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Intellectual disability - microarray and sequencing v5.377 CLCN6 Sarah Leigh edited their review of gene: CLCN6: Added comment: Review copied from Neuronal ceroid lipofuscinosis panel: PMID 33217309: Three unrelated families reported with recurrent GOF de novo c.1658A>G (p.Tyr553Cys) and severe developmental delay with pronounced generalized hypotonia, respiratory insufficiency, and variable neurodegeneration and diffusion restriction in cerebral peduncles, midbrain, and/or brainstem in MRI scans. Previously, monoallelic variants reported in 3 families with BPEI, but functional data/segregation not compelling. Mouse knockout model has features of NCL (Zornitza Stark (Australian Genomics), 9 Dec 2020).; Changed rating: GREEN; Changed mode of pathogenicity: Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments
Intellectual disability - microarray and sequencing v5.374 COG3 Achchuthan Shanmugasundram changed review comment from: Comment on list classification: As reviewed by Zornitza Stark, there are two unrelated cases reported with biallelic COG3 variants and hence this gene should be rated amber with current evidence.; to: Comment on list classification: As reviewed by Zornitza Stark, there are two unrelated families reported with biallelic COG3 variants and hence this gene should be rated amber with current evidence.
Intellectual disability - microarray and sequencing v5.373 SGSM3 Achchuthan Shanmugasundram changed review comment from: Comment on list classification: As reviewed by Zornitza Stark, there are eight families reported with the same variant from the same Ashkenazi Jewish ancestry and the variant co-segregated with the disease in all family members.

The 'founder-effect' tag has been added as 1 in 52 Ashkenazi Jews carry the variant.; to: Comment on list classification: As reviewed by Zornitza Stark, there are eight families reported with the same variant from the same Ashkenazi Jewish ancestry and the variant co-segregated with the disease in all family members. This gene should therefore be rated amber with the current evidence.

The 'founder-effect' tag has been added as 1 in 52 Ashkenazi Jews carry the variant.
Intellectual disability - microarray and sequencing v5.373 SGSM3 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there are eight families reported with the same variant from the same Ashkenazi Jewish ancestry and the variant co-segregated with the disease in all family members.

The 'founder-effect' tag has been added as 1 in 52 Ashkenazi Jews carry the variant.
Intellectual disability - microarray and sequencing v5.373 SGSM3 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there are eight families reported with the same variant from the same Ashkenazi Jewish ancestry and the variant co-segregated with the disease in all family members.

The 'founder-effect' tag has been added as 1 in 52 Ashkenazi Jews carry the variant.
Intellectual disability - microarray and sequencing v5.366 AGPAT3 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, only one family was reported so far with AGPAT3 biallelic variants and intellectual disability. In addition, functional evidence is also available, Hence, this gene should be rated amber.
Intellectual disability - microarray and sequencing v5.336 VCP Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there is sufficient evidence available for adding this gene with green rating in the next GMS update.
Intellectual disability - microarray and sequencing v5.285 RAB5C Achchuthan Shanmugasundram changed review comment from: Comment on list classification: As reviewed by Zornitza Stark, there is sufficient evidence for this gene to be promoted to green rating at the next GMS update.; to: Comment on list classification: As reviewed by Zornitza Stark, there is sufficient evidence (12 unrelated cases) for this gene to be promoted to green rating at the next GMS update.
Intellectual disability - microarray and sequencing v5.285 RAB5C Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there is sufficient evidence for this gene to be promoted to green rating at the next GMS update.
Intellectual disability - microarray and sequencing v5.200 FOXR1 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there is one case with global developmental delay and supporting functional evidence including mouse model. Hence, this gene should be rated amber.
Intellectual disability - microarray and sequencing v5.200 FOXR1 Achchuthan Shanmugasundram changed review comment from: Comment on list classification: As reviewed by Zornitza Stark, there is one case with global developmental delay and supporting functional evidence including mouse model. Hence, this gene should be rated amber.; to: Comment on list classification: As reviewed by Zornitza Stark, there is one case with global developmental delay supported by functional evidence including mouse model. Hence, this gene should be rated amber.
Intellectual disability - microarray and sequencing v5.200 FOXR1 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there is one case with global developmental delay and supporting functional evidence including mouse model. Hence, this gene should be rated amber.
Intellectual disability - microarray and sequencing v5.199 FOXR1 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there is one case with global developmental delay and supporting functional evidence including mouse model. Hence, this gene should be rated amber.
Intellectual disability - microarray and sequencing v5.200 FOXR1 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there is one case with global developmental delay and supporting functional evidence including mouse model. Hence, this gene should be rated amber.
Intellectual disability - microarray and sequencing v5.199 FOXR1 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there is one case with global developmental delay and supporting functional evidence including mouse model. Hence, this gene should be rated amber.
Intellectual disability - microarray and sequencing v5.199 FOXR1 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there is one case with global developmental delay and supporting functional evidence including mouse model. Hence, this gene should be rated amber.
Intellectual disability - microarray and sequencing v5.199 FOXR1 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there is one case with global developmental delay and supporting functional evidence including mouse model. Hence, this gene should be rated amber.
Intellectual disability - microarray and sequencing v5.199 FOXR1 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark, there is one case with global developmental delay and supporting functional evidence including mouse model. Hence, this gene should be rated amber.
Intellectual disability - microarray and sequencing v5.171 TRA2B Achchuthan Shanmugasundram changed review comment from: This gene has already been associated with phenotypes in Gene2Phenotype (with 'moderate' rating in the DD panel), but not in OMIM.
Sources: Literature; to: PMID:36549593 reported 12 individuals from 11 unrelated families identified with 11 different heterozygous variants in TRA2B gene. The variants arose de novo in 10 families, while the variant was inherited from father to son in one family. 6 variants were expected to disrupt the translation start site in exon 1 (start-loss variants), 3 were expected to disrupt the splicing process at the exon 2/3 boundary (splice-affecting variants), and the remaining 2 were expected to produce a premature stop codon (truncating variants).

These patients presented with a neurodevelopmental disorder comprising developmental delay/ intellectual disability (in all patients), axial or global hypotonia (10 patients), delayed motor milestones (all patients), behavioural issues (8 patients), speech impairment (9 patients), epilepsy (7 patients, initial presentation as infantile spasms in 6 and unclassified epileptic encephalopathy in 1), brain abnormalities (10 patients) and microcephaly (5 patients). The degree of ID was severe to profound for 6 individuals, moderate to severe for 2 and mild to moderate for 3.

In addition, functional studies in mice showed that heterozygous knockout mice developed normal, while complete knockout mice cannot develop embryonically.

This gene has already been associated with phenotypes in Gene2Phenotype (with 'moderate' rating in the DD panel), but not in OMIM.
Sources: Literature
Intellectual disability - microarray and sequencing v5.107 ITPR1 Tracy Lester edited their review of gene: ITPR1: Added comment: PMID:29925855 - All 7 EOA patients with ITPR1 de novo variants (3 from cohort #1; 4 from cohort #2) presented with infantile onset cerebellar ataxia starting before the age of 2 years, including delayed motor milestones (Table 2). Cognitive deficits of variable degree were observed in 3 out of 4 patients where this information was available, reaching from only mild dyscalculia (P2) to severe intellectual disability with a speech vocabulary of only a few words (P7 at age 12 years). In contrast, patient P1 showed normal intelligence with an IQ of 97.

PMID:27108797 - Here, we report that both recessive and dominant ITPR1 mutations cause Gillespie syndrome. ITPR1 is a predominant isoform in the brain among the three types of ITPRs and is strongly expressed in cerebellar Purkinje cells.31 Mice with complete homozygosity for Itpr1 ablation suffer from severe epilepsy and ataxia and die either in utero or before weaning.32 Consistently, ITPR1 mutations have been reported to cause cerebellar diseases including late-onset spinocerebellar ataxia type 15 (SCA15 [MIM: 606658]),33 congenital nonprogressive spinocerebellar ataxia and mild cognitive impairment (SCA29 [MIM: 117360]),34 infantile-onset cerebellar ataxia with mild cognitive deficit,35 and childhood-onset ataxic cerebellar palsy with moderate intellectual disability36 (see ITPR1 schematic diagram in Figure 3A).
Affected individuals had similar iris anomalies and neonatal ataxia with progressive cerebellar atrophy (Figure 2). Moderate to severe intellectual disabilities were noted in the three individuals with recessive mutations (F1:II1, F2:II1, and F3:II1; Table 1). In contrast, the affected individual F4:II1 aged 18 years and harboring the de novo c.7687_7689del mutation was reported to have normal intelligence (Table 1).

As de novo variants are associated with ID/DD the inheritance should be updated to be BOTH AD and AR.; Set current diagnostic: yes
Intellectual disability - microarray and sequencing v5.100 CSTF2 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark (Australian Genomics), there is one family with intellectual disability, supported by functional studies. This gene should therefore be promoted to AMBER in this panel.
Intellectual disability - microarray and sequencing v5.100 CSTF2 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark (Australian Genomics), there is one family with intellectual disability, supported by functional studies. This gene should therefore be promoted to AMBER in this panel.
Intellectual disability - microarray and sequencing v5.100 CSTF2 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark (Australian Genomics), there is one family with intellectual disability, supported by functional studies. This gene should therefore be promoted to AMBER in this panel.
Intellectual disability - microarray and sequencing v5.99 CSTF2 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark (Australian Genomics), there is one family with intellectual disability, supported by functional studies. This gene should therefore be promoted to AMBER in this panel.
Intellectual disability - microarray and sequencing v5.99 CSTF2 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark (Australian Genomics), there is one family with intellectual disability, supported by functional studies. This gene should therefore be promoted to AMBER in this panel.
Intellectual disability - microarray and sequencing v5.99 CSTF2 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark (Australian Genomics), there is one family with intellectual disability, supported by functional studies. This gene should therefore be promoted to AMBER in this panel.
Intellectual disability - microarray and sequencing v5.85 HNRNPD Achchuthan Shanmugasundram changed review comment from: As reviewed by Zornitza Stark (Australian Genomics), several additional individuals with neurodevelopmental disorders carrying de novo HNRNPD variants identified in an international cohort have been reported in PMID:33874999. These probands displayed a high prevalence of DD/ID, speech delay, and ASD and/or other behavioural phenotypes. As this is a large cohort study and there is no complete information about DD/ID phenotypes in these probands, this gene should remain as AMBER.; to: As reviewed by Zornitza Stark (Australian Genomics), several additional individuals with neurodevelopmental disorders carrying de novo HNRNPD variants identified in an international cohort have been reported in PMID:33874999. These probands displayed a high prevalence of DD/ID, speech delay, and ASD and/or other behavioural phenotypes. As this is a large cohort study and there is no complete information about DD/ID phenotypes in these probands, this gene should remain as AMBER.

The 'watchlist' tag has been added to review this rating in light of new evidence in the future.
Intellectual disability - microarray and sequencing v5.85 WIPI2 Achchuthan Shanmugasundram changed review comment from: Comment on list classification: As reviewed by Zornitza Stark (Australian Genomics), there are three unrelated families with homozygous variants in WIPI2 gene presenting with varying degrees of intellectual disability supported by functional evidence. Hence, this gene can be promoted to GREEN at the next major review.; to: Comment on list classification: As reviewed by Zornitza Stark (Australian Genomics), there are three unrelated families with homozygous variants in WIPI2 gene presenting with varying degrees of intellectual disability (moderate to profound) and supported by functional evidence. Hence, this gene can be promoted to GREEN at the next major review.
Intellectual disability - microarray and sequencing v5.81 WIPI2 Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark (Australian Genomics), there are three unrelated families with homozygous variants in WIPI2 gene presenting with varying degrees of intellectual disability supported by functional evidence. Hence, this gene can be promoted to GREEN at the next major review.
Intellectual disability - microarray and sequencing v5.72 KIF4A Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Zornitza Stark (Australian Genomics), there are at least four unrelated cases with hemizygous variants in KIF4A gene and presenting with intellectual disability. This evidence is sufficient for promoting to GREEN rating at the next major review.
Intellectual disability - microarray and sequencing v5.71 KIF4A Achchuthan Shanmugasundram changed review comment from: As reviewed by Zornitza Stark (Australian Genomics), there are at least four unrelated cases with hemizygous variants in KIF4A gene and presenting with intellectual disability.

PMID:24812067 reported a family in which five males spanning three generations had intellectual disability, speech delay and global developmental delay and four of these males developed seizures in late childhood–adolescence.

