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| Genetic Epilepsy v0.2331 | MMS19 |
Paul De Fazio gene: MMS19 was added gene: MMS19 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: MMS19 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: MMS19 were set to 38411040 Phenotypes for gene: MMS19 were set to Neuromuscular disease, MMS19-related (MONDO:0019056) Review for gene: MMS19 was set to RED gene: MMS19 was marked as current diagnostic Added comment: Single patient reported with postnatal microcephaly, bilateral cataracts, failure to thrive, progressive spastic tetraparesis, scoliosis, myoclonic epilepsy and precocious puberty. Cerebral MRI at age 4 years showed pontocerebellar atrophy and white matter abnormalities. Patient died age 13 after recurrent respiratory tract infections. A homozygous in-frame deletion p.(Glu213del) was identified. Cell line studies supported pathogenicity of the variant. A zebrafish knockout model showed Mms19 deficiency had detrimental effects on development. Sources: Literature |
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| Genetic Epilepsy v0.2328 | SNF8 |
Chern Lim gene: SNF8 was added gene: SNF8 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: SNF8 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: SNF8 were set to 38423010 Phenotypes for gene: SNF8 were set to Neurodevelopmental disorder (MONDO:0700092), SNF8-related Review for gene: SNF8 was set to AMBER gene: SNF8 was marked as current diagnostic Added comment: PMID: 38423010 - Nine individuals from six families presenting with a spectrum of neurodevelopmental/neurodegenerative features caused by bi-allelic variants in SNF8. In total, three putative LoF variants and four missense variants were identified. - The phenotypic spectrum included four individuals with severe developmental and epileptic encephalopathy, massive reduction of white matter, hypo-/aplasia of the corpus callosum, neurodevelopmental arrest, and early death. A second cohort shows a milder phenotype with intellectual disability, childhood-onset optic atrophy, or ataxia. All mildly affected individuals shared the same hypomorphic variant, c.304G>A (p.Val102Ile) as compound heterozygous. - Two of the patients also had seizures. - Functional studies using fibroblasts derived from patients and zebrafish model showed LoF is the disease mech. Sources: Literature |
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| 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. |
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| Genetic Epilepsy v0.1914 | PIP5K1C |
Zornitza Stark gene: PIP5K1C was added gene: PIP5K1C was added to Genetic Epilepsy. Sources: Expert Review Mode of inheritance for gene: PIP5K1C was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: PIP5K1C were set to 37451268 Phenotypes for gene: PIP5K1C were set to Neurodevelopmental disorder and microcephaly, MONDO:0700092, PIP5K1C-related Review for gene: PIP5K1C was set to GREEN Added comment: Three de novo heterozygous missense variants in PIP5K1C (p.Glu146Lys, p.Tyr205Cys & p.Tyr221Cys) were identified in nine unrelated children exhibiting intellectual disability, developmental delay, acquired microcephaly, seizures, visual abnormalities, and dysmorphic features. Intellectual disability was reported in all nine children and seizures were present in seven children, of which three had developmental and epileptic encephalopathy. In addition, there is functional evidence available, which includes an in vivo zebrafish model that recapitulates the human phenotype (developmental defects affecting the forebrain, including the eyes, as well as craniofacial abnormalities) (PMID:37451268). Sources: Expert Review |
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| Genetic Epilepsy v0.1682 | MED11 |
Ain Roesley gene: MED11 was added gene: MED11 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: MED11 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: MED11 were set to 36001086 Phenotypes for gene: MED11 were set to neurodevelopmental disorder MONDO#0700092, MED11-related Review for gene: MED11 was set to GREEN gene: MED11 was marked as current diagnostic Added comment: 7 affected from 5 families (3x consang) with the same recurrent variant of p.(Arg109*). Protein truncating, NOT NMD as proven by RT-PCR and western blot. Zebrafish knockout model recapitulates key clinical phenotypes NO evidence of founder effect from haplotype analysis 7/7 cerebral dysgyria, cortical atrophy 5/7 limb contracture 4/7 epilepsy 3/7 families with IUGR 3/7 GDD 3/7 hearing loss 3/7 undescended testis 2/7 nystagmus 1/7 congenital cataract Sources: Literature |
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| Genetic Epilepsy v0.1448 | EEF1B2 |
