previous in vitro data are in line with the role of HMGB1 in neurodevelopment. They suggest that haploinsufficiency of the HMGB1 gene may play a critical role in the pathogenesis of the 13q12.3 microdeletion syndrome.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1303 TNPO2 Arina Puzriakova Phenotypes for gene: TNPO2 were changed from to Intellectual disability; Dysmorphic features; Microcephaly; Seizures; Hypotonia
Intellectual disability - microarray and sequencing v3.1280 RFX7 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). 14 unrelated individuals were identified with different variants in the RFX7 gene (13 de novo, 1 unknown). Presenting phenotypes were predominantly of ID/GDD (13/14) and dysmorphism (12/14).

There are sufficient unrelated cases with a relevant phenotype associated with variants in this gene to rate as Green at the next GMS panel update.
Intellectual disability - microarray and sequencing v3.1262 ZNF668 Zornitza Stark gene: ZNF668 was added
gene: ZNF668 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: ZNF668 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: ZNF668 were set to 34313816; 26633546
Phenotypes for gene: ZNF668 were set to DNA damage repair defect; microcephaly; growth deficiency; severe global developmental delay; brain malformation; facial dysmorphism
Review for gene: ZNF668 was set to AMBER
Added comment: 2 consanguineous families reported with different biallelic truncating (not NMD) variants in ZNF668. Phenotypes included microcephaly, growth deficiency, severe global developmental delay, brain malformation, and distinct facial dysmorphism.

Immunofluorescence indicated ZNF668 deficiency. An increased DNA damage phenotype was demonstrated in patient fibroblasts.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1262 CHRM1 Zornitza Stark gene: CHRM1 was added
gene: CHRM1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CHRM1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: CHRM1 were set to 34212451; 31981491; 12483218
Phenotypes for gene: CHRM1 were set to Neurodevelopmental delay; intellectual disability; autism
Review for gene: CHRM1 was set to AMBER
Added comment: PMID: 34212451 - 2 unrelated cases with de novo missense variants (p.Pro380Leu and p.Phe425Ser), one case with early-onset refractory epilepsy, severe disability, and progressive cerebral and cerebellar atrophy, and the second case with mild dysmorphism, global developmental delay, and moderate intellectual disability. In vitro biochemical analyses of p.Pro380Leu demonstrated a reduction in protein levels, impaired cellular trafficking, and defective activation of intracellular signaling pathways.
PMID: 31981491 - an autism spectrum disorder (no other information on phenotype, except ascertained to have severe neurodevelopmental delay) case with a de novo missense variant p.(Arg210Leu)
PMID: 12483218 - null mouse model assessing memory demonstrated selective cognitive dysfunction.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1262 ZNF699 Zornitza Stark gene: ZNF699 was added
gene: ZNF699 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: ZNF699 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: ZNF699 were set to 33875846
Phenotypes for gene: ZNF699 were set to DEGCAGS syndrome, MIM# 619488
Review for gene: ZNF699 was set to GREEN
Added comment: DEGCAGS syndrome is a neurodevelopmental disorder characterized by global developmental delay, coarse and dysmorphic facial features, and poor growth and feeding apparent from infancy. Affected individuals have variable systemic manifestations often with significant structural defects of the cardiovascular, genitourinary, gastrointestinal, and/or skeletal systems. Additional features may include sensorineural hearing loss, hypotonia, anaemia or pancytopaenia, and immunodeficiency with recurrent infections.

12 unrelated families reported, 5 different homozygous frameshift variants.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1262 JAKMIP1 Zornitza Stark gene: JAKMIP1 was added
gene: JAKMIP1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: JAKMIP1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: JAKMIP1 were set to 29158550; 26627310; 27799067
Phenotypes for gene: JAKMIP1 were set to Intellectual disability; seizures
Review for gene: JAKMIP1 was set to AMBER
Added comment: Identified in two independent patients in the literature with a mouse model. Patient 1 (27799067) with developmental delay, speech delay, and cognitive impairment; self-injurious and aggressive behaviour, seizures, dysmorphic features. De-novo missense JAKMIP1 (p.D586H). Patient 2 (29158550) with feeding difficulties, hypotonia, epilepsy, severe ID, no active speech, kyphoscoliosis, constipation, autism, short stature. Splice variant c.1432-2A>G, no segregation or RNA data available. KO mouse model (27799067) displays social deficits, stereotyped activity, abnormal postnatal vocalizations, and other autistic-like behaviors.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1220 PLXNA2 Konstantinos Varvagiannis changed review comment from: Altuame et al (2021 - PMID: 34327814) describe 3 individuals from 2 consanguineous Arab families with biallelic PLXNA2 variants.

The index patient from the 1st family presented with CHD (hypoplastic right ventricle, ASD), DD and moderate ID (IQ of 40), failure to thrive as well as some dysmorphic features (obtuse mandibular angle, mild overbite, synophrys with downslanting p-f, strabismus, etc). There were additional features (eg. postaxial polydactyly) which were found in other affected and unaffected family members.

Exome sequencing with autozygome analysis revealed homozygosity for a PLXNA2 stopgain variant (NM_025179:c.3603C>A / p.(Cys1201*)).

Sanger confirmation was carried out and segregation analyses confirmed carrier status of the unaffected parents and a sib as well as a brother homozygous for the same variant. Clinical evaluation of the latter, following this finding revealed borderline intellectual functioning, ADHD, failure to thrive. There was no mandibular anomaly or overbite and no clinical evidence of CHD (no echo performed).

The index patient from the 2nd consanguineous family was evaluated for ID (IQ of 63), with previous borderline motor development, ADHD and some dysmorphic features (obtuse mandibular angle and overbite). There was no clinical evidence of CHD (no echo performed).

Exome sequencing with autozygosity mapping revealed a homozygous missense PLXNA2 variant (c.3073G>A / p.(Asp1025Asn), present only once in gnomAD (htz), with rather non-concordant in silico predictions SIFT 0.22, PolyPhen 0.682 and CADD 23.5. The aa was however highly conserved.

Segregation analysis confirmed carrier state of the parents and 2 unaffected sibs, with a 3rd sib homozygous for the wt allele.

As the authors discuss:
*PLXNA2 belongs to the plexin family of genes, encoding transmbembrane proteins functioning as semaphorin receptors. It has predominant expression in neural tissue. The protein is thought to bind semaphorin-3A, -3C or -5 followed by plexin A2 dimerization, activation of its GTPase-activating protein domain, negative regulation of Rap1B GTPase and initiation of a signal transduction cascade mediating axonal repulsion/guidance, dendritic guidance, neuronal migration.
*Murine Plxna2 knockout models display structural brain defects. In addition they display congenital heart defects incl. persistent truncus arteriosus and interrupted aortic arch.
*Rare CNVs in adult humans with tetralogy of Fallot have suggested a potential role of PLXNA2 in cardiac development and CHD.
*Expression and the role of PLXNA2 in human chondrocytes as well as a GWAS in 240 japanese patients with mandibular prognathism where PLXNA2 was suggested as a susceptibility locus.

Overall, the authors recognize some common features (as for cognitive functioning, some dysmorphic features incl. obtuse mandibular angle and overbite in 2 unrelated subjects, failure to thrive 3/3) and provide plausible explanations for the variability / discordance of others eg:
- Cyanotic heart disease explaining discordance in cognitive outcome among sibs
- Incomplete penetrance for CHD (and/or ID or mandibular anomaly) as for few AR disorders and/or
- Additional pathogenic variants explaining the CHD in the first subject.

There is no associated phenotype in OMIM or G2P. SysID includes PLXNA2 among the candidate ID genes.
Sources: Literature, Other; to: Altuame et al (2021 - PMID: 34327814) describe 3 individuals from 2 consanguineous Arab families with biallelic PLXNA2 variants.

The index patient from the 1st family presented with CHD (hypoplastic right ventricle, ASD), DD and moderate ID (IQ of 40), failure to thrive as well as some dysmorphic features (obtuse mandibular angle, mild overbite, synophrys with downslanting p-f, strabismus, etc). There were additional features (eg. postaxial polydactyly) which were found in other affected and unaffected family members.

Exome sequencing with autozygome analysis revealed homozygosity for a PLXNA2 stopgain variant (NM_025179:c.3603C>A / p.(Cys1201*)).

Sanger confirmation was carried out and segregation analyses confirmed carrier status of the unaffected parents and a sib as well as a brother homozygous for the same variant. Clinical evaluation of the latter, following this finding revealed borderline intellectual functioning, ADHD, failure to thrive. There was no mandibular anomaly or overbite and no clinical evidence of CHD (no echo performed).

The index patient from the 2nd consanguineous family was evaluated for ID (IQ of 63), with previous borderline motor development, ADHD and some dysmorphic features (obtuse mandibular angle and overbite). There was no clinical evidence of CHD (no echo performed).

Exome sequencing with autozygosity mapping revealed a homozygous missense PLXNA2 variant (c.3073G>A / p.(Asp1025Asn), present only once in gnomAD (htz), with rather non-concordant in silico predictions SIFT 0.22, PolyPhen 0.682 and CADD 23.5. The aa was however highly conserved.

Segregation analysis confirmed carrier state of the parents and 2 unaffected sibs, with a 3rd sib homozygous for the wt allele.

As the authors discuss:
*PLXNA2 belongs to the plexin family of genes, encoding transmbembrane proteins functioning as semaphorin receptors. It has predominant expression in neural tissue. The protein is thought to bind semaphorin-3A, -3C or -5 followed by plexin A2 dimerization, activation of its GTPase-activating protein domain, negative regulation of Rap1B GTPase and initiation of a signal transduction cascade mediating axonal repulsion/guidance, dendritic guidance, neuronal migration.
*Murine Plxna2 knockout models display structural brain defects. In addition they display congenital heart defects incl. persistent truncus arteriosus and interrupted aortic arch.
*Rare CNVs in adult humans with tetralogy of Fallot have suggested a potential role of PLXNA2 in cardiac development and CHD.
*Expression and the role of PLXNA2 in human chondrocytes as well as a GWAS in 240 japanese patients with mandibular prognathism where PLXNA2 was suggested as a susceptibility locus.

Overall, the authors recognize some common features (as for cognitive functioning, some dysmorphic features incl. obtuse mandibular angle and overbite in 2 unrelated subjects, failure to thrive 3/3) and provide plausible explanations for the variability / discordance of others eg:
- Cyanotic heart disease explaining discordance in cognitive outcome among sibs
- Incomplete penetrance for CHD (and/or ID or mandibular anomaly) as for few AR disorders and/or
- Additional pathogenic variants possibly explaining the CHD in the first subject.

There is no associated phenotype in OMIM or G2P. SysID includes PLXNA2 among the candidate ID genes.
Sources: Literature, Other
Intellectual disability - microarray and sequencing v3.1220 PLXNA2 Konstantinos Varvagiannis gene: PLXNA2 was added
gene: PLXNA2 was added to Intellectual disability. Sources: Literature,Other
Mode of inheritance for gene: PLXNA2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PLXNA2 were set to 34327814
Phenotypes for gene: PLXNA2 were set to Intellectual disability; Abnormality of the face; Failure to thrive; Abnormal heart morphology
Penetrance for gene: PLXNA2 were set to Incomplete
Review for gene: PLXNA2 was set to AMBER
Added comment: Altuame et al (2021 - PMID: 34327814) describe 3 individuals from 2 consanguineous Arab families with biallelic PLXNA2 variants.

The index patient from the 1st family presented with CHD (hypoplastic right ventricle, ASD), DD and moderate ID (IQ of 40), failure to thrive as well as some dysmorphic features (obtuse mandibular angle, mild overbite, synophrys with downslanting p-f, strabismus, etc). There were additional features (eg. postaxial polydactyly) which were found in other affected and unaffected family members.

Exome sequencing with autozygome analysis revealed homozygosity for a PLXNA2 stopgain variant (NM_025179:c.3603C>A / p.(Cys1201*)).

Sanger confirmation was carried out and segregation analyses confirmed carrier status of the unaffected parents and a sib as well as a brother homozygous for the same variant. Clinical evaluation of the latter, following this finding revealed borderline intellectual functioning, ADHD, failure to thrive. There was no mandibular anomaly or overbite and no clinical evidence of CHD (no echo performed).

The index patient from the 2nd consanguineous family was evaluated for ID (IQ of 63), with previous borderline motor development, ADHD and some dysmorphic features (obtuse mandibular angle and overbite). There was no clinical evidence of CHD (no echo performed).

Exome sequencing with autozygosity mapping revealed a homozygous missense PLXNA2 variant (c.3073G>A / p.(Asp1025Asn), present only once in gnomAD (htz), with rather non-concordant in silico predictions SIFT 0.22, PolyPhen 0.682 and CADD 23.5. The aa was however highly conserved.

Segregation analysis confirmed carrier state of the parents and 2 unaffected sibs, with a 3rd sib homozygous for the wt allele.

As the authors discuss:
*PLXNA2 belongs to the plexin family of genes, encoding transmbembrane proteins functioning as semaphorin receptors. It has predominant expression in neural tissue. The protein is thought to bind semaphorin-3A, -3C or -5 followed by plexin A2 dimerization, activation of its GTPase-activating protein domain, negative regulation of Rap1B GTPase and initiation of a signal transduction cascade mediating axonal repulsion/guidance, dendritic guidance, neuronal migration.
*Murine Plxna2 knockout models display structural brain defects. In addition they display congenital heart defects incl. persistent truncus arteriosus and interrupted aortic arch.
*Rare CNVs in adult humans with tetralogy of Fallot have suggested a potential role of PLXNA2 in cardiac development and CHD.
*Expression and the role of PLXNA2 in human chondrocytes as well as a GWAS in 240 japanese patients with mandibular prognathism where PLXNA2 was suggested as a susceptibility locus.

Overall, the authors recognize some common features (as for cognitive functioning, some dysmorphic features incl. obtuse mandibular angle and overbite in 2 unrelated subjects, failure to thrive 3/3) and provide plausible explanations for the variability / discordance of others eg:
- Cyanotic heart disease explaining discordance in cognitive outcome among sibs
- Incomplete penetrance for CHD (and/or ID or mandibular anomaly) as for few AR disorders and/or
- Additional pathogenic variants explaining the CHD in the first subject.

There is no associated phenotype in OMIM or G2P. SysID includes PLXNA2 among the candidate ID genes.
Sources: Literature, Other
Intellectual disability - microarray and sequencing v3.1217 PIDD1 Konstantinos Varvagiannis changed review comment from: There is enough evidence to include this gene in the current panel with green rating.

Biallelic PIDD1 pathogenic variants have been reported in 26 individuals (11 families) with DD (all), variable degrees of ID (mild to severe), behavioral (eg. aggression/self-mutilation in several, ADHD) and/or psychiatric abnormalities (ASD, psychosis in 5 belonging to 3 families), well-controlled epilepsy is some (9 subjects from 6 families) and MRI abnormalities notably abnormal gyration pattern (pachygyria with predominant anterior gradient) as well as corpus callosum anomalies (commonly thinning) in several. Dysmorphic features have been reported in almost all, although there has been no specific feature suggested.

The first reports on the phenotype associated with biallelic PIDD1 mutations were made by Harripaul et al (2018 - PMID: 28397838) and Hu et al (2019 - PMID: 29302074) [both studies investigating large cohorts of individuals with ID from consanguineous families].

Sheikh et al (2021 - PMID: 33414379) provided details on the phenotype of 15 individuals from 5 families including those from the previous 2 reports and studied provided evidence on the role of PIDD1 and the effect of variants.

Zaki et al (2021 - PMID: 34163010) reported 11 additional individuals from 6 consanguineous families, summarize the features of all subjects published in the literature and review the neuroradiological features of the disorder.

PIDD1 encodes p53-induced death domain protein 1. The protein is part of the PIDDosome, a multiprotein complex also composed of the bipartite linker protein CRADD (also known as RAIDD) and the proform of caspase-2 and induces apoptosis in response to DNA damage.

There are 5 potential PIDD1 mRNA transcript variants with NM_145886.4 corresponding to the longest. Similar to the protein encoded by CRADD, PIDD1 contains a death domain (DD - aa 774-893). Constitutive post-translational processing gives PIDD1-N, PIDD1-C the latter further processed into PIDD1-CC (by auto-cleavage). Serine residues at pos. 446 and 588 are involved in this autoprocessing generating PIDD1-C (aa 446-910) and PIDD1-CC (aa 774-893). The latter is needed for caspase-2 activation.

Most (if not all) individuals belonged to consanguineous families of different origins and harbored pLoF or missense variants.

Variants reported so far include : c.2587C>T; p.Gln863* / c.1909C>T ; p.Arg637* / c.2443C>T / p.Arg815Trp / c.2275-1G>A which upon trap assay was shown to lead to skipping of ex15 with direct splicing form exon14 to the terminal exon 16 (resulting to p.Arg759Glyfs*1 with exlcusion of the entire DD) / c.2584C>T; p.Arg862Trp / c.1340G>A; p.Trp447* / c.2116_2120del; p.Val706His*, c.1564_1565del; p.Gly602fs*26

Evidence so far provided includes:
- Biallelic CRADD variants cause a NDD disorder and a highly similar gyration pattern.
- Confirmation of splicing effect (eg. for c.2275-1G>A premature stop in position 760) or poor expression (NM_145886.3:c.2587C>T; p.Gln863*). Arg815Trp did not affect autoprocessing or protein stability.
- Abnormal localization pattern, loss of interaction with CRADD and failure to activate caspase-2 (MDM2 cleavage assay) [p.Gln863* and Arg815Trp]
- Available expression data from GTEx (PIDD1 having broad expression in multiple tissues, but higher in brain cerebellum) as well as BrainSpan and PsychEncode studies suggesting high coexpression of PIDD1, CRADD and CASP2 in many regions in the developing human brain.
- Variants in other genes encoding proteins interacting with PIDD1 (MADD, FADD, DNAJ, etc) are associated with NDD.

Pidd-1 ko mice (ex3-15 removal) lack however CNS-related phenotypes. These show decreased anxiety but no motor anomalies. This has also been the case with Cradd-/- mice displaying no significant CNS phenotypes without lamination defects.

There is currently no associated phenotype in OMIM, PanelApp Australia. PIDD1 is listed in the DD panel of G2P (PIDD1-relared NDD / biallelic / loss of function / probable) . SysID includes PIDD1 among the current primary ID genes.

Overall the gene appears to be relevant for the epilepsy panel, panels for gyration and/or corpus callosum anomalies etc.
Sources: Literature, Other; to: There is enough evidence to include this gene in the current panel with green rating.

Biallelic PIDD1 pathogenic variants have been reported in 26 individuals (11 families) with DD (all), variable degrees of ID (mild to severe), behavioral (eg. aggression/self-mutilation in several, ADHD) and/or psychiatric abnormalities (ASD, psychosis in 5 belonging to 3 families), well-controlled epilepsy is some (9 subjects from 6 families) and MRI abnormalities notably abnormal gyration pattern (pachygyria with predominant anterior gradient) as well as corpus callosum anomalies (commonly thinning) in several. Dysmorphic features have been reported in almost all, although there has been no specific feature suggested.

The first reports on the phenotype associated with biallelic PIDD1 mutations were made by Harripaul et al (2018 - PMID: 28397838) and Hu et al (2019 - PMID: 29302074) [both studies investigating large cohorts of individuals with ID from consanguineous families].

Sheikh et al (2021 - PMID: 33414379) provided details on the phenotype of 15 individuals from 5 families including those from the previous 2 reports and studied provided evidence on the role of PIDD1 and the effect of variants.

Zaki et al (2021 - PMID: 34163010) reported 11 additional individuals from 6 consanguineous families, summarize the features of all subjects published in the literature and review the neuroradiological features of the disorder.

PIDD1 encodes p53-induced death domain protein 1. The protein is part of the PIDDosome, a multiprotein complex also composed of the bipartite linker protein CRADD (also known as RAIDD) and the proform of caspase-2 and induces apoptosis in response to DNA damage.

