| Date | Panel | Item | Activity | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Genetic Epilepsy v0.2296 | TRIO | Elena Savva Classified gene: TRIO as Green List (high evidence) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.2296 | TRIO | Elena Savva Gene: trio has been classified as Green List (High Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.2295 | TRIO | Elena Savva Marked gene: TRIO as ready | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.2295 | TRIO | Elena Savva Gene: trio has been classified as Red List (Low Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.2295 | TRIO |
Elena Savva gene: TRIO was added gene: TRIO was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: TRIO was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal Phenotypes for gene: TRIO were set to Intellectual developmental disorder, autosomal dominant 44, with microcephaly MIM#617061; Intellectual developmental disorder, autosomal dominant 63, with macrocephaly MIM#618825 Review for gene: TRIO was set to GREEN Added comment: Seizures described in OMIM as a rare feature of both AR and AD disease GeneReviews: seizures described in 7/19 probands with GOF variants, and 7/29 in individuals with LOF variants. Only one in ten individuals with a TRIO missense variant in the GEFD1 domain had seizures Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.2071 | FAM50A |
Zornitza Stark changed review comment from: Lee et al (2020 - PMID: 32703943) provide evidence that Armfield X-Linked intellectual disability syndrome is caused by monoallelic FAM50A pathogenic variants. The current review is based only on this reference. The authors provide clinical details on 6 affected individuals from 5 families. Features included postnatal growth delay, DD and ID (6/6 - also evident for those without formal IQ assesment), seizures (3/6 from 2 families), prominent forehead with presence of other facial features and variable head circumference (5th to >97th %le), ocular anomalies (5/6 - strabismus/nystagmus/Axenfeld-Rieger), cardiac (3/6 - ASD/Fallot) and genitourinary anomalies (3/6). In the first of these families (Armfield et al 1999 - PMID: 10398235), linkage analysis followed by additional studies (Sanger, NGS of 718 genes on chrX, X-exome NGS - several refs provided) allowed the identification of a FAM50A variant. Variants in other families were identified by singleton (1 fam) or trio-ES (3 fam). In affected individuals from 3 families, the variant had occurred de novo. Carrier females in the other families were unaffected (based on pedigrees and/or the original publication). XCI was rather biased in most obligate carrier females from the 1st family (although this ranged from 95:5 to 60:40). Missense variants were reported in all affected subjects incl. Trp206Gly, Asp255Gly, Asp255Asn (dn), Glu254Gly (dn), Arg273Trp (dn) (NM_004699.3). Previous studies have demonstrated that FAM50A has ubiquitous expression in human fetal and adult tissues (incl. brain in fetal ones). Immunostaining suggests a nuclear localization for the protein (NIH/3T3 cells). Comparison of protein levels in LCLs from affected males and controls did not demonstrate significant differences. Protein localization for 3 variants (transfection of COS-7 cells) was shown to be similar to wt. Complementation studies in zebrafish provided evidence that the identified variants confer partial loss of function (rescue of the morpholino phenotype with co-injection of wt but not mt mRNA). The zebrafish ko model seemed to recapitulate the abnormal development of cephalic structures and was indicative of diminished/defective neurogenesis. Transcriptional dysregulation was demonstrated in zebrafish (altered levels and mis-splicing). Upregulation of spliceosome effectors was demonstrated in ko zebrafish. Similarly, mRNA expression and splicing defects were demonstrated in LCLs from affected individuals. FAM50A pulldown followed by mass spectrometry in transfected HEK293T cells demonstrated enrichment of binding proteins involved in RNA processing and co-immunoprecipitation assays (transfected U-87 cells) suggested that FAM50A interacts with spliceosome U5 and C-complex proteins. Overall aberrant spliceosome C-complex function is suggested as the underlying pathogenetic mechanism. Several other neurodevelopmental syndromes are caused by variants in genes encoding C-complex affiliated proteins (incl. EFTUD2, EIF4A3, THOC2, etc.). Sources: Literature; to: Lee et al (2020 - PMID: 32703943) 6 affected individuals from 5 families. Seizures in 3/6 from 2 families. |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1851 | UNC79 |