PMID:34346154 reported 11 unrelated cases expanding the phenotypic spectrum to include developmental delay and intellectual disability with or without epilepsy to a congenital anomaly phenotype with hydrocephalus and various brain anomalies at the more severe end of clinical manifestations. Of eight patients with congenital anomalies, one each had severe to profound developmental delay, mild psychomotor delay and severe psychomotor delay, while the remaining five had no developmental delays. However, all three patients without congenital structural anomalies had intellectual disability (borderline intellectual functioning in one case), speech delay and global developmental delay, while motor delay and autism spectrum disorder was reported in two cases each. Isolated febrile seizure was reported in one case.

This gene has been reported in OMIM (MIM #300923) and Gene2Phenotype (with 'limited' rating) on the basis of one family from PMID:24812067.; to: PMID:24812067 reported a family in which five males spanning three generations had intellectual disability, speech delay and global developmental delay and four of these males developed seizures in late childhood–adolescence.

PMID:34346154 reported 11 unrelated cases expanding the phenotypic spectrum to include developmental delay and intellectual disability with or without epilepsy to a congenital anomaly phenotype with hydrocephalus and various brain anomalies at the more severe end of clinical manifestations. Of eight patients with congenital anomalies, one each had severe to profound developmental delay, mild psychomotor delay and severe psychomotor delay, while the remaining five had no developmental delays. However, all three patients without congenital structural anomalies had intellectual disability (borderline intellectual functioning in one case), speech delay and global developmental delay, while motor delay and autism spectrum disorder was reported in two cases each. Isolated febrile seizure was reported in one case.

This gene has been reported in OMIM (MIM #300923) and Gene2Phenotype (with 'limited' rating) on the basis of one family from PMID:24812067.
Intellectual disability - microarray and sequencing v5.71 KIF4A Achchuthan Shanmugasundram changed review comment from: As reviewed by Zornitza Stark (Australian Genomics), there are at least four unrelated cases with hemizygous variants in KIF4A gene and presenting with intellectual disability.

PMID:24812067 reported a family in which five males spanning three generations had intellectual disability, speech delay and global developmental delay and four of these males developed seizures in late childhood–adolescence.

PMID:34346154 reported 11 unrelated cases expanding the phenotypic spectrum to include developmental delay and intellectual disability with or without epilepsy to a congenital anomaly phenotype with hydrocephalus and various brain anomalies at the more severe end of clinical manifestations. Of eight patients with congenital anomalies, one each had severe to profound developmental delay, mild psychomotor delay and severe psychomotor delay, while the remaining five had no developmental delays. However, all three patients without congenital structural anomalies had intellectual disability (borderline intellectual functioning in one case), speech delay and global developmental delay, while motor delay and autism spectrum disorder was reported in two cases each. Isolated febrile seizure was reported in one case.; to: As reviewed by Zornitza Stark (Australian Genomics), there are at least four unrelated cases with hemizygous variants in KIF4A gene and presenting with intellectual disability.

PMID:24812067 reported a family in which five males spanning three generations had intellectual disability, speech delay and global developmental delay and four of these males developed seizures in late childhood–adolescence.

PMID:34346154 reported 11 unrelated cases expanding the phenotypic spectrum to include developmental delay and intellectual disability with or without epilepsy to a congenital anomaly phenotype with hydrocephalus and various brain anomalies at the more severe end of clinical manifestations. Of eight patients with congenital anomalies, one each had severe to profound developmental delay, mild psychomotor delay and severe psychomotor delay, while the remaining five had no developmental delays. However, all three patients without congenital structural anomalies had intellectual disability (borderline intellectual functioning in one case), speech delay and global developmental delay, while motor delay and autism spectrum disorder was reported in two cases each. Isolated febrile seizure was reported in one case.

This gene has been reported in OMIM (MIM #300923) and Gene2Phenotype (with 'limited' rating) on the basis of one family from PMID:24812067.
Intellectual disability - microarray and sequencing v5.54 SHANK1 Achchuthan Shanmugasundram changed review comment from: As reviewed by Zornitza Stark (Australian Genomics), PMID:34113010 reported six individuals who presented with neurodevelopmental disorders and identified with de novo truncating variants in SHANK1 gene. Of these six individuals, four had intellectual disability, one had severe learning difficulties and one with auditory processing disorder, difficulty with executive functioning, mathematic concepts, verbal reasoning and problem solving.; to: As reviewed by Zornitza Stark (Australian Genomics), PMID:34113010 reported six unrelated individuals who presented with neurodevelopmental disorders and identified with de novo truncating variants in SHANK1 gene. Of these six individuals, four had intellectual disability, one had severe learning difficulties and one with auditory processing disorder, difficulty with executive functioning, mathematic concepts, verbal reasoning and problem solving. Three of these patients were also reported with autism spectrum disorder.

This gene has been associated with relevant phenotypes in Gene2Phenotype (with 'strong' rating in the DD panel).
Intellectual disability - microarray and sequencing v5.53 SHANK1 Achchuthan Shanmugasundram edited their review of gene: SHANK1: Added comment: As reviewed by Zornitza Stark (Australian Genomics), PMID:34113010 reported six individuals who presented with neurodevelopmental disorders and identified with de novo truncating variants in SHANK1 gene. Of these six individuals, four had intellectual disability, one had severe learning difficulties and one with auditory processing disorder, difficulty with executive functioning, mathematic concepts, verbal reasoning and problem solving.; Changed phenotypes to: nearodevelopmental disorder, MONDO:0700092, intellectual disability, MONDO:0001071
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 v4.13 SLC35F1 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). Rating Red as only a single patient with a heterozygous missense variant has been reported to date (PMID:33821533). Limited information on the SLC35F1 gene is known in general.
Intellectual disability - microarray and sequencing v3.1742 TGFB1 Arina Puzriakova changed review comment from: Comment on mode of inheritance: Updated from 'monoallelic' to 'biallelic' inline with review by Zornitza Stark indicating two unrelated families with GDD/ID and biallelic variants in this gene. Added watchlist_moi tag to monitor for further cases. There was no evidence linking monoallelic variants to ID.; to: Comment on mode of inheritance: Updated from 'monoallelic' to 'biallelic' inline with review by Zornitza Stark indicating two unrelated families with GDD/ID and biallelic variants in this gene. Added watchlist_moi tag to monitor for further cases. Cognition is typically normal in Camurati-Engelmann disease (caused by monoallelic TGFB1 variants).
Intellectual disability - microarray and sequencing v3.1740 TGFB1 Arina Puzriakova Added comment: Comment on mode of inheritance: Updated from 'monoallelic' to 'biallelic' inline with review by Zornitza Stark indicating two unrelated families with GDD/ID and biallelic variants in this gene. Added watchlist_moi tag to monitor for further cases. There was no evidence linking monoallelic variants to ID.
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 v3.1643 OGDHL Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is sufficient evidence to promote to Green at the next GMS panel update.

The NSRP1 gene is not yet associated with any phenotype in OMIM but has a 'moderate' disease confidence rating in G2P for 'OGDHL-related neurodevelopmental disorder with seizures, hearing loss and gait ataxia'.

At least 10 individuals from 9 unrelated families identified with biallelic variants in this gene (PMIDs: 28017472; 34800363). Main clinical features include mild-to-severe DD/ID (9/10), seizures (5/10), gait ataxia (5/10), profound bilateral sensorineural hearing loss (4/10), spasticity (3/10).
Intellectual disability - microarray and sequencing v3.1641 NSRP1 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is sufficient evidence to promote to Green at the next GMS panel update.

The NSRP1 gene is not yet associated with any phenotype in OMIM but has a 'strong' disease confidence rating in G2P for 'NSRP1-associated developmental delay, epilepsy and microcephaly'.

Six individuals from three families with different homozygous LoF NSRP1 variants identified by Calame et al. 2021 (PMID: 34385670). Main clinical features include ID/DD (6/6), epilepsy (6/6, drug-resistant in 3/6), hypotonia (6/6), appendicular spasticity (6/6), microcephaly (5/6, Z-scores −0.95 to −5.60). Brain abnormalities included under-opercularization (3/4), simplified gyral pattern (3/4), superior and/or inferior cerebellar vermian hypoplasia (3/4), corpus callosum dysgenesis (1/4), and thin brainstem (1/4).
Intellectual disability - microarray and sequencing v3.1612 ATP6V0A1 Sarah Leigh changed review comment from: Comment on mode of inheritance: Monallelic mode of inheritance has been selected for ATP6V0A1, although four families showed biallelic ATP6V0A1 variants. This in line Gen2Phen and the views Zornitza Stark and Mike Spiller who have reviewed this gene, and reflects the inconstitancies of the phenotypes amongst these individuals. As more data is obtained, it maybe that the mode of inheritance is changed to both mono and biallelic.; to: Comment on mode of inheritance: Monoallelic mode of inheritance has been selected for ATP6V0A1, although four families showed biallelic ATP6V0A1 variants. This in line Gen2Phen and the views Zornitza Stark and Mike Spiller who have reviewed this gene.
Intellectual disability - microarray and sequencing v3.1611 ATP6V0A1 Sarah Leigh changed review comment from: Comment on mode of inheritance: Monallelic mode of inheritance has been selected for ATP6V0A1, although four families showed biallelic ATP6V0A1 variants. This in line the views Zornitza Stark and Mike Spiller who have reviewed this gene, and reflects the inconstitancies of the phenotypes amongst these individuals. As more data is obtained, it maybe that the mode of inheritance is changed to both mono and biallelic.; to: Comment on mode of inheritance: Monallelic mode of inheritance has been selected for ATP6V0A1, although four families showed biallelic ATP6V0A1 variants. This in line Gen2Phen and the views Zornitza Stark and Mike Spiller who have reviewed this gene, and reflects the inconstitancies of the phenotypes amongst these individuals. As more data is obtained, it maybe that the mode of inheritance is changed to both mono and biallelic.
Intellectual disability - microarray and sequencing v3.1611 ATP6V0A1 Sarah Leigh Added comment: Comment on mode of inheritance: Monallelic mode of inheritance has been selected for ATP6V0A1, although four families showed biallelic ATP6V0A1 variants. This in line the views Zornitza Stark and Mike Spiller who have reviewed this gene, and reflects the inconstitancies of the phenotypes amongst these individuals. As more data is obtained, it maybe that the mode of inheritance is changed to both mono and biallelic.
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).

-----

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 v3.1580 DROSHA Konstantinos Varvagiannis gene: DROSHA was added
gene: DROSHA was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DROSHA was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: DROSHA were set to 35405010
Phenotypes for gene: DROSHA were set to Global developmental delay; Intellectual disability; Seizures; Cerebral white matter atrophy; Abnormality of the corpus callosum; Abnormality of movement; Stereotypic behavior; Abnormality of head or neck; Short foot
Penetrance for gene: DROSHA were set to unknown
Mode of pathogenicity for gene: DROSHA 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: DROSHA was set to AMBER
Added comment: Profound DD, ID and seizures have been reported in 2 unrelated subjects with de novo missense variants. The gene has a role in miRNA biogenesis. Both variants described have been shown to have effect on DROSHA's function in Drosophila / C. elegans (partial loss-of-function vs possibility of antimorphic effect discussed || in gnomAD several individuals with LoF alleles / Z=3.98 – pLI : 0.09).

There is currently no DROSHA-related phenotype in OMIM, G2P, SysNDD. In PanelApp Australia the gene has amber rating in genetic epilepsy and microcephaly panels (not currently included in the ID one).

Consider inclusion in the current panel with amber rating. Also consider inclusion in other possibly relevant panels (given postnatal microcephaly, abn. corpus callosum, progressive white matter atrophy, etc) [ NOT added ]

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Barish, Senturk, Schoch et al (2022 - PMID: 35405010) describe the phenotype of 2 unrelated individuals with de novo missense DROSHA variants.

Features included generalized hypotonia, postnatal microcephaly (-2,6 and -6 SD), feeding difficulties, profound DD and ID, seizures, abnormal movements (choreoathetosis / stereotypic movements), variable respiratory symptoms (in one case episodes of hyperventilation/apnea), cardiovascular or skeletal findings. Brain MRI demonstrated white matter atrophy and thin corpus callosum in both. Brachycephaly with broad face as well as short feet were also among the shared features.

Both were investigated by trio ES/GS which were otherwise non diagnostic and without other candidate variants. The 1st individual harbored a de novo htz missense DROSHA variant (c.3656A>G/p.Asp1219Gly) while the 2nd subject had another missense variant (c.4024C>T/p.Arg1342Trp) [NM_013235.4] confirmed by Sanger seq.