Zornitza Stark gene: EEF1B2 was added gene: EEF1B2 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: EEF1B2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: EEF1B2 were set to 31845318; 21937992; 35015920 Phenotypes for gene: EEF1B2 were set to Neurodevelopmental disorder MONDO:0700092; non-syndromic ID and seizures Review for gene: EEF1B2 was set to GREEN Added comment: Now 7 individuals in 3 unrelated families with a phenotype of non-syndromic ID and fever-sensitive seizures. Knockout zebrafish model demonstrated abnormal development and a photosensitive seizure-like behavioural phenotype. Sources: Literature |
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| Genetic Epilepsy v0.1317 | LIG3 |
Ain Roesley gene: LIG3 was added gene: LIG3 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: LIG3 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: LIG3 were set to 33855352 Phenotypes for gene: LIG3 were set to mitochondrial neurogastrointestinal encephalomyopathy Penetrance for gene: LIG3 were set to Complete Review for gene: LIG3 was set to GREEN gene: LIG3 was marked as current diagnostic Added comment: 7 affecteds from 3 families All had severe dysmotility of the gut, leukoencephalopathy and/or progressive cortical atrophy and 1 family with cerebellar atrophy All had epilepsy, stroke-like episodes, migraine and developmental delay, reminiscent of MELAS. 4 missense (K537N led to splicing defects) and 2 nonsense molecular defects demonstrated on patients' fibroblasts KO models done on zebrafish Sources: Literature |
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| Genetic Epilepsy v0.1267 | PLXNA1 |
Zornitza Stark gene: PLXNA1 was added gene: PLXNA1 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: PLXNA1 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal Publications for gene: PLXNA1 were set to 34054129 Phenotypes for gene: PLXNA1 were set to Neurodevelopmental disorder with cerebral and eye anomalies Review for gene: PLXNA1 was set to GREEN Added comment: Dworschak et al. (2021) via WES reported 10 patients from 7 families with biallelic (n=7) or de novo (n=3) PLXNA1 variants. Shared phenotypic features include global developmental delay (9/10), brain anomalies (6/10), and eye anomalies (7/10). Seizures were predominantly reported in patients with monoallelic variants. Zebrafish studies showed an embryonic role of plxna1a in the development of the central nervous system and the eye. Biallelic variants in the extracellular Plexin-A1 domains lead to impaired dimerization or lack of receptor molecules, whereas monoallelic variants in the intracellular Plexin-A1 domains might impair downstream signaling through a dominant-negative effect. Sources: Literature |
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| Genetic Epilepsy v0.1200 | BRAF | Zornitza Stark Marked gene: BRAF as ready | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1200 | BRAF | Zornitza Stark Gene: braf has been classified as Green List (High Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1200 | BRAF | Zornitza Stark Phenotypes for gene: BRAF were changed from to Cardiofaciocutaneous syndrome, MIM# 115150 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1199 | BRAF | Zornitza Stark Publications for gene: BRAF were set to | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1198 | BRAF | Zornitza Stark Mode of inheritance for gene: BRAF was changed from Unknown to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1197 | BRAF | Zornitza Stark reviewed gene: BRAF: Rating: GREEN; Mode of pathogenicity: None; Publications: 34309696; Phenotypes: Cardiofaciocutaneous syndrome, MIM# 115150; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1168 | VPS50 |
Konstantinos Varvagiannis gene: VPS50 was added gene: VPS50 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: VPS50 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: VPS50 were set to 34037727 Phenotypes for gene: VPS50 were set to Neonatal cholestatic liver disease; Failure to thrive; Profound global developmental delay; Postnatal microcephaly; Seizures; Abnormality of the corpus callosum Penetrance for gene: VPS50 were set to Complete Review for gene: VPS50 was set to AMBER Added comment: Schneeberger et al (2021 - PMID: 34037727) describe the phenotype of 2 unrelated individuals with biallelic VPS50 variants. Common features included transient neonatal cholestasis, failure to thrive, severe DD with failure to achieve milestones (last examination at 2y and 2y2m respectively), postnatal microcephaly, seizures (onset at 6m and 25m) and irritability. There was corpus callosum hypoplasia on brain imaging. Both individuals were homozygous for variants private to each family (no/not known consanguinity applying to each case). The first individual was homozygous for a splicing variant (NM_017667.4:c.1978-1G>T) and had a similarly unaffected sister deceased with no available DNA for testing. The other individual was homozygous for an in-frame deletion (c.1823_1825delCAA / p.