There are 5 potential PIDD1 mRNA transcript variants with NM_145886.4 corresponding to the longest. Similar to the protein encoded by CRADD, PIDD1 contains a death domain (DD - aa 774-893). Constitutive post-translational processing gives PIDD1-N, PIDD1-C the latter further processed into PIDD1-CC (by auto-cleavage). Serine residues at pos. 446 and 588 are involved in this autoprocessing generating PIDD1-C (aa 446-910) and PIDD1-CC (aa 774-893). The latter is needed for caspase-2 activation.

Most (if not all) individuals belonged to consanguineous families of different origins and harbored pLoF or missense variants.

Variants reported so far include : c.2587C>T; p.Gln863* / c.1909C>T ; p.Arg637* / c.2443C>T / p.Arg815Trp / c.2275-1G>A which upon trap assay was shown to lead to skipping of ex15 with direct splicing form exon14 to the terminal exon 16 (resulting to p.Arg759Glyfs*1 with exlcusion of the entire DD) / c.2584C>T; p.Arg862Trp / c.1340G>A; p.Trp447* / c.2116_2120del; p.Val706His*, c.1564_1565del; p.Gly602fs*26

Evidence so far provided includes:
- Biallelic CRADD variants cause a NDD disorder and a highly similar gyration pattern.
- Confirmation of splicing effect (eg. for c.2275-1G>A premature stop in position 760) or poor expression (NM_145886.3:c.2587C>T; p.Gln863*). Arg815Trp did not affect autoprocessing or protein stability.
- Abnormal localization pattern, loss of interaction with CRADD and failure to activate caspase-2 (MDM2 cleavage assay) [p.Gln863* and Arg815Trp]
- Available expression data from GTEx (PIDD1 having broad expression in multiple tissues, but higher in brain cerebellum) as well as BrainSpan and PsychEncode studies suggesting high coexpression of PIDD1, CRADD and CASP2 in many regions in the developing human brain.
- Variants in other genes encoding proteins interacting with PIDD1 (MADD, FADD, DNAJ, etc) are associated with NDD.

Pidd-1 ko mice (ex3-15 removal) lack however CNS-related phenotypes. These show decreased anxiety but no motor anomalies. This has also been the case with Cradd-/- mice displaying no significant CNS phenotypes without lamination defects.

There is currently no associated phenotype in OMIM, PanelApp Australia. PIDD1 is listed in the DD panel of G2P (PIDD1-related NDD / biallelic / loss of function / probable) . SysID includes PIDD1 among the current primary ID genes.

Overall the gene appears to be relevant for the epilepsy panel, panels for gyration and/or corpus callosum anomalies etc.
Sources: Literature, Other
Intellectual disability - microarray and sequencing v3.1217 PIDD1 Konstantinos Varvagiannis gene: PIDD1 was added
gene: PIDD1 was added to Intellectual disability. Sources: Literature,Other
Mode of inheritance for gene: PIDD1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PIDD1 were set to 28397838; 29302074; 33414379; 34163010
Phenotypes for gene: PIDD1 were set to Global developmental delay; Intellectual disability; Seizures; Autism; Behavioral abnormality; Psychosis; Pachygyria; Lissencephaly; Abnormality of the corpus callosum
Penetrance for gene: PIDD1 were set to Complete
Review for gene: PIDD1 was set to GREEN
Added comment: There is enough evidence to include this gene in the current panel with green rating.

Biallelic PIDD1 pathogenic variants have been reported in 26 individuals (11 families) with DD (all), variable degrees of ID (mild to severe), behavioral (eg. aggression/self-mutilation in several, ADHD) and/or psychiatric abnormalities (ASD, psychosis in 5 belonging to 3 families), well-controlled epilepsy is some (9 subjects from 6 families) and MRI abnormalities notably abnormal gyration pattern (pachygyria with predominant anterior gradient) as well as corpus callosum anomalies (commonly thinning) in several. Dysmorphic features have been reported in almost all, although there has been no specific feature suggested.

The first reports on the phenotype associated with biallelic PIDD1 mutations were made by Harripaul et al (2018 - PMID: 28397838) and Hu et al (2019 - PMID: 29302074) [both studies investigating large cohorts of individuals with ID from consanguineous families].

Sheikh et al (2021 - PMID: 33414379) provided details on the phenotype of 15 individuals from 5 families including those from the previous 2 reports and studied provided evidence on the role of PIDD1 and the effect of variants.

Zaki et al (2021 - PMID: 34163010) reported 11 additional individuals from 6 consanguineous families, summarize the features of all subjects published in the literature and review the neuroradiological features of the disorder.

PIDD1 encodes p53-induced death domain protein 1. The protein is part of the PIDDosome, a multiprotein complex also composed of the bipartite linker protein CRADD (also known as RAIDD) and the proform of caspase-2 and induces apoptosis in response to DNA damage.

There are 5 potential PIDD1 mRNA transcript variants with NM_145886.4 corresponding to the longest. Similar to the protein encoded by CRADD, PIDD1 contains a death domain (DD - aa 774-893). Constitutive post-translational processing gives PIDD1-N, PIDD1-C the latter further processed into PIDD1-CC (by auto-cleavage). Serine residues at pos. 446 and 588 are involved in this autoprocessing generating PIDD1-C (aa 446-910) and PIDD1-CC (aa 774-893). The latter is needed for caspase-2 activation.

Most (if not all) individuals belonged to consanguineous families of different origins and harbored pLoF or missense variants.

Variants reported so far include : c.2587C>T; p.Gln863* / c.1909C>T ; p.Arg637* / c.2443C>T / p.Arg815Trp / c.2275-1G>A which upon trap assay was shown to lead to skipping of ex15 with direct splicing form exon14 to the terminal exon 16 (resulting to p.Arg759Glyfs*1 with exlcusion of the entire DD) / c.2584C>T; p.Arg862Trp / c.1340G>A; p.Trp447* / c.2116_2120del; p.Val706His*, c.1564_1565del; p.Gly602fs*26

Evidence so far provided includes:
- Biallelic CRADD variants cause a NDD disorder and a highly similar gyration pattern.
- Confirmation of splicing effect (eg. for c.2275-1G>A premature stop in position 760) or poor expression (NM_145886.3:c.2587C>T; p.Gln863*). Arg815Trp did not affect autoprocessing or protein stability.
- Abnormal localization pattern, loss of interaction with CRADD and failure to activate caspase-2 (MDM2 cleavage assay) [p.Gln863* and Arg815Trp]
- Available expression data from GTEx (PIDD1 having broad expression in multiple tissues, but higher in brain cerebellum) as well as BrainSpan and PsychEncode studies suggesting high coexpression of PIDD1, CRADD and CASP2 in many regions in the developing human brain.
- Variants in other genes encoding proteins interacting with PIDD1 (MADD, FADD, DNAJ, etc) are associated with NDD.

Pidd-1 ko mice (ex3-15 removal) lack however CNS-related phenotypes. These show decreased anxiety but no motor anomalies. This has also been the case with Cradd-/- mice displaying no significant CNS phenotypes without lamination defects.

There is currently no associated phenotype in OMIM, PanelApp Australia. PIDD1 is listed in the DD panel of G2P (PIDD1-relared NDD / biallelic / loss of function / probable) . SysID includes PIDD1 among the current primary ID genes.

Overall the gene appears to be relevant for the epilepsy panel, panels for gyration and/or corpus callosum anomalies etc.
Sources: Literature, Other
Intellectual disability - microarray and sequencing v3.1216 CLCN3 Zornitza Stark gene: CLCN3 was added
gene: CLCN3 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CLCN3 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: CLCN3 were set to 34186028
Phenotypes for gene: CLCN3 were set to Neurodevelopmental disorder
Mode of pathogenicity for gene: CLCN3 was set to Other
Review for gene: CLCN3 was set to GREEN
gene: CLCN3 was marked as current diagnostic
Added comment: 11 individuals reported, 9 that carried 8 different rare heterozygous missense variants in CLCN3, and 2 siblings that were homozygous for an NMD-predicted frameshift variant likely abolishing ClC-3 function. All missense variants were confirmed to be de novo in eight individuals for whom parental data was available.

The 11 individuals in the cohort share clinical features of variable severity. All 11 have GDD or ID and dysmorphic features, and a majority has mood or behavioural disorders and structural brain abnormalities:
- Structural brain abnormalities on MRI (9/11) included partial or full agenesis of the corpus callosum (6/9), disorganized cerebellar folia (4/9), delayed myelination (3/9), decreased white matter volume (3/9), pons hypoplasia (3/9), and dysmorphic dentate nuclei (3/9). Six of those with brain abnormalities also presented with seizures.
- Nine have abnormal vision, including strabismus in four and inability to fix or follow in the two with homozygous loss-of-function variants.
- Hypotonia ranging from mild to severe was reported in 7 of the 11 individuals.
- Six have mood or behavioural disorders, particularly anxiety (3/6).
- Consistent dysmorphic facial features included microcephaly, prominent forehead, hypertelorism, down-slanting palpebral fissures, full cheeks, and micrognathia.

The severity of disease in the two siblings with homozygous disruption of ClC-3 is consistent with the drastic phenotype seen in Clcn3 KO mice. The disease was more severe in two siblings carrying homozygous loss-of-function variants with the presence of GDD, absent speech, seizures, and salt and pepper fundal pigmentation in both individuals, with one deceased at 14 months of age. The siblings also had significant neuroanatomical findings including diffusely decreased white matter volume, thin corpora callosa, small hippocampi, and disorganized cerebellar folia. Supporting biallelic inheritance for LoF variants, disruption of mouse Clcn3 results in drastic neurodegeneration with loss of the hippocampus a few months after birth and early retinal degeneration. Clcn3−/− mice display severe neurodegeneration, whereas heterozygous Clcn3+/− mice appear normal.

Patch-clamp studies were used to investigate four of the missense variants. These suggested a gain of function in two variants with increased current in HEK cells, however they also showed reduced rectification of voltage and a loss of transient current, plus decreased current amplitude, glycosylation and surface expression when expressed in oocytes, and were suspected to interfere with channel gating and a negative feedback mechanism. These effects were also shown to vary depending on pH levels. The current of the remaining two variants did not differ from WT. For heterozygous missense variants, the disruption induced may be at least partially conferred to mutant/WT homodimers and mutant/ClC-4 heterodimers.

Both loss and gain of function in this gene resulted in the same phenotype.

Green for mono-allelic variants, Amber/Red for bi-allelic.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1216 TNPO2 Zornitza Stark reviewed gene: TNPO2: Rating: GREEN; Mode of pathogenicity: None; Publications: 34314705; Phenotypes: Intellectual disability, dysmorphic features; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Current diagnostic: yes
Intellectual disability - microarray and sequencing v3.1179 NAA20 Sarah Leigh changed review comment from: Not associated with a phenotype in OMIM nor Gen2Phen. Two missense variants reported as homozygotes in one family each. In silico predictions and in vitro functional studies provide evidence that these variants will adversely affect their capacity to form a NatB complex with NAA25, and in vitro acetylation assays revealed reduced catalytic activities toward different NatB substrates (PMID 34230638). Children from these two families had developmental delay, intellectual disability (mild to moderate family 1, severe family 2).
The two children in family 1 in this study had a head circumcernces of -2.3 & -1.9 SD (which is not regarded as severe microcephaly).
The three children from family 2 this study had a head circumcernces of -3.5, -3.0 & -3.5 SD (which is regarded as severe microcephaly). Subtle dysmorphic features were also reported.
Sources: Literature; to: Not associated with a phenotype in OMIM nor Gen2Phen. Two missense variants reported as homozygotes in one family each. In silico predictions and in vitro functional studies provide evidence that these variants will adversely affect their capacity to form a NatB complex with NAA25, and in vitro acetylation assays revealed reduced catalytic activities toward different NatB substrates (PMID 34230638). Children from these two families had developmental delay, intellectual disability (mild to moderate family 1, severe family 2).
The two children in family 1 in this study had a head circumcernces of -2.3 & -1.9 SD (which is not regarded as severe microcephaly).
The three children from family 2 in this study had a head circumcernces of -3.5, -3.0 & -3.5 SD (which is regarded as severe microcephaly). Subtle dysmorphic features were also reported.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1177 NAA20 Sarah Leigh gene: NAA20 was added
gene: NAA20 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: NAA20 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: NAA20 were set to 34230638
Phenotypes for gene: NAA20 were set to autosomal recessive developmental delay, intellectual disability, and microcephaly
Review for gene: NAA20 was set to AMBER
Added comment: Not associated with a phenotype in OMIM nor Gen2Phen. Two missense variants reported as homozygotes in one family each. In silico predictions and in vitro functional studies provide evidence that these variants will adversely affect their capacity to form a NatB complex with NAA25, and in vitro acetylation assays revealed reduced catalytic activities toward different NatB substrates (PMID 34230638). Children from these two families had developmental delay, intellectual disability (mild to moderate family 1, severe family 2).
The two children in family 1 in this study had a head circumcernces of -2.3 & -1.9 SD (which is not regarded as severe microcephaly).
The three children from family 2 this study had a head circumcernces of -3.5, -3.0 & -3.5 SD (which is regarded as severe microcephaly). Subtle dysmorphic features were also reported.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1167 ERGIC3 Zornitza Stark gene: ERGIC3 was added
gene: ERGIC3 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: ERGIC3 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: ERGIC3 were set to 33710394; 31585110
Phenotypes for gene: ERGIC3 were set to Intellectual disability
Review for gene: ERGIC3 was set to AMBER
Added comment: PMID: 33710394 - two homozygous sibs with mild ID, a novel canonical splice (c.717+1G>A). Absent in gnomAD, no splice studies. Classed as a VUS.

PMID: 31585110 - 1 hom (p.Gln233Argfs*10) in a male 8yo with Growth retardation, Microcephaly, Learning disability, Facial dysmorphism, Abnormal pigmentation.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1166 PPP1R21 Ivone Leong 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 to Neurodevelopmental disorder with hypotonia, facial dysmorphism, and brain abnormalities, OMIM:619383
Intellectual disability - microarray and sequencing v3.1162 GNB2 Arina Puzriakova gene: GNB2 was added
gene: GNB2 was added to Intellectual disability. Sources: Literature
Q3_21_rating tags were added to gene: GNB2.
Mode of inheritance for gene: GNB2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: GNB2 were set to 31698099; 33971351; 34183358
Phenotypes for gene: GNB2 were set to Intellectual disability
Review for gene: GNB2 was set to GREEN
Added comment: GNB2 is not yet associated with any phenotype in OMIM, but has a 'confirmed' disease confidence rating for 'GNB2-related developmental disorder (monoallelic)' in G2P.

At least 14 unrelated individuals with de novo monoallelic variants, including 5 recurrent variants in 13 individuals (PMIDs: 31698099; 33971351; 34183358). All patients (except one fetus owing to termination of pregnancy) have DD/ID of variable severity (mild to severe) which appeared to correlate with the variant each individual harboured. Other variable features include non-specific facial dysmorphism, hypotonia, and autistic behaviour.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1154 EPHA7 Konstantinos Varvagiannis gene: EPHA7 was added
gene: EPHA7 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: EPHA7 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: EPHA7 were set to 34176129; 19664229
Phenotypes for gene: EPHA7 were set to Global developmental delay; Intellectual disability; Delayed speech and language development; Behavioral abnormality
Penetrance for gene: EPHA7 were set to Incomplete
Review for gene: EPHA7 was set to AMBER
Added comment: Lévy et al (2021 - PMID: 34176129) provide evidence that haploinssuficiency of EPHA7 results in a neurodevelopmental disorder.

The authors report on 12 individuals belonging to 9 unrelated families, all harboring with 6q microdeletions spanning EPHA7.

Overlapping features included DD (13/13), ID (10/10 - mild in most cases, individuals with larger CNVs/additional variants had more severe phenotype), speech delay and behavioral disorders. Variable other features incl. hypotonia (70%), non specific facial features, eye abnormalities (40%) and cardiac defects (25%).

The CNVs ranged from 152 kb to few Mb in size but in 4 subjects (P5-8) were only minimal, involving only EPHA7.

The 6q microdeletion included additional ID-related genes in at least one case (eg. ZNF292 in P12) while one subject (P4) harbored also a 7q11.23 Williams syndrome deletion.

Confirmation (e.g. with FISH or qPCR) and segregation analyses were performed. 9 out of 12 individuals had inherited the deletion (5 subjects paternal, 4 maternal), in 1 subject (P12) this occured de novo, while for 2 others inheritance was not specified. Most deletions were inherited from an unaffected parent (in 6/7 families), with unclear contribution in a further one.

Sequencing of an ID gene panel was performed for 5 subjects (P1-4 (sibs) and P9) and exome for 4 ones (P1,2,10,11). CNVs in all these subjects were not limited to EPHA7. These investigations did not reveal other variants responsible for the phenotype of these subjects.

EPHA7 encodes ephrin receptor A7. As the authors comment, ephrin receptors are the largest family of transmembrane receptor tyrosine kinases. These receptors interact with membrane bound ephrins and binding activates the tyrosine kinase activity of the receptor.

The authors discuss on previous studies suggesting an important role for EphA7 in brain development (modulation of cell-cell adhesion and repulsion, regulation of dendrite morphogenesis in early corticogenesis, role in dendritic spine formation later in development. EphA7 has also been proposed to drive neuronal maturation and synaptic function).

Haploinsufficiency for other ephrins or ephrin receptors has been implicated in other NDDs.

Finally the authors comment on a previous report of a de novo 2.16 Mb microdeletion spanning EPHA7 and another gene (TSG1). This deletion, reported by Traylor et al (2009 - PMID: 19664229) was identified in a 15-month old male with DD, microcephaly and dysmorphic features.

Overall Lévy et al promote incomplete penetrance and variable expressivity with haploinsufficiency of this gene being a risk factor for NDD. [The gene has also an %HI of 2.76% and a pLI of 1].

In DECIPHER there are 2 indivuals (DDD participants) with de novo missense variants and abnormality of the nervous system.