DROSHA (on 5p13.3) encodes a ribonuclease, subunit of the microprocessor complex, involved in miRNA biogenesis. Specifically, miRNAs are transcribed as part of pri-miRNAs (primary-miRNAs) which are cleaved to pre-miRNAs (precursor-miRNAs) in the nucleus by DROSHA (and its partner DGCR8 or Pasha) and then exported to the cytoplasm for further processing. Cleavage of pre-miRNAs by DICER1 generates mature miRNAs subsequently loaded to the RISC (RNA-induced silencing) complex which uses miRNA as template for recognition and cleavage of complementary mRNA with RNAse.

As the authors discuss, miRNA defects have a well-established role in development of model organisms e.g. (several Refs. provided):
- in C. elegans miRNA mutants causing lethality, developmental arrest and heterochronicity
- in Drosophila playing a role in the development of ovary, eye, nervous system etc.
- in mice mRNAs play a role in BMP and TGF-beta signaling while neuronal loss of miRNA processing leads to neurodegeneration/anatomical defects.

Feingold syndrome 2 is the single Mendelian disease associated to date with miRNAs, through deletion of a cluster containing 6 MIR genes.

miRNA dysregulation is also observed in Rett syndrome - and DROSHA implicated in the pathogenesis of the syndrome - as MECP2 and FOXG1 are cofactors of the microprocessor complex regulating processing of miRNA. One of the individuals here reported had a clinical diagnosis of Rett spectrum while both had overlapping features with Rett s.

Studies of DROSHA-dependent miRNAs in fibroblasts from one individual revealed significantly altered expression of mature miRNA (e.g. increased miR98, a miRNA with reduced expression in studies of somatic DROSHA variants) although this was not likely due to processing errors (given only a modest decrease of precursor miRNAs).

Previous studies have demonstrated that drosha (the Drosophila ortholog) null mutants die during post-embryonic development with 100% lethality before adulthood (3rd instar larval stage/beginning of pupariation). Mosaic flies with mutant eyes are small-eyed, while viable hypomorphic alleles display synaptic transmission defects (several Refs provided).

Here, homozygous flies for null alleles died at the end of 3rd instar larval stage/beginning of pupariation, while loss of drosha resulted in lack of imaginal disc tissue (which surrounds the larval brain) and severely reduced brain size, the latter similar to the microcephaly phenotype. [To the best of my understanding] introduction of a mutated genomic rescue construct (carrying similar substitutions as those observed in human subjects) in eye-specific drosha null (W1123X) flies was partially able to rescue eye/head size for wt or Asp1219Gly (human:Asp1084Gly) suggesting that the latter is a partial LoF allele. Arg1210Trp (corresponding to human Arg1342Trp) was able to rescue the eye phenotype and was not damaging to the function in the specific assay. Drosha expression levels were similar for genomic rescue flies either for wt or for the Asp-Gly variant suggesting that the effect was not due to expression levels (but rather function). Expression of mature miRNAs known to be regulated by Drosha were not affected when comparing wildtype larvae with genomic construct for wt or Asp1084Gly.

Upon expression of human cDNA using GAL4/UAS system in drosha mutant (null) eye clones, the reference partially rescued the eye size defect, Asp-Gly behaved as partial loss-of-function allele (~50% function compared to ref), while the Arg-Trp variant was shown to behave as a weaker loss-of-function allele.

The authors generated eye-specific drosha mutant clones to study the aging adult eye using ERG recordings. While null mutants display almost no response to light (7- and 20-day old flies), wt genomic rescue was shown to rescue ERG responses, Asp-Gly variant had significant defects (at both 7 and 20 days) and the Arg-Trp had defects approaching statistical significance only at the age of 20 days. Overall these data suggested that Arg-Trp had less severe effect compared to Asp-Gly (as above) while both variants led to progressive neuronal dysfunction.

Using CRISPR/Cas9 the authors generated C.elegans knock-ins for a variant analogous to the Asp1219Gly human one. Homozygous animals were inviable at larval stages, displayed a heterochronic phenotype (heterochronicity : development of cells or tissues at an abnormal time relative to other unaffected events in an organism / miRNAs are known to be involved in the heterochronic gene pathway) while this variant was deleterious to the Drosha's ability to process miRNAs.
Sources: Literature
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 v3.1564 BUB1 Konstantinos Varvagiannis gene: BUB1 was added
gene: BUB1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: BUB1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: BUB1 were set to 35044816
Phenotypes for gene: BUB1 were set to Congenital microcephaly; Global developmental delay; Intellectual disability; Abnormal heart morphology; Growth delay
Penetrance for gene: BUB1 were set to Complete
Review for gene: BUB1 was set to AMBER
Added comment: A recent study provides evidence that this gene (biallelic variants) is relevant for inclusion in the DD/ID panel likely with amber / green rating (2 unrelated individuals with similar phenotype, 3 variants, role of this gene, extensive variant studies and demonstrated effects on cohesion and chromosome segregation, similarities with other disorders caused by mutations in mitosis-associated genes at the clinical and cellular level || number of affected subjects/families, different protein levels/kinase activity likely underlying few differences observed, role of monoallelic variants unclear).

This gene could probably be included in other panels e.g. for microcephaly (not added).

There is no BUB1-related phenotype in OMIM, G2P, SysID, PanelApp Australia.

------

Carvalhal, Bader et al (2022 - PMID: 35044816) describe the phenotype of 2 unrelated individuals with biallelic BUB1 pathogenic variants and provide evidence for the underlying mechanism for this condition.

Common features comprised congenital microcephaly (2/2 | -2,8 and -2.9 SDs respectively / -7 and -4,9 SDs on last evaluation), DD/ID (2/2 - in one case with formal evaluation mild), some degree of growth retardation (2/2) and cardiovascular findings (2/2 - small ASD type II). Other findings limited to one subject included Pierre-Robin sequence, Axenfeld-Rieger anomaly, choanal stenosis, hypospadias, tracheal stenosis, etc.

Initial genetic testing was normal (incl. CMA in both, metabolic testing and individual genes incl. PITX2, GREM1, FOXD3, FOXC1 for one proband).

Exome sequencing revealed homozygosity for a start-lost variant (NM_004336.4:c.2T>G / p.?) in the first subject (P1). The variant lied within a 14-Mb region of homozygosity (no reported consanguinity). The second individual (P2) was compound htz for a splice-site and a frameshift variant (c.2625+1G>A and c.2197dupG) with Sanger sequencing used for confirmation and segregation studies.

BUB1 encodes BUB1 Mitotic checkpoint serine/threonine kinase (/Budding uninhibited by benzimidazoles 1, s. cerevisiae, homolog of) a multifunctional component of the segregation machinery contributing to multiple mitotic processes. The protein has a kinetochore localization domain, multiple binding motifs and a C-terminal kinase domain (aa 784-1085) this structure allowing both kinase dependent/independent activities.

cDNA sequencing revealed that the splice variant leads to skipping of ex21 and in-frame deletion of 54 residues in the kinase domain (c.2625+1G>A / p.Val822_Leu875del).

Both individuals exhibited normal BUB1 mRNA levels (fibroblasts in both, tracheal tissue in one) but severely reduced protein levels (fibroblasts). A shorter protein product corresponding to the in-frame deletion variant was also detected.

The authors performed additional experiments to confirm small amounts of full-length protein produced by the start-lost variant. This was shown in SV40-transformed fibroblasts from the corresponding individual (treatment with a proteasome inhibitor resulted also in higher levels). Upon generation RPE1 cells using CRISPR for the start-lost variant, again, small amounts of full length protein were detected, which was not the case for complete knockout HAP1 cells. No shorter versions could be detected in the patient cells or RPE1 cells, arguing against utilization of an alternative start codon. (Use of non-AUG start codons discussed based on literature).

In line with small amounts of full-length protein the authors provided evidence for residual kinase activity for the start-loss variant (through proxy of phosphorylation of its substrate and use of a BUB1 kinase inhibitor). Cells from the individual with the frameshift variant and the splice variant had no residual kinase activity.

The authors provide evidence for mitotic defects in cells from both individuals with prolonged mitosis duration and chromosome segregation defects. Some patient-specific findings were thought to be related with BUB1 protein levels (affecting BUB1-mediated kinetochore recruitment of BUBR1, important for chromosome alignment) and others due to residual kinase activity [->phosphorylation of H2A at Threonine 120-> affecting centromeric recruitment of Aurora B, SGO1 (role in protection of centromeric cohesion), TOP2A (a protein preventing DNA breakage during sister chromatid separation), these correlated with high anaphase bridges (in P2), aneuploidy observed in lymphoblasts and primary fibroblasts from P2 but not P2's lymphocytes or lymphocytes from P1) and defective sister chromatid cohesion defects (in primary fibroblasts from P2, milder effect for P1).

Overall the authors provide evidence for overlapping clinical and cellular phenotype for this condition with primary microcephalies (MCPH - mutations in genes for mitotic regulators incl. kinetochore proteins or regulators of chromosome organization), mosaic variegated aneuploidy (biallelic variants in genes for kinetochore proteins, with random aneuploidies occurring in >5% cells of different tissues) and cohesinopathies (mostly Roberts or Warsaw breakage syndromes - characterized by cohesion loss and/or spontaneous railroad chromosomes).

Mouse model: Hmz disruption in mice is lethal shortly after E3.5 (cited PMID: 19772675), while a hypomorphic mutant mouse (lacking exons 2-3, expressing <5% of wt protein levels) is viable but exhibits increased tumorigenesis with aging and aneuploidy (cited PMID: 19117986). Mutant mice that lack kinase activity though with preserved Bub1 protein abundance, did not display increased susceptibility, despite substantial segregation errors and aneuploidies (cited PMID: 23209306).

The authors note that monoallelic germline BUB1 variants have been described in small number of individuals with CRC, exhibiting reduced expression levels and variegated aneuploidy in multiple tissues (cited PMID: 23747338) although the role of BUB1 is debated (cited PMIDs: 27713038, 29448935).

Based on the discussion, complete loss of BUB1 activity is presumed to be embryonically lethal based on the mouse study (PMID: 19772675) and reduced BUB1 expression associated with spontaneous miscarriages (cited PMID: 20643875, to my understanding in this study mRNA levels remained relatively constant despite reduced Bub1 protein levels, mRNA RT-PCR followed by sequencing revealed only 2 synonymous BUB1 variants).
Sources: Literature
Intellectual disability - microarray and sequencing v3.1500 CHKA Konstantinos Varvagiannis gene: CHKA was added
gene: CHKA was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CHKA was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CHKA were set to 35202461
Phenotypes for gene: CHKA were set to Abnormal muscle tone; Global developmental delay; Intellectual disability; Seizures; Microcephaly; Abnormality of movement; Abnormality of nervous system morphology; Short stature
Penetrance for gene: CHKA were set to Complete
Review for gene: CHKA was set to GREEN
Added comment: Klöckner (2022 - PMID: 35202461) describe the phenotype of 6 individuals (from 5 unrelated families) harboring biallelic CHKA variants.

Shared features incl. abnormal muscle tone(6/6 - hypertonia or hypotonia, 3/6 each), DD/ID (6/6,severe in 4, severe/profound in 2), epilepsy (6/6 - onset: infancy - 3y2m | epileptic spasms or GS at onset), microcephaly (6/6), movement disorders (3/6 - incl. dyskinesia, rigidity, choreoatetotic movements). 2/5 individuals exhibited MRI abnormalities, notably hypomyelination. Short stature was observed in 4/6.

Eventual previous genetic testing was not discussed.

Exome sequencing (quattro ES for 2 sibs, trio ES for 1 individual, singleton for 3 probands) revealed biallelic CHKA variants in all affected individuals. Sanger sequencing was performed for confirmation and segregation studies.

Other variants (in suppl.) were not deemed to be causative for the neurodevelopmental phenotype.

3 different missense, 1 start-loss and 1 truncating variant were identified, namely (NM_0012772.2):
- c.421C>T/p.(Arg141Trp) [3 hmz subjects from 2 consanguineous families],
- c.580C>T/p.Pro194Ser [1 hmz individual born to consanguineous parents],
- c.2T>C/p.(Met1?) [1 hmz individual born to related parents],
- c.14dup/p.(Cys6Leufs*19) in trans with c.1021T>C/p.(Phe341Leu) in 1 individual.

CHKA encodes choline kinase alpha, an enzyme catalyzing the first step of phospholipid synthesis in the Kennedy pathway. The pathway is involved in de novo synthesis of glycerophospholipids, phosphatidylcholine and phosphatidylethanolamine being the most abundant in eukaryotic membranes.

CHKA with its paralog (CHKB) phosphorylates either choline or ethanolamine to phosphocholine or phosphoethanolamine respectively with conversion of ATP to ADP.

As the authors comment, biallelic pathogenic variants in CHKB cause a NDD with muscular dystrophy, hypotonia, ID, microcephaly and structural mitochondrial anomalies (MIM 602541). [Prominent mitochondrial patterning was observed in a single muscle biopsy available from an individual with biallelic CHKA variants].