Krithika Murali gene: UNC79 was added gene: UNC79 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: UNC79 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: UNC79 were set to PMID:37183800 Phenotypes for gene: UNC79 were set to Complex neurodevelopmental disorder - MONDO:0100038 Review for gene: UNC79 was set to AMBER Added comment: PMID:37183800 Bayat et al 2023 report 6 unrelated patients with heterozygous NMD-predicted LoF variants in UNC79 - x1 canonical splice site variant, x5 nonsense/frameshift. 5 were confirmed de novo, 1 not identified in mother - father unavailable for testing. All variants absent in gnomAD and v2 pLI score for UNC79 is 1. Patients with UNC79 variants were identified through GeneMatcher or an international network of Epilepsy and Genetics departments. x1 patient underwent duo exome sequencing, remaining had trio exome sequencing - no other causative variants identified. Phenotypic features included: - 4/6 autistic features - 5/6 patients mild-moderate ID - 4/6 behavioural issues (aggression, stereotypies) - 4/6 epilepsy (focal to bilateral tonic-clonic seizures) - 5/6 hypotonia unc79 knockdown drosophila flies exhibited significantly higher rate of seizure-like behaviour than controls. unc79 haploinsufficiency shown to lead to significant reduction in protein levels of both unc79 and unc80 in mouse brains anddeficiency in hippocampal-dependent learning and memory in mice. Authors have reviewed their own evidence in relation to the gene-disease criteria detailed by Strande et al 2017 and note that their clinical and experimental data provides moderate-level evidence supporting the association between UNC79 and a neurodevelopment disorder including ASD. Evidence emerging is promising, however Amber association favoured due to clinical phenotypic range reported between affected individuals and their lack of specificity. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1829 | BSN |
Krithika Murali changed review comment from: Ye et al 2022, Neurogenetics identified 4 unrelated individuals with epilepsy and compound heterozygous BSN variants via trio WES (combination of null and missense). Homozygous knockout mouse models showed abnormal CNS transmission and seizure activity. None of the identified variants were present in population databases as homozygotes. One individual had ID and microcephaly but all other individuals with biallelic variants had normal development. In addition, heterozygous variants were identified in unrelated affected individuals - 2 apparently co-segregating missense variants and 2 de novo null variants. These variants were either absent in population databases or rare. The authors note that affected individuals with heterozygous variants had milder disease - either requiring no therapy or monotherapy only. Heterozygous knockout mice had no phenotype and there were not enough affected individuals in the families to truly determine co-segregation. In addition, carrier parents of individuals with biallelic variants did not appear to be affected. Association between biallelic variants and epilepsy stronger than for monoallelic. Sources: Literature; to: Ye et al 2022, Neurogenetics https://jmg.bmj.com/content/early/2022/12/12/jmg-2022-108865 Identified 4 unrelated individuals with epilepsy and compound heterozygous BSN variants via trio WES (combination of null and missense). Homozygous knockout mouse models showed abnormal CNS transmission and seizure activity. None of the identified variants were present in population databases as homozygotes. One individual had ID and microcephaly but all other individuals with biallelic variants had normal development. In addition, heterozygous variants were identified in unrelated affected individuals - 2 apparently co-segregating missense variants and 2 de novo null variants. These variants were either absent in population databases or rare. The authors note that affected individuals with heterozygous variants had milder disease - either requiring no therapy or monotherapy only. Heterozygous knockout mice had no phenotype and there were not enough affected individuals in the families to truly determine co-segregation. In addition, carrier parents of individuals with biallelic variants did not appear to be affected. Association between biallelic variants and epilepsy stronger than for monoallelic. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1824 | BSN |
Krithika Murali gene: BSN was added gene: BSN was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: BSN was set to BIALLELIC, autosomal or pseudoautosomal Phenotypes for gene: BSN were set to Epilepsy MONDO:0005027 Review for gene: BSN was set to GREEN Added comment: Ye et al 2022, Neurogenetics identified 4 unrelated individuals with epilepsy and compound heterozygous BSN variants via trio WES (combination of null and missense). Homozygous knockout mouse models showed abnormal CNS transmission and seizure activity. None of the identified variants were present in population databases as homozygotes. One individual had ID and microcephaly but all other individuals with biallelic variants had normal development. In addition, heterozygous variants were identified in unrelated affected individuals - 2 apparently co-segregating missense variants and 2 de novo null variants. These variants were either absent in population databases or rare. The authors note that affected individuals with heterozygous variants had milder disease - either requiring no therapy or monotherapy only. Heterozygous knockout mice had no phenotype and there were not enough affected individuals in the families to truly determine co-segregation. In addition, carrier parents of individuals with biallelic variants did not appear to be affected. Association between biallelic variants and epilepsy stronger than for monoallelic. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1680 | GABRG1 |