As a result this gene can be considered for inclusion in the ID panel with amber rating pending further evidence.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1143 BCAS3 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is sufficient evidence to promote this gene to Green at the next GMS panel update (see details below).
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Hengel et al. 2021 (PMID: 34022130) report 8 unrelated families, all with different biallelic variants in the BCAS3 gene. All affected individuals (15 total, +1 additional proband but with unphased variants but consistent phenotype) had severe GDD and ID, with 10 subjects having minimal vocabulary and 4 never learning to speak. All probands had a severe motor disorder with pyramidal tract involvement resulting in hyperreflexia and spasticity of the lower limbs (15/15). Other variable features observed in the cohort include microcephaly, short stature, seizures, and dysmorphic facial features.
Intellectual disability - microarray and sequencing v3.1125 PGM2L1 Zornitza Stark gene: PGM2L1 was added
gene: PGM2L1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: PGM2L1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PGM2L1 were set to 33979636
Phenotypes for gene: PGM2L1 were set to Neurodevelopmental disorder
Review for gene: PGM2L1 was set to GREEN
Added comment: PMID: 33979636:
- Bi-allelic PTVs in 4 unrelated individuals. All four affected individuals had severe developmental and speech delay, dysmorphic facial features, ear anomalies, high arched palate, strabismus, hypotonia, and keratosis pilaris. Early obesity and seizures were present in three individuals.
- Studies on patient fibroblasts and cell lines indicated that PGM2L1 deficiency causes a decrease, but not a disappearance, of the sugar bisphosphates needed for the formation of NDP-sugars and that there is no evidence that this leads to a glycosylation defect.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1123 EMC10 Arina Puzriakova edited their review of gene: EMC10: Added comment: There are now at least 15 individuals from 8 families reported with biallelic variants in the EMC10 gene associated with disease. One variant found in a single population is likely to be a founder variant; however, the identification of a different variant in a family presenting with a similar phenotype corroborates causality. Both variants were shown to significantly reduce EMC10 RNA expression. All affected individuals show a core phenotype of GDD/ID with variable severity. Seizures were noted in 7/15 individuals, typically during childhood or in the neonatal period, and included multifocal as well as generalized tonic–clonic seizures.; Changed rating: GREEN; Changed publications to: 32869858, 33531666; Changed phenotypes to: Neurodevelopmental disorder with dysmorphic facies and variable seizures, OMIM:619264; Changed mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability - microarray and sequencing v3.1123 BCAS3 Zornitza Stark gene: BCAS3 was added
gene: BCAS3 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: BCAS3 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: BCAS3 were set to 34022130
Phenotypes for gene: BCAS3 were set to Syndromic neurodevelopmental disorder
Review for gene: BCAS3 was set to GREEN
Added comment: 15 individuals from eight unrelated families with germline bi-allelic loss-of-function variants in BCAS3. All probands share a global developmental delay accompanied by pyramidal tract involvement, microcephaly, short stature, strabismus, dysmorphic facial features, and seizures. Patient fibroblasts confirmed absence of BCAS3 protein.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1122 EMC10 Arina Puzriakova Added comment: Comment on phenotypes: EMC10 is now associated with a relevant phenotype in OMIM - 'Neurodevelopmental disorder with dysmorphic facies and variable seizures, OMIM:619264' and is listed in G2P with a 'probable' disease confidence rating for 'EMC10-related neurodevelopmental disorder'
Intellectual disability - microarray and sequencing v3.1122 EMC10 Arina Puzriakova Phenotypes for gene: EMC10 were changed from Neurodevelopmental disorder with dysmorphic facies and variable seizures, OMIM:619264 to Neurodevelopmental disorder with dysmorphic facies and variable seizures, OMIM:619264
Intellectual disability - microarray and sequencing v3.1121 EMC10 Arina Puzriakova Phenotypes for gene: EMC10 were changed from Intellectual disability to Neurodevelopmental disorder with dysmorphic facies and variable seizures, OMIM:619264
Intellectual disability - microarray and sequencing v3.1120 SMARCA5 Zornitza Stark reviewed gene: SMARCA5: Rating: GREEN; Mode of pathogenicity: None; Publications: 33980485; Phenotypes: Neurodevelopmental disorder, microcephaly, dysmorphic features; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability - microarray and sequencing v3.1103 DPH1 Arina Puzriakova Phenotypes for gene: DPH1 were changed from Developmental delay with short stature, dysmorphic features, and sparse hair, 616901 to Developmental delay with short stature, dysmorphic facial features, and sparse hair, OMIM:616901
Intellectual disability - microarray and sequencing v3.1069 ANKRD17 Zornitza Stark gene: ANKRD17 was added
gene: ANKRD17 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: ANKRD17 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: ANKRD17 were set to 33909992
Phenotypes for gene: ANKRD17 were set to Intellectual disability, speech delay, and dysmorphism
Review for gene: ANKRD17 was set to GREEN
gene: ANKRD17 was marked as current diagnostic
Added comment: 34 predominantly LoF variants reported - 29 de novo, 1 inherited from an affected parent, 1 inherited from a suspected mosaic parent. Main phenotypes were dev delay/ID, motor delay, and speech delay.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1069 SIN3B Zornitza Stark gene: SIN3B was added
gene: SIN3B was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: SIN3B was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: SIN3B were set to 33811806
Phenotypes for gene: SIN3B were set to Syndromic intellectual disability
Review for gene: SIN3B was set to GREEN
gene: SIN3B was marked as current diagnostic
Added comment: PMID: 33811806
- 9 affected individuals, variants all de novo (2 PTCs, 2 missense, multigenic CNVs)
- syndrome hallmarked by intellectual disability, developmental delay, and dysmorphic facial features with variably penetrant ASD, congenital malformations, corpus callosum defects, and impaired growth.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1069 EMC10 Zornitza Stark edited their review of gene: EMC10: Added comment: PMID 33531666: Additional 12 individuals from 7 Middle Eastern families reported. Same variant in all, suggestive of founder effect (but different to the previously reported family).; Changed rating: GREEN; Changed publications to: 32869858, 33531666; Changed phenotypes to: Neurodevelopmental disorder with dysmorphic facies and variable seizures, MIM# 619264
Intellectual disability - microarray and sequencing v3.1018 MAPKAPK5 Zornitza Stark gene: MAPKAPK5 was added
gene: MAPKAPK5 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: MAPKAPK5 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: MAPKAPK5 were set to 3344202
Phenotypes for gene: MAPKAPK5 were set to Developmental delay, variable brain anomalies, congenital heart defects, dysmorphism
Review for gene: MAPKAPK5 was set to GREEN
gene: MAPKAPK5 was marked as current diagnostic
Added comment: 3 individuals from 2 families with severe developmental delay, variable brain anomalies, congenital heart defects, dysmorphic facial features, and a distinctive type of synpolydactyly with an additional hypoplastic digit between the fourth and fifth digits of hands and/or feet. Exome sequencing identified different homozygous truncating variants in MAPKAPK5 in both families, segregating with disease and unaffected parents as carriers.

Patient-derived cells showed no expression of MAPKAPK5 protein isoforms and reduced levels of the MAPKAPK5-interacting protein ERK3. F-actin recovery after latrunculin B treatment was found to be less efficient in patient-derived fibroblasts than in control cells, supporting a role of MAPKAPK5 in F-actin polymerization.

Borderline Amber/Green but high impact variants and a distinctive phenotype with some functional data.
Sources: Literature
Intellectual disability - microarray and sequencing v3.993 EIF5A Arina Puzriakova Added comment: Comment on list classification: There is enough evidence to rate this gene Green at the next review - PMID: 33547280 (2021) reports 7 unrelated individuals with different de novo heterozygous variants in the EIF5A gene. All were affected by variable degrees of DD and/or ID, mostly within the moderate severity range. Other features such as microcephaly and craniofacial dysmorphism were prominent but overall, the phenotype is best represented by this panel. Supportive functional data included.

EIF5A is currently not associated with any phenotype in OMIM (last edited on 18/07/2019), but is listed in Gene2Phenotype with a 'probable' disease confidence rating for 'EIF5A-related craniofacial-neurodevelopmental disorder'
Intellectual disability - microarray and sequencing v3.976 SIAH1 Arina Puzriakova gene: SIAH1 was added
gene: SIAH1 was added to Intellectual disability. Sources: Literature
Q2_21_rating tags were added to gene: SIAH1.
Mode of inheritance for gene: SIAH1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: SIAH1 were set to 32430360
Phenotypes for gene: SIAH1 were set to Developmental delay; Infantile hypotonia; Dysmorphic features; Laryngomalacia
Review for gene: SIAH1 was set to GREEN
Added comment: - PMID: 32430360 (2021) - Five unrelated individuals with shared features of developmental delay, infantile hypotonia, dysmorphic features and laryngomalacia. All had speech delay and where cognitive assessment was age appropriate individuals exhibited learning difficulties. Trio WES revealed distinct de novo variants in SIAH1. In vitro assays demonstrated that SIAH1 mutants induce loss of Wnt stimulatory activity.
Sources: Literature
Intellectual disability - microarray and sequencing v3.975 EIF5A Zornitza Stark gene: EIF5A was added
gene: EIF5A was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: EIF5A was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: EIF5A were set to 33547280
Phenotypes for gene: EIF5A were set to Intellectual disability; microcephaly; dysmorphism
Review for gene: EIF5A was set to GREEN
Added comment: 7 unrelated individuals reported with de novo variants in this gene and variable combinations of developmental delay, microcephaly, micrognathia and dysmorphism.
Sources: Literature
Intellectual disability - microarray and sequencing v3.975 SPEN Zornitza Stark edited their review of gene: SPEN: Added comment: PMID: 33596411
- 34 individuals with truncating variants in SPEN reported, most are de novo variants.
- Clinical profile includes developmental delay/intellectual disability, autism spectrum disorder, anxiety, aggressive behavior, attention deficit disorder, hypotonia, brain and spine anomalies, congenital heart defects, high/narrow palate, facial dysmorphisms, and obesity/increased BMI, especially in females.
- Authors showed haploinsufficiency of SPEN is associated with a distinctive DNA methylation episignature of the X chromosome in affected females.; Changed rating: GREEN; Changed publications: 33057194, 33596411; Changed phenotypes: Developmental delay/intellectual disability, autism spectrum disorder, anxiety, aggressive behavior, attention deficit disorder, hypotonia, brain and spine anomalies, congenital heart defects, high/narrow palate, facial dysmorphisms, and obesity/increased BMI; Set current diagnostic: yes
Intellectual disability - microarray and sequencing v3.969 SETD1B Arina Puzriakova Phenotypes for gene: SETD1B were changed from Epilepsy, developmental delay, intellectual disability, autistic behavior and craniofacial dysmorphic features to Intellectual developmental disorder with seizures and language delay, OMIM:619000; Intellectual developmental disorder with seizures and language delay, MONDO:0033559
Intellectual disability - microarray and sequencing v3.922 SMO Arina Puzriakova Source: Expert Review Amber was removed from gene: SMO
Intellectual disability - microarray and sequencing v3.773 OTUD5 Zornitza Stark changed review comment from: PMID 33523931: Another 10 individuals from 7 families reported, promote to Green. X-linked multiple congenital anomalies-neurodevelopmental syndrome (MCAND) is an X-linked recessive congenital multisystemic disorder characterized by poor growth, global developmental delay with impaired intellectual development, and variable abnormalities of the cardiac, skeletal, and genitourinary systems. Most affected individuals also have hypotonia and dysmorphic craniofacial features. Brain imaging typically shows enlarged ventricles and thin corpus callosum; some have microcephaly, whereas others have hydrocephalus. The severity of the disorder is highly variable, ranging from death in early infancy to survival into the second or third decade.; to: PMID 33523931: Another 10 individuals from 7 families reported. Key features include poor growth, global developmental delay with impaired intellectual development, and variable abnormalities of the cardiac, skeletal, and genitourinary systems. Most affected individuals also have hypotonia and dysmorphic craniofacial features. Brain imaging typically shows enlarged ventricles and thin corpus callosum; some have microcephaly, whereas others have hydrocephalus. The severity of the disorder is highly variable, ranging from death in early infancy to survival into the second or third decade.
Intellectual disability - microarray and sequencing v3.773 OTUD5 Zornitza Stark edited their review of gene: OTUD5: Added comment: PMID 33523931: Another 10 individuals from 7 families reported, promote to Green. X-linked multiple congenital anomalies-neurodevelopmental syndrome (MCAND) is an X-linked recessive congenital multisystemic disorder characterized by poor growth, global developmental delay with impaired intellectual development, and variable abnormalities of the cardiac, skeletal, and genitourinary systems. Most affected individuals also have hypotonia and dysmorphic craniofacial features. Brain imaging typically shows enlarged ventricles and thin corpus callosum; some have microcephaly, whereas others have hydrocephalus. The severity of the disorder is highly variable, ranging from death in early infancy to survival into the second or third decade.; Changed rating: GREEN; Changed publications: 33131077, 33523931
Intellectual disability - microarray and sequencing v3.749 METAP1 Zornitza Stark gene: METAP1 was added
gene: METAP1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: METAP1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: METAP1 were set to 32764695
Phenotypes for gene: METAP1 were set to Intellectual disability, aggression, neurodevelopmental delay
Review for gene: METAP1 was set to RED
Added comment: Biallelic nonsense (NMD-predicted) variant identified in 4 sibs in a consanguineous family with dev delay. One sib had bilateral clinodactyly of her toes and her left 3rd finger, other sibs were not dysmorphic. Rated red due to single consanguineous family.
Sources: Literature
Intellectual disability - microarray and sequencing v3.749 MSMO1 Arina Puzriakova Phenotypes for gene: MSMO1 were changed from Microcephaly, congenital cataract, and psoriasiform dermatitis, 616834 to Microcephaly, congenital cataract, and psoriasiform dermatitis, OMIM:616834; Microcephaly-congenital cataract-psoriasiform dermatitis syndrome, MONDO:0014793
Intellectual disability - microarray and sequencing v3.738 UBR7 Arina Puzriakova Phenotypes for gene: UBR7 were changed from AUTOSOMAL RECESSIVE MENTAL RETARDATION to Intellectual disability; epilepsy; hypothyroidism; congenital anomalies; dysmorphic features
Intellectual disability - microarray and sequencing v3.694 UBR7 Zornitza Stark reviewed gene: UBR7: Rating: GREEN; Mode of pathogenicity: None; Publications: 33340455; Phenotypes: Intellectual disability, epilepsy, hypothyroidism, congenital anomalies, dysmorphic features; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal; Current diagnostic: yes
Intellectual disability - microarray and sequencing v3.684 SMG8 Arina Puzriakova Phenotypes for gene: SMG8 were changed from Intellectual disability; Microcephaly; Short stature; Facial dysmorphism Edit to Intellectual disability; Microcephaly; Short stature; Facial dysmorphism
Intellectual disability - microarray and sequencing v3.684 SMG8 Arina Puzriakova Phenotypes for gene: SMG8 were changed from Intellectual disability to Intellectual disability; Microcephaly; Short stature; Facial dysmorphism Edit
Intellectual disability - microarray and sequencing v3.681 SMG8 Arina Puzriakova edited their review of gene: SMG8: Added comment: PMID: 33242396 (2020) - 9 affected individuals from 4 consanguineous families with different biallelic variants in the SMG8 gene. Clinical features include GDD (8/8), dysmorphic features (9/9) microcephaly (6/9), short stature (4/9), brain imaging anomalies (4/5), congenital heart disease (3/9) and cataract (3/8). Only two sibs from Family 2 had a formal ID diagnosis, but this can be inferred from the clinical reports of the other cases demonstrating severe language delays, difficulties to follow simple instructions or perform daily activities.
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Several features described here overlap with those in the previously reported cases from PMID: 31130284 (e.g. microcephaly, ID, cataract, VSD); Changed rating: GREEN; Changed publications: 31130284, 33242396
Intellectual disability - microarray and sequencing v3.681 KCNMA1 Arina Puzriakova changed review comment from: Multiple individuals reported with either mono- or biallelic variants. Developmental delay and intellectual disability of relevant severity to this panel has been reported in a sufficient number of cases for inclusion on this panel. Although in most cases the phenotypes are primarily characterised by seizures or dyskinesia, it is plausible that these individuals may still be tested under the ID panel.

Furthermore, several individuals have been reported with severe GDD/ID and other variable feature such as craniofacial dysmorphism, ataxia, bone dysplasia, visceral malformations, and brain imaging anomalies, but without epilepsy or paroxysmal dyskinesia (namely Liang-Wang syndrome, PMID: 31152168). In less severely affected cases DD with significant speech delay has been noted as the main clinical indication of the presenting phenotypes, further indicating benefit of inclusion on a diagnostic ID panel.; to: Multiple individuals reported with either mono- or biallelic variants. Developmental delay and intellectual disability of relevant severity has been reported in a sufficient number of cases for inclusion on this panel. Although in most cases the phenotypes are primarily characterised by seizures or dyskinesia, it is plausible that these individuals may still be tested under the ID panel in context of the severe intellectual impairment that may be observed.

Furthermore, several individuals have been reported with severe GDD/ID and other variable feature such as craniofacial dysmorphism, ataxia, bone dysplasia, visceral malformations, and brain imaging anomalies, but without epilepsy or paroxysmal dyskinesia (namely Liang-Wang syndrome, PMID: 31152168). In less severely affected cases DD with significant speech delay has been noted as the main clinical indication of the presenting phenotypes, further indicating benefit of inclusion on a diagnostic ID panel.
Intellectual disability - microarray and sequencing v3.676 H3F3B Arina Puzriakova Phenotypes for gene: H3F3B were changed from to Developmental delay; Intellectual disability; Neurodegeneration; Epilepsy; Facial dysmorphism; Congenital anomalies
Intellectual disability - microarray and sequencing v3.673 H3F3B Arina Puzriakova reviewed gene: H3F3B: Rating: GREEN; Mode of pathogenicity: None; Publications: 33268356; Phenotypes: Developmental delay, Neurodegeneration, Epilepsy, Facial dysmorphism, Congenital anomalies; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability - microarray and sequencing v3.673 H3F3A Arina Puzriakova Phenotypes for gene: H3F3A were changed from to Developmental delay; Intellectual disability; Neurodegeneration; Epilepsy; Facial dysmorphism; Congenital anomalies
Intellectual disability - microarray and sequencing v3.669 H3F3A Arina Puzriakova reviewed gene: H3F3A: Rating: GREEN; Mode of pathogenicity: None; Publications: 31942419, 33268356; Phenotypes: Developmental delay, Neurodegeneration, Epilepsy, Facial dysmorphism, Congenital anomalies; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability - microarray and sequencing v3.661 RAP1B Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is associated with a phenotype in Gene2Phenotype but not OMIM.

PMID: 32627184 describes 2 patients.
36 yo patient of non-consanguineous parents. Had unclear pancytopenia, multiple congenital malformations, mild intellectual disability, endocrine disorders (short stature with growth hormone deficiency), dysmorphism and other features. Parents and sibling unaffected.
13 yo of non-consanguineous parents with thrombocytopenia, multiple congenital anomalies and learning difficulties. He had normal developmental milestones, walk was achieved at 14 months and there was no speech delay. He attended mainstream school with auxiliary help because of learning difficulties with graphism, syntaxic comprehension, logical reasoning and attention deficit. Parents and siblings unaffected.

PMID: 26280580 describes another patient with variant in RAP1B. The clinical features can be found in supplementary table 2. The table lists ID, but doesn't say severity and lists a host of other features including short stature, facial dysmorphism and skeletal findings.

All 3 cases seem to have a very wide spectrum of differing phenotypes and therefore, this gene has been given an Amber rating until further evidence is available.
Intellectual disability - microarray and sequencing v3.648 NARS Arina Puzriakova changed review comment from: Associated with relevant phenotype in OMIM, and in Gene2Phenotype with 'confirmed' disease confidence for 'NARS1 Neurodevelopmental Disorder (monoallelic)' and 'probable' for 'NARS1 Neurodevelopmental Disorder (biallelic)'

Total of 23 patients from 13 unrelated families with biallelic variants in the NARS1 gene (PMIDs: 32738225 and 32788587) and 8 unrelated patients with de novo heterozygous nonsense variants (PMIDs: 32738225). All individuals had GDD and ID, which varied in severity from moderate to profound. Other features include microcephaly, seizures, ataxia, and dysmorphism. Supportive functional data.; to: Associated with relevant phenotype in OMIM, and in Gene2Phenotype with 'confirmed' disease confidence for 'NARS1 Neurodevelopmental Disorder (monoallelic)' and 'probable' for 'NARS1 Neurodevelopmental Disorder (biallelic)'

Total of 24 patients from 13 unrelated families with biallelic variants in the NARS1 gene (PMIDs: 32738225 and 32788587) and 8 unrelated patients with de novo heterozygous variants (PMIDs: 32738225). All individuals had GDD and ID, which varied in severity from moderate to profound. Other features include microcephaly, seizures, ataxia, and dysmorphism. Supportive functional data.
Intellectual disability - microarray and sequencing v3.648 NARS Arina Puzriakova changed review comment from: Associated with relevant phenotype in OMIM, and in Gene2Phenotype with 'confirmed' disease confidence for 'NARS1 Neurodevelopmental Disorder (monoallelic)' and 'probable' for 'NARS1 Neurodevelopmental Disorder (biallelic)'

Total of 23 patients from 13 unrelated families with biallelic variants in the NARS1 gene (PMIDs: 32738225 and 32788587) and 6 unrelated patients with de novo heterozygous nonsense variants (PMIDs: 32738225). All individuals had GDD and ID, which varied in severity from moderate to profound. Other features include microcephaly, seizures, ataxia, and dysmorphism. Supportive functional data.; to: Associated with relevant phenotype in OMIM, and in Gene2Phenotype with 'confirmed' disease confidence for 'NARS1 Neurodevelopmental Disorder (monoallelic)' and 'probable' for 'NARS1 Neurodevelopmental Disorder (biallelic)'

Total of 23 patients from 13 unrelated families with biallelic variants in the NARS1 gene (PMIDs: 32738225 and 32788587) and 8 unrelated patients with de novo heterozygous nonsense variants (PMIDs: 32738225). All individuals had GDD and ID, which varied in severity from moderate to profound. Other features include microcephaly, seizures, ataxia, and dysmorphism. Supportive functional data.
Intellectual disability - microarray and sequencing v3.644 BICRA Zornitza Stark gene: BICRA was added
gene: BICRA was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: BICRA was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: BICRA were set to 33232675
Phenotypes for gene: BICRA were set to Developmental delay, intellectual disability, autism spectrum disorder,behavioral abnormalities, dysmorphic features
Review for gene: BICRA was set to GREEN
Added comment: 12 individuals reported, 11 de novo (1 not resolved), with neurodevelopmental phenotypes—developmental delay (HP:0001263), intellectual disability (HP:0001249), autism spectrum disorder (HP:0000729), and/or behavioral phenotypes (HP:0000708)—and variable structural birth defects and dysmorphic features. Mostly LoF or gene deletions, but 2 missense reported. Zebrafish model supports the gene-disease association.
Sources: Literature
Intellectual disability - microarray and sequencing v3.644 HS2ST1 Zornitza Stark gene: HS2ST1 was added
gene: HS2ST1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HS2ST1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: HS2ST1 were set to 33159882
Phenotypes for gene: HS2ST1 were set to Intellectual disability; dysmorphic features; congenital anomalies
Review for gene: HS2ST1 was set to GREEN
Added comment: Four affected individuals from 3 unrelated families. 3 unique missense and 2 PTCs. Clinical features included developmental delay, corpus callosum hypoplasia or aplasia, and skeletal and renal abnormalities as well as joint contractures/arthrogryposis.
Sources: Literature
Intellectual disability - microarray and sequencing v3.644 KDM4B Zornitza Stark gene: KDM4B was added
gene: KDM4B was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: KDM4B was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: KDM4B were set to 33232677
Phenotypes for gene: KDM4B were set to Global developmental delay, intellectual disability and neuroanatomical defects
Review for gene: KDM4B was set to GREEN
Added comment: Nine individuals with mono-allelic de novo or inherited variants in KDM4B.