Other disorders of the Kennedy pathway (due to biallelic PCYT2, SELENOI, PCYT1A variants) present with overlapping features incl. variable DD/ID (no-severe), microcephaly, seizures, visual impairment etc.

CHKA variants were either absent or observed once in gnomAD, affected highly conserved AAs with multiple in silico predictions in favor of a deleterious effect.

In silico modeling suggests structural effects for several of the missense variants (Arg141Trp, Pro194Ser presumably affect ADP binding, Phe341 lying close to the binding site of phosphocholine).

Each of the missense variants was expressed in yeast cells and W. Blot suggested expression at the expected molecular weight at comparative levels. The 3 aforementioned variants exhibited reduced catalytic activity (20%, 15%, 50% respectively).

NMD is thought to underly the deleterious effect of the frameshift one (not studied).

The start-loss variant is expected to result in significantly impaired expression and protein function as eventual utilization of the next possible start codon - occurring at position 123 - would remove 26% of the protein.

Chka(-/-) is embryonically lethal in mice, suggesting that complete loss is not compatible with life. Reduction of choline kinase activity by 30% in heterozygous mice did not appear to result in behavioral abnormalities although this was not studied in detail (PMID cited: 18029352). Finally, screening of 1566 mouse lines identified 198 genes whose disruption yields neuroanatomical phenotypes, Chka(+/-) mice being among these (PMID cited: 31371714).

There is no associated phenotype in OMIM, Gene2Phenotype or SysID.

Overall this gene can be considered for inclusion in the ID and epilepsy panes with green or amber rating (>3 individuals, >3 variants, variant studies, overlapping phenotype of disorders belonging to the same pathway, etc). Consider also inclusion in the microcephaly panel (where available this seemed to be of postnatal onset).
Sources: Literature
Intellectual disability - microarray and sequencing v3.1496 SPRED2 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 (Strong) but not in OMIM. There is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.
Intellectual disability - microarray and sequencing v3.1496 SPRED2 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 (Strong) but not in OMIM. There is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.
Intellectual disability - microarray and sequencing v3.1491 SPATA5L1 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is associated with a phenotype in OMIM and Gene2Phenotype (limited). There is enough evidence to support a gene-disease association, this gene should be rated Green.
Intellectual disability - microarray and sequencing v3.1480 KCND2 Eleanor Williams gene: KCND2 was added
gene: KCND2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: KCND2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: KCND2 were set to 34245260; 16934482; 24501278
Phenotypes for gene: KCND2 were set to global developmental delay, HP:0001263
Mode of pathogenicity for gene: KCND2 was set to Other
Added comment: 6 new unrelated cases with developmental delay reported in PMID: 34245260 (Zhang et al 2021), 3 of whom had seizures. All had heterozygous missense variants of KCND2 in sites known to be critical for channel gating (E323K, P403A, two individuals, V404L, two individuals and V404M). Functional studies suggest that these missense changes cause both a partial loss-of-function (LOF) and gain-of-function (GOF). The V404 change appears to increase epileptic seizure susceptibility with the 3 patients with a V404 change showing this phenotype.

PMID:16934482 - Singh et al, 2006 - reports a patient with cognitive impairment who also went on to have seizures starting from age 13 with a 5 bp deletion in KCND2 leading to premature stop codon. The proband's asymptomatic father also shared this variant.

Also:
PMID:24501278 - Lee et al, 2014 - reports pair of monozygotic twin boys with infantile onset severe refractory epilepsy and autism. A de novo heterozygous missense variant was identified by WES - V404M.
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 v3.1375 ARFGEF1 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 (probable) but not in OMIM. There are >3 unrelated cases. ID in patients ranged from mild to moderate, which does not satisfy the criteria for this panel (moderate to severe); however, as this is one of the presenting features this gene has will be recommended to be Green at the next review.
Intellectual disability - microarray and sequencing v3.1359 ABHD16A Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a phenotype in OMIM or Gene2Phenotype. There are >3 unrelated cases, therefore there is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.
Intellectual disability - microarray and sequencing v3.1356 SARS Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is associated with a phenotype in OMIM and Gene2Phenotype. As there are only 2 cases there is not enough evidence to support a gene-disease association. This gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.1354 ATP6V0C Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a phenotype in OMIM or Gene2Phenotype. There is currently not enough evidence to support a gene-disease association. This gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.1353 ATP11A Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a phenotype in OMIM or Gene2Phenotype. There is currently only 1 case and a mouse model which showed neurological deficit phenotypes (including tremors, abnormal gait, hind limb clasping and reduction in brain size. The patient was a 26 yo male born to healthy non-consanguineous Japanese parents. At birth his length was -3.3. SD and OFC was -1.3 SD. Developed epilepsy at 2 weeks followed by global developmental delay and mild hypothyroidism and cataracts.He suffered gradual lost of developmental milestones. At 18 yo, height was -4.6 SD and OFC was -4.0 SD.

As there is currently not enough evidence to support a gene-disease association, this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.1339 CACNA1I Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a phenotype in OMIM or Gene2Phenotype. There is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.
Intellectual disability - microarray and sequencing v3.1338 CHRM1 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a phenotype in OMIM or Gene2Phenotype. As there is currently not enough evidence to support a gene-disease association this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.1338 CHRM1 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a phenotype in OMIM or Gene2Phenotype. As there is currently not enough evidence to support a gene-disease association this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.1336 ZNF699 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is associated with a phenotype in OMIM but not Gene2Phenotype. There is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.
Intellectual disability - microarray and sequencing v3.1334 JAKMIP1 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a phenotype in OMIM or Gene2Phenotype. Currently there are only 2 cases; however, there is very little information about the two cases in the papers. Therefore, this gene has been given an Amber rating until more evidence is available.
Intellectual disability - microarray and sequencing v3.1332 ZNF668 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is currently no phenotypes associated with this gene in OMIM or Gene2Phenotype. As there are only 2 cases there is currently not enough evidence to support a gene-disease association. Therefore, this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.1331 UBE2U Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a disease in Gene2Phenotype (there is currently no entry for this gene in OMIM). As there is currently only 1 case this gene has been given a Red rating.
Intellectual disability - microarray and sequencing v3.1301 LINGO4 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There a sufficient unrelated cases with a relevant phenotype to rate as Green at the next GMS panel update.
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PMID: 33098801 - 4 individuals from 3 unrelated families harbouring private biallelic variants in this gene which co-segregated with disease. 4/4 cases presented with GDD and ID.
Intellectual disability - microarray and sequencing v3.1300 IMPDH2 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. This gene is not yet associated with a relevant phenotype in OMIM or G2P, but sufficient unrelated cases with relevant phenotype to rate Green at the next GMS review. Neurodevelopmental delay is an early feature that may be evident prior to other manifestations (plausible that other cases may develop dystonic signs later in life) and so inclusion on this panel is warranted.
Intellectual disability - microarray and sequencing v3.1299 CLCN3 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is enough evidence to promote this gene to Green at the next GMS panel update. Sufficient number of unrelated cases with relevant phenotype to add to the ID and epilepsy panels. Functional studies and animal model support pathogenicity. CLCN3 is also associated with a relevant phenotype in OMIM (MIM# 619512 and 619517)
Intellectual disability - microarray and sequencing v3.1296 ANK2 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is sufficient evidence to promote this gene to Green at the next GMS panel review - sufficient unrelated cases with relevant phenotype and de novo PTVs in this gene. Definitive gene-disease association is supported by the ClinGen ID and Autism Expert Panel.
Intellectual disability - microarray and sequencing v3.1292 AP1G1 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Usmani et al., 2021 (PMID: 34102099) identified 9 families with heterozygous and 2 families with homozygous variants in this gene. All individuals (12) had GDD and ID of various severity (mild to severe), except one patient who died at 22 days. Other features include hypotonia (9/10), seizures (6/10) and spasticity (4/10). Some supportive functional data included.

There is sufficient evidence to promote this gene to Green at the next GMS panel update, with 'monoallelic' MOI. Biallelic cases would still be picked up by the Genomics England pipeline - but this may be reviewed if additional cases are discovered.
Intellectual disability - microarray and sequencing v3.1282 ATP1A3 Arina Puzriakova commented on gene: ATP1A3: Gene was reassessed following a further Green review by Zornitza Stark (8 Jul 2021). Vetro et al. (PMID: 33880529) identified several individuals with variants in this gene who presented with DD/ID as the predominant feature. Therefore, ATP1A3 will be flagged for GMS expert review as inclusion on this panel may be of value in some patients but previous comments regarding association with several phenotypes should be considered.
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 v3.1279 RFX4 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). 6 individuals from 4 unrelated families were identified with different variants in the RFX4 gene (3 de novo, 1 inherited). Presenting phenotypes include ID/GDD (6/6) and ASD (5/6).

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 v3.1278 RFX3 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). 18 individuals from 15 unrelated families were identified with different heterozygous variants in the RFX3 gene (14 de novo, 1 inherited). Presenting phenotypes include ID/GDD (14/18), ASD (13/18) and ADHD (10/18).

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 v3.1273 HID1 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is enough evidence to promote this gene to Green at the next GMS panel update.
Intellectual disability - microarray and sequencing v3.1263 PARP6 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. At least 3 individuals with heterozygous PARP6 variants and a relevant phenotype have been reported (PMID: 34067418) - however, segregation analysis has only been complete for one of these cases. Furthermore, identification of two sibs with biallelic variants and unaffected parents who were heterozygous carriers arises possibility of incomplete penetrance or role of variants in other genes.

Overall there is not enough evidence to add this gene as diagnostic grade, so rating Amber with watchlist tag.
Intellectual disability - microarray and sequencing v3.1262 CACNA1I Zornitza Stark gene: CACNA1I was added
gene: CACNA1I was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: CACNA1I was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted
Publications for gene: CACNA1I were set to 33704440
Phenotypes for gene: CACNA1I were set to Neurodevelopmental disorder
Mode of pathogenicity for gene: CACNA1I was set to Other
Review for gene: CACNA1I was set to GREEN
gene: CACNA1I was marked as current diagnostic
Added comment: 4 different missense variants identified and shown to result in a gain of function.

2 individuals with de novo variants (a 3rd also suspected de novo but their father was unavailable for testing) - these patients all had severe neurodevelopmental disorders, involving severe global developmental delay, absence of speech, gross motor delay, muscular hypotonia, early-onset seizures, cortical visual impairment, and feeding difficulties. Variable clinical features include various brain malformations, startle response or seizures, postnatal growth retardation, gastroesophageal reflux, and gastrostomy.

1 family had three affected individuals - variable cognitive impairment in all, involving borderline intellectual functioning or mild or moderate intellectual disability as main clinical feature, with late-onset seizures in the mother and speech retardation in one of the children. This variant had a milder functional effect than the variants in sporadic cases.
Sources: Literature
Intellectual disability - microarray and sequencing v3.1219 CTC1 Arina Puzriakova Added comment: Comment on list classification: This gene should be demoted from Green to Amber, as per the recent review by Zornitza Stark. The disorder is primarily characterised by intracranial calcifications to which cognitive decline is secondary. Some individuals have normal cognition.
Intellectual disability - microarray and sequencing v3.1218 PGM2L1 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is sufficient evidence to promote this gene to Green at the next GMS panel update (tagged).

Morava et al. 2021 (PMID: 33979636) identified 4 unrelated individuals with different biallelic protein-truncating variants in the PGM2L1 gene. All had severe GDD/ID. Other features that reach the threshold for inclusion on the relevant panels (observed in at least 3 cases) are epilepsy and early obesity (99th centile at ages 2 to 3). Some functional data included.
Intellectual disability - microarray and sequencing v3.1209 PTPN4 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a phenotype in OMIM or Gene2Phenotype. Based on the expert review, there is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.
Intellectual disability - microarray and sequencing v3.1209 PTPN4 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a phenotype in OMIM or Gene2Phenotype. Based on the expert review, there is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.
Intellectual disability - microarray and sequencing v3.1200 CEP85L Sarah Leigh edited their review of gene: CEP85L: Added comment: Associated with relevant phenotype in OMIM, but not associated with phenotype in Gen2Phen. At least nine variants reported in nine unrelated families. PMID 32097630 comments that - the CEP85L gene as a whole is tolerant to loss of function and to missense variation. However, the 4 missense variants that have been identified in patients affect a 15-aa region of the protein that is highly intolerant to missense variation, the splicing and start-loss variants are predicted to produce a shortened protein that excludes the same 15-aa region. It is speculated that variants in this constrained region, may act through a dominant-negative mechanism.
Intellectual disability was apparent in eight of the families studied, ranging from mild (three families) to moderate (five families).
Supportive studies were also presented (PMID 32097630, 32097629).; Changed rating: GREEN
Intellectual disability - microarray and sequencing v3.1198 DPYSL5 Ivone Leong changed review comment from: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is associated with a phenotype in Gene2Phenotype (probable) but not in OMIM.