Anna Ritchie gene: GABRG1 was added gene: GABRG1 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: GABRG1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: GABRG1 were set to PMID: 36121006 Phenotypes for gene: GABRG1 were set to developmental and epileptic encephalopathy MONDO:0100062 Review for gene: GABRG1 was set to RED Added comment: 2-year-old patient with epileptic encephalopathy, hypotonia, and global developmental delays. Clinical trio exome sequencing showed a novel, de novo missense variant in the GABRG1 gene. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1675 | NAPB |
Paul De Fazio gene: NAPB was added gene: NAPB was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: NAPB was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: NAPB were set to 26235277; 28097321; 33189936 Phenotypes for gene: NAPB were set to Developmental and epileptic encephalopathy 107 MIM#620033 Review for gene: NAPB was set to GREEN gene: NAPB was marked as current diagnostic Added comment: PMID 26235277: homozygous nonsense variant identified in a 6 year old girl by trio WES with early-onset epileptic encephalopathy characterised by multifocal seizures and profound GDD PMID 28097321: exome sequencing in 152 consanguineous families with at least one member affected with ID. Homozygous nonsense variant identified in a patient with profound ID, seizures, feeding difficulties in infancy, muscularhypotonia, microcephaly, and impaired vision PMID 33189936: homozygous canonical splice variant identified by trio exome sequencing in two siblings with seizures, intellectual disability and global developmental delay, microcephaly (<-3SD), and muscular hypotonia. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1657 | UBAP2L |
Konstantinos Varvagiannis gene: UBAP2L was added gene: UBAP2L was added to Genetic Epilepsy. 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 AMBER Added comment: Seizures have been reported in several individuals although a formal diagnosis of epilepsy was retained in ~30% in a small cohort discussed below. Consider inclusion with amber rating. ----- 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. -------- 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 |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1451 | CHKA |
Konstantinos Varvagiannis gene: CHKA was added gene: CHKA was added to Genetic Epilepsy. 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 |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1317 | DAB1 |
Daniel Flanagan gene: DAB1 was added gene: DAB1 was added to Genetic Epilepsy. Sources: Expert list Mode of inheritance for gene: DAB1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: DAB1 were set to PMID: 33928188 Phenotypes for gene: DAB1 were set to epilepsy; developmental delay; cerebellar ataxia; structural brain abnormalities; oral motor difficulty Review for gene: DAB1 was set to RED Added comment: WES trio analysis identified compound heterozygous DAB1 canonical splice variants in a child with epilepsy (onset 6 years), developmental delay, cerebellar ataxia, oral motor difficulty, and structural brain abnormalities. RT-PCR confirms that the first variant (c.307-2A>T) causes a in-frame deletion of 3 amino acids. The second variant (c.67+1G>T) is reported to causes an in-frame deletion of exon 4 (first coding exon) and loss of the ATG initiation site. New LoF mechanism suggested. Repeat expansion in this gene is known to be associated with disease. Sources: Expert list |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1260 | UNC13B |
Krithika Murali changed review comment from: No OMIM human disease association. Gene encodes a presynaptic protein Munc13-2 highly expressed in the brain (predominantly cerebral cortex). Variant interpretation data in human epilepsy cohort somewhat conflicting and restricted to a single study. Wang et al, Brain, 2021 - trio-based whole-exome sequencing identified UNC13B in 12 individuals affected by partial epilepsy and/or febrile seizures from 8 unrelated families. Identified: x1 de novo nonsense variant, absent in gnomad, damaging in silicos x1 de novo splice site, absent in gnomad, damaging in silicos x1 de novo splice site in unaffected mother (low frequency in gnomad) x2 compound het in one individual - more severe phenotype postulated (x1 variant present in contro cohortl, the other variant present in low frequency in gnomad) x1 missense variant - in Han Chinese major depressive disorders study, not in gnomad x1 missense variant - highly conserved residue, not in gnomad x2 other missense variant - highly conserved residue, low frequency in gnomad Latter 4 missense variants cosegregated with affected individuals in the families In Drosophila, seizure rate and duration were increased by Unc13b knockdown compared to wild-type flies, but these effects were less pronounced than in sodium voltage-gated channel alpha subunit 1 (Scn1a) knockdown Drosophila De novo UNC13B variants previously reported in bipolar disorder and autism spectrum disorder Sources: Expert list, Literature; to: No OMIM human disease association. Gene encodes a presynaptic protein Munc13-2 highly expressed in the brain (predominantly cerebral cortex). Variant interpretation data in human epilepsy