All individuals presented with dysmorphic features and global developmental delay (GDD) with language and motor skills most affected. Three individuals had a history of seizures, and four had anomalies on brain imaging ranging from agenesis of the corpus callosum with hydrocephalus to cystic formations, abnormal hippocampi, and polymicrogyria.

In a knockout mouse the total brain volume was significantly reduced with decreased
size of the hippocampal dentate gyrus, partial agenesis of the corpus callosum, and ventriculomegaly.
Sources: Literature
Intellectual disability - microarray and sequencing v3.641 MORC2 Arina Puzriakova Phenotypes for gene: MORC2 were changed from Charcot-Marie-Tooth disease, axonal, type 2Z, MIM #616688 to Developmental delay; Intellectual disability; Growth retardation; Microcephaly; Craniofacial dysmorphism; Charcot-Marie-Tooth disease, axonal, type 2Z, OMIM:616688
Intellectual disability - microarray and sequencing v3.638 MORC2 Arina Puzriakova reviewed gene: MORC2: Rating: GREEN; Mode of pathogenicity: None; Publications: 32693025; Phenotypes: Developmental delay, Intellectual disability, Growth retardation, Microcephaly, Craniofacial dysmorphism; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability - microarray and sequencing v3.602 ZFHX4 Ivone Leong Phenotypes for gene: ZFHX4 were changed from to Developmental disorders; intellectual disability, dysmorphic features
Intellectual disability - microarray and sequencing v3.510 MAP1B Arina Puzriakova commented on gene: MAP1B: Only one homozygous case identified in a screening study of a congenital microcephaly cohort. Other features included hypochromic microcytic anaemia, lymphocytic colitis, retinal coloboma, dysmorphic features, and normal brain MRI. As this is only considered a candidate variant and the phenotype is not compatible with other monoallelic reports, the evidence is currently insufficient for a disease association with biallelic variants (PMID:30214071)
Intellectual disability - microarray and sequencing v3.510 ZFHX4 Zornitza Stark reviewed gene: ZFHX4: Rating: AMBER; Mode of pathogenicity: None; Publications: 33057194, 24038936; Phenotypes: Developmental disorders, intellectual disability, dysmorphic features; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability - microarray and sequencing v3.504 SETD1A Arina Puzriakova Phenotypes for gene: SETD1A were changed from Schizophrenia; developmental disorder; Intellectual disability to Neurodevelopmental disorder with speech impairment and dysmorphic facies, 619056; Epilepsy, early-onset, with or without developmental delay, 618832
Intellectual disability - microarray and sequencing v3.500 MPP5 Konstantinos Varvagiannis gene: MPP5 was added
gene: MPP5 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: MPP5 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: MPP5 were set to 33073849
Phenotypes for gene: MPP5 were set to Global developmental delay; Intellectual disability; Delayed speech and language development; Developmental regression; Behavioral abnormality
Penetrance for gene: MPP5 were set to unknown
Review for gene: MPP5 was set to GREEN
Added comment: Sterling et al (2020 - PMID: 33073849) provide information on the phenotype of 3 individuals with de novo MPP5 variants.

Common features included global developmental delay, intellectual disability (3/3 - severe in 2/3), speech delay/regression (the latter in at least 2) and behavioral abnormalities. Variable other features were reported, among others microcephaly (1/3), abnormal vision (1/3 : CVI, retinal dystrophy, nystagmus), brain MRI abnormalities (2/3), late-onset seizures (1/3). These subjects displayed variable and non-specific dysmorphic features.

All were investigated by exome sequencing (previous tests not mentioned).

One subject was found to harbor a de novo mosaic (5/25 reads) stopgain variant, further confirmed by Sanger sequencing [NM_022474.4:c.1555C>T - p.(Arg519Ter). The specific variant is reported once in gnomAD (1/251338). Two de novo missense variants were identified in the remaining individuals [c.1289A>G - p.Glu430Gly / c.974A>C - p.His325Pro).

All variants had in silico predictions in favor of a deleterious effect (CADD score >24).

The authors comment that MPP5 encodes an apical complex protein with asymmetric localization to the apical side of polarized cells. It is expressed in brain, peripheral nervous system and other tissues. MPP5 is a member of the membrane-associated guanylate kinase family of proteins (MAGUK, p55 subfamily), determining cell polarity at tight junctions.

Previous animal models suggest that complete Mpp5(Pals1) KO in mice leads to near absence of cerebral cortical neurons. Htz KO mice display reduction in size of cerebral cortex and hippocampus. The gene is expressed in proliferating cell populations of cerebellum and important for establishment cerebellar architecture. Conditional KO of Mpp5(Pals1) in retinal progenitor cells mimics the retinal pathology observed in LCA. [Several refs. provided]

The authors studied a heterozygous CNS-specific Mpp5 KO mouse model. These mice presented microcephaly, decreased cerebellar volume and cortical thickness, decreased ependymal cells and Mpp5 at the apical surface of cortical vertrical zone. The proportion of cortical cells undergoing apoptotic cell death was increased. Mice displayed behavioral abnormalities (hyperactivity) and visual deficits, with ERG traces further suggesting retinal blindness.

Overall the mouse model was thought to recapitulate the behavioral abnormalities observed in affected subjects as well as individual rare features such as microcephaly and abnormal vision.

Haploinsufficiency (rather than a dominant negative effect) is favored as the underlying disease mechanism. This is also in line with a dose dependent effect observed in mice.
Sources: Literature
Intellectual disability - microarray and sequencing v3.485 ZNF148 Arina Puzriakova reviewed gene: ZNF148: Rating: AMBER; 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, imprinted status unknown
Intellectual disability - microarray and sequencing v3.461 KCNK4 Ivone Leong Phenotypes for gene: KCNK4 were changed from Neurodevelopmental delay; Intellectual disability; Seizures; Gingival overgrowth; Hypertrichosis to Facial dysmorphism, hypertrichosis, epilepsy, intellectual/developmental delay, and gingival overgrowth syndrome, 618381
Intellectual disability - microarray and sequencing v3.432 BCORL1 Arina Puzriakova Phenotypes for gene: BCORL1 were changed from Intellectual disability, developmental delay and dysmorphism; Behavioral abnormality to Shukla-Vernon syndrome, 301029
Intellectual disability - microarray and sequencing v3.420 SHMT2 Konstantinos Varvagiannis gene: SHMT2 was added
gene: SHMT2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: SHMT2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SHMT2 were set to 33015733
Phenotypes for gene: SHMT2 were set to Congenital microcephaly; Infantile axial hypotonia; Spastic paraparesis; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum; Abnormal cortical gyration; Hypertrophic cardiomyopathy; Abnormality of the face; Proximal placement of thumb; 2-3 toe syndactyly
Penetrance for gene: SHMT2 were set to Complete
Review for gene: SHMT2 was set to GREEN
Added comment: García‑Cazorla et al. (2020 - PMID: 33015733) report 5 individuals (from 4 families) with a novel brain and heart developmental syndrome caused by biallelic SHMT2 pathogenic variants.

All affected subjects presented similar phenotype incl. microcephaly at birth (5/5 OFC < -2 SD though in 2/5 cases N OFC was observed later), DD and ID (1/5 mild-moderate, 1/5 moderate, 3/5 severe), motor dysfunction in the form of spastic (5/5) paraparesis, ataxia/dysmetria (3/4), intention tremor (in 3/?) and/or peripheral neuropathy (2 sibs). They exhibited corpus callosum hypoplasia (5/5) and perisylvian microgyria-like pattern (4/5). Cardiac problems were reported in all, with hypertrophic cardiomyopathy in 4/5 (from 3 families) and atrial-SD in the 5th individual (1/5). Common dysmorphic features incl. long palpebral/fissures, eversion of lateral third of lower eylids, arched eyebrows, long eyelashes, thin upper lip, short Vth finger, fetal pads, mild 2-3 toe syndactyly, proximally placed thumbs.

Biallelic variants were identified following exome sequencing in all (other investigations not mentioned). Identified variants were in all cases missense SNVs or in-frame del, which together with evidence from population databases and mouse model might suggest a hypomorphic effect of variants and intolerance/embryonic lethality for homozygous LoF ones.

SHMT2 encodes the mitohondrial form of serine hydroxymethyltransferase. The enzyme transfers one-carbon units from serine to tetrahydrofolate (THF) and generates glycine and 5,10,methylene-THF.

Mitochondrial defect was suggested by presence of ragged red fibers in myocardial biopsy of one patient. Quadriceps and myocardial biopsies of the same individual were overall suggestive of myopathic changes.

While plasma metabolites were within N range and SHMT2 protein levels not significantly altered in patient fibroblasts, the authors provide evidence for impaired enzymatic function eg. presence of the SHMT2 substrate (THF) in patient but not control (mitochondria-enriched) fibroblasts , decrease in glycine/serine ratios, impared folate metabolism. Patient fibroblasts displayed impaired oxidative capacity (reduced ATP levels in a medium without glucose, diminished oxygen consumption rates). Mitochondrial membrane potential and ROS levels were also suggestive of redox malfunction.

Shmt2 ko in mice was previously shown to be embryonically lethal attributed to severe mitochondrial respiration defects, although there was no observed brain metabolic defect.

The authors performed Shmt2 knockdown in motoneurons in Drosophila, demonstrating neuromuscular junction (# of satellite boutons) and motility defects (climbing distance/velocity).

Overall this gene can be considered for inclusion with (probably) green rating in gene panels for ID, metabolic / mitochondrial disorders, cardiomyopathy, congenital microcephaly, corpus callosum anomalies, etc.
Sources: Literature
Intellectual disability - microarray and sequencing v3.405 NUP214 Eleanor Williams changed review comment from: Associated with {Encephalopathy, acute, infection-induced, susceptibility to, 9} 618426 in OMIM and Gene2Phenotype (probable).

PMID: 31178128 - Fichtman et al 2019 - report on two families one of Palestinian decent, the other Northern European (not Finnish descent). Each had two affected siblings in which neurological decline was seen after febrile events. The older son in family A, exhibited minor developmental delay from infancy. A homozygous missense variant was identified in NUP214 (p.Arg38Cys) in family A and segregated with the disease in available family members. In family B affected sisters were compound heterozygous for a frameshift and a missense variant in NUP214 (p.Pro387Ser and p.Pro525Leufs∗6). Functional studies with fibroblasts from one patient in family A showed a decrease in NUP214 and NUP88 levels compared to controls,

PMID: 30758658 - Shamseldin et al 2019 - describe a multiplex consanguineous family in which four affected members presented with severe neonatal hypotonia, profound global developmental delay, progressive microcephaly and early death. Whole exome sequencing revealed the presence of a novel homozygous missense variant in NUP214, p.D154G.

PMID: 29483668 - Egloff et al 2018 - report a 4-year-old girl presenting with developmental delay, growth retardation and facial dysmorphism. She was found to have a 9q deletion inherited from her healthy mother and a a hemizygous one-base pair deletion in the NUP214 gene inherited from her father. From patient leukocytes it was found that the expression level of the NUP214 transcript was significantly decreased and close to zero in the patient compared to the controls. ; to: Associated with {Encephalopathy, acute, infection-induced, susceptibility to, 9} 618426 in OMIM and Gene2Phenotype (probable).

PMID: 31178128 - Fichtman et al 2019 - report on two families one of Palestinian decent, the other Northern European (not Finnish descent). Each had two affected siblings in which neurological decline was seen after febrile events. The older son in family A, exhibited minor developmental delay from infancy. A homozygous missense variant was identified in NUP214 (p.Arg38Cys) in family A and segregated with the disease in available family members. In family B affected sisters were compound heterozygous for a frameshift and a missense variant in NUP214 (p.Pro387Ser and p.Pro525Leufs∗6). Functional studies with fibroblasts from one patient in family A showed a decrease in NUP214 and NUP88 levels compared to controls,

PMID: 30758658 - Shamseldin et al 2019 - describe a multiplex consanguineous family in which four affected members presented with severe neonatal hypotonia, profound global developmental delay, progressive microcephaly and early death (<2 year old). Whole exome sequencing revealed the presence of a novel homozygous missense variant in NUP214, p.D154G.

PMID: 29483668 - Egloff et al 2018 - report a 4-year-old girl presenting with developmental delay, growth retardation and facial dysmorphism. She was found to have a 9q deletion inherited from her healthy mother and a hemizygous one-base pair deletion in the NUP214 gene inherited from her father. From patient leukocytes it was found that the expression level of the NUP214 transcript was significantly decreased and close to zero in the patient compared to the controls.
Intellectual disability - microarray and sequencing v3.405 NUP214 Eleanor Williams changed review comment from: Associated with {Encephalopathy, acute, infection-induced, susceptibility to, 9} 618426 in OMIM and Gene2Phenotype (probable).

PMID: 31178128 - Fichtman et al 2019 - report on two families. Family A have first-cousin parents of Palestinian descent. The proband exhibited minor developmental delay from infancy, presented with ataxia, mental retardation, and intractable epilepsy and died at 11 years. He suffered deterioration in association with febrile illnesses. His cousin presented at 5.5 months with partially reversible encephalopathy and developmental regression after a febrile illness. Family B were sisters born to non-consanguineous parents of Northern European (non-Finnish) descent. The older sister had nystagmus at 2 months and mild hypotonia, but she was otherwise meeting milestones appropriately . At 15 months of age, she developed a fever that led to a rapid neurological decline, seizures, and abnormal movements. The younger sister presented at 7 months with failure to thrive and hyponatremia but was meeting developmental milestones appropriately. By 24 months of age, she had motor and speech delay, ataxic gait, and occasional very mild head bobbing. In family A a homozygous NUP214 p.Arg38Cys variant segregated with the disease in available family members. In family B the sisters were found to be compound heterozygous for a frameshift and a missense variant in NUP214 (p.Pro387Ser and p.Pro525Leufs∗6).; to: Associated with {Encephalopathy, acute, infection-induced, susceptibility to, 9} 618426 in OMIM and Gene2Phenotype (probable).

PMID: 31178128 - Fichtman et al 2019 - report on two families one of Palestinian decent, the other Northern European (not Finnish descent). Each had two affected siblings in which neurological decline was seen after febrile events. The older son in family A, exhibited minor developmental delay from infancy. A homozygous missense variant was identified in NUP214 (p.Arg38Cys) in family A and segregated with the disease in available family members. In family B affected sisters were compound heterozygous for a frameshift and a missense variant in NUP214 (p.Pro387Ser and p.Pro525Leufs∗6). Functional studies with fibroblasts from one patient in family A showed a decrease in NUP214 and NUP88 levels compared to controls,

PMID: 30758658 - Shamseldin et al 2019 - describe a multiplex consanguineous family in which four affected members presented with severe neonatal hypotonia, profound global developmental delay, progressive microcephaly and early death. Whole exome sequencing revealed the presence of a novel homozygous missense variant in NUP214, p.D154G.

PMID: 29483668 - Egloff et al 2018 - report a 4-year-old girl presenting with developmental delay, growth retardation and facial dysmorphism. She was found to have a 9q deletion inherited from her healthy mother and a a hemizygous one-base pair deletion in the NUP214 gene inherited from her father. From patient leukocytes it was found that the expression level of the NUP214 transcript was significantly decreased and close to zero in the patient compared to the controls.
Intellectual disability - microarray and sequencing v3.391 MADD Ivone Leong Phenotypes for gene: MADD were changed from to Neurodevelopmental disorder with dysmorphic facies, impaired speech and hypotonia, 619005; DEEAH syndrome, 619004
Intellectual disability - microarray and sequencing v3.360 SETD1A Zerin Hyder reviewed gene: SETD1A: Rating: GREEN; Mode of pathogenicity: None; Publications: 32346159; Phenotypes: Epilepsy, early-onset, with or without developmental delay, craniofacial dysmorphisms, behavioural/psychiatric abnormalities; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Intellectual disability - microarray and sequencing v3.315 ZMYM2 Konstantinos Varvagiannis gene: ZMYM2 was added
gene: ZMYM2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: ZMYM2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: ZMYM2 were set to 32891193
Phenotypes for gene: ZMYM2 were set to Abnormality of the urinary system; Global developmental delay; Intellectual disability; Microcephaly; Abnormality of the cardiovascular system; Autism; Seizures; Abnormality of the head or neck; Abnormality of the nail; Small hand; Short foot; Clinodactyly
Penetrance for gene: ZMYM2 were set to unknown
Review for gene: ZMYM2 was set to AMBER
Added comment: Heterozygous pathogenic (pLoF) ZMYM2 variants have been reported in individuals with syndromic presentation including CAKUT (in several cases) and variable neurological manifestations among extra-renal features. DD and ID were reported in some of the families described to date as summarized below. You might consider inclusion with green/amber rating in the ID panel and green in the panel for CAKUT.

--

Connaughton et al (2020 - PMID: 32891193) report on 19 individuals (from 15 unrelated families) with heterozygous pathogenic ZMYM2 variants. [Article not reviewed in detail].

Affected individuals from 7 families presented with CAKUT while all of them displayed extra-renal features. Neurological manifestations were reported in 16 individuals from 14 families (data not available for 1 fam), among others hypotonia (3/14 fam), speech delay (4/14 fam), global DD (9/14 fam), ID (4/14 fam), microcephaly (4/14 fam). ASD was reported in 4 fam (4 indiv). Seizures were reported in 2 fam (2 indiv). Variable other features included cardiac defects, facial dysmorphisms, small hands and feet with dys-/hypo-plastic nails and clinodactyly.

14 pLoF variants were identified, in most cases as de novo events (8 fam). In 2 families the variant was inherited from an affected parent. Germline mosaicism occurred in 1 family.

The human disease features were recapitulated in a X. tropicalis morpholino knockdown, with expression of truncating variants failing to rescue renal and craniofacial defects. Heterozygous Zmym2-deficient mice also recapitulated the features of CAKUT.

ZMYM2 (previously ZNF198) encodes a nuclear zinc finger protein localizing to the nucleus (and PML nuclear body).

It has previously been identified as transcriptional corepressor interacting with nuclear receptors and the LSD1-CoREST-HDAC1 complex. It has also been shown to interact with FOXP transcription factors.