PMID: 33894126. 10 individuals (2 of whom are related). 7/7 had severe ID, 9/9 DD and hypotonia, 3/6 ataxia, 3/10 seizures, 6/7 cerebellar hypoplasia and 7/10 corpus callosum agenesis.

Based on literature and expert review, there is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.; to: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is associated with a phenotype in Gene2Phenotype (probable) but not in OMIM.

PMID: 33894126. 10 individuals (2 of whom are related). 7/7 had severe ID, 9/9 DD and hypotonia, 3/6 ataxia, 3/10 seizures, 6/7 cerebellar hypoplasia and 7/10 corpus callosum agenesis. Age range from 2.5 years to 33 years.

Based on literature and expert review, there is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.
Intellectual disability - microarray and sequencing v3.1198 DPYSL5 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 (probable) but not in OMIM.

PMID: 33894126. 10 individuals (2 of whom are related). 7/7 had severe ID, 9/9 DD and hypotonia, 3/6 ataxia, 3/10 seizures, 6/7 cerebellar hypoplasia and 7/10 corpus callosum agenesis.

Based on literature and expert review, there is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.
Intellectual disability - microarray and sequencing v3.1197 CHD5 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 (possible) but not in OMIM.

PMID: 33944996. Age ranged from 3 years - 22 years. 9/14 individuals had ID (only 6 of 9 patients were assessed for severity with 2 moderate ID and 4 severe cases). 10/16 individuals had epilepsy. 7/14 had hypotonia and 3/7 had craniosynostosis. 16 different variants were identified (11 missense, 1 frameshift, 2 nonsense and 2 splice site variants).

There are >3 unrelated cases, therefore there is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.
Intellectual disability - microarray and sequencing v3.1193 ATXN2L Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not asssociated with a phenotype in OMIM or Gene2Phenotype. There is not enough evidence to support a gene-disease association. This gene has been given a Amber rating.
Intellectual disability - microarray and sequencing v3.1190 ERGIC3 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not asssociated with a phenotype in OMIM or Gene2Phenotype. There is not enough evidence to support a gene-disease association. This gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.1188 HEATR5B Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a phenotype in OMIM or Gene2Phenotype. There is currently not enough evidence to support a gene-disease association. This gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.1186 JPH3 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is asssociated with a phenotype in OMIM but not Gene2Phenotype. As there is only one case there is not enough evidence to support a gene-disease association. This gene has been given a Red rating.
Intellectual disability - microarray and sequencing v3.1185 KIF1B Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is asssociated with a phenotype in OMIM but not Gene2Phenotype. As there is only one case there is not enough evidence to support a gene-disease association. This gene has been given a Red rating.
Intellectual disability - microarray and sequencing v3.1183 SAMD9L Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is associated with a phenotype in OMIM and Gene2Phenotype, but nothing related to ID. There is currently not enough evidence to support a gene-disease association. This gene has been given a Red status.
Intellectual disability - microarray and sequencing v3.1174 MYT1 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 in OMIM. There is currently not enough evidence to support a gene-disease association. This gene has been given a Red rating.
Intellectual disability - microarray and sequencing v3.1145 GEMIN5 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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Kour et al. 2021 (PMID: 33963192) report 30 individuals from 22 unrelated families with biallelic variants in the GEMIN5 gene. All affected individuals displayed predominantly motor DD, although cognitive and speech delays were also seen in most patients (18/19). 23/30 had central hypotonia, and variable appendicular spasticity was observed in 13/30 cases. 8 individuals were nonambulatory, while all ambulatory patients (19) had a gait ataxia. Brain MRI in all cases showed cerebellar atrophy.

Variants perturbed the subcellular distribution, stability, and expression of GEMIN5 protein and its interacting partners, and disrupted snRNP complex assembly formation in patient iPSC-derived neurons, suggesting a LoF mechanism. Knockdown in Drosophila lead to developmental defects, motor dysfunction, and a reduced lifespan

GEMIN5 is associated with a relevant phenotype in OMIM (Neurodevelopmental disorder with cerebellar atrophy and motor dysfunction, MIM# 619333) but is not yet listed in G2P.
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 v3.1142 CPE Arina Puzriakova changed review comment from: Comment on list classification: New gene added by Zornitza Stark. Two consanguineous families in literature with different homozygous variants in the CPE gene. Affected individuals presented with obesity, intellectual disability and hypogonadotropic hypogonadism. Rating Amber, awaiting further cases (added watchlist tag); to: Comment on list classification: New gene added by Zornitza Stark. Two consanguineous families in literature to date with different homozygous variants in the CPE gene (PMIDs: 26120850; 32936766). Affected individuals presented with obesity, intellectual disability and hypogonadotropic hypogonadism. Rating Amber, awaiting further cases (added watchlist tag)
Intellectual disability - microarray and sequencing v3.1142 CPE Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Two consanguineous families in literature with different homozygous variants in the CPE gene. Affected individuals presented with obesity, intellectual disability and hypogonadotropic hypogonadism. Rating Amber, awaiting further cases (added watchlist tag)
Intellectual disability - microarray and sequencing v3.1125 SIN3B Arina Puzriakova Added comment: Comment on list classification: New gene added and reviewed by Zornitza Stark (Green) and Konstantinos Varvagiannis (Green/Amber). Overall there are sufficient unrelated cases (>3) of ID associated with SNVs in this gene to warrant a Green rating on this panel at the next GMS review. Deletions of the region containing SIN3B have also been linked to ID, lending further support to this gene-disease association.
Intellectual disability - microarray and sequencing v3.1120 CAPN15 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Sufficient number of cases presenting with DD/ID (5/7 individuals from 3 unrelated families - PMIDs: 33410501; 32885237) to warrant a Green rating on this panel.
Intellectual disability - microarray and sequencing v3.1118 ANKRD17 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is sufficient evidence to rate this gene Green at the next GMS panel update.

Chopra et al. 2021 (PMID: 33909992) report 34 individuals from 32 families with a heterozygous variant or microdeletion of ANKRD17. GDD/ID was the most common feature, affecting 31/33 individuals with variable severity - 7 severe, 12 moderate, 5 mild, 7 borderline. Deletions of the region containing ANKRD17 have also been associated with ID.
Intellectual disability - microarray and sequencing v3.1049 UBE4A Arina Puzriakova changed review comment from: Comment on list classification: New gene added by Zornitza Stark. Sufficient evidence to rate this gene Green at the next GMS panel update - 4 unrelated families with different homozygous LoF variants in UBE4A, supported by some functional data and animal model. Severe ID and GDD was a feature in all affected individuals (8 total).

UBE4A is not associated with any phenotype in OMIM (last edited on 17/09/2010) but has a 'probable' disease confidence rating for 'UBE4A-associated neurodevelopmental disorder' in Gene2Phenotype.; to: Comment on list classification: New gene added by Zornitza Stark. Sufficient evidence to rate this gene Green at the next GMS panel update - PMID:33420346 report 4 unrelated families with different homozygous LoF variants in UBE4A, supported by some functional data and animal model. Severe ID and GDD was a feature in all affected individuals (8 total).

UBE4A is not associated with any phenotype in OMIM (last edited on 17/09/2010) but has a 'probable' disease confidence rating for 'UBE4A-associated neurodevelopmental disorder' in Gene2Phenotype.
Intellectual disability - microarray and sequencing v3.1049 UBE4A Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Sufficient evidence to rate this gene Green at the next GMS panel update - 4 unrelated families with different homozygous LoF variants in UBE4A, supported by some functional data and animal model. Severe ID and GDD was a feature in all affected individuals (8 total).

UBE4A is not associated with any phenotype in OMIM (last edited on 17/09/2010) but has a 'probable' disease confidence rating for 'UBE4A-associated neurodevelopmental disorder' in Gene2Phenotype.
Intellectual disability - microarray and sequencing v3.1048 NCDN Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Sufficient evidence to rate this gene as Green with 'monoallelic' MOI at next GMS panel update.

- PMID: 33711248 (2021) - Six affected individuals (3 sibs with homozygous missense, and 3 unrelated patients with different de novo missense variants) with variable degrees of DD, ID, and seizures. Severity of ID in individuals with heterozygous variants is severe, moderate, and mild (but also learning disabilities), respectively. ID in the 3 sibs was determined as mild. Supportive functional data included.

NCDN is not yet associated with any phenotype in OMIM (last edited on 08/08/2012) but in Gene2Phenotype monoallelic disease has a 'probable' confidence rating while biallelic variants have a 'possible' disease confidence rating.
Intellectual disability - microarray and sequencing v3.1045 MAPKAPK5 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Rating Amber, awaiting further cases (added watchlist tag)

- PMID: 33442026 report on 2 unrelated families with a comparable phenotype including severe GDD, who harbour different homozygous truncating variants in MAPKAPK5. Some functional evidence indicating the variants impact expression and function of MAPKAPK5 protein.

MAPKAPK5 is not yet associated with any phenotype in OMIM (last edited on 06/04/2016) but has a 'probable' disease confidence rating for 'MAPKAPK5-associated syndrome with synpolydactyly' in Gene2Phenotype.
Intellectual disability - microarray and sequencing v3.1044 COPB1 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. PMID:33632302 reports on six individuals from two unrelated families with different homozygous variants in this gene. All affected patients had severe ID. Rating Amber, awaiting further cases.
Intellectual disability - microarray and sequencing v3.1028 DPYS Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Overall variable clinical presentation, even including asymptomatic subjects. However, DD and/or ID have been reported in multiple published cases (PMIDs: 9266350; 17383919; 20362666; 27604308; 26771602; 29054612). Sufficient unrelated cases (>3) to rate Green but will seek opinion from the GMS expert group due to highly variable penetrance of this phenotype.
Intellectual disability - microarray and sequencing v3.777 KCNN2 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is enough evidence to promote this gene to Green at the next GMS panel update - variable degrees of cognitive impairment were a universal feature amongst individuals with KCNN2 variants (at least 10 unrelated cases with unique variants). Pathogenicity was supported by functional data.
Intellectual disability - microarray and sequencing v3.774 OTUD5 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is enough evidence to rate this gene Green at the next GMS panel update.

At least 8 families reported with a multiple congenital anomaly disorder and distinct hemizygous variants in this gene. GDD/ID is part of the disease presentation and was noted in all cases of relevant age (PMIDs: 33131077 and 33523931).
Intellectual disability - microarray and sequencing v3.773 PIGF Arina Puzriakova changed review comment from: Comment on list classification: New gene added by Zornitza Stark. Rating Red as 2 families with the same (likely founder) variant reported at present (PMID: 33386993). Phenotypes did include severe ID or DD, respectively - but additional cases with other variants in the LRRC32 gene required to substantiate causation (added founder-effect tag); to: Comment on list classification: New gene added by Zornitza Stark. Rating Red as 2 families with the same (likely founder) variant reported at present (PMID: 33386993). Phenotypes did include severe ID or DD, respectively - but additional cases with other variants in the PIGF gene required to substantiate causation (added founder-effect tag)
Intellectual disability - microarray and sequencing v3.773 PIGF Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Rating Red as 2 families with the same (likely founder) variant reported at present (PMID: 33386993). Phenotypes did include severe ID or DD, respectively - but additional cases with other variants in the LRRC32 gene required to substantiate causation (added founder-effect tag)
Intellectual disability - microarray and sequencing v3.770 METAP1 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Rating Red as only one family reported at present (PMID:32764695). Phenotypes do include ID/DD, but additional cases required to corroborate this gene-disease association.
Intellectual disability - microarray and sequencing v3.766 HIRA Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. At least 4 unrelated individuals with heterozygous variants in this gene - however, only 1 presented moderate ID (2 had ASD rather than ID, while the phenotype is unclear for the fourth individual). HIRA is a good candidate for neurodevelopmental impairment, supported by an animal model, but additional cases are required to ascertain the relevance of ID.