(Thr608del)). VPS50 encodes a critical component of the endosome-associated recycling protein (EARP) complex, which functions in recycling endocytic vesicles back to the plasma membrane [OMIM based on Schindler et al]. The complex contains VPS50, VPS51, VPS52, VPS53, the three latter also being components of GARP (Golgi-associated-retrograde protein) complex. GARP contains VPS54 instead of VPS50 and is required for trafficking of proteins to the trans-golgi network. Thus VPS50 (also named syndetin) and VPS54 function in the EARP and GARP complexes, to define directional movement of their endocytic vesicles [OMIM based on Schindler et al]. The VPS50 subunit is required for recycling of the transferrin receptor. As discussed by Schneeberger et al (refs provided in text): - VPS50 has a high expression in mouse and human brain as well as throughout mouse brain development. - Mice deficient for Vps50 have not been reported. vps50 knockdown in zebrafish results in severe developmental defects of the body axis. Knockout mice for other proteins of the EARP/GARP complex (e.g. Vps52, 53 and 54) display embryonic lethality. Studies performed by Schneeberger et al included: - Transcript analysis for the 1st variant demonstrated skipping of ex21 (in patient derived fabriblasts) leading to an in frame deletion of 81 bp (r.1978_2058del) with predicted loss of 27 residues (p.Leu660_Leu686del). - Similar VPS50 mRNA levels but significant reduction of protein levels (~5% and ~8% of controls) were observed in fibroblasts from patients 1 and 2. Additionally, significant reductions in the amounts of VPS52 and VPS53 protein levels were observed despite mRNA levels similar to controls. Overall, this suggested drastic reduction of functional EARP complex levels. - Lysosomes appeared to have similar morphology, cellular distribution and likely unaffected function in patient fibroblasts. - Transferrin receptor recycling was shown to be delayed in patient fibroblasts suggestive of compromise of endocytic-recycling function. As the authors comment, the phenotype of both individuals with biallelic VPS50 variants overlaps with the corresponding phenotype reported in 15 subjects with biallelic VPS53 or VPS51 mutations notably, severe DD/ID, microcephaly and early onset epilepsy, CC anomalies. Overall, for this group, they propose the term "GARP and/or EARP deficiency disorders". There is no VPS50-associated phenotype in OMIM or G2P. SysID includes VPS50 among the ID candidate genes. Consider inclusion in other relevant gene panels (e.g. for neonatal cholestasis, epilepsy, microcephaly, growth failure in early infancy, corpus callosum anomalies, etc) with amber rating pending further reports. Sources: Literature |
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| Genetic Epilepsy v0.1154 | AP1G1 |
Danielle Ariti gene: AP1G1 was added gene: AP1G1 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: AP1G1 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal Publications for gene: AP1G1 were set to 34102099 Phenotypes for gene: AP1G1 were set to Neurodevelopmental disorder (NDD); Intellectual Disability; Epilepsy Review for gene: AP1G1 was set to GREEN Added comment: Two bi-allelic homozygous missense variants were found in two distinct families with Italian and Pakistani origins; homozygous missense variants. Eight de novo heterozygous variants were identified in nine isolated affected individuals from nine families; including five missense, two frameshift, and one intronic variant that disrupts the canonical splice acceptor site. Knocking out AP1G1 Zebrafish model resulted in severe developmental abnormalities and increased lethality. All individuals had neurodevelopmental disorder (NDD) including global developmental delay and ID, which varied in severity from mild to severe. Sources: Literature |
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| Genetic Epilepsy v0.1140 | C2orf69 |
Zornitza Stark gene: C2orf69 was added gene: C2orf69 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: C2orf69 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: C2orf69 were set to 34038740; 33945503 Phenotypes for gene: C2orf69 were set to Combined oxidative phosphorylation deficiency-53 (COXPD53), MIM#619423 Review for gene: C2orf69 was set to GREEN Added comment: PMID 34038740: 20 affected children from 8 unrelated families reported, presenting with fatal syndrome consisting of severe autoinflammation and progredient leukoencephalopathy with recurrent seizures; 12 of these subjects, whose DNA was available, segregated homozygous loss-of-function C2orf69 variants. Endogenous C2ORF69 was found to be (1) loosely bound to mitochondria, (2) affects mitochondrial membrane potential and oxidative respiration in cultured neurons, and (3) controls the levels of the glycogen branching enzyme 1 (GBE1) consistent with a glycogen-storage-associated mitochondriopathy. Zebrafish model. PMID 33945503: 8 individuals from 5 families reported with muscle hypotonia, developmental delay, progressive microcephaly, and brain MRI abnormalities. Age at onset ranged from birth to 6 months of age. Six patients had vision impairment, liver abnormalities, inflammation/inflammatory arthritis, and 5 patients had seizures. Sources: Literature |