cohort somewhat conflicting and restricted to a single study. Wang et al, Brain, 2021 - trio-based whole-exome sequencing identified UNC13B in 12 individuals affected by partial epilepsy and/or febrile seizures from 8 unrelated families. Identified: x1 de novo nonsense variant, absent in gnomad, damaging in silicos x1 de novo splice site, absent in gnomad, damaging in silicos x1 splice site variant present in unaffected mother (low frequency in gnomad) x2 compound het in one individual - more severe phenotype postulated (x1 variant present in contro cohortl, the other variant present in low frequency in gnomad) x1 missense variant - in Han Chinese major depressive disorders study, not in gnomad x1 missense variant - highly conserved residue, not in gnomad x2 other missense variant - highly conserved residue, low frequency in gnomad Latter 4 missense variants cosegregated with affected individuals in the families In Drosophila, seizure rate and duration were increased by Unc13b knockdown compared to wild-type flies, but these effects were less pronounced than in sodium voltage-gated channel alpha subunit 1 (Scn1a) knockdown Drosophila De novo UNC13B variants previously reported in bipolar disorder and autism spectrum disorder Sources: Expert list, Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1260 | UNC13B |
Krithika Murali gene: UNC13B was added gene: UNC13B was added to Genetic Epilepsy. Sources: Expert list,Literature Mode of inheritance for gene: UNC13B was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: UNC13B were set to 33876820 Phenotypes for gene: UNC13B were set to Epilepsy Penetrance for gene: UNC13B were set to unknown Review for gene: UNC13B was set to RED Added comment: No OMIM human disease association. Gene encodes a presynaptic protein Munc13-2 highly expressed in the brain (predominantly cerebral cortex). Variant interpretation data in human epilepsy cohort somewhat conflicting and restricted to a single study. Wang et al, Brain, 2021 - trio-based whole-exome sequencing identified UNC13B in 12 individuals affected by partial epilepsy and/or febrile seizures from 8 unrelated families. Identified: x1 de novo nonsense variant, absent in gnomad, damaging in silicos x1 de novo splice site, absent in gnomad, damaging in silicos x1 de novo splice site in unaffected mother (low frequency in gnomad) x2 compound het in one individual - more severe phenotype postulated (x1 variant present in contro cohortl, the other variant present in low frequency in gnomad) x1 missense variant - in Han Chinese major depressive disorders study, not in gnomad x1 missense variant - highly conserved residue, not in gnomad x2 other missense variant - highly conserved residue, low frequency in gnomad Latter 4 missense variants cosegregated with affected individuals in the families In Drosophila, seizure rate and duration were increased by Unc13b knockdown compared to wild-type flies, but these effects were less pronounced than in sodium voltage-gated channel alpha subunit 1 (Scn1a) knockdown Drosophila De novo UNC13B variants previously reported in bipolar disorder and autism spectrum disorder Sources: Expert list, Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1169 | ARF3 |
Konstantinos Varvagiannis gene: ARF3 was added gene: ARF3 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: ARF3 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: ARF3 were set to 34346499 Phenotypes for gene: ARF3 were set to Global developmental delay; Intellectual disability; Seizures; Morphological abnormality of the central nervous system Penetrance for gene: ARF3 were set to unknown Review for gene: ARF3 was set to AMBER Added comment: Sakamoto et al (2021 - PMID: 34346499) provide some evidence that monoallelic ARF3 pathogenic variants may be associated with a NDD with brain abnormality. Using trio exome sequencing, the authors identified 2 individuals with NDD harboring de novo ARF3 variants, namely: NM_001659.2:c.200A>T / p.Asp67Val and c.296G>T / p.Arg99Leu. Individual 1 (with Asp67Val / age : 4y10m), appeared to be more severelely affected with prenatal onset progressive microcephaly, severe global DD, epilepsy. Upon MRI there was cerebellar and brainstem atrophy. Individual 2 (Arg99Leu / 14y) had severe DD and ID (IQ of 23), epilepsy and upon MRI cerebellar hypoplasia. This subject did not exhibit microcephaly. Common facial features incl. broad nose, full cheeks, small philtrum, strabismus, thin upper lips and abnormal jaw. There was no evidence of systemic involvement in both. ARF3 encodes ADP-ribosylation factor 3. Adenosine diphosphate ribosylation factors (ARFs) are key proteins for regulation of cargo sorting at the Golgi network, with ARF3 mainly working at the trans-Golgi network. ARFs belong to the small GTP-binding protein (G protein) superfamily. ARF3 switches between an active GTP-bound form and an inactive GDP-bound form, regulated by guanine nucleotide exchange factors (GEFs) and GTPase activating proteins (GAPs) respectively. Members of the ARF superfamily regulate various aspects of membrane traffic, among others in neurons. There are 5 homologs of ARF families, divided in 3 classes. ARF3 and ARF1 belong to class I. Monoallelic ARF1 mutations are associated with Periventricular