Therefore, at present there is only enough evidence to rate Amber awaiting further cases/clinical evidence (added 'watchlist' tag)
Intellectual disability - microarray and sequencing v3.740 UBR7 Arina Puzriakova Added comment: Comment on list classification: In view of recent expert review by Zornitza Stark, upgraded from Red to Amber but with a recommendation of rating Green at the next GMS panel update (added 'for-review' tag)

At least 6 SNVs and 1 intragenic deletion reported in 7 individuals from 6 families with a comparable neurodevelopmental disorder. DD/ID was a feature in all cases (PMID:33340455)
Intellectual disability - microarray and sequencing v3.731 TANC2 Arina Puzriakova Added comment: Comment on list classification: This gene should be promoted to Green at the next GMS panel update - multiple unrelated families with a comparable neurodevelopmental disorder (including ID). As highlighted in review by Zornitza Stark, most reported SNVs are de novo putative disruptive variants, or missense variants that are predicted in silico to have a damaging or possibly damaging effect. Gene expression and function are neurodevelopmentally-relevant, and there is some limited functional data.

Gene-disease association is also now listed in both OMIM and Gene2Phenotype.
Intellectual disability - microarray and sequencing v3.728 PPIL1 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Currently not associated with any phenotype in OMIM (last edited on: 10/07/2001) but has a 'probable' gene rating for 'PPIL1-related Neurodegenerative Pontocerebellar Hypoplasia with Microcephaly' in Gene2Phenotype.

At least 12 variants identified in 17 individuals from 9 unrelated families (PMID: 33220177). All displayed pontocerebellar hypoplasia and congenital microcephaly. Severe ID, with or without seizures, was noted in all subjects (14) where information was provided (see table S1). Pathogenicity is supported by animal model.

Sufficient evidence to promote this gene to Green at the next GMS panel update (added 'for-review' tag)
Intellectual disability - microarray and sequencing v3.726 FGF13 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Three variants (c.31C>T, c.41G>C, c.32G>C) identified by WES/WGS in seven individuals from five unrelated families who presented with severe infantile-onset seizures and severe-to-profound ID. Supportive functional data.

Sufficient number of unrelated cases with relevant phenotype; however, early-onset epilepsy represents the main feature of the disorder and ID appears to be a secondary manifestation (see supplemental note in PMID:33245860 for clinical details). Therefore, rating Amber on this panel but will add the FGF13 gene to 'Genetic epilepsy syndromes'
Intellectual disability - microarray and sequencing v3.722 FBRSL1 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is enough evidence to promote this gene to Green at the next GMS panel update (added 'for-review' tag) - sufficient number of unrelated cases with distinct variants and relevant phenotype, supported by functional data.

Currently not associated with any phenotype in OMIM or Gene2Phenotype.
Intellectual disability - microarray and sequencing v3.721 DPH2 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Currently not associated with any phenotype in OMIM or Gene2Phenotype.

At least 2 unrelated families with biallelic variants in this gene. Phenotypes included DD with expressive language delays in the 19-month-old male in PMID: 32576952 (2020); and intellectual disability in both sibs in PMID: 27421267 (2016), albeit within the mild range (Stanford-Binet scale IQ = 58 and 68, respectively). However in the latter case, KALRN was proposed as the causative gene at the time of publication, as scarce data was known for the DPH2 gene.

Additional cases would help corroborate this gene-disease association and so rating Amber, awaiting further cases/clinical evidence.
Intellectual disability - microarray and sequencing v3.720 CDC40 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. CDC40 currently not associated with any phenotype in OMIM (last edited: 23/08/19) but has a 'possible' disease confidence for 'CDC40-related Neurodegenerative Pontocerebellar Hypoplasia with Microcephaly' in Gene2Phenotype.

Rating Red as currently only a single individual reported in PMID: 33220177 (2021). There is some functional and animal model data to support pathogenicity, so have added 'watchlist' tag. If additional cases arise, CDC40 may also be considered for other panels (e.g. Malformations of cortical development, Genetic epilepsy syndromes, Cytopenia - NOT Fanconi anaemia, etc)
Intellectual disability - microarray and sequencing v3.713 GLS Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Early developmental delay, which preceded other progressive neurological concerns, was reported in the three unrelated cases from PMID:30970188. Following discussion with Helen Brittain (Genomics England Clinical Team) it was agreed that this is sufficient for inclusion on this panel.

However, detection of the 5' UTR triplet expansion must first be internally validated for the interpretation pipeline. In the meantime, rating Amber but will raise the STR for validation with the Rare Disease team.
Intellectual disability - microarray and sequencing v3.690 SLC9A7 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Associated with relevant phenotype in OMIM and Gene2Phenotype. However, only 2 unrelated families reported at present (PMID: 30335141) and therefore only sufficient for an Amber rating, awaiting further publications/clinical evidence (added 'watchlist' tag)
Intellectual disability - microarray and sequencing v3.686 AGO2 Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. All patients reported in PMID: 33199684 presented GDD/ID, while other features were relatively heterogenous. However, cognitive impairment was perhaps too mild in majority of cases. Tagged 'for-review' to assess whether there is sufficient evidence for a Green rating in light of the scope of the ID panel.
Intellectual disability - microarray and sequencing v3.681 LSS Eleanor Williams changed review comment from: In light of the recent expert review green by Zornitza Stark, this gene should be considered for a green rating by the GMS. The phenotype is variable with the ID phenotype being part of the presentation in approx half the families.; to: In light of the recent expert review green by Zornitza Stark, this gene should be considered for a green rating by the GMS, as agreed with Genomics England clinicians. The phenotype is variable with the ID phenotype being part of the presentation in approx half the families.
Intellectual disability - microarray and sequencing v3.681 LSS Eleanor Williams edited their review of gene: LSS: Added comment: In light of the recent expert review green by Zornitza Stark, this gene should be considered for a green rating by the GMS. The phenotype is variable with the ID phenotype being part of the presentation in approx half the families.; Changed rating: GREEN
Intellectual disability - microarray and sequencing v3.669 KDM4B Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Rating Amber but may be promoted to Green at the next GMS panel update (added 'for-review' tag).

9 unrelated individuals reported at present (PMID: 33232677). Although all presented GDD, only 1 individual had severe ID (IQ = 50) and 3 had mild ID. Although ID is too mild in majority of cases, developmental delay was the universal feature amongst affected individuals and other phenotypes were heterogenous (e.g. seizures, brain malformations). Therefore, there may be value in inclusion on this panel for capturing this phenotype.
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 v3.654 HS2ST1 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with a relevant phenotype in OMIM or Gene2Phenotype. Only 2 of 3 unrelated families with affected individuals described in PMID: 33159882 were reported to have ID. The affected individuals in the third family could not be assessed for ID. Therefore, there is currently not enough evidence to support a gene-disease association. This gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.653 BICRA Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with any phenotypes in OMIM or Gene2Phenotype. There is enough evidence to support a gene-disease association. This gene should be rated Green at the next review.
Intellectual disability - microarray and sequencing v3.652 EMC10 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is not associated with any phenotypes in OMIM or Gene2Phenotype. As there is only 1 case, this gene has been given a Red rating.
Intellectual disability - microarray and sequencing v3.632 SH3PXD2B Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.631 SEC23B Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.630 SCN11A Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.629 SCARF2 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.628 SBDS Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.627 SALL4 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.626 PRSS56 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.625 PROP1 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.624 PRDM12 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.623 PPA2 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.622 POLR1D Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.621 POLD1 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.620 POC1B Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.619 PMS2 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.618 PLOD2 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.617 PKHD1 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.616 PKD1L1 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.615 PITX3 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.614 PITX2 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark (Australian Genomics)
Intellectual disability - microarray and sequencing v3.613 PIK3R1 Arina Puzriakova Added comment: Comment on list classification: Following discussion with the Genomics England clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark
Intellectual disability - microarray and sequencing v3.601 ZFHX4 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). This gene is associated with a phenotype in OMIM. Based on the available evidence there is enough evidence to support a gene-disease association. This gene should be promoted to Green at the next review.
Intellectual disability - microarray and sequencing v3.599 UPF1 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics).

PMID: 28539120 describes a patient with significant ID. The patient has SNVs in SQSTM1 and UPF1. The authors suggests that it is plausible that the haploinsufficiency of SQSTM1 may have caused neurofunctional defects, which the haploinsufficiency of UPF1 may have exacerbated.

As the patient in the second case has another variant in another gene, there is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.597 U2AF2 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.596 TCF7L2 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.595 SRRM2 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.594 SPEN Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.590 MSL2 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.590 MSL2 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.589 RAB14 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.588 PSMC5 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.587 MMGT1 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.586 HNRNPD Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.585 FBXO31 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.582 FOXP4 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). As ID is not present in the majority of affected patients, and the affected individuals only show mild ID, this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.581 DHX32 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.580 GIGYF1 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.579 ATP6V0A1 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.578 DDX23 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.577 ARHGAP35 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.575 AP2S1 Ivone Leong Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is not enough evidence to support a gene-disease association so this gene has been given an Amber rating.
Intellectual disability - microarray and sequencing v3.569 RNPC3 Ivone Leong gene: RNPC3 was added
gene: RNPC3 was added to Intellectual disability. Sources: Expert Review,Literature
Mode of inheritance for gene: RNPC3 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: RNPC3 were set to 24480542; 29866761; 32462814
Phenotypes for gene: RNPC3 were set to isolated growth hormone deficiency; ?Growth hormone deficiency, isolated, type V, 618160; developmental delay/intellectual deficiency and delayed puberty
Review for gene: RNPC3 was set to RED
Added comment: This gene is an Amber gene on the Growth failure in early childhood panel (v1.16). The following reviews are present for this gene on that panel:

"Comment on list classification: Based on the available evidence and expert review, this gene has been promoted from Red to Amber. This gene is associated with a relevant phenotype on OMIM. The family described in PMIDs 24480542 and 29866761 are the same. The 3 sisters in this family had GH deficiency only. PMID: 32462814 had GH deficiency and almost undetectable levels of prolactin as well.
Ivone Leong (Genomics England Curator), 15 Oct 2020

Two families reported. PMID 29866761: isolated growth deficiency and pituitary hypoplasia. PMID 32462814: growth hormone deficiency, central congenital hypothyroidism, congenital cataract, developmental delay/intellectual deficiency and delayed puberty. Full spectrum of phenotype unclear at present.
Zornitza Stark (Australian Genomics), 5 Oct 2020"