The authors provide evidence for loss of interaction of the truncated ZMYM2 with FOXP1 (mutations in the latter having recently been reported in syndromic CAKUT).
Sources: Literature
Intellectual disability - microarray and sequencing v3.314 LMNB1 Konstantinos Varvagiannis gene: LMNB1 was added
gene: LMNB1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: LMNB1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: LMNB1 were set to 32910914
Phenotypes for gene: LMNB1 were set to Global developmental delay; Intellectual disability; Microcephaly; Short stature; Seizures; Abnormality of the corpus callosum; Cortical gyral simplification; Feeding difficulties; Scoliosis
Penetrance for gene: LMNB1 were set to unknown
Mode of pathogenicity for gene: LMNB1 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: LMNB1 was set to GREEN
Added comment: Cristofoli et al (2020 - PMID: 32910914) report 7 individuals (from 5 families) harboring mostly de novo LMNB1 variants.

The common phenotype consisted of primary microcephaly (7/7 ranging from -4.4 to -10 SD), DD/ID (7/7), relative short stature in most (+0.7 to -4 SD). Additional features included brain MRI abnormalities (abnormal CC in 3, simplified gyral pattern in 3, small structurally normal brain, etc), seizures (4 individuals from 2 families), limb spasticity (1/7), cortical visual impairment (in 3), feeding difficulties (5/7), scoliosis (4/7). Non-overlapping dysmorphic features were reported in some.

Variants were identified by WES or custom-designed gene panel and included 3 missense variants, 1 in-frame deletion and a splice variant. The in-frame deletion was inherited from a similarly affected parent in whom the variant occurred as a dn event. The splice SNV(NM_005573.3:c.939+1G>A) occurred in 3 sibs and was present as mosaic variant (15%) in the parent. This variant was predicted to result to extension of exon 5 by 6 amino-acids (samples were unavailable for mRNA studies).

LMNB1 encodes a B-type lamin (the other being encoded by LMNB2). A- and B- type lamins are major components of the nuclear lamina. As the authors comment, LMNB1 is expressed in almost all cell types beginning at the earliest stages of development.

Lamin-deficient mouse models support an essential role of B-type lamins in organogenesis, neuronal migration, patterning during brain development.

Functional studies performed, demonstrated impaired formation of LMNB1 nuclear lamina in LMNB1-null HeLa cells transfected with cDNAs for 3 missense variants.

Two variants (Lys33Glu/Arg42Trp) were shown to result in decreased nuclear localization with increased abundance in the cytosolic fraction. In patient derived LCLs these variants led to abnormal nuclear morphology. A missense variant in another domain (Ala152Gly - 1st coil domain) resulted also in lower abundance of lamin B1, irregular lamin A/C nuclear lamina, as well as more condensed nuclei (HeLa cells).

LMNB1 duplications or missense mutations increasing LMNB1 expression are associated with a different presentation of AD leuodystrophy. A variant previously associated with leukodystrophy (Arg29Trp) was shown to behave differently (present in the nuclear extract but not in the cytosol, lamin B1 to A/C ratio in nuclear extract was not significantly altered compared to wt as was the case for Arg42Trp, Lys33Glu).

Given the pLI score of 0.55 as well as the phenotype of individuals with deletions (not presenting microcephaly) the authors predict that a dominant-negative effect applies (rather than haploinsufficiency).

Consider inclusion in the following panels : DD/ID (green), epilepsy (amber - 4 of 7 patients belonging to 2 families), primary microcephaly (green), callosome (amber/green - 3 individuals belonging to 3 families), mendeliome (green), etc.
Sources: Literature
Intellectual disability - microarray and sequencing v3.295 ATP1A3 Zornitza Stark edited their review of gene: ATP1A3: Added comment: Four additional individuals with dystonia, dysmorphism, encephalopathy with developmental delay, brain MRI abnormalities always including cerebellar hypoplasia, no hemiplegia, and neonatal onset. All had de novo missense variants. All are described to have global developmental delay, hence supporting upgrade in rating on this panel.; Changed rating: GREEN; Changed publications: https://doi.org/10.1212/NXG.0000000000000466; Changed phenotypes: Alternating hemiplegia of childhood 2, MIM#614820, Neurodevelopmental disorder; Set current diagnostic: yes
Intellectual disability - microarray and sequencing v3.267 TUBGCP2 Arina Puzriakova reviewed gene: TUBGCP2: Rating: AMBER; Mode of pathogenicity: None; Publications: 31630790; Phenotypes: Pachygyria, microcephaly, developmental delay, and dysmorphic facies, with or without seizures, 618737; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability - microarray and sequencing v3.262 LMBRD2 Konstantinos Varvagiannis gene: LMBRD2 was added
gene: LMBRD2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: LMBRD2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: LMBRD2 were set to 32820033; https://doi.org/10.1101/797787
Phenotypes for gene: LMBRD2 were set to Global developmental delay; Intellectual disability; Microcephaly; Seizures; Abnormality of nervous system morphology; Abnormality of the eye
Penetrance for gene: LMBRD2 were set to unknown
Review for gene: LMBRD2 was set to AMBER
Added comment: You may consider inclusion with green (13 individuals with dn missense SNVs overall, overlapping features for 10 with available phenotype / a recurring variant has been identified in 2 different studies) or amber rating (role of the gene not known, no variant studies, animal model probably not available).

► Malhotra et al (2020 - PMID: 32820033) report on 10 unrelated individuals with de novo missense LMBRD2 variants.

Features included DD (9/10), ID (6/8 of relevant age), microcephaly (7/10), seizures (5/10 - >=3 different variants), structural brain abnormalities (e.g. thin CC in 6/9), highly variable ocular abnormalities (5/10) and dysmorphic features in some (7/10 - nonspecific).

All had variable prior non-diagnostic genetic tests (CMA, gene panel, mendeliome, karyotype). WES/WGS revealed LMBRD2 missense variants, in all cases de novo. A single individual had additional variants with weaker evidence of pathogenicity.

5 unique missense SNVs and 2 recurrent ones (NM_001007527:c.367T>C - p.Trp123Arg / c.1448G>A - p.Arg483His) were identified. These occurred in different exons. Variants were not present in gnomAD and all had several in silico predictions in favor of a deleterious effect.

There was phenotypic variability among individuals with the same variant (e.g. seizures in 1/3 and microchephaly in 2/3 of those harboring R483H).

The gene has a pLI of 0 (although o/e ranges from 0.23 to 0.55), %HI of 15.13 and z-score of 2.27. The authors presume that haploinsufficiency may not apply, and consider a gain-of-function/dominant-negative effect more likely.

As the authors comment LMBRD2 (LMBR1 domain containing 2) encodes a membrane bound protein with poorly described function. It is widely expressed across tissues with notable expression in human brain (also in Drosophila, or Xenopus laevis). It displays high interspecies conservation.

It has been suggested (Paek et al - PMID: 28388415) that LMBRD2 is a potential regulator of β2 adrenoreceptor signalling through involvement in GPCR signalling.

► Kaplanis et al (2020 - https://doi.org/10.1101/797787) in a dataset of 31058 parent-offspring trios (WES) previously identified 3 individuals with developmental disorder, harboring c.1448G>A - p.Arg483His. These individuals (1 from the DDD study, and 2 GeneDx patients) appear in Decipher. [ https://decipher.sanger.ac.uk/ddd/research-variant/40e17c78cc9655a6721006fc1e0c98db/overview ]. The preprint by Kaplanis et al is cited by Malhotra et al, with Arg483His reported in 6 patients overall in both studies.
Sources: Literature
Intellectual disability - microarray and sequencing v3.262 SPOP Arina Puzriakova changed review comment from: Comment on list classification: There is enough evidence for this gene to be rated GREEN at the next major review.

Associated with Nabais Sa-de Vries syndrome in OMIM, and a probable gene for SPOP-related Neurodevelopmental Disorder in G2P.

At least 7 unrelated individuals with mild-severe ID, associated with de novo missense variants in the SPOP gene. Additional variable features include craniofacial dysmorphisms, cardiovascular abnormalities, hearing impairment, and endocrine abnormalities. Functional studies show differing effects of the variants (gain-of-function or dominant-negative) that correspond to the different clinical manifestations.; to: Comment on list classification: There is enough evidence for this gene to be rated GREEN at the next major review.

Associated with Nabais Sa-de Vries syndrome in OMIM, and a probable gene for SPOP-related Neurodevelopmental Disorder in G2P.

At least 7 unrelated individuals with mild-severe ID, associated with de novo missense variants in the SPOP gene. Additional variable features include craniofacial dysmorphisms, cardiovascular abnormalities, hearing impairment, and endocrine abnormalities. Functional studies show differing effects of the variants (gain-of-function or dominant-negative) that correspond to differences in additional clinical manifestations.
Intellectual disability - microarray and sequencing v3.261 SPOP Arina Puzriakova Phenotypes for gene: SPOP were changed from Intellectual disability; dysmorphism; microcephaly; macrocephaly to Nabais Sa-de Vries syndrome, type 1, 618828; Nabais Sa-de Vries syndrome, type 2, 618829
Intellectual disability - microarray and sequencing v3.260 SPOP Arina Puzriakova Added comment: Comment on list classification: There is enough evidence for this gene to be rated GREEN at the next major review.

Associated with Nabais Sa-de Vries syndrome in OMIM, and a probable gene for SPOP-related Neurodevelopmental Disorder in G2P.

At least 7 unrelated individuals with mild-severe ID, associated with de novo missense variants in the SPOP gene. Additional variable features include craniofacial dysmorphisms, cardiovascular abnormalities, hearing impairment, and endocrine abnormalities. Functional studies show differing effects of the variants (gain-of-function or dominant-negative) that correspond to the different clinical manifestations.
Intellectual disability - microarray and sequencing v3.223 CHD1 Arina Puzriakova changed review comment from: Gene is associated with Pilarowski-Bjornsson syndrome in OMIM, but not in G2P.

Pilarowski et al (2018) (PMID: 28866611) reported heterozygous missense variants in five individuals (two sibs and three singletons) as the cause of developmental delay, speech apraxia, hypotonia, and facial dysmorphic features. Two variants were confirmed de novo, while segregation for others could not be determined (including the two sibs who were conceived by egg donor). Developmental delay was noted for all participants; however, ID was only reported in the two sibs.; to: Gene is associated with Pilarowski-Bjornsson syndrome in OMIM, but not in G2P.

Pilarowski et al (2018) (PMID: 28866611) reported heterozygous missense variants in five individuals (two sibs and three singletons) as the cause of developmental delay, speech apraxia, hypotonia, and facial dysmorphic features. Two variants were confirmed de novo, while segregation for others could not be determined (including the two sibs who were conceived by egg donor). Developmental delay was noted for all participants; however, ID was only reported in the two sibs. Further insight may be gained from re-evaluation of the two patients in the present study who were too young for a formal neurocognitive evaluation at the time of publication.
Intellectual disability - microarray and sequencing v3.219 NARS Konstantinos Varvagiannis changed review comment from: [Please note that HGNC Approved Gene Symbol for this gene is NARS1]

Manole et al (2020 - PMID: 32738225) provide evidence that both biallelic and monoallelic (de novo) pathogenic NARS1 variants cause a neurodevelopmental disorder. In total 32 individuals from 21 families are reported, with biallelic variants identified in individuals from 13 families and de novo in 8 families.

Similar features were reported for AR/AD occurrences of the disorder and included of microcephaly (90% - most often primary), epilepsy (23/32 or 74% - variable semiology incl. partial/myoclonic/generalized tonic-clonic seizures), DD and ID (as a universal feature), abnormal tone in several (hypotonia/spasticity), ataxia, demyelinating peripheral neuropathy (in 3 or more for each inheritance mode - or a total of 25%). Some individuals had dysmorphic features.

NARS1 encodes an aminoacyl-tRNA synthetase (ARS) [asparaginyl-tRNA synthetase 1]. Aminoacyl-tRNA synthetases constitute a family of enzymes catalyzing attachment of amino-acids to their cognate tRNAs. As the authors comment, mutations in genes encoding several other ARSs result in neurological disorders ranging from peripheral neuropathy to severe multi-systemic NDD. Dominant, recessive or both modes for inheritance for mutations in the same gene (e.g. AARS1, YARS1, MARS1, etc) have been reported.

Some variants were recurrent, e.g. the c.1600C>T / p.Arg534* which occurred in 6 families as a de novo event or c.1633C>T p.Arg545Cys (homozygous in 6 families). 3 different variants were reported to have occured de novo (c.965G>T - p.Arg322Leu, c.1525G>A - p.Gly509Ser, p.Arg534*) with several other variants identified in hmz/compound htz individuals. A single SNV (c.1067A>C - p.Asp356Ala) was suggested to be acting as modifier and pathogenic only when in trans with a severe variant. [NM_004539.4 used as RefSeq for all].

The authors provide several lines of evidence for a partial loss-of-function effect (e.g. reduction in mRNA expression, enzyme levels and activity in fibroblasts or iNPCs) underlying pathogenicity of the variants identified in individuals with biallelic variants. A gain-of-function (dominant-negative) effect is proposed for de novo variants (such effect also demonstrated for the p.Arg534* in a zebrafish model).

As also Manole et al suggest, NARS1 can be considered for inclusion in gene panels for DD/ID, epilepsy and/or demyelinating neuropathy.
Sources: Literature; to: [Please note that HGNC Approved Gene Symbol for this gene is NARS1]

Manole et al (2020 - PMID: 32738225) provide evidence that both biallelic and monoallelic (de novo) pathogenic NARS1 variants cause a neurodevelopmental disorder. In total 32 individuals from 21 families are reported, with biallelic variants identified in individuals from 13 families and de novo in 8 families.

Similar features were reported for AR/AD occurrences of the disorder and included microcephaly (90% - most often primary), epilepsy (23/32 or 74% - variable semiology incl. partial/myoclonic/generalized tonic-clonic seizures), DD and ID (as a universal feature), abnormal tone in several (hypotonia/spasticity), ataxia, demyelinating peripheral neuropathy (in 3 or more for each inheritance mode - or a total of 25%). Some individuals had dysmorphic features.

NARS1 encodes an aminoacyl-tRNA synthetase (ARS) [asparaginyl-tRNA synthetase 1]. Aminoacyl-tRNA synthetases constitute a family of enzymes catalyzing attachment of amino-acids to their cognate tRNAs. As the authors comment, mutations in genes encoding several other ARSs result in neurological disorders ranging from peripheral neuropathy to severe multi-systemic NDD. Dominant, recessive or both modes for inheritance for mutations in the same gene (e.g. AARS1, YARS1, MARS1, etc) have been reported.

Some variants were recurrent, e.g. the c.1600C>T / p.Arg534* which occurred in 6 families as a de novo event or c.1633C>T p.Arg545Cys (homozygous in 6 families). 3 different variants were reported to have occured de novo (c.965G>T - p.Arg322Leu, c.1525G>A - p.Gly509Ser, p.Arg534*) with several other variants identified in hmz/compound htz individuals. A single SNV (c.1067A>C - p.Asp356Ala) was suggested to be acting as modifier and pathogenic only when in trans with a severe variant. [NM_004539.4 used as RefSeq for all].

The authors provide several lines of evidence for a partial loss-of-function effect (e.g. reduction in mRNA expression, enzyme levels and activity in fibroblasts or iNPCs) underlying pathogenicity of the variants identified in individuals with biallelic variants. A gain-of-function (dominant-negative) effect is proposed for de novo variants (such effect also demonstrated for the p.Arg534* in a zebrafish model).

As also Manole et al suggest, NARS1 can be considered for inclusion in gene panels for DD/ID, epilepsy and/or demyelinating neuropathy.
Sources: Literature
Intellectual disability - microarray and sequencing v3.219 NARS Konstantinos Varvagiannis gene: NARS was added
gene: NARS was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: NARS was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal
Publications for gene: NARS were set to 32738225
Phenotypes for gene: NARS were set to Abnormal muscle tone; Microcephaly; Global developmental delay; Intellectual disability; Seizures; Ataxia; Abnormality of the face; Demyelinating peripheral neuropathy
Penetrance for gene: NARS were set to Complete
Review for gene: NARS was set to GREEN
Added comment: [Please note that HGNC Approved Gene Symbol for this gene is NARS1]

Manole et al (2020 - PMID: 32738225) provide evidence that both biallelic and monoallelic (de novo) pathogenic NARS1 variants cause a neurodevelopmental disorder. In total 32 individuals from 21 families are reported, with biallelic variants identified in individuals from 13 families and de novo in 8 families.

Similar features were reported for AR/AD occurrences of the disorder and included of microcephaly (90% - most often primary), epilepsy (23/32 or 74% - variable semiology incl. partial/myoclonic/generalized tonic-clonic seizures), DD and ID (as a universal feature), abnormal tone in several (hypotonia/spasticity), ataxia, demyelinating peripheral neuropathy (in 3 or more for each inheritance mode - or a total of 25%). Some individuals had dysmorphic features.

NARS1 encodes an aminoacyl-tRNA synthetase (ARS) [asparaginyl-tRNA synthetase 1]. Aminoacyl-tRNA synthetases constitute a family of enzymes catalyzing attachment of amino-acids to their cognate tRNAs. As the authors comment, mutations in genes encoding several other ARSs result in neurological disorders ranging from peripheral neuropathy to severe multi-systemic NDD. Dominant, recessive or both modes for inheritance for mutations in the same gene (e.g. AARS1, YARS1, MARS1, etc) have been reported.

Some variants were recurrent, e.g. the c.1600C>T / p.Arg534* which occurred in 6 families as a de novo event or c.1633C>T p.Arg545Cys (homozygous in 6 families). 3 different variants were reported to have occured de novo (c.965G>T - p.Arg322Leu, c.1525G>A - p.Gly509Ser, p.Arg534*) with several other variants identified in hmz/compound htz individuals. A single SNV (c.1067A>C - p.Asp356Ala) was suggested to be acting as modifier and pathogenic only when in trans with a severe variant. [NM_004539.4 used as RefSeq for all].

The authors provide several lines of evidence for a partial loss-of-function effect (e.g. reduction in mRNA expression, enzyme levels and activity in fibroblasts or iNPCs) underlying pathogenicity of the variants identified in individuals with biallelic variants. A gain-of-function (dominant-negative) effect is proposed for de novo variants (such effect also demonstrated for the p.Arg534* in a zebrafish model).

As also Manole et al suggest, NARS1 can be considered for inclusion in gene panels for DD/ID, epilepsy and/or demyelinating neuropathy.
Sources: Literature
Intellectual disability - microarray and sequencing v3.201 MORC2 Konstantinos Varvagiannis gene: MORC2 was added
gene: MORC2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: MORC2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: MORC2 were set to https://doi.org/10.1016/j.ajhg.2020.06.013
Phenotypes for gene: MORC2 were set to Charcot-Marie-Tooth disease, axonal, type 2Z, MIM #616688
Penetrance for gene: MORC2 were set to unknown
Mode of pathogenicity for gene: MORC2 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: MORC2 was set to GREEN
Added comment: The current review is based on a recent report by Sacoto et al (2020 - https://doi.org/10.1016/j.ajhg.2020.06.013).

While several previous studies focused on the phenotype of axonal motor and senory neuropathy in individuals with heterozygous MORC2 pathogenic variants (Charcot-Marie-Tooth disease, axonal, type 2Z, MIM #616688) some of them presented among others with hypotonia, muscle weakness, intellectual disability, microcephaly or hearing loss [refs provided by Sacoto et al - learning disabilities (in some patients) also listed in OMIM's clinical synopsis].

Sacoto et al present a cohort of 20 individuals having genetic testing for developmental delay or growth failure (with a single one for a diagnosis of sensorimotor neuropathy).

Overlapping features included DD, ID (18/20 - mild to severe), short stature (18/20), microcephaly (15/20) and variable craniofacial dysmorphisms. The authors comment that features suggestive of neuropathy (weakness, hyporeflexia, abnormal EMG/NCS) were frequent but not the predominant complaint. EMG/NCS abnormalities were abnormal in 6 out of 10 subjects investigated in this cohort. Other findings included brain MRI abnormalities (12/18 - in 5/18 Leigh-like lesions), hearing loss (11/19) and pigmentary retinopathy in few (5).