nodular heterotopia 8 (MIM 618185). In vivo, in vitro and in silico studies for the 2 variants suggest that both impair the Golgi transport system although each variant most likely exerts a different effect (gain-of-function for Arg99Leu vs loss-of-function/dominant-negative for Asp67Val). This was also reflected in somewhat different phenotype of the subjects with the respective variants. Common features included severe DD, epilepsy and brain abnormalities although Asp67Val was associated with diffuse brain atrophy as well as congenital microcephaly and Arg99Leu with cerebellar hypoplasia. Evidence to support the effect of each variant include: Arg99Leu: Had identical Golgi localization to that of wt Had increased binding activity with GGA1, a protein recruited by the GTP-bound active form of ARF3 to the TGN membrane (supporting GoF) In silico structural analysis suggested it may fail to stabilize the conformation of Asp26, resulting in impaired GTP hydrolysis (GoF). In transgenic fruit flies, evaluation of the ARF3 variant toxicity using the rough eye phenotype this variant was associated with increased severity of the r-e phenotype similar to a previously studied GoF variant (Gln71Leu) Asp67Val: Did not show a Golgi-like pattern of localization (similar to Thr31Asn a previously studied dominant-negative variant) Displayed decreased protein stability In silico structural analysis suggested that Asp67Val may lead to compromised binding of GTP or GDP (suggestive of LoF) In transgenic Drosophila eye-specific expression of Asp67Val (similar to Thr31Asn, a known dominant-negative variant) was lethal possibly due to high toxicity in very small amounts in tissues outside the eye. There is no associated phenotype in OMIM, G2P or SysID. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1148 | SYNCRIP |
Konstantinos Varvagiannis gene: SYNCRIP was added gene: SYNCRIP was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: SYNCRIP was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: SYNCRIP were set to 34157790; 30504930; 27479843; 23020937 Phenotypes for gene: SYNCRIP were set to Global developmental delay; Intellectual disability; Autism; Myoclonic atonic seizures; Abnormality of nervous system morphology Review for gene: SYNCRIP was set to AMBER Added comment: Semino et al (2021 - PMID: 34157790) provide clinical details on 3 unrelated individuals with de novo SYNCRIP variants and provide a review of 5 additional subjects previously identified within large cohorts in the literature and databases. Features included DD, ID (7/7 for whom this information was available), ASD or autistic features (4/7). MRI abnormalities were observed in 3 (widening of CSF spaces, periventricular nodular heterotopia, prominent lat. ventricles). Epilepsy (myoclonic-astatic epilepsy / Doose syndrome) was reported for 2(/8) individuals. The 3 patients here reported were identified following trio/singleton exome with Sanger confirmation of the variants and their de novo occurrence. Variants are in almost all cases de novo (7/7 for whom this was known) and in 5/8 cases were pLoF, in 2/8 missense SNVs while a case from DECIPHER had a 77.92 kb whole gene deletion not involving other genes with unknown inheritance. Overall the variants reported to date include [NM_006372.5]: 1 - c.858_859del p.(Gly287Leufs*5) 2 - c.854dupA p.(Asn285Lysfs*8) 3 - c.734T>C p.(Leu245Pro) 4 - chr6:85605276-85683190 deletion (GRCh38) 5 - c.629T>C p.(Phe210Ser) 6 - c.1573_1574delinsTT p.(Gln525Leu) 7 - c.1247_1250del p.(Arg416Lysfs*145) 8 - c.1518_1519insC p.(Ala507Argfs*14) [P1-3: this report, P4: DECIPHER 254774, P5-6: Guo et al 2019 - PMID: 30504930, P7: Lelieveld et al 2016 - PMID: 27479843, P8: Rauch et al 2012 - PMID: 23020937 / all other Refs not here reviewed, clinical details summarized by Semino et al in table 1] SYNCRIP (also known as HNRNPQ) encodes synaptotagmin‐binding cytoplasmic RNA‐interacting protein. As the authors note, this RNA-binding protein is involved in multiple pathways associated with neuronal/muscular developmental disorders. Several references are provided for its involvement in regulation of RNA metabolism, among others sequence recognition, pre-mRNA splicing, translation, transport and degradation. Mutations in other RNA-interacting proteins and hnRNP members (e.g. HNRNPU, HNRNPD) are associated with NDD. The missense variant (p.Leu245Pro) is within RRM2 one of the 3 RNA recognition motif (RRM) domains of the protein. These 3 domains, corresponding to the central part of the protein (aa 150-400), are relatively intolerant to variation (based on in silico predictions and/or variation in gnomAD). Leu245 localizes within an RNA binding pocket and in silico modeling suggests alteration of the tertiary structure and RNA-binding capacity of RRM2. There are no additional studies performed. Overall haploinsufficiency appears to be the underlying disease mechanism based on the truncating variants and the gene deletion. [pLI in gnomAD : 1, %HI : 2.48%] Animal models are not discussed. There is no associated phenotype in OMIM. This gene is included in the DD panel of G2P (monoallelic LoF variants / SYNCRIP-related developmental disorder). SysID also lists SYNCRIP within the current primary ID genes. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.776 | LMBRD2 |