As only 1 affected family has developmental delay/intellectual deficiency, this gene is given a Red rating.
Sources: Expert Review, Literature
Intellectual disability - microarray and sequencing v3.546 COX6B1 Arina Puzriakova Added comment: Comment on list classification: This gene should be demoted from Green to Red and will be flagged for evaluation at the next GMS panel update (added 'for-review' tag) in view of the recent review by Zornitza Stark. As discussed the disease presentation is not prominent for ID, and rather is primarily characterised by lactate acidosis and encephalopathy which should be sufficient indications for diagnostic testing - COX6B1 is already Green on relevant metabolic/mitochondrial panels.
Intellectual disability - microarray and sequencing v3.540 SCO1 Arina Puzriakova Added comment: Comment on list classification: This gene should be demoted from Green to Red and will be flagged for evaluation at the next GMS panel update (added 'for-review' tag), in view of the recent review by Zornitza Stark. As discussed the phenotype is primarily characterised by lactate acidosis and encephalopathy which should be sufficient indications for diagnostic testing - SCO1 is already Green on relevant metabolic/mitochondrial panels.
Intellectual disability - microarray and sequencing v3.531 PET100 Eleanor Williams Added comment: Comment on list classification: Leaving this gene rating as amber until the next GMS review, but as reviewer Zornitza Stark notes there are 8 Lebanese familes with the same variant, plus an Asian British family with a similar phenotype and a different variant, plus functional data to support the disease causation, so would recommend Green rating.
Intellectual disability - microarray and sequencing v3.421 STAR Arina Puzriakova Source Expert Review Red was added to STAR.
Rating Changed from Amber List (moderate evidence) to Red List (low evidence)
Intellectual disability - microarray and sequencing v3.417 ATP8B1 Arina Puzriakova changed review comment from: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark; to: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark and Konstantinos Varvagiannis
Intellectual disability - microarray and sequencing v3.393 MADD Ivone Leong Added comment: Comment on list classification: Based on expert review provided by Konstantinos Varvagiannis and Zornitza Stark, there is enough evidence to support a gene-disease association. This gene has been promoted from Red to Amber and will be promoted to Green status at next panel review.
Intellectual disability - microarray and sequencing v3.371 STS Arina Puzriakova changed review comment from: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark; to: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark and Helen Brittain
Intellectual disability - microarray and sequencing v3.331 STAT1 Arina Puzriakova changed review comment from: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark; to: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark and Konstantinos Varvagiannis
Intellectual disability - microarray and sequencing v3.331 RASA1 Arina Puzriakova changed review comment from: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark; to: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark and Konstantinos Varvagiannis
Intellectual disability - microarray and sequencing v3.330 ABCC6 Arina Puzriakova changed review comment from: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark; to: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark and Konstantinos Varvagiannis
Intellectual disability - microarray and sequencing v3.324 AFG3L2 Arina Puzriakova Added comment: Comment on list classification: This gene should be downgraded from Green to Red at the next major review, in accordance with the review by Zornitza Stark.
Intellectual disability - microarray and sequencing v3.310 FIBP Arina Puzriakova Added comment: Comment on list classification: Rating upgraded from Red to Amber based on review by Zornitza Stark.
Intellectual disability - microarray and sequencing v3.295 ELN Arina Puzriakova changed review comment from: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark; to: Following discussion with the clinical team, this gene has been demoted from Amber to Red, in accordance with the external review by Zornitza Stark and Konstantinos Varvagiannis.
Intellectual disability - microarray and sequencing v3.284 CCDC88A Arina Puzriakova Added comment: Comment on list classification: This gene has been upgraded from Red to Amber based on the external reviews by Konstantinos Varvagiannis and Zornitza Stark.
Intellectual disability - microarray and sequencing v3.254 STAR Arina Puzriakova commented on gene: STAR
Intellectual disability - microarray and sequencing v3.91 WNT1 Catherine Snow Added comment: Comment on list classification: Identified by expert review from Zornitza Stark, sufficient number of unrelated patients for WNT1 to be classified as Green
Intellectual disability - microarray and sequencing v3.78 AGMO Rebecca Foulger changed review comment from: Comment on list classification: Gene was added to the panel and rated Green by Zornitza Stark. One family presented in PMID:27000257, and 2 compound het cases in PMID:31555905 (though there is one individual in gnomAD who is homozygous for the p.Gly144Arg variant). Functional data shows decreased enzyme activity of the variants. Although there are 3 cases, the phenotype is variable between patients (ID/DD vs regression). Therefore, rated as Amber awaiting further cases and clinical opinion.; to: Comment on list classification: Gene was added to the panel and rated Green by Zornitza Stark. One family presented in PMID:27000257, and 2 compound het cases in PMID:31555905 (though there is one individual in gnomAD who is homozygous for the p.Gly144Arg variant). Functional data shows decreased enzyme activity of the variants. Although there are 3 cases, the phenotype is variable between patients (ID/DD vs regression) and therefore this is borderline. Therefore, rated as Amber awaiting further cases and clinical opinion.
Intellectual disability - microarray and sequencing v3.78 AGMO Rebecca Foulger changed review comment from: Comment on list classification: Gene was added to the panel and rated Green by Zornitza Stark. One homozygous case presented in PMID:27000257, and 2 compound het cases in PMID:31555905 (though there is one individual in gnomAD who is homozygous for the p.Gly144Arg variant). Functional data shows decreased enzyme activity of the variants. Although there are 3 cases, the phenotype is variable between patients (ID/DD vs regression). Therefore, rated as Amber awaiting further cases and clinical opinion.; to: Comment on list classification: Gene was added to the panel and rated Green by Zornitza Stark. One family presented in PMID:27000257, and 2 compound het cases in PMID:31555905 (though there is one individual in gnomAD who is homozygous for the p.Gly144Arg variant). Functional data shows decreased enzyme activity of the variants. Although there are 3 cases, the phenotype is variable between patients (ID/DD vs regression). Therefore, rated as Amber awaiting further cases and clinical opinion.
Intellectual disability - microarray and sequencing v3.78 AGMO Rebecca Foulger Added comment: Comment on list classification: Gene was added to the panel and rated Green by Zornitza Stark. One homozygous case presented in PMID:27000257, and 2 compound het cases in PMID:31555905 (though there is one individual in gnomAD who is homozygous for the p.Gly144Arg variant). Functional data shows decreased enzyme activity of the variants. Although there are 3 cases, the phenotype is variable between patients (ID/DD vs regression). Therefore, rated as Amber awaiting further cases and clinical opinion.
Intellectual disability - microarray and sequencing v3.74 KAT8 Rebecca Foulger Added comment: Comment on list classification: Gene was added to the panel and rated Green by Konstantinos Varvagiannis, and subsequently reviewed Green by Zornitza Stark. Not yet associated with a disorder in OMIM or G2P. All cases come from PMID:31794431 (Li et al.2019) who report 8 unrelated individuals with heterozygous de novo pathogenic KAT8 variants (T1,T2,T3 had the same variant), plus one individual compound het for a nonsense and a missense variant (p.Lys175* and p.Arg325Cys). All individuals had DD and/or ID (Supplementary materials). Knockout mice failed to thrive, and showed early lethality and cerebral hypoplasia.
Intellectual disability - microarray and sequencing v3.73 CXorf56 Rebecca Foulger Added comment: Comment on list classification: Updated rating from Grey to Green. Gene was added to panel by Konstantinos Varvagiannis, with a subsequent Green review by Zornitza Stark. Sufficient cases in PMIDs:29374277 and 31822863. The reported pattern of X-inactivation differs between the papers, but sufficient cases and relevant phenotype for inclusion on the panel.
Intellectual disability - microarray and sequencing v3.71 UGP2 Rebecca Foulger Added comment: Comment on list classification: Gene added to panel and rated Green by Konstantinos Varvagiannis. Subsequently reviewed Green by Zornitza Stark. Sufficient evidence and appropriate phenotype (DD seen in all patients in PMID:31820119) for inclusion on panel: 20 patients from 13 unrelated families all with the same variant identified in PMID:31820119 (2019 publication). Therefore updated rating from Grey to Green.
Intellectual disability - microarray and sequencing v3.69 TRAPPC4 Rebecca Foulger Added comment: Comment on list classification: Added to panel and rated Green by Konstantinos Varvagiannis. Subsequent Green review by Zornitza Stark. Updated rating from Grey to Green: 7 children from 3 unrelated families with MIM:618741 reported by, Van Bergen et al. (2020) with a recurring homozygous splice site variant in TRAPPC4 resulting in a splice site alteration, the skipping of exon 3, a frameshift, and premature termination (Leu120AspfsTer9). The variant segregated within the disorder within the families and was only found in heterozygous state in gnomAD. Appropriate phenotype and cases just reach threshold for inclusion.
Intellectual disability - microarray and sequencing v3.38 ALG9 Rebecca Foulger Added comment: Comment on list classification: As highlighted by Zornitza Stark, since the last curation review, a number of papers have been published on the ALG9 phenotype, including PMID:26453364 and PMID:28932688 who review the literature and report additional cases. At least 6-7 (of 10/11) patients have developmental delay. Therefore sufficient cases to support causation and have updated rating from Red to Green.
Intellectual disability - microarray and sequencing v3.33 CTU2 Rebecca Foulger Added comment: Comment on list classification: Gene was added to panel and rated Green by Zornitza Stark. Sufficient cases of global DD in PMID:31301155 in patients that survived infancy to support causation. Therefore updated rating from Grey to Green.
Intellectual disability - microarray and sequencing v3.3 STAR Zornitza Stark reviewed gene: STAR: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Lipoid adrenal hyperplasia, MIM# 201710; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal
Intellectual disability - microarray and sequencing v3.0 UGP2 Konstantinos Varvagiannis gene: UGP2 was added
gene: UGP2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: UGP2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: UGP2 were set to 31820119
Phenotypes for gene: UGP2 were set to Seizures; Global developmental delay; Intellectual disability; Feeding difficulties; Abnormality of vision; Abnormality of the face
Penetrance for gene: UGP2 were set to Complete
Review for gene: UGP2 was set to GREEN
Added comment: Perenthaler et al. (2019 - PMID: 31820119) provide evidence that homozygosity for a variant abolishing the start codon of the UGP2 transcript (NM_001001521.1) encoding the predominant (short) protein isoform in brain, leads to a severe epileptic encephalopathy.

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

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

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

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

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

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

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

The authors provide several lines of evidence for a the role of the gene in the CNS as well as for the deleterious effect of the specific variant :
- In patient fibroblasts total UGP2 levels were not signifficantly different compared to parent / control fibroblasts, the longer isoform being upregulated (and stable) when the shorter is missing. Immunocytochemistry demonstrated similar localization of UGP2 in the case of mutant or wt cells. Enzymatic activity (/capacity to produce UDP-glucose) was similar between homozygous mut, heterozygous and wt fibroblasts.
- In H9-derived neural stem cells, Western Blot, RT-PCR and qRT-PCR suggested that the short isoform is the predominant one. (In embryonic stem cells, or fibroblasts the ratio between short and long isoform was lower).
- Analysis of RNA-seq data from human fetal tissues suggested that the short isoform is the predominant in brain.
- UGP2 was detected upon immunohistochemistry in fetal brain tissues from first to third trimester of pregnancy while Western Blot confirmed preferential expression of the shorter isoform.
- Homozygous embryonic (ESC) or neural stem cells (NSC) for the variant (knock-in/KI) or for a frameshift variant (knock-out/KO) were generated. Study of NSCs demonstrated reduced total UGP2 protein expression upon Western Blot in the case of KI cells and depleted in KO ones. Transcriptome analysis did not show major transcriptome alterations in KI/KO ESCs compared to wt. In NSC KI/KO cells transcriptome alterations were observed compared to wt with upregulation among others of genes for synaptic processes and genes implicated in epilepsy.
- The absence of UGP2 was shown to result in reduced ability of KO/KI NSCs to produce UDP-glucose, reduced capacity to synthesize glycogen under hypoxia (rescued in the case of KO cells by overexpression of wt or long isoform), defects of protein glycosylation as well as in increased unfolded protein response (/susceptibility to ER stress). These alterations are commented to be possibly implicated in pathogenesis of epilepsy, progressive microcephaly, etc.
- A CRISPR-Cas9 zebrafish model leading with loss of ugp2a and hypomorphic ugp2b (the zebrafish homologs of UGP2) demonstrated abnormal behavior, reduced eye movements and increased frequency/duration of movements upon stimulation with a potent convulsant (suggestive of increased seizure susceptibility).
- UGP knockout in drosophila is lethal while flies compound heterozygous for hypomorphic alleles are viable but show a movement defects due to altered synaptogenesis secondary to glycosylation defects (cited PMID: 27466186).
- The authors make speculations as for the occurrence of a single variant (and not others) eg. absence of UGP2 (in the case of LoF variants affecting both isoforms) would possibly be incompatible with life, Met12Val being tolerable for the long transcript not affecting stability/enzymatic activity (which may not be the case for other substitutions affecting Met12), etc.
Sources: Literature
Intellectual disability - microarray and sequencing v2.1135 TRAPPC4 Konstantinos Varvagiannis gene: TRAPPC4 was added
gene: TRAPPC4 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: TRAPPC4 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: TRAPPC4 were set to 31794024
Phenotypes for gene: TRAPPC4 were set to Feeding difficulties; Progressive microcephaly; Intellectual disability; Seizures; Spastic tetraparesis; Abnormality of the face; Scoliosis; Cortical visual impairment; Hearing impairment
Penetrance for gene: TRAPPC4 were set to Complete
Review for gene: TRAPPC4 was set to GREEN
Added comment: Van Bergen et al. (2019 - PMID: 31794024) report on 7 affected individuals from 3 famillies (only 1 of which consanguineous), all homozygous for a TRAPPC4 splicing variant.

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

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

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

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

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

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

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

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

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

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

TRAPPC4 is the human orthologue of the yeast Trs23. In a yeast model of reduced Trs23 (due to temperature instability) the authors demonstrated impaired assembly of the TRAPP core. The yeast model recapitulated the autophagy as well as well as the secretory defect observed in patient fibroblasts.
Sources: Literature
Intellectual disability - microarray and sequencing v2.1134 OXR1 Konstantinos Varvagiannis gene: OXR1 was added
gene: OXR1 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: OXR1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: OXR1 were set to https://doi.org/10.1016/j.ajhg.2019.11.002
Phenotypes for gene: OXR1 were set to Central hypotonia; Global developmental delay; Delayed speech and language development; Intellectual disability; Seizures; Abnormality of the cerebellum
Penetrance for gene: OXR1 were set to Complete
Review for gene: OXR1 was set to GREEN
Added comment: Wang et al (2019 - https://doi.org/10.1016/j.ajhg.2019.11.002 ) report on 5 individuals (from 3 families) with biallelic OXR1 LoF variants.