Affected subjects were found to harbor in all cases missense variants in the ATPase module of MORC2 [residues 1 to 494 - NM_001303256.1 - the module consists of an ATPase domain (aa 1-265), a transducer S5-like domain (266-494) and a coiled-coiled domain (CC1 - aa 282-361)].

Variants had occured mostly as de novo events although inheritance from a similarly affected parent was also reported.

Some of them were recurring within this cohort and/or the literature eg. c.79G>A/p.Glu27Lys (x5), c.260C>T/p.Ser87Leu (x2), c.394C>T/p.Arg132Cys (4x), c.1164C>G/p.Ser388Arg (x2), c.1181A>G/p.Tyr394Cys (x3).

MORC2 encodes an ATPase involved in chromatin remodeling, DNA repair and transcriptional regulation. Chromatin remodeling and epigenetic silencing by MORC2 is mediated by the HUSH (Human Silencing Hub) complex. Functional studies (MORC2-knockout HeLa cells harboring a HUSH-sensitive GFP reporter were transduced with wt or mt MORC2 followed by measurement of reporter repression) supported the deleterious effect of most variants known at the time (hyperactivation of HUSH-mediating silencing, in line with previous observations).

Overall this gene can be considered for inclusion in the ID panel with green rating. Also other gene panels (e.g. for short stature, microcephaly, hearing loss, pigmentary retinopathy, etc) if it meets the respective criteria for inclusion.
Sources: Literature
Intellectual disability - microarray and sequencing v3.201 HIST1H4J Arina Puzriakova changed review comment from: This is a possible gene for intellectual disability with facial dysmorphism in G2P.

Tessadori et al. (2020) (PMID: 31804630) reported a 14-year old Hispanic male with profound intellectual disability, who was heterozygous for a de novo (c.274 A>G, p.K91E) variant in HIST1H4J. Clinical features were said to resemble those reported in patients with HIST1H4C variants, which encodes an identical H4 protein to that of HIST1H4J. Functional data obtained in zebrafish showed the missense variant caused developmental defects, specifically resulting in defective head structures and reduced body axis length.; to: Added new-gene-name tag, new approved HGNC gene symbol is H4C11.

This is a possible gene for intellectual disability with facial dysmorphism in G2P.

Tessadori et al. (2020) (PMID: 31804630) reported a 14-year old Hispanic male with profound intellectual disability, who was heterozygous for a de novo (c.274 A>G, p.K91E) variant in HIST1H4J. Clinical features were said to resemble those reported in patients with HIST1H4C variants, which encodes an identical H4 protein to that of HIST1H4J. Functional data obtained in zebrafish showed the missense variant caused developmental defects, specifically resulting in defective head structures and reduced body axis length.
Intellectual disability - microarray and sequencing v3.200 HIST1H4J Arina Puzriakova reviewed gene: HIST1H4J: Rating: AMBER; Mode of pathogenicity: None; Publications: 31804630; Phenotypes: Microcephaly, Intellectual disability, Dysmorphic facial features, Growth delay; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability - microarray and sequencing v3.170 EXOC2 Konstantinos Varvagiannis gene: EXOC2 was added
gene: EXOC2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: EXOC2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: EXOC2 were set to 32639540
Phenotypes for gene: EXOC2 were set to Global developmental delay; Intellectual disability; Abnormality of the face; Abnormality of brain morphology
Penetrance for gene: EXOC2 were set to Complete
Review for gene: EXOC2 was set to AMBER
Added comment: Van Bergen et al (2020 - PMID: 32639540) report on 3 individuals from 2 families, harboring biallelic EXOC2 mutations.

Clinical presentation included DD, ID (severe in 2 subjects from fam1, borderline intellectual functioning in fam2), dysmorphic features and brain abnormalities. Cerebellar anomalies were common to all with a molar tooth sign observed in one (1/3). Other findings limited to subjects from one family included acquired microcephaly, congenital contractures, spastic quadriplegia (each observed 2/3).

Previous investigations were in all cases non-diagnostic. WES identified biallelic EXOC2 mutations in all affected individuals.

EXOC2 encodes an exocyst subunit. The latter is an octameric complex, component of the membrane transport machinery, required for tethering and fusion of vesicles at the plasma membrane. As discussed ,vesicle transport is important for the development of brain and the function of neurons and glia. Exocyst function is also important for delivery of Arl13b to the primary cilium (biallelic ARL13B mutations cause Joubert syndrome 8) and ciliogenesis.

Affected subjects from a broader consanguineous family (fam1) were homozygous for a truncating variant. Fibroblast studies revealed mRNA levels compatible with NMD (further restored in presence of CHX) as well as reduced protein levels. The female belonging to the second non-consanguineous family was found to harbor 2 missense variants in trans configuration.

An exocytosis defect was demonstrated in fibroblasts from individuals belonging to both families. Ciliogenesis appeared to be normal, however Arl13b localization/recruitment to the cilia was reduced compared with control cells with the defect rescued upon exogenous expression of wt EXOC2.

Mutations in other genes encoding components of the exocyst complex have been previously reported in individuals with relevant phenotypes (e.g. EXOC8 in a boy with features of Joubert s. or EXOC4 in nephrotic syndrome).

The authors discuss on the essential role of EXOC2 based on model organism studies (e.g. impaired neuronal membrane traffic, failure of neuronal polarization and neuromuscular junction expansion seen in Drosophila Sec5 (EXOC2) null mutants).
Sources: Literature
Intellectual disability - microarray and sequencing v3.135 SLC12A2 Zornitza Stark gene: SLC12A2 was added
gene: SLC12A2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: SLC12A2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SLC12A2 were set to 30740830
Phenotypes for gene: SLC12A2 were set to Kilquist syndrome; deafness; intellectual disability; dysmorphic features; absent salivation; ectodermal dysplasia; constipation; intestinal malrotation; multiple congenital anomalies
Review for gene: SLC12A2 was set to GREEN
gene: SLC12A2 was marked as current diagnostic
Added comment: Two families reported and a mouse model. New report is not on PubMed yet: (https://doi.org/10.1212/NXG.0000000000000478)
Sources: Literature
Intellectual disability - microarray and sequencing v3.135 RAP1GDS1 Zornitza Stark gene: RAP1GDS1 was added
gene: RAP1GDS1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: RAP1GDS1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: RAP1GDS1 were set to 32431071
Phenotypes for gene: RAP1GDS1 were set to Intellectual disability; dysmorphic features
Review for gene: RAP1GDS1 was set to AMBER
Added comment: Four individuals from two consanguineous families, same homozygous splice site variant detected, borderline Red/Amber.
Sources: Literature
Intellectual disability - microarray and sequencing v3.133 RIC1 Sarah Leigh Phenotypes for gene: RIC1 were changed from Cleft lip; cataract; tooth abnormality; intellectual disability; facial dysmorphism; ADHD to CATIFA syndrome 618761; Cleft lip; cataract; tooth abnormality; intellectual disability; facial dysmorphism; ADHD
Intellectual disability - microarray and sequencing v3.132 OTUD7A Sarah Leigh Added comment: Comment on list classification: Not associated with phenotype in OMIM or in Gen2Phen, Although the region ISCA-46295-Loss, which encompasses the OTUD7A locus, is associated with seizures 20236110, mental retardation 22775350, dysmorphic features, developmental delay and severe epileptic encephalopathy. PMID 31997314 report a homozygous variant in a case of severe global developmental delay, language impairment and epileptic encephalopathy; segregation and functional studies support this gene disease association.
Intellectual disability - microarray and sequencing v3.126 HNRNPH1 Zornitza Stark gene: HNRNPH1 was added
gene: HNRNPH1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HNRNPH1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: HNRNPH1 were set to 32335897; 29938792
Phenotypes for gene: HNRNPH1 were set to HNRNPH1‐related syndromic intellectual disability
Review for gene: HNRNPH1 was set to GREEN
Added comment: 1st patient reported in 2018 with intellectual disability and dysmorphic features and HNRNPH1 heterozygous missense variant. 2020 paper reports additional 7 cases with ID, short stature, microcephaly, distinctive dysmorphic facial features, and congenital anomalies (cranial, brain, genitourinary, palate, ophthalmologic). They all had HNRNPH1 heterozygous pathogenic variants (missense, frameshift, in‐frame deletion, entire gene duplication) and were identified using clinical networks and GeneMatcher.
Sources: Literature
Intellectual disability - microarray and sequencing v3.80 OTUD7A Zornitza Stark gene: OTUD7A was added
gene: OTUD7A was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: OTUD7A was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: OTUD7A were set to 31997314; 29395075; 29395074
Phenotypes for gene: OTUD7A were set to Epileptic encephalopathy, intellectual disability, no OMIM# yet
Review for gene: OTUD7A was set to RED
Added comment: One patient with severe global developmental delay, language impairment and epileptic encephalopathy reported. Homozygous OTUD7A missense variant (c.697C>T, p.Leu233Phe), predicted to alter an ultraconserved amino acid, lying within the OTU catalytic domain. Its subsequent segregation analysis revealed that the parents, presenting with learning disability, and brother were heterozygous carriers. Biochemical assays demonstrated that proteasome complex formation and function were significantly reduced in patient‐derived fibroblasts and in OTUD7A knockout HAP1 cell line. Gene lies in the chromosome 15q13.3 region. Heterozygous microdeletions of chromosome 15q13.3 show incomplete penetrance and are associated with a highly variable phenotype that may include intellectual disability, epilepsy, facial dysmorphism and digit anomalies. Mouse model and other data support the role of this gene in neurodevelopmental phenotypes but nevertheless, single family to date.
Sources: Literature
Intellectual disability - microarray and sequencing v3.80 HIST1H4J Zornitza Stark gene: HIST1H4J was added
gene: HIST1H4J was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: HIST1H4J was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: HIST1H4J were set to 31804630
Phenotypes for gene: HIST1H4J were set to microcephaly; intellectual disability; dysmorphic features
Review for gene: HIST1H4J was set to AMBER
Added comment: Single case report but with functional evidence in zebrafish and phenotypic similarity to HIST1H4C phenotype
Sources: Literature
Intellectual disability - microarray and sequencing v3.45 PHF21A Rebecca Foulger Phenotypes for gene: PHF21A were changed from Potocki-Shaffer syndrome, 601224; PSS; Intellectual disability; Intellectual developmental disorder with behavioral abnormalities and craniofacial dysmorphism with or without seizures, 618725 to Potocki-Shaffer syndrome, 601224; PSS; Intellectual disability; Intellectual developmental disorder with behavioral abnormalities and craniofacial dysmorphism with or without seizures, 618725
Intellectual disability - microarray and sequencing v3.44 PHF21A Rebecca Foulger Phenotypes for gene: PHF21A were changed from Potocki-Shaffer syndrome, 601224; PSS; Intellectual disability to Potocki-Shaffer syndrome, 601224; PSS; Intellectual disability; Intellectual developmental disorder with behavioral abnormalities and craniofacial dysmorphism with or without seizures, 618725
Intellectual disability - microarray and sequencing v3.40 CNOT3 Rebecca Foulger Phenotypes for gene: CNOT3 were changed from CNOT3 syndrome; intellectual disability, global developmental delay to CNOT3 syndrome; intellectual disability, global developmental delay; Intellectual developmental disorder with speech delay, autism, and dysmorphic facies, 618672
Intellectual disability - microarray and sequencing v3.36 ALG9 Rebecca Foulger commented on gene: ALG9: PMID:28932688. Davis et al., 2017 review the literature for ALG9:CDG cases. They summarise 10 patients from 6 different families with one of four ALG9 variants (including the 4 new patients reported by PMID:26453364). They also report an additional patient with ALG9-CDH with a milder phenotype. Prenatally, dysmorphic features, renal cysts and cardiac malformations were detected. She had seizures and developmental delay. She had a homozygous variant in ALG9: p.Tyr287Cys.
Intellectual disability - microarray and sequencing v3.36 ALG9 Rebecca Foulger changed review comment from: PMID:26453364. AlSubhi et al., 2016 summarise 6 patients with ALG9-CDG from the literature and report 4 additional patients from a large consanguineous family. 6/10 patients had developmental disability including the index patient (IV:5), a6 year old girl with global DD, skeletal dysplasia, epilepsy, facial dysmorphisms amongst her phenotypes. The three affected cousins had similar phenotypes.; to: PMID:26453364. AlSubhi et al., 2016 summarise 6 patients with ALG9-CDG from the literature and report 4 additional patients from a large consanguineous family. 6/10 patients had developmental disability including the index patient (IV:5), a 6 year old girl with global DD, skeletal dysplasia, epilepsy, facial dysmorphisms amongst her phenotypes. The three affected cousins had similar phenotypes.
Intellectual disability - microarray and sequencing v3.35 CDC42BPB Konstantinos Varvagiannis gene: CDC42BPB was added
gene: CDC42BPB was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CDC42BPB was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: CDC42BPB were set to 32031333
Phenotypes for gene: CDC42BPB were set to Central hypotonia; Global developmental delay; Intellectual disability; Seizures; Autistic behavior; Behavioral abnormality
Penetrance for gene: CDC42BPB were set to unknown
Review for gene: CDC42BPB was set to GREEN
Added comment: Chilton et al (2020 - PMID: 32031333) report on 14 individuals with missense and loss-of-function CDC42BPB variants.

Features included hypotonia (8/11), DD (12/13 - the 14th was a fetus), ID (7/13), ASD (8/12), clinical seizures (in 3 - a 4th had abnormal EEG without seizures), behavioral abnormalities. Variable non-specific dysmorphic features were reported in some (sparse hair being the most frequent - 4/8). Additional features were observed in few (=<4) incl. cryptorchidism, ophthalmological issues, constipation, kidney abnormalities, micropenis, etc.

All individuals had non-diagnostic prior genetic testing (incl. CMA, FMR1, MECP2, Angelman/Prader-Willi methylation studies, autism gene panel - suggesting relevance to the current panel) or metabolic testing.

Variants were identified following clinical exome sequencing with Sanger confirmation. Most occurred as de novo events (11/14) while inheritance was not available for few (3/14). Missense variants did not display (particular) clustering.

Almost all variants were absent from gnomAD and were predicted to be deleterious in silico (among others almost all had CADD scores >25).

As the authors comment, CDC42BPB encodes myotonic dystrophy-related Cdc42-binding kinase β (MRCKβ) a serine/threonine protein kinase playing a role in regulation of cytoskeletal reorganization and cell migration in nonmuscle cells (through phosporylation of MLC2).

Previous studies have demonstrated that it is ubiquitously expressed with prenatal brain expression.

The gene appears to be intolerant to pLoF (pLI of 1) as well as to missense variants (Z-score of 3.66).

CDC42BPB is a downstream effector of CDC42. Mutations of the latter cause Takenouchi-Kosaki syndrome with DD/ID and some further overlapping features (with CDC42BPB-associated phenotypes).

Homozygous Cdc42bpb KO in mouse appears to be nonviable (MGI:2136459). Loss of gek in the eyes of Drosophila results in disrupted growth cone targeting to the lamina (gek is the fly CDC42BPB ortholog).

Please consider inclusion with amber / green rating in the ID panel (>=4 relevant individuals / variants) and other panels (e.g. for epilepsy, ASD).
Sources: Literature
Intellectual disability - microarray and sequencing v3.32 CTU2 Rebecca Foulger Phenotypes for gene: CTU2 were changed from Microcephaly, facial dysmorphism, renal agenesis, and ambiguous genitalia syndrome, MIM#618142 to DREAM‐PL syndrome; Microcephaly, facial dysmorphism, renal agenesis, and ambiguous genitalia syndrome, 618142
Intellectual disability - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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).
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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 - microarray and sequencing 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].
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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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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.
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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) .
Intellectual disability - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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].
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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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing 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 - microarray and sequencing v2.855 BCORL1 Rebecca Foulger Phenotypes for gene: BCORL1 were changed from to Intellectual disability, developmental delay and dysmorphism; Behavioral abnormality
Intellectual disability - microarray and sequencing v2.847 DOCK3 Rebecca Foulger commented on gene: DOCK3: Helbig et al., 2017 (PMID:28195318) report 2 Ashkenazi and Yemeni Jewish siblings with severe developmental disability amongst phenotypes. WES of the siblings identified a heterozygous maternally-inherited c.382C>G (p.Gln128*) plus a paternally-inherited 458kb heterozygous deletion in 3p21.2 (which includes part of DOCK3).

PMID:30976111 (Wiltrout et al., 2019) report 3 unrelated patients with biallelic DOCK3-related global developmental delay (together with dysmorphic features in 2/3 cases).
Intellectual disability - microarray and sequencing v2.845 ACTL6B Rebecca Foulger commented on gene: ACTL6B: Bell et al., 2019 (PMID:31031012) identified 11 individuals (from 10 families) with biallelic variants in ACTL6B and global developmental delay, epileptic encephalopathy, and spasticity. They also identified 10 unrelated individuals with de novo heterozygous variants with ID, developmental delay, hypotonia, Rett-like stereotypies (e.g. handwringing), and minor facial dysmorphisms: 9/10 of these individuals had the identical de novo c.1027G>A (p.Gly343Arg) mutation. Engineered knock-out of ACTL6B in wild-type human neurons resulted in profound deficits in dendrite development.
Intellectual disability - microarray and sequencing v2.816 TMEM94 Rebecca Foulger Added comment: Comment on list classification: TMEM94 was added to the ID panel by Konstantinos Varvagiannis, and rated Amber. Stephen et al., 2018 (PMID:30526868) identified biallelic (homozygous or compound het) variants in 10 patients from 6 unrelated families of different ethnic origins. All affected individuals manifested with delays in development and dysmorphic facial features. All variants were predicted to be truncating variants. There is a question from Konstantinos over whether the phenotypes fall under the scope of the ID panel since the authors refer to ID in the abstract, and speech delay, motor delay and learning disability in Table 1. Global developmental delay is reported for individual II.1 in Family 1, gross developmental delay is reported in Family 3, mild DD and an IQ of 58 is reported for individual II.2 in Family 5, and developmental delay was reported for Individual II.2 in Family 6. TMEM94 has now also been associated with a disorder in OMIM: Intellectual developmental disorder with cardiac defects and dysmorphic facies, 618316. Therefore on balance and because of sufficient numbers of general DD reported in PMID:30526868, I have included TMEM94 on the ID panel as a Green gene.
Intellectual disability - microarray and sequencing v2.815 TMEM94 Rebecca Foulger Phenotypes for gene: TMEM94 were changed from Global developmental delay; Intellectual disability; Abnormal heart morphology; Abnormality of head or neck to Intellectual developmental disorder with cardiac defects and dysmorphic facies, 618316; Global developmental delay; Intellectual disability; Abnormal heart morphology; Abnormality of head or neck
Intellectual disability - microarray and sequencing v2.813 TELO2 Rebecca Foulger Added comment: Comment on list classification: TELO2 was added to the ID panel by Konstantinos Varvagiannis, and rated Green. Updated rating from Grey to Green based on the evidence Konstantinos provides. In summary, PMID:27132593 (You et al., 2016) report six individuals from 4 families with syndromic ID and compound het variants in TELO2. PMID:28944240 (Moosa et al., 2017) report a family with two sisters harbouring compound het TEL02 variants and with dysmorphic features. The surviving sister had severe ID and global DD in addition to the dysmorphism. Therefore sufficient cases to support association with You-Hoover-Fong syndrome (MIM:616954), which has a spectrum of phenotypes but includes intellectual disability as a consistent feature.
Intellectual disability - microarray and sequencing v2.761 SOX4 Rebecca Foulger Phenotypes for gene: SOX4 were changed from Global developmental delay; Intellectual disability; Growth delay; Clinodactyly of the 5th finger; Abnormality of head or neck to Syndromic intellectual disability; Global developmental delay; Intellectual disability; Growth delay; Clinodactyly of the 5th finger; facial dysmorphism
Intellectual disability - microarray and sequencing v2.751 SMARCC2 Rebecca Foulger Phenotypes for gene: SMARCC2 were changed from to Global developmental delay; Intellectual disability; neurodevelopmental delay and growth retardation; prominent speech impairment, hypotonia, feeding difficulties, behavioral abnormalities, and dysmorphic features
Intellectual disability - microarray and sequencing v2.740 ITCH Ivone Leong Added comment: Comment on publications: PMID: 20170897 describes a large Amish family with 10 affected individuals from 8 consanguineous and related families with multisystem autoimmune disease with facial dysmorphism. The affected individuals have organomegaly, failure to thrive, developmental delay, dysmorphic features, and autoimmune inflammatory cell infiltration of the lungs, liver, and gut.
Intellectual disability - microarray and sequencing v2.739 ITCH Ivone Leong Phenotypes for gene: ITCH were changed from to Autoimmune disease, multisystem, with facial dysmorphism, 613385
Intellectual disability - microarray and sequencing v2.717 CCDC47 Louise Daugherty commented on gene: CCDC47: Trichohepatoneurodevelopmental syndrome is a complex multisystem disorder characterized by woolly or coarse hair, liver dysfunction, pruritus, dysmorphic features, hypotonia, and severe global developmental delay (Morimoto el al., 2018)
Intellectual disability - microarray and sequencing v2.712 BCL11B Louise Daugherty Phenotypes for gene: BCL11B were changed from Intellectual disability to Intellectual disability; Intellectual developmental disorder with dysmorphic facies, speech delay, and T-cell abnormalities, 618092
Intellectual disability - microarray and sequencing v2.632 LSS Konstantinos Varvagiannis gene: LSS was added
gene: LSS was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: LSS was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: LSS were set to 30723320; 30401459
Phenotypes for gene: LSS were set to Alopecia; Abnormality of the skin; Hypotonia; Global developmental delay; Intellectual disability; Seizures; Abnormality of the genital system; Microcephaly
Penetrance for gene: LSS were set to Complete
Review for gene: LSS was set to GREEN
Added comment: DD and ID seem to be among the features observed in some individuals with biallelic LSS mutations, although the clinical presentation appears to be highly variable.