Konstantinos Varvagiannis gene: LMBRD2 was added gene: LMBRD2 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: LMBRD2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: LMBRD2 were set to 32820033; https://doi.org/10.1101/797787 Phenotypes for gene: LMBRD2 were set to Global developmental delay; Intellectual disability; Microcephaly; Seizures; Abnormality of nervous system morphology; Abnormality of the eye Penetrance for gene: LMBRD2 were set to unknown Mode of pathogenicity for gene: LMBRD2 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: LMBRD2 was set to AMBER Added comment: You may consider inclusion with green (13 individuals with dn missense SNVs overall, overlapping features for 10 with available phenotype / a recurring variant has been identified in 2 different studies) or amber rating (role of the gene not known, no variant studies, animal model probably not available). ► Malhotra et al (2020 - PMID: 32820033) report on 10 unrelated individuals with de novo missense LMBRD2 variants. Features included DD (9/10), ID (6/8 of relevant age), microcephaly (7/10), seizures (5/10 - >=3 different variants), structural brain abnormalities (e.g. thin CC in 6/9), highly variable ocular abnormalities (5/10) and dysmorphic features in some (7/10 - nonspecific). All had variable prior non-diagnostic genetic tests (CMA, gene panel, mendeliome, karyotype). WES/WGS revealed LMBRD2 missense variants, in all cases de novo. A single individual had additional variants with weaker evidence of pathogenicity. 5 unique missense SNVs and 2 recurrent ones (NM_001007527:c.367T>C - p.Trp123Arg / c.1448G>A - p.Arg483His) were identified. These occurred in different exons. Variants were not present in gnomAD and all had several in silico predictions in favor of a deleterious effect. There was phenotypic variability among individuals with the same variant (e.g. seizures in 1/3 and microchephaly in 2/3 of those harboring R483H). The gene has a pLI of 0 (although o/e ranges from 0.23 to 0.55), %HI of 15.13 and z-score of 2.27. The authors presume that haploinsufficiency may not apply, and consider a gain-of-function/dominant-negative effect more likely. As the authors comment LMBRD2 (LMBR1 domain containing 2) encodes a membrane bound protein with poorly described function. It is widely expressed across tissues with notable expression in human brain (also in Drosophila, or Xenopus laevis). It displays high interspecies conservation. It has been suggested (Paek et al - PMID: 28388415) that LMBRD2 is a potential regulator of β2 adrenoreceptor signalling through involvement in GPCR signalling. ► Kaplanis et al (2020 - https://doi.org/10.1101/797787) in a dataset of 31058 parent-offspring trios (WES) previously identified 3 individuals with developmental disorder, harboring c.1448G>A - p.Arg483His. These individuals (1 from the DDD study, and 2 GeneDx patients) appear in Decipher. [ https://decipher.sanger.ac.uk/ddd/research-variant/40e17c78cc9655a6721006fc1e0c98db/overview ]. The preprint by Kaplanis et al is cited by Malhotra et al, with Arg483His reported in 6 patients overall in both studies. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.772 | FAM50A |
Konstantinos Varvagiannis gene: FAM50A was added gene: FAM50A was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: FAM50A was set to X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) Publications for gene: FAM50A were set to 32703943 Phenotypes for gene: FAM50A were set to Mental retardation syndrome, X-linked, Armfield type (MIM #300261) Penetrance for gene: FAM50A were set to unknown Review for gene: FAM50A was set to AMBER Added comment: Lee et al (2020 - PMID: 32703943) provide evidence that Armfield X-Linked intellectual disability syndrome is caused by monoallelic FAM50A pathogenic variants. The current review is based only on this reference. The authors provide clinical details on 6 affected individuals from 5 families. Features included postnatal growth delay, DD and ID (6/6 - also evident for those without formal IQ assesment), seizures (3/6 from 2 families), prominent forehead with presence of other facial features and variable head circumference (5th to >97th %le), ocular anomalies (5/6 - strabismus/nystagmus/Axenfeld-Rieger), cardiac (3/6 - ASD/Fallot) and genitourinary anomalies (3/6). In the first of these families (Armfield et al 1999 - PMID: 10398235), linkage analysis followed by additional studies (Sanger, NGS of 718 genes on chrX, X-exome NGS - several refs provided) allowed the identification of a FAM50A variant. Variants in other families were identified by singleton (1 fam) or trio-ES (3 fam). In affected individuals from 3 families, the variant had occurred de novo. Carrier females in the other families were unaffected (based on pedigrees and/or the original publication). XCI was rather biased in most obligate carrier females from the 1st family (although this ranged from 95:5 to 60:40). Missense variants were reported in all affected subjects incl. Trp206Gly, Asp255Gly, Asp255Asn (dn), Glu254Gly (dn), Arg273Trp (dn) (NM_004699.3). Previous studies have demonstrated that FAM50A has ubiquitous expression in human fetal and adult tissues (incl. brain