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

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

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

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

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

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

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

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

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

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

Although previous reports suggested that OXR1 is involved in oxidative stress resistance, studies performed by the authors suggested that oxidative stress is probably not the driver of the mutant fly defects.
Sources: Literature
Intellectual disability - microarray and sequencing v2.1022 PIGP Konstantinos Varvagiannis gene: PIGP was added
gene: PIGP was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: PIGP was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: PIGP were set to 28334793; 31139695
Phenotypes for gene: PIGP were set to Generalized hypotonia; Global developmental delay; Seizures; Intellectual disability; Feeding difficulties; Cortical visual impairment
Penetrance for gene: PIGP were set to Complete
Review for gene: PIGP was set to GREEN
gene: PIGP was marked as current diagnostic
Added comment: Johnstone et al. (2017 - PMID: 28334793) report on 2 sibs born to non-consanguineous parents of French-Irish ancestry. Both presented with seizures (onset at the age of 2 and 7 weeks respectively), hypotonia and profound DD. Other features included CVI and feeding difficulties. Extensive metabolic testing as well as prior genetic testing (ARX, STXBP1, MECP2, aCGH) in the family were non-diagnostic. WES suggested the presence of 2 PIGP variants with Sanger sequencing used for confirmation and segregation studies.

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

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

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

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

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

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

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

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

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

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

(Please consider inclusion in other possibly relevant panels eg. CDGs, etc).
Sources: Literature
Intellectual disability - microarray and sequencing v2.1015 GOT2 Konstantinos Varvagiannis gene: GOT2 was added
gene: GOT2 was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: GOT2 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: GOT2 were set to 31422819
Phenotypes for gene: GOT2 were set to Global developmental delay; Intellectual disability; Seizures; Increased serum lactate; Hyperammonemia; Microcephaly; Failure to thrive; Feeding difficulties; Abnormality of nervous system morphology
Penetrance for gene: GOT2 were set to Complete
Review for gene: GOT2 was set to GREEN
Added comment: van Karnebeek et al. (2019 - PMID: 31422819) report on 4 individuals from 3 families, with biallelic GOT2 pathogenic variants (3 missense SNVs and 1 in-frame deletion).

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

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

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

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

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

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

[Please consider inclusion in other relevant panels eg. mitochondrial disorders, metabolic disorders and/or addition of the 'treatable' tag].
Sources: Literature
Intellectual disability - microarray and sequencing v2.931 PIGC Rebecca Foulger Added comment: Comment on list classification: Updated rating from Red to Amber following external review by Zornitza Stark. Not yet associated with a disorder in OMIM, and two cases in the current literature (PMID:27694521).
Intellectual disability - microarray and sequencing v2.736 HEPACAM Ivone Leong Added comment: Comment on list classification: Promoted from red to green, based on the evidence provided by Konstantinos Varvagiannis (Other) and Zornitza Stark (Australian Genomics).
Intellectual disability - microarray and sequencing v2.644 KARS Ivone Leong Added comment: Comment on list classification: Promoted from amber to green based on the evidence provided by Zornitza Stark (Australian Genomics) and Konstantinos Varvagiannis (Other).
Intellectual disability - microarray and sequencing v2.597 DHPS Konstantinos Varvagiannis gene: DHPS was added
gene: DHPS was added to Intellectual disability. Sources: Literature
Mode of inheritance for gene: DHPS was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: DHPS were set to 21389784; 21850436
Phenotypes for gene: DHPS were set to Abnormal muscle tone; Global developmental delay; Intellectual disability; Seizures; EEG abnormality; Behavioral abnormality; Abnormality of head or neck
Penetrance for gene: DHPS were set to Complete
Review for gene: DHPS was set to GREEN
Added comment: Ganapathi et al. (doi.org/10.1016/j.ajhg.2018.12.017 - PMID : NA) report on 5 individuals from 4 unrelated families with biallelic pathogenic variants in DHPS.

The phenotype consisted of DD/ID (5/5), tone abnormalities (hypotonia/hypertonia/spasticity - 5/5), seizures (5/5 - in one case though unclear staring spells) with EEG abnormalities (5/5). Additionally most individuals displayed behavioral issues, or some common facial features.

Several other disorders had been ruled prior to the diagnosis, in all cases by exome sequencing.

All individuals harbored a specific missense variant (c.518A>G or p.Asn173Ser) in trans with various other variants incl. a splice site mutation (c.1014+1G>A), an in-frame deletion of 2 amino acids (c.912_917delTTACAT or p.Tyr305_Ile306del) or a variant abolishing the translation initiation codon (c.1A>G or p.Met1?) [All variants using NM_001930.3 as a reference].

Deoxyhypusine synthase (encoded by DHPS) is an enzyme participating in the first step of hypusine synthesis, an amino-acid which is specific to eukaryotic initiation factor 5A (eIF5A) and its homolog (eIF5A2).

eIF5A, its hypusinated form and DHPS have all been previously implicated in cellular proliferation/differentiation. eIF5A has also been proposed to be a mRNA translation elongation factor. A role of eIF5A in neuronal growth and survival has been proposed previously (all ref. in present article).

Neither eIF5A, nor DHPS or DOHH (an enzyme required for the second step of hypusination) have been associated to any disorders previously. Mutations in genes encoding other eukaryotic elongator factors (eg. EEF1A2, EEF2) have been associated with neurodevelopmental disorders.

Concerning the DHPS variants reported:

cDNA studies suggested that the c.1014+1G>A variant is translated but results in aberrant splicing and truncation of the protein before its active site.

The in-frame deletion as well as the missense variant were shown to have absent or partial (20%) enzyme activity in vitro respectively compared to wild-type (following expression in E.coli BL21(DE3) cells).

In line with this, reduced hypusination of eIF5A was observed for these 2 variants when compared to wild-type DHPS, upon co-transfection of constructs overexpressing DHPS (wt or mut.) and eIF5A in HEK293T cells.

Absence of homozygous DHPS LoF variants in population databases might suggest that complete deficiency is incompatible with normal embryonic development. Mice heterozygous for Dhps deletion do not demonstrate severe phenotypes, though homozygosity is embryonically lethal (PMIDs: 21389784, 21850436).
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DHPS is not associated with any phenotype in G2P, nor in OMIM.
This gene is not - at least commonly - included in gene panels for ID offered by diagnostic laboratories.
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As a result, DHPS can be considered for inclusion in this panel as green (or amber).
Sources: Literature
Intellectual disability - microarray and sequencing v2.588 CWF19L1 Konstantinos Varvagiannis gene: CWF19L1 was added
gene: CWF19L1 was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen
Mode of inheritance for gene: CWF19L1 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: CWF19L1 were set to 25361784
Phenotypes for gene: CWF19L1 were set to Spinocerebellar ataxia, autosomal recessive 17 (MIM 616127)
Penetrance for gene: CWF19L1 were set to Complete
Review for gene: CWF19L1 was set to GREEN
gene: CWF19L1 was marked as current diagnostic
Added comment: Biallelic pathogenic variants in CWF19L1 cause Spinocerebellar ataxia, autosomal recessive 17 (MIM 616127).
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Burns et al. (2014 - PMID: 25361784) report on 2 sibs born to consanguineous parents, homozygous for a splice site variant (NM_018294.5:c.964+1G>A). Congenital ataxia with hypoplasia of vermis and cerebellar hemispheres and ID were features reported in both in this study.

Clinical details on this family were published previously (Yapici and Eraksoy - PMID: 15981765) where ID appeared to be a feature for one of the sibs (FSIQ of 68) but not the other (IQ of 90) [the sibs seem to correspond to patients 5 and 6 from the third family of the original report].

Expression in patient lymphoblastoid cell lines was reduced using expression micro-arrays and quantitative reverse-transcription PCR.

The variant was shown to lead to skipping of exon 9. Introduction of an out-of-frame stop codon (thus NMD) may explain mRNA levels.

Western blot using epitope spanning exons 5-7 demonstrated absence (in patient but not in control LCLs) of the 2 protein bands expected based on this epitope. [A shorter isoform due to downstream alternative start site would not be detectable].

Using commercial normal tissue brain lysates revealed only the canonical protein band suggesting that this is the isoform present in brain.

Morpholino knockdown of cwf91l1 in zebrafish resulted in altered cerebellar staining (/structure) and abnormal motor behavior.
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Nguyen et al. (2016 - PMID: 26197978) report on a further individual with ID, ataxia and abnormal cerebellum (extensive discussions whether this represents hypoplasia/atrophy) compound heterozygous for a missense (NM_018294.4:c.37G>C / p.Asp13His) and a nonsense variant (c.946A>T / p.Lys316*).

mRNA expression in patient fibroblasts was similar to control while cDNA sequence analysis was suggestive of lower levels for the r.946A>U transcript (compared to r.37G>C) possibly due to NMD.
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Evers et al. (2016 - PMID: 27016154) report on a further individual, born to consanguineous parents, homozygous a frameshift variant (NM_018294.5:c.467delC or p.Pro156Hisfs). This individual presented with ID, ataxia and similar cerebellar anomalies.

cDNA of 3 different regions of CWF19L1 suggested tht mRNA was not entirely degraded by NMD. Western blot demonstrated absence of a band corresponding to the longest isoform in patient LCL cells. [All isoforms discussed in Fig3].

A subsequent pregnancy of the same couple was terminated due to presence of additional fetal anomalies possibly not explained by homozygosity (only) for this variant which was confirmed (cerebellar measurements were in the the low-normal range and morphology reportedly normal).
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In ClinVar additional variants have been submitted as pathogenic/likely pathogenic (although a phenotype is not specified for all).
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CWF19L1 is not associated with any phenotype in G2P.
This gene is included in gene panels for ID offered by diagnostic laboratories (incl. Radboudumc).
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As a result CWF19L1 can be considered for inclusion in this panel probably as green (rather than amber).
Sources: Literature, Radboud University Medical Center, Nijmegen
Intellectual disability - microarray and sequencing v2.516 SLC1A4 Louise Daugherty gene: SLC1A4 was added
gene: SLC1A4 was added to Intellectual disability. Sources: Expert Review
Mode of inheritance for gene: SLC1A4 was set to BIALLELIC, autosomal or pseudoautosomal
Publications for gene: SLC1A4 were set to 29989513; 27193218; 26138499; 26041762; 25930971
Phenotypes for gene: SLC1A4 were set to Spastic tetraplegia, thin corpus callosum, and progressive microcephaly, 616657; Intellectual disability
Review for gene: SLC1A4 was set to GREEN
Added comment: From review left on the Genetic Epilepsy Syndromes panel by Zornitza Stark (Australian Genomics) 4 Sep 2018, 3:29 a.m. Multiple affected individuals reported in the literature, seizures/EE are part of the phenotype. While initial reports identified a recurrent missense variant in individuals of Ashkenazi Jewish ancestry, there have been more recent reports of individuals from other ethnic backgrounds with different variants. Gene is also relevant to the ID panel.
Sources: Expert Review
Intellectual disability - microarray and sequencing v2.510 TRIM8 Konstantinos Varvagiannis gene: TRIM8 was added
gene: TRIM8 was added to Intellectual disability. Sources: Expert Review,Literature
Mode of inheritance for gene: TRIM8 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown
Publications for gene: TRIM8 were set to 30244534; 27346735; 23934111
Phenotypes for gene: TRIM8 were set to Global developmental delay; Intellectual disability; Seizures
Penetrance for gene: TRIM8 were set to Complete
Review for gene: TRIM8 was set to GREEN
Added comment: PMID: 30244534 is a collaborative study reporting on the phenotype of TRIM8-related epileptic encephalopathy and summarizing the findings in previously published patients. Developmental delay, intellectual disability, seizures are common findings in the 6 unrelated individuals reported. Proteinuria was observed in 3 subjects.

Seizures were universal feature with highly variable age of onset (2 months to 3 years and 5 months).

Several individuals were investigated for developmental delay prior to seizure onset (eg. pat.1 had an MRI at 10 months, sat at 16 months, walked at 22 months and developed seizures at 2 years, pat.3 sat at 12 months, walked at 22 and developed seizures at 3 years and 5 months, pat. 4 and 5 had significant/severe delay prior to the age of 21 months when they started having seizures).

All variants reported to date are truncating, affecting the last (sixth exon) and as a result may escape nonsense-mediated decay. Since TRIM8 homodimerizes via its (upstream) coiled-coil domain and its C-terminal domain is required for nuclear localization, a dominant-negative effect is postulated by the authors. Haploinsufficiency appears less likely.

A previously reported patient (from PMID: 27346735) as well as an individual reported by the Epi4K consortium (PMID: 23934111 - among the co-authors of the present study) are included in the table of this article.

As a result this gene can be considered for inclusion in the intellectual disability and epilepsy panels as green.
Sources: Expert Review, Literature
Intellectual disability - microarray and sequencing STAR BRIDGE consortium edited their review of STAR
Intellectual disability - microarray and sequencing STAR Louise Daugherty commented on STAR
Intellectual disability - microarray and sequencing STAR Louise Daugherty classified STAR as amber
Intellectual disability - microarray and sequencing STAR BRIDGE consortium reviewed STAR