PMID: 30723320 [Besnrard et al, 2019] reports on 10 individuals from 6 unrelated families with biallelic LSS variants. One additional subject from a seventh family was found to harbor only a missense SNV (in the maternal allele) while the transcript corresponding to the other (/paternal) allele was less expressed upon RNA studies from patient fibroblasts. The allelic imbalance and the phenotypic overlap with the other individuals of the study were thought to be explained by an LSS defect.

The phenotype consisted of total alopecia (11/11) with additional dermatological features in most (9/11), hypotonia (7/11), DD with variable degrees of ID (11/11 both), epilepsy (8/11), microcephaly and genital anomalies in few. Cataracts were not noted in any individuals. The authors suggest that the phenotype corresponds to that observed in a neuroectodermal syndrome previously known as APMR (alopecia with mental retardation - other genes or loci earlier proposed).

Variants included: 7 missense SNVs, 1 nonsense, 1 frameshift, 2 splice variants (c.1109+2T>C / c.1194+5G>A - using NM_002340.5).

Using a minigene assay the latter variants were confirmhed (both) to affect splicing, at least to some important extent. However the splicing defect for one SNV (c.1194+5G>A - skipping of exon 12) was not confirmed upon RNA studies from blood samples of the respective individuals but an allelic balance in favor of the other allele instead (due to presumed utilisation of an alternative splice site, introduction of a premature stop codon and NMD).

Allelic imbalance is discussed for the individual with the single LSS variant but not shown.

Variants did not show clustering (also upon 3D modelling).

Lanosterol synthase converts (S)-2,3-oxidosqualene to lanosterol in the cholesterol biosynthesis pathway. Quantification of cholesterol and its precursors in affected individuals did not however reveal any important imbalance.

As most individuals harbored an allele with missense variant, and mice homozygous for an allele with absent LSS activity show variable lethality, residual LSS activity is suggested for the individuals studied.

Several other disorders affecting cholesterol biosynthesis present overlapping features eg. DD/ID in Lathosterolosis, Desmosterolosis, Smith-Lemli-Opitz syndrome (in this case also genital anomalies), etc or cutaneous anomalies in others.

A neurodevelopmental phenotype in animal models for LSS deficiency is not commented.
-----
Based on the discussion of the current article (and OMIM):

Earlier studies [PMIDs : 26200341, 29016354 - Zhao et al 2015 and Chen and Liu 2017 respectively] found biallelic missense in individuals with congenital cataracts. DD/ID were not commented/observed. The subject reported by Chen had baldness and genital defects. Shumiya cataract rats due to mutation in Lss gene recapitulate the specific human phenotype [PMID: 16440058 and OMIM]. Cataract was not a feature in any of the individuals of the present study. The corresponding entry for this phenotype in OMIM is Cataract 44 (#616509).

PMID: 30401459 [Romano et al, 2018] reported biallelic LSS mutations in 3 unrelated families with hypotrichosis. Intellectual disability was a feature in 2 sibs from 1 non-consanguineous family (among the three). ID was considered to be coincidental by the authors. The respective entry in OMIM is Hypotrichosis 14 (#618275).
-----
LSS is not included in the DD panel of G2P, nor in gene panels for ID offered by diagnostic laboratories.
-----
As a result this gene can be considered for inclusion in this panel as green (or amber).
Sources: Literature
Intellectual disability - microarray and sequencing v2.556 DPH1 Konstantinos Varvagiannis gene: DPH1 was added
gene: DPH1 was added to Intellectual disability. Sources: Literature,Expert Review
Mode of inheritance for gene: DPH1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: DPH1 were set to 25558065; 26220823; 29362492; 29410513
Phenotypes for gene: DPH1 were set to Developmental delay with short stature, dysmorphic features, and sparse hair, 616901
Penetrance for gene: DPH1 were set to Complete
Review for gene: DPH1 was set to GREEN
gene: DPH1 was marked as current diagnostic
Added comment: Biallelic mutations in DPH1 cause Developmental delay with short stature, dysmorphic features, and sparse hair, MIM 616901.

Overall 11 patients from 6 different families have probably been reported in detail. DD/ID is a universal feature.

In PMID 25558065, Alazami et al. identified 1 patient from the same consanguineous Saudi Arabian family (of 8 total similarly affected individuals) homozygous for the Leu234Pro (NM_001383.3:c.701T>C) variant. This individual was part of a large cohort of patients with neurogenetic disorders from consanguineous families. The phenotype is not described in detail.

In PMID 26220823 Louks et al. report on 4 patients from 3 families belonging to the same genetic isolate from North America and provide details on 4 of the individuals identified by Alazami et al.

The individuals identified in this study were homozygous for Met6Lys which was however predicted to be benign and tolerated (by PolyPhen2 and SIFT respectively) in silico.

DD/ID, unusual skull shape, ectodermal anomalies were universal (8/8) with additional features including short stature (7/8), renal (4/6) or cardiac anomalies (3/8). Some facial features appeared to be common, too.

Functional studies were not performed. However Dph1 pathogenic variants in mice result in restricted growth, craniofacial and developmental defects similar to the human phenotypes (PMIDs 14744934 and 24895408 are cited).

PMIDs 29362492 and 29410513 report on 3 further patients with similar (as well as some additional) features including DD/ID. The individual in the first article was compound heterozygous for a missense (Leu164Pro) and a frameshift variant (c.289delG) while 2 sibs born to consanguineous parents in the second article were homozygous for a frameshift variant (c.1227delG).

The phenotype appears to be consistent among all the published patients.

DPH1 is included in gene panels for intellectual disability offered by different diagnostic laboratories.

As a result, this gene can be considered for inclusion in this panel as green.
Sources: Literature, Expert Review
Intellectual disability - microarray and sequencing v2.513 PCGF2 Louise Daugherty Phenotypes for gene: PCGF2 were changed from Intellectual disability; dysmorphic features; Global developmental delay; Intellectual disability; Abnormality of the cardiovascular system; Abnormality of the cerebrum; Abnormality of the skeletal system to Intellectual disability; dysmorphic features; Global developmental delay; Abnormality of the cardiovascular system; Abnormality of the cerebrum; Abnormality of the skeletal system
Intellectual disability - microarray and sequencing v2.512 PCGF2 Louise Daugherty Phenotypes for gene: PCGF2 were changed from Intellectual disability; dysmorphic features to Intellectual disability; dysmorphic features; Global developmental delay; Intellectual disability; Abnormality of the cardiovascular system; Abnormality of the cerebrum; Abnormality of the skeletal system
Intellectual disability - microarray and sequencing v2.510 CACNA1E Konstantinos Varvagiannis gene: CACNA1E was added
gene: CACNA1E was added to Intellectual disability. Sources: Expert Review,Literature
Mode of inheritance for gene: CACNA1E was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: CACNA1E were set to 29942082
Phenotypes for gene: CACNA1E were set to Global developmental delay; Intellectual disability; Seizures; Dystonia; Congenital contracture; Macrocephaly
Penetrance for gene: CACNA1E were set to Incomplete
Mode of pathogenicity for gene: CACNA1E was set to Other
Review for gene: CACNA1E was set to GREEN
Added comment: Helbig et al. (https://doi.org/10.1016/j.ajhg.2018.09.006) report on 30 individuals with pathogenic variants in CACNA1E.

The phenotype was consistent with a developmental and epileptic encephalopathy, with hypotonia, early-onset and refractory seizures, severe to profound developmental delay and intellectual disability. Additional relatively common features included hyperkinetic movement disorder (severe dystonia which was observed in 40%, other dyskinesias in another 20%), congenital joint contractures of variable degree and joint involvement (approx. 40% of individuals) and macrocephaly (approx. 40%). There were no common facial dysmorphic features observed.

Of note, epilepsy was not a feature in 4 cases (age 1 to 4 years) so few of these individuals may be investigated for their developmental delay/intellectual disability or other features.

Missense variants:
All the 30 subjects described harbored a missense variant in CACNA1E which in all cases where parental studies were possible (29/30) occurred as a de novo event. There were 4 recurrent variants, explaining the phenotype in 20 patients in total while the rest of the individuals had private mutations. Functional studies were performed and suggested a gain-of-function effect for these variants (increased calcium inward currents).

Loss-of-function (LoF) variants:
Apart from the main cohort of patients, the authors note the presence of 3 individuals with such variants incl.:
- one individual with a nonsense variant present in the mosaic state (6/22 reads) in peripheral blood.
- one individual with a frameshift variant inherited from his unaffected parent.
- one individual with a nonsense variant for whom parental studies were not possible.

The authors comment that these indivdiduals presented with milder phenotype compared to those with missense variants. More information on these subjects is provided in the supplement as the article focuses on missense SNVs.

As the authors also note, several LoF variants exist in gnomAD, although the gene appears to be LoF intolerant (pLI=1).

Penetrance:
Seems to be complete for missense SNVs and possibly incomplete for LoF ones.

---

A previous study by Heyne et al. (PMID: 29942082) implicated de novo variants (DNVs) in CACNA1E with neurodevelopmental disorders for the first time. This study however does not provide clinical details on the phenotype of the affected individuals, while it seems to present overlap as to the individuals reported (eg. includes subjects from the DDD study and others).

---

Details as to a few - possibly further - de novo coding variants reported to date can be found at the denovo-db:
http://denovo-db.gs.washington.edu/denovo-db/QueryVariantServlet?searchBy=Gene&target=CACNA1E

---

As a result this gene can be considered for inclusion in this panel as green.
Sources: Expert Review, Literature
Intellectual disability - microarray and sequencing v2.510 NSD2 Konstantinos Varvagiannis gene: NSD2 was added
gene: NSD2 was added to Intellectual disability. Sources: Literature,Expert Review
Mode of inheritance for gene: NSD2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: NSD2 were set to 29892088; 29760529; 29884796; 30244530
Phenotypes for gene: NSD2 were set to Intrauterine growth retardation; Growth delay; Microcephaly; Muscular hypotonia; Neurodevelopmental delay; Intellectual disability
Penetrance for gene: NSD2 were set to unknown
Review for gene: NSD2 was set to GREEN
gene: NSD2 was marked as current diagnostic
Added comment: PMID: 29892088 reports on 2 individuals with de novo SNVs affecting NSD2 (WHSC1). Both individuals presented with pre- and postnatal growth retardation, hypotonia, developmental delay / intellectual disability, as well as microcephaly. The authors suggest partial overlap with the phenotype of Wolf-Hirschhorn syndrome (WHS). Seizures are not part of the phenotype.The first subject had a splice site mutation while the second individual had a stopgain variant (affecting the PWWP domain).

PMID: 29760529 describes a further patient with de novo nonsense mutation in NSD2. The boy was evaluated for probable growth delay ("low physical development"), hypotonia, psychomotor delay and microcephaly. The variant affected the SET domain.

Three individuals with de novo likely loss-of-function (two frameshift and one stop gained) variants in Decipher [ https://decipher.sanger.ac.uk/search?q=NSD2#research-variants/results ].

A further patient with de novo frameshift mutation in NSD2 and a phenotype overlapping WHS reported in ClinVar [ https://www.ncbi.nlm.nih.gov/clinvar/variation/547999/ ]

PMID: 29884796 (Zollino M and Doronzio PN) comments that NSD2 (WHSC1) is a neurodevelopmental gene with a role in growth delay, intellectual disability and dysmorphic facial features.

PMID: 30244530 describes patients with 4p16.3 microdeletions spanning (exclusively) NSD2 and reviews the literature on patients with small microdeletions reported to date. All relevant individuals present with developmental delay and (rather mild) intellectual disability apart from other characteristics such as microcephaly, growth retardation and some facial features also observed in WHS.

In Decipher one individual (286913) with a single CNV spanning exclusively NSD2 presenting with IUGR, failure to thrive, feeding difficulties, postnatal microcephaly, hypotonia, developmental delay as well as possibly relevant facial features.

The gene is included in ID gene panels offered by various labs (either as NSD2 or WHSC1).

As a result it can be considered for inclusion in the panel as green.
Sources: Literature, Expert Review
Intellectual disability - microarray and sequencing v2.510 KCNK4 Konstantinos Varvagiannis gene: KCNK4 was added
gene: KCNK4 was added to Intellectual disability. Sources: Literature,Expert Review
Mode of inheritance for gene: KCNK4 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: KCNK4 were set to 30290154
Phenotypes for gene: KCNK4 were set to Neurodevelopmental delay; Intellectual disability; Seizures; Gingival overgrowth; Hypertrichosis
Penetrance for gene: KCNK4 were set to unknown
Mode of pathogenicity for gene: KCNK4 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: KCNK4 was set to AMBER
Added comment: PMID: 30290154 reports on 3 unrelated individuals with de novo missense KCNK4 variants. All three individuals presented with developmental delay and epilepsy. Severe intellectual disability was a feature in two of these individuals while the third displayed low average intellectual functioning (IQ of 85). Other features common in all included facial dysmorphism (bushy eyebrows, long eyelashes, thin everted upper lip, micrognathia), generalized hypertrichosis and gingival overgrowth.

The two missense variants reported [(p.Ala172Glu) and (p.Ala244Pro)] occurred as de novo events in all subjects, while the first SNV was observed in 2 (of the 3) patients with severe intellectual disability.

Functional studies were suggestive of a gain-of-function effect. In line with this mechanism, Kcnk4 knockout mice did not seem to exhibit seizures, deficits in cognition or other neurodevelopmental phenotypes in a study conducted earlier and cited by the authors (PMID: 15175651).