in fetal ones). Immunostaining suggests a nuclear localization for the protein (NIH/3T3 cells). Comparison of protein levels in LCLs from affected males and controls did not demonstrate significant differences. Protein localization for 3 variants (transfection of COS-7 cells) was shown to be similar to wt. Complementation studies in zebrafish provided evidence that the identified variants confer partial loss of function (rescue of the morpholino phenotype with co-injection of wt but not mt mRNA). The zebrafish ko model seemed to recapitulate the abnormal development of cephalic structures and was indicative of diminished/defective neurogenesis. Transcriptional dysregulation was demonstrated in zebrafish (altered levels and mis-splicing). Upregulation of spliceosome effectors was demonstrated in ko zebrafish. Similarly, mRNA expression and splicing defects were demonstrated in LCLs from affected individuals. FAM50A pulldown followed by mass spectrometry in transfected HEK293T cells demonstrated enrichment of binding proteins involved in RNA processing and co-immunoprecipitation assays (transfected U-87 cells) suggested that FAM50A interacts with spliceosome U5 and C-complex proteins. Overall aberrant spliceosome C-complex function is suggested as the underlying pathogenetic mechanism. Several other neurodevelopmental syndromes are caused by variants in genes encoding C-complex affiliated proteins (incl. EFTUD2, EIF4A3, THOC2, etc.). Please consider inclusion in the ID panel with green rating and epilepsy panel with amber (seizures in individuals from 2 families). Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.745 | TBC1D2B |
Konstantinos Varvagiannis gene: TBC1D2B was added gene: TBC1D2B was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: TBC1D2B was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: TBC1D2B were set to 32623794 Phenotypes for gene: TBC1D2B were set to Global developmental delay; Intellectual disability; Seizures; Gingival overgrowth; Behavioral abnormality; Abnormality of the mandible; Abnormality of brain morphology; Abnormality of the eye; Hearing abnormality Penetrance for gene: TBC1D2B were set to Complete Review for gene: TBC1D2B was set to GREEN Added comment: Harms et al (2020 - PMID: 32623794) report on 3 unrelated individuals with biallelic pLoF TBC1D2B variants. Features included cognitive impairment (mild ID in one case, regression at the age of 12y in another, hypotonia and delayed milestones in a third aged 8m), seizures (3/3 - variable age of onset) and/or gingival overgrowth (2/3 - prior to initiation of AEDs). Other findings included behavioral abnormalities, mandibular anomalies, abnormal brain imaging and ophthalmologic or (rarely) audiometric evaluations. All were born to non-consanguineous couples and additional investigations were performed in some. Variants were identified by WES or trio WGS, with Sanger confirmation/compatible segregation analyses. In line with the pLoF variants, mRNA studies in fibroblasts from 2 unrelated affected individuals demonstrated significantly reduced (~80-90%) TBC1C2D mRNA levels compared to controls, restored following cycloheximide treatment. Protein was absent in patient fibroblasts. TBC-domain containing GTPase activating proteins are known as key regulators of RAB GTPase activity. TBC1D2B was shown to colocalize with RAB5-positive endocytic vesicles. CRISPR/Cas9-mediated ko of TBC1D2B in HeLa cells suggested a role in EGF receptor endocytosis and decreased cell viability of TBC1D2B-deficient HeLa cells upon serum deprivation. Genes encoding other TBC domain-containg GTPase-activating proteins, e.g. TBC1D7 and TBC1D20, TBC1D24 are associated with recessive neurodevelopmental disorders (with ID and/or seizures) and the pathophysiological defect in TBC1D2B-related disorder (deficit in vesicle trafficking and/or cell survival) is proposed to be similar to that of TBC1D24. Overall this gene can be considered for inclusion with amber/green rating in the ID panel and green in epilepsy panel. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.700 | NR4A2 |
Konstantinos Varvagiannis gene: NR4A2 was added gene: NR4A2 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: NR4A2 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: NR4A2 were set to https://doi.org/10.1038/s41436-020-0815-4; 31428396 Phenotypes for gene: NR4A2 were set to Generalized hypotonia, Global developmental delay, Intellectual disability, Seizures, Behavioral abnormality, Abnormality of movement, Joint hypermobility Penetrance for gene: NR4A2 were set to unknown Review for gene: NR4A2 was set to GREEN Added comment: Seizures have been reported in at least 6 unrelated individuals with NR4A2 variants (not including cases with contiguous gene deletions spanning also this gene). Please consider inclusion with amber or green rating. --- Singh et al (2020 - https://doi.org/10.1038/s41436-020-0815-4) provide details on the phenotype of 9 unrelated individuals with NR4A2 pathogenic variants (in almost all cases de novo). Features included hypotonia (in 6/9), DD (9/9), varying levels of ID (mild to severe in 8/8 for whom this information was available), seizures (6/9 - variable epilepsy phenotypes), behavioral problems (5/9 - with autism reported for one). Less frequent features incl. hypermobility (in 3), ataxia/movement disorder (in 3). 