As a result this gene can be considered for inclusion in the panel as amber (or green).
Sources: Literature, Expert Review
Intellectual disability - microarray and sequencing v2.457 PHIP Louise Daugherty Phenotypes for gene: PHIP were changed from INTELLECTUAL DISABILITY to INTELLECTUAL DISABILITY; Developmental delay, intellectual disability, obesity, and dysmorphic features, 617991
Intellectual disability - microarray and sequencing v2.455 PHIP Louise Daugherty edited their review of gene: PHIP: Added comment: Recommendation that this gene should be Green based on recent publication PMID:29209020, more than 20 unrelated cases Pers comm. Ian Berry (NHS Leeds Genetics Laboratory); Changed rating: GREEN; Changed publications: 29209020, 23033978, 27900362; Changed phenotypes: Developmental delay, intellectual disability, obesity, and dysmorphic features, 617991; Changed mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Intellectual disability - microarray and sequencing v2.452 FBXO11 Sarah Leigh Phenotypes for gene: FBXO11 were changed from Intellectual developmental disorder with dysmorphic facies and behavioral abnormalities 618089 to Intellectual developmental disorder with dysmorphic facies and behavioral abnormalities 618089
Intellectual disability - microarray and sequencing v2.451 FBXO11 Sarah Leigh Phenotypes for gene: FBXO11 were changed from Intellectual developmental disorder with dysmorphic facies and behavioral abnormalities 618089 to Intellectual developmental disorder with dysmorphic facies and behavioral abnormalities 618089
Intellectual disability - microarray and sequencing v2.450 FBXO11 Sarah Leigh Phenotypes for gene: FBXO11 were changed from Intellectual developmental disorder with dysmorphic facies and behavioral abnormalities 618089 to Intellectual developmental disorder with dysmorphic facies and behavioral abnormalities 618089
Intellectual disability - microarray and sequencing v2.449 FBXO11 Sarah Leigh Phenotypes for gene: FBXO11 were changed from Generalized hypotonia; Global developmental delay; Intellectual disability; Seizures to Intellectual developmental disorder with dysmorphic facies and behavioral abnormalities 618089
Intellectual disability - microarray and sequencing v2.443 ISCA-46290-Gain Louise Daugherty Region: ISCA-46290-Gain was added
Region: ISCA-46290-Gain was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-46290-Gain was set to X-LINKED: hemizygous mutation in males, biallelic mutations in females
Publications for Region: ISCA-46290-Gain were set to 25425167; 19716111; 21418194
Phenotypes for Region: ISCA-46290-Gain were set to Idiopathic mental retardation, speech delay, and a peculiar electroencephalographic (EEG) pattern in childhood. Autism and epilepsy, severe intellectual disability and dysmorphic facial features. Moderate to severe intellectual disability, early onset of puberty, language impairment, and age related epileptic syndromes such as West syndrome and focal epilepsy with activation during sleep evolving in some patients to continuous spikes-and-waves during slow sleep; 300801
Intellectual disability - microarray and sequencing v2.443 ISCA-37431-Gain Louise Daugherty Region: ISCA-37431-Gain was added
Region: ISCA-37431-Gain was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37431-Gain was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37431-Gain were set to 25205021; 22241097; 18183042
Phenotypes for Region: ISCA-37431-Gain were set to early onset of baldness (15 years old), dental enamel hypoplasia and minor facial dysmorphism; Chromosome 17q11.2 deletion syndrome, 1.4Mb; DD/ID, facial dysmorphisms, and seizures
Intellectual disability - microarray and sequencing v2.443 ISCA-37431-Loss Louise Daugherty Region: ISCA-37431-Loss was added
Region: ISCA-37431-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37431-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Phenotypes for Region: ISCA-37431-Loss were set to dysmorphic features, cardiac anomalies and mental retardation; 613675; variable facial dysmorphism, cafe-au-lait spots, neurofibromas and Lisch nodules in the iris, mental retardation, developmental delay, an excessive number of early-onset neurofibromas and an increased risk for malignant peripheral nerve sheath tumors; NEUROFIBROMATOSIS 1 MICRODELETION SYNDROME; NF1 MICRODELETION SYNDROME; Chromosome 17q11.2 deletion syndrome, 1.4Mb
Intellectual disability - microarray and sequencing v2.428 BPTF Louise Daugherty Phenotypes for gene: BPTF were changed from Neurodevelopmental disorder with dysmorphic facies and distal limb anomalies to Neurodevelopmental disorder with dysmorphic facies and distal limb anomalies, 617755; intellectual disability
Intellectual disability - microarray and sequencing v2.402 ISCA-37433-Gain Louise Daugherty 22q11.2 recurrent (DGS/VCFS) region (proximal region, LCR22-A to -B) Gain was changed to 22q11.2 recurrent (DGS/VCFS) region (proximal, A-B) (includes TBX1) Gain
Added phenotypes 608363; Chromosome 22q11.2 microduplication syndrome; dysmorphic facial features, cognitive deficits, velopharyngeal insufficiency, congenital heart defects and immunologic derangement; delayed psychomotor development, growth retardation, and/or hypotonia for Region: ISCA-37433-Gain
Intellectual disability - microarray and sequencing v2.402 ISCA-37433-Loss Louise Daugherty 22q11.2 recurrent (DGS/VCFS) region (proximal region, LCR22-A to -B) Loss was changed to 22q11.2 recurrent (DGS/VCFS) region (proximal, A-B) (includes TBX1) Loss
Added phenotypes 188400; immune deficiency; renal anomalies; 22q11.2 deletion syndrome; 192430; facial dysmorphic features, high frequency of cardiac defects, including conotruncal defects, prematurity, growth restriction, microcephaly, and mild developmental delay; polyhydramnios; Velocardiofacial syndrome; Learning difficulties; diaphragmatic hernia; DiGeorge syndrome; congenital heart disease; cleft palate, polydactyly for Region: ISCA-37433-Loss
Publications for Region: ISCA-37433-Loss were changed from 15545748; 15889418; 20301696 to 15889418; 20301696; 15545748
Intellectual disability - microarray and sequencing v2.401 ISCA-37404-Gain Louise Daugherty Phenotypes for Region: ISCA-37404-Gain were changed from chromosome 15q11-q13 duplication syndrome; include autism, mental retardation, ataxia, seizures, developmental delays, and behavioral problems; 608636; elayed development and intellectual disability associated with abnormal behavior and dysmorphic facial features. Additional variable features may include thin corpus callosum on brain imaging and sleep disturbances. Carrier females may be mildly affected to chromosome 15q11-q13 duplication syndrome; include autism, mental retardation, ataxia, seizures, developmental delays, and behavioral problems; 608636; delayed development and intellectual disability associated with abnormal behavior and dysmorphic facial features. Additional variable features may include thin corpus callosum on brain imaging and sleep disturbances. Carrier females may be mildly affected
Intellectual disability - microarray and sequencing v2.398 ISCA-37404-Gain Louise Daugherty Region: ISCA-37404-Gain was added
Region: ISCA-37404-Gain was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37404-Gain was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37404-Gain were set to 18374305; 16840569; 9106540
Phenotypes for Region: ISCA-37404-Gain were set to chromosome 15q11-q13 duplication syndrome; include autism, mental retardation, ataxia, seizures, developmental delays, and behavioral problems; 608636; elayed development and intellectual disability associated with abnormal behavior and dysmorphic facial features. Additional variable features may include thin corpus callosum on brain imaging and sleep disturbances. Carrier females may be mildly affected
Intellectual disability - microarray and sequencing v2.398 ISCA-37421-Gain Louise Daugherty Region: ISCA-37421-Gain was added
Region: ISCA-37421-Gain was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37421-Gain was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37421-Gain were set to 3298277; 3817079
Phenotypes for Region: ISCA-37421-Gain were set to Chromosome 1q21.1 duplication syndrome; ncomplete penetrance and variable expression characterized by macrocephaly, developmental delay, intellectual disability, psychiatric disturbances (autism spectrum disorder, attention deficit hyperactivity disorder, schizophrenia, mood disorders) and mild facial dysmorphism (high forehead, hypertelorism). Other associated features include congenital heart defects, hypotonia, short stature, scoliosis; 612475; 1q21.1 microduplication syndrome
Intellectual disability - microarray and sequencing v2.398 ISCA-37421-Loss Louise Daugherty Region: ISCA-37421-Loss was added
Region: ISCA-37421-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37421-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Phenotypes for Region: ISCA-37421-Loss were set to dysmorphic features; 612474; Moderate mental retardation, microcephaly, cardiac abnormalities, and cataracts; mild to moderate developmental delay
Intellectual disability - microarray and sequencing v2.398 ISCA-37423-Gain Louise Daugherty Region: ISCA-37423-Gain was added
Region: ISCA-37423-Gain was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37423-Gain was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37423-Gain were set to 21933911; 23345203
Phenotypes for Region: ISCA-37423-Gain were set to Behavioral problems, cleft lip and/or palate, macrocephaly, and seizures were confirmed as additional features among the new patients, and novel features included neonatal respiratory distress, attention deficit hyperactivity disorder (ADHD), ocular anomalies, balance problems, hypotonia, and hydrocele.; mild to moderate developmental delay, intellectual disability, mild facial dysmorphism (incl. prominent forehead, arched eyebrows, broad nasal bridge, upturned nares, cleft lip and/or palate) and congenital cardiac anomalies (e.g., atrioventricular septal defect). Other reported features include macrocephaly, behavioral abnormalities (e.g., attention deficit disorder), seizures, hypotonia and ocular and digital anomalies (poly/syndactyly); congenital heart disease; 8p23.1 duplication syndrome
Intellectual disability - microarray and sequencing v2.398 ISCA-37425-Gain Louise Daugherty Region: ISCA-37425-Gain was added
Region: ISCA-37425-Gain was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37425-Gain was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37425-Gain were set to 23913520; 23599694
Phenotypes for Region: ISCA-37425-Gain were set to Microcephaly, short stature and developmental delay; short stature, microcephaly, learning disability or mild to moderate ID, and distinctive facial features comprising periorbital fullness, short palpebral fissures, a long nose with broad or long nasal tip, a smooth philtrum and a thin upper lip vermilion. Behavioral problems, ocular and minor hand anomalies may be associated.
Intellectual disability - microarray and sequencing v2.398 ISCA-37430-Gain Louise Daugherty Region: ISCA-37430-Gain was added
Region: ISCA-37430-Gain was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37430-Gain was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37430-Gain were set to 23813913; 19520700; 19136950
Phenotypes for Region: ISCA-37430-Gain were set to 613215; Chromosome 17p13.3 duplication syndrome; variable psychomotor delay and dysmorphic features; 17q11.2 microduplication syndrome
Intellectual disability - microarray and sequencing v2.398 ISCA-37430-Loss Louise Daugherty Region: ISCA-37430-Loss was added
Region: ISCA-37430-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37430-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Phenotypes for Region: ISCA-37430-Loss were set to microcephaly, dysgenesis of the corpus callosum, and cerebellar atrophy, as well as neurobehavioral disorders, including delayed development, mental retardation, and attention deficit-hyperactivity disorder. Patients with duplications of YWHAE tended to have macrosomia, facial dysmorphism, and mild developmental delay; growth restriction, craniofacial dysmorphisms, structural abnormalities of brain and cognitive impairment; Chromosome 17p13.3 duplication syndrome; prominent forehead, bitemporal hollowing, short nose with upturned nares, protuberant upper lip, thin vermilion border, and small jaw; Characteristic facies, pre- and post-natal growth retardation; 247200; classic lissencephaly (pachygyria, incomplete or absent gyration of the cerebrum), microcephaly, wrinkled skin over the glabella and frontal suture, prominent occiput, narrow forehead, downward slanting palpebral fissures, small nose and chin, cardiac malformations, hypoplastic male extrenal genitalia, growth retardation, and mental deficiency with seizures and EEG abnormalities; Miller-Dieker lissencephaly syndrome
Intellectual disability - microarray and sequencing v2.398 ISCA-37432-Gain Louise Daugherty Region: ISCA-37432-Gain was added
Region: ISCA-37432-Gain was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37432-Gain was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Phenotypes for Region: ISCA-37432-Gain were set to developmental delay, mild to severe intellectual disability, speech delay, seizures, microcephaly, behavioral abnormalities, autism spectrum disorder, eye or vision defects (such as strabismus, astigmatism, amblyopia, cataract, coloboma, and microphthalmia), non-specific dysmorphic features, hypotonia, cardiac and renal anomalies, schizophrenia; Speech and language delay; Seizures (not all); Chromosome 17q12 duplication syndrome; 614526; Behavioural difficulties
Intellectual disability - microarray and sequencing v2.398 ISCA-37433-Gain Louise Daugherty Region: ISCA-37433-Gain was added
Region: ISCA-37433-Gain was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37433-Gain was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37433-Gain were set to 17250668; 20301749; 18414210
Phenotypes for Region: ISCA-37433-Gain were set to delayed psychomotor development, growth retardation, and/or hypotonia; dysmorphic facial features, cognitive deficits, velopharyngeal insufficiency, congenital heart defects and immunologic derangement; Chromosome 22q11.2 microduplication syndrome; 608363
Intellectual disability - microarray and sequencing v2.398 ISCA-37433-Loss Louise Daugherty Region: ISCA-37433-Loss was added
Region: ISCA-37433-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37433-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37433-Loss were set to 15545748; 15889418; 20301696
Phenotypes for Region: ISCA-37433-Loss were set to facial dysmorphic features, high frequency of cardiac defects, including conotruncal defects, prematurity, growth restriction, microcephaly, and mild developmental delay; diaphragmatic hernia; Learning difficulties; 192430; immune deficiency; congenital heart disease; 22q11.2 deletion syndrome; Velocardiofacial syndrome; DiGeorge syndrome; cleft palate, polydactyly; polyhydramnios; 188400; renal anomalies
Intellectual disability - microarray and sequencing v2.398 ISCA-37434-Loss Louise Daugherty Region: ISCA-37434-Loss was added
Region: ISCA-37434-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37434-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37434-Loss were set to 17918734; 22766398; 18245432
Phenotypes for Region: ISCA-37434-Loss were set to posteriorly rotated, low-set, abnormal ears; brachycephaly; epicanthus; heart defects; pointed chin; deep-set eyes; microcephaly; hypotonia; seizures; poor/absent speech; central nervous system anomalies; large anterior fontanels; microbrachycephaly; mental retardation; growth impairment; large, late-closing anterior fontanel; flat nose; nasal bridge; developmental delay; hearing impairment; distinct dysmorphic features; 1p36 deletion syndrome; 607872
Intellectual disability - microarray and sequencing v2.398 ISCA-37440-Loss Louise Daugherty Region: ISCA-37440-Loss was added
Region: ISCA-37440-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37440-Loss was set to BIALLELIC, autosomal or pseudoautosomal
Publications for Region: ISCA-37440-Loss were set to 11524703; 18234729; 16385448
Phenotypes for Region: ISCA-37440-Loss were set to mild/moderate mental retardation; facial dysmorphism; Hypotonia-cystinuria syndrome (HCS); 2p21 deletion syndrome; rapid weight gain in late childhood; failure to thrive; growth hormone deficiency; 606407; lactic acidemia; respiratory chain complex IV deficiency; hyperphagia; minor facial dysmorphism; severe somatic and developmental delay; nephrolithiasis; cystinuria; neonatal seizures; hypotonia
Intellectual disability - microarray and sequencing v2.398 ISCA-37443-Loss Louise Daugherty Region: ISCA-37443-Loss was added
Region: ISCA-37443-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37443-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Phenotypes for Region: ISCA-37443-Loss were set to . mild to moderate mental retardation, with only slightly dysmorphic facial features that were similar in most patients: long and narrow face, short philtrum, and high nasal bridge. Autism, gait ataxia, chest wall deformity, and long and tapering fingers were noted in at least 2 of the 6 patients. delayed psychomotor development with mild to moderate mental retardation and/or learning disabilities with speech delay. All had low birth weight, microcephaly, high nasal bridge, and short philtrum, and 3 had clinodactyly of the toes. primary pulmonary hypertension, patent ductus arteriosus (PDA), subvalvular aortic stenosis, and gastroesophageal reflux, and required neonatal intensive care for 57 days after birth due to complications of meconium aspiration. He had mild dysmorphic features, including posteriorly rotated ears, shallow orbits, frontal bossing, prominent nose, long thin lip, and broad face. He also had bilateral sandal gap toes, single palmar creases, and bilateral inguinal hernia. However, he was developmentally normal at age 6 months. delayed psychomotor development with delayed waking and poor motor skills, autism with speech delay, mental retardation, and psychiatric disturbances, including aggression, anxiety, hyperactivity, and bipolar disorder with psychosis in 1. Both had dysmorphic features, including high nasal bridge, asymmetric face, and crowded/dysplastic teeth; 1 had micrognathia and epicanthal folds. Both had tapered fingers. 609425; Chromosome 3q29 microdeletion syndrome
Intellectual disability - microarray and sequencing v2.398 ISCA-37500-Loss Louise Daugherty Region: ISCA-37500-Loss was added
Region: ISCA-37500-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37500-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37500-Loss were set to 23166063; 17847001; 24352913
Phenotypes for Region: ISCA-37500-Loss were set to mild to moderate cognitive deficit; Diamond-Blackfan anemia; intellectual disability; 614294; anemia; congenital diaphragmatic hernia; cryptorchidism in males; severe speech and psychomotor delay; mental retardation; postnatal short stature; behavioral problem; mild dysmorphic feature; developmental delay
Intellectual disability - microarray and sequencing v2.398 ISCA-37390-Loss Louise Daugherty Region: ISCA-37390-Loss was added
Region: ISCA-37390-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37390-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37390-Loss were set to 11238681; 15635506
Phenotypes for Region: ISCA-37390-Loss were set to 123450; PMID 15635506: characteristic cry, speech delay, facial dysmorphology, and level of mental retardation. PMID 11238681: interstitial deletions and one with a small terminal deletion confirmed the existence of two critical regions, one for dysmorphism and mental retardation in p15.2 and the other for the cat cry in p15.3. Results from one patient permitted the cat cry region to be distally narrowed from D5S13 to D5S731, study supports hypothesis of a separate region in p15.3 for the speech delay
Intellectual disability - microarray and sequencing v2.398 ISCA-37408-Loss Louise Daugherty Region: ISCA-37408-Loss was added
Region: ISCA-37408-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37408-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37408-Loss were set to 16963482; 22579565; 18245392
Phenotypes for Region: ISCA-37408-Loss were set to PMID: 16963482 idiopathic intellectual disability including moderate to severe intellectual disability, autism/autistic features, microcephaly, structural brain anomalies including cortical dysplasia/pachygyria, renal anomalies (multicystic kidney, hydronephrosis), digital camptodactyly, visual impairment, strabismus, neuromotor deficits, communication and attention impairments, and a distinctive pattern of craniofacial features. Dysmorphic craniofacial features include progressive microcephaly, flat occiput, widened inner canthal distance, small palpebral fissures, ptosis, long and straight eyelashes, broad and high nasal root extending to a widened, prominent nasal tip with elongated, smooth philtrum, rounding of the upper vermillion border and everted lower lips. PMID: 18245392 A 32-year-old, mentally retarded male was referred to our centre for further clinical genetic analysis. He was born to non-consanguineous parents after 42 weeks gestation with a birth weight of 3500 g. He had a healthy older brother. In the neonatal period he was hypotonic and at 8 weeks of age he underwent surgery because of an inguinal hernia with removal of an atrophic right testis. His motor development was severely delayed with sitting at 3.5 years and walking at 5 years of age. Speech was poorly developed, characterised by the usage of only a few words. During infancy an optic nerve hypoplasia was diagnosed, and during childhood he frequently suffered from luxations of the patellae, which required surgery. At the age of 32 years his height is 163 cm (_3 SDS) and head circumference 52.5 cm (_2.5 SDS). He has a narrow receding forehead, widened inner canthal distance of 3.5 cm (90th centile), normal outer canthal distance of 8.5 cm (25th centile), telecanthus, short and down slanting palpebral fissures, epicanthal folds, ptosis, long, straight eyelashes, high nasal bridge, low set large ears, flat philtrum, small mouth with high, narrow palate and retrognathia. The thorax is broad with increased internipple distance and slight gynaecomastia. A recent renal ultrasound revealed multiple cysts in the left, dystrophic kidney and two uncomplicated cysts in the enlarged, right kidney. The patient has a normally sized phallus with absent right testis and small left testis. His hands show a simian crease right and tapering fingers with broad proximal interphalangeal joints. He shows sandal gaps on both flat feet with clinodactyly of the fourth and fifth toes (and more); 612513; PMID: 22579565 severe developmental delay, congenital microcephaly, intractable epilepsy, and renal anomalies, as well as a congenital choledochal cyst which has not been previously reported in other patients with this cytogenetic defect
Intellectual disability - microarray and sequencing v2.398 ISCA-37411-Loss Louise Daugherty Region: ISCA-37411-Loss was added
Region: ISCA-37411-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37411-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37411-Loss were set to 19289393; 19136953; 18278044
Phenotypes for Region: ISCA-37411-Loss were set to PMID: 19289393 incomplete penetrance for developmental delay, mental retardation, or borderline IQ in most and autistic spectrum disorder (6/14), speech delay, aggressiveness, attention deficit hyperactivity disorder, and other behavioural problems; 612001; PMID: 18278044 mental retardation, epilepsy and variable facial and digital dysmorphisms; PMID: 19136953 idiopathic generalized epilepsy without other features previously associated with 15q13.3 microdeletions, such as intellectual disability, autism or schizophrenia
Intellectual disability - microarray and sequencing v2.398 ISCA-37420-Loss Louise Daugherty Region: ISCA-37420-Loss was added
Region: ISCA-37420-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37420-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37420-Loss were set to 25217958; 18628315
Phenotypes for Region: ISCA-37420-Loss were set to PMID: 18628315 developmental delay, hypotonia, facial dysmorphisms including a long face, a tubular or pear-shaped nose and a bulbous nasal tip, and a friendly/amiable behaviour, other clinically important features include epilepsy, heart defects and kidney/urologic anomalies; 610443; PMID: 25217958; Koolen-De Vries syndrome 610443
Intellectual disability - microarray and sequencing v2.398 ISCA-37424-Loss Louise Daugherty Region: ISCA-37424-Loss was added
Region: ISCA-37424-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-37424-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-37424-Loss were set to 25217958; 20345475; 21248748; 24550761
Phenotypes for Region: ISCA-37424-Loss were set to PMID 20345475 macrocephaly, hypertelorism, and arachnodactyly, and neurodevelopmental delay that includes failure to thrive, hypotonia, and feeding difficulties in the neonatal period, and receptive and expressive language delay with global neurodevelopmental delay after the neonatal period. PMID: 21248748 developmental delay, mainly affecting speech. In addition, macrocephaly, mild facial dysmorphisms, cerebellar anomalies, cardiac defects and congenital breast aplasia; PMID: 25217958 none specified; PMID: 24550761 age-appropriate language development evaluated by a standardized test at an age of 2 years and 3 months. The boy was born with a cleft palate - a feature not present in any of the patients described before, phenotype of patients with an LCR3/4-flanked 10q22.3q23.2 deletion can be rather variable
Intellectual disability - microarray and sequencing v2.398 ISCA-46295-Loss Louise Daugherty Region: ISCA-46295-Loss was added
Region: ISCA-46295-Loss was added to Intellectual disability. Sources: ClinGen,Expert Review Green
Mode of inheritance for Region: ISCA-46295-Loss was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for Region: ISCA-46295-Loss were set to 19898479; 20236110; 22775350
Phenotypes for Region: ISCA-46295-Loss were set to seizures; 20236110; mental retardation; 22775350; dysmorphic features; developmental delay; severe epileptic encephalopathy
Intellectual disability - microarray and sequencing SMOC1 BRIDGE consortium edited their review of SMOC1
Intellectual disability - microarray and sequencing SMO BRIDGE consortium edited their review of SMO
Intellectual disability - microarray and sequencing SMO Louise Daugherty classified SMO as amber
Intellectual disability - microarray and sequencing SMO Louise Daugherty commented on SMO
Intellectual disability - microarray and sequencing SMOC1 BRIDGE consortium edited their review of SMOC1
Intellectual disability - microarray and sequencing SMO BRIDGE consortium reviewed SMO
Intellectual disability - microarray and sequencing SMOC1 BRIDGE consortium reviewed SMOC1
Intellectual disability - microarray and sequencing MSMO1 Sarah Leigh classified MSMO1 as green
Intellectual disability - microarray and sequencing MSMO1 Sarah Leigh classified MSMO1 as green
Intellectual disability - microarray and sequencing MSMO1 Sarah Leigh added MSMO1 to panel
Intellectual disability - microarray and sequencing MSMO1 Sarah Leigh reviewed MSMO1