8 total pLoF and missense variants were identified as de novo events following trio exome sequencing with Sanger validation (7/8 variants). For 1(/8) individual with a stopgain variant, a single parental sample was available. A 9th individual was found to harbor a ~3.7 Mb 2q deletion spanning also other genes (which might also contribute to his phenotype of epilepsy). Only the effect of a variant affecting the splice-acceptor site was studied (c.865-1_865delGCinsAAAAAGGAGT - NM_006186.3) with RT-PCR demonstrating an out-of-frame skipping of exon 4. Another variant (NM_006186.3:c.325dup) found in a subject with DD, ID and epilepsy had also previously been reported in another individual with similar phenotype of epilepsy and ID (Ramos et al - PMID: 31428396 - the variant was de novo with other causes for his phenotype excluded). As discussed by Singh et al, NR4A2 encodes a steroid-thyroid-retinoid receptor which acts as a nuclear receptor transcription factor. The authors summarize previous reports on NR4A2 haploinsufficiency (NR4A2 has a pLI of 1 and HI score of 1.28% - Z-score is 2.24). The authors comment on mouse models suggesting a role of NR4A2 for dopaminergic neurons, and provide plausible explanations for the phenotype of ID/seizures. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.698 | CUL3 |
Konstantinos Varvagiannis gene: CUL3 was added gene: CUL3 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: CUL3 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: CUL3 were set to 32341456 Phenotypes for gene: CUL3 were set to Global developmental delay; Intellectual disability; Seizures; Abnormality of cardiovascular system morphology; Abnormality of the palate; Pseudohypoaldosteronism, type IIE - MIM #614496 Penetrance for gene: CUL3 were set to unknown Review for gene: CUL3 was set to AMBER Added comment: Nakashima et al (2020 - PMID:32341456) provide clinical details on 3 unrelated individuals with de novo CUL3 variants. Features included DD, variable degrees of ID (P1: severe, P3: mild, P2: NA although he displayed motor and severe speech and language delay and had severe learning difficulties). Two out of three had intractable seizures (onset 2 - 6 months). One presented with congenital heart defects (ASD, PV stenosis) and another submucosal palatoschisis/bifid uvula. There were no facial dysmorphisms reported. CUL3 encodes Cullin-3, a core piece of the E3 ubiquitin ligase complex, thus playing a role in the ubiquitin-proteasome system. [ https://ghr.nlm.nih.gov/gene/CUL3 ]. Germline variants in some other Cullin family genes (eg. CUL4B, CUL7) cause disorders with ID as a feature. The 3 individuals reported by Nakashima had variable previous investigations (karyotype, CMA, metabolic testing) which were non-diagnostic. Singleton or trio exome sequencing identified 2 frameshift and 1 missense variant (NM_003590.4:c.854T>C / p.Val285Ala), further confirmed with Sanger sequencing. De novo occurrence was confirmed by analysis of microsatellite markers in an individual with singleton ES. While the frameshift variants were presumed to lead to NMD (not studied), studies in HEK293T cells suggested that the Val285Ala reduced binding ability with KEAP1, possibly leading to instability of the Cullin-RING ligase (CRL) complex and impairment of the ubiquitin-proteasome system. In OMIM, the phenotype associated with heterozygous CUL3 mutations is Pseudohypoaldosteronism type IIE (PHA2E - # 614496). As OMIM and Nakashima et al comment, PHA2E-associated variants are clustered around exon 9, most lead to skipping of exon 9 and produce an in-frame deletion of 57 aa in the cullin homology domain. Few (probably 3) missense variants in exon 9 have also been reported. Individuals with PHA2E do not display DD/ID and conversely individuals with NDD did not display features of PHA2E. Nakashima et al summarize the phenotypes associated with 12 further de novo CUL3 variants in the literature with most pLOF ones detected in individuals with autism and/or developmental disorders and in few cases with congenital heart disease. Few additional missense variants and a stoploss one have been reported in individuals with NDD and one in SCZ. Heterozygous Cul3 (/tissue-specific) deletion in mice resulted in autism-like behavior. Cul3 deficient mice also demonstrated NMDAR hypofunction and decreased spine density. [PMIDs cited : 31455858, 31780330] Overall haploinsufficiency is favored as the underlying mechanism of variants associated with NDD. Nakashima et al comment that the pathogenesis of missense variants remains unknown and/or that a dominant-negative effect on CRL may be possible. Studies on larger cohorts reporting on individuals with relevant phenotypes due to de novo CUL3 variants (eg. DDD study - PMID: 28135719, Lelieveld et al - PMID: 27479843), are better summarized in denovo-db (after filtering for coding variants): http://denovo-db.gs.washington.edu/denovo-db/QueryVariantServlet?searchBy=Gene&target=cul3 Overall, this gene can be considered for inclusion in the ID (amber/green), epilepsy (amber) and/or ASD panels. Sources: Literature |
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||