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| Genetic Epilepsy v0.1002 | ZNF526 |
Zornitza Stark gene: ZNF526 was added gene: ZNF526 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: ZNF526 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: ZNF526 were set to 21937992; 25558065; 33397746 Phenotypes for gene: ZNF526 were set to Intellectual disability; Microcephaly; Cataracts; Epilepsy; Hypertonia; Dystonia Review for gene: ZNF526 was set to GREEN Added comment: - PMID: 21937992 (2011) - Two unrelated families (with 4 affected individuals in each) with non-syndromic ID (mild or moderate, respectively) identified harbouring different biallelic missense variants in the ZNF526 gene. - PMID: 25558065 (2015) - One family with ID, Noonan-like facies, pulmonary stenosis and a homozygous missense variant in this gene. No further details provided. - PMID: 33397746 (2021) - Five individuals from four unrelated families with homozygous ZNF526 variants. Four harboured truncating variants, and were all affected by profound DD and severe ID, microcephaly (ranging from -4 SD to -8 SD), bilateral progressive cataracts, hypertonic-dystonic movements, epilepsy and brain MRI anomalies. The fifth patient had a homozygous missense variant and a slightly less severe disorder, with postnatal microcephaly (-2 SD), progressive bilateral cataracts, severe ID, and normal brain MRI. Zebrafish model demonstrated brain and eye malformations resembling findings seen in the human holoprosencephaly spectrum Sources: Literature |
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| 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 |
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| Genetic Epilepsy v0.766 | NARS |
Konstantinos Varvagiannis changed review comment from: [Please note that HGNC Approved Gene Symbol for this gene is NARS1] Manole et al (2020 - PMID: 32738225) provide evidence that both biallelic and monoallelic (de novo) pathogenic NARS1 variants cause a neurodevelopmental disorder. In total 32 individuals from 21 families are reported, with biallelic variants identified in individuals from 13 families and de novo in 8 families. Similar features were reported for AR/AD occurrences of the disorder and included of microcephaly (90% - most often primary), epilepsy (23/32 or 74% - variable semiology incl. partial/myoclonic/generalized tonic-clonic seizures), DD and ID (as a universal feature), abnormal tone in several (hypotonia/spasticity), ataxia, demyelinating peripheral neuropathy (in 3 or more for each inheritance mode - or a total of 25%). Some individuals had dysmorphic features. NARS1 encodes an aminoacyl-tRNA synthetase (ARS) [asparaginyl-tRNA synthetase 1]. Aminoacyl-tRNA synthetases constitute a family of enzymes catalyzing attachment of amino-acids to their cognate tRNAs. As the authors comment, mutations in genes encoding several other ARSs result in neurological disorders ranging from peripheral neuropathy to severe multi-systemic NDD. Dominant, recessive or both modes for inheritance for mutations in the same gene (e.g. AARS1, YARS1, MARS1, etc) have been reported. Some variants were recurrent, e.g. the c.1600C>T / p.Arg534* which occurred in 6 families as a de novo event or c.1633C>T p.Arg545Cys (homozygous in 6 families). 3 different variants were reported to have occured de novo (c.965G>T - p.Arg322Leu, c.1525G>A - p.Gly509Ser, p.Arg534*) with several other variants identified in hmz/compound htz individuals. A single SNV (c.1067A>C - p.Asp356Ala) was suggested to be acting as modifier and pathogenic only when in trans with a severe variant. [NM_004539.4 used as RefSeq for all]. The authors provide several lines of evidence for a partial loss-of-function effect (e.g. reduction in mRNA expression, enzyme levels and activity in fibroblasts or iNPCs) underlying pathogenicity of the variants identified in individuals with biallelic variants. A gain-of-function (dominant-negative) effect is proposed for de novo variants (such effect also demonstrated for the p.Arg534* in a zebrafish model). As also Manole et al suggest, NARS1 can be considered for inclusion in gene panels for DD/ID, epilepsy and/or demyelinating neuropathy. Sources: Literature; to: [Please note that HGNC Approved Gene Symbol for this gene is NARS1] Manole et al (2020 - PMID: 32738225) provide evidence that both biallelic and monoallelic (de novo) pathogenic NARS1 variants cause a neurodevelopmental disorder. In total 32 individuals from 21 families are reported, with biallelic variants identified in individuals from 13 families and de novo in 8 families. Similar features were reported for AR/AD occurrences of the disorder and included microcephaly (90% - most often primary), epilepsy (23/32 or 74% - variable semiology incl. partial/myoclonic/generalized tonic-clonic seizures), DD and ID (as a universal feature), abnormal tone in several (hypotonia/spasticity), ataxia, demyelinating peripheral neuropathy (in 3 or more for each inheritance mode - or a total of 25%). Some individuals had dysmorphic features. NARS1 encodes an aminoacyl-tRNA synthetase (ARS) [asparaginyl-tRNA synthetase 1]. Aminoacyl-tRNA synthetases constitute a family of enzymes catalyzing attachment of amino-acids to their cognate tRNAs. As the authors comment, mutations in genes encoding several other ARSs result in neurological disorders ranging from peripheral neuropathy to severe multi-systemic NDD. Dominant, recessive or both modes for inheritance for mutations in the same gene (e.g. AARS1, YARS1, MARS1, etc) have been reported. Some variants were recurrent, e.g. the c.1600C>T / p.Arg534* which occurred in 6 families as a de novo event or c.1633C>T p.Arg545Cys (homozygous in 6 families). 3 different variants were reported to have occured de novo (c.965G>T - p.Arg322Leu, c.1525G>A - p.Gly509Ser, p.Arg534*) with several other variants identified in hmz/compound htz individuals. A single SNV (c.1067A>C - p.Asp356Ala) was suggested to be acting as modifier and pathogenic only when in trans with a severe variant. [NM_004539.4 used as RefSeq for all]. The authors provide several lines of evidence for a partial loss-of-function effect (e.g. reduction in mRNA expression, enzyme levels and activity in fibroblasts or iNPCs) underlying pathogenicity of the variants identified in individuals with biallelic variants. A gain-of-function (dominant-negative) effect is proposed for de novo variants (such effect also demonstrated for the p.Arg534* in a zebrafish model). As also Manole et al suggest, NARS1 can be considered for inclusion in gene panels for DD/ID, epilepsy and/or demyelinating neuropathy. Sources: Literature |
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| Genetic Epilepsy v0.766 | NARS |
Konstantinos Varvagiannis gene: NARS was added gene: NARS was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: NARS was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal Publications for gene: NARS were set to 32738225 Phenotypes for gene: NARS were set to Abnormal muscle tone; Microcephaly; Global developmental delay; Intellectual disability; Seizures; Ataxia; Abnormality of the face; Demyelinating peripheral neuropathy Penetrance for gene: NARS were set to Complete Review for gene: NARS was set to GREEN Added comment: [Please note that HGNC Approved Gene Symbol for this gene is NARS1] Manole et al (2020 - PMID: 32738225) provide evidence that both biallelic and monoallelic (de novo) pathogenic NARS1 variants cause a neurodevelopmental disorder. In total 32 individuals from 21 families are reported, with biallelic variants identified in individuals from 13 families and de novo in 8 families. Similar features were reported for AR/AD occurrences of the disorder and included of microcephaly (90% - most often primary), epilepsy (23/32 or 74% - variable semiology incl. partial/myoclonic/generalized tonic-clonic seizures), DD and ID (as a universal feature), abnormal tone in several (hypotonia/spasticity), ataxia, demyelinating peripheral neuropathy (in 3 or more for each inheritance mode - or a total of 25%). Some individuals had dysmorphic features. NARS1 encodes an aminoacyl-tRNA synthetase (ARS) [asparaginyl-tRNA synthetase 1]. Aminoacyl-tRNA synthetases constitute a family of enzymes catalyzing attachment of amino-acids to their cognate tRNAs. As the authors comment, mutations in genes encoding several other ARSs result in neurological disorders ranging from peripheral neuropathy to severe multi-systemic NDD. Dominant, recessive or both modes for inheritance for mutations in the same gene (e.g. AARS1, YARS1, MARS1, etc) have been reported. Some variants were recurrent, e.g. the c.1600C>T / p.Arg534* which occurred in 6 families as a de novo event or c.1633C>T p.Arg545Cys (homozygous in 6 families). 3 different variants were reported to have occured de novo (c.965G>T - p.Arg322Leu, c.1525G>A - p.Gly509Ser, p.Arg534*) with several other variants identified in hmz/compound htz individuals. A single SNV (c.1067A>C - p.Asp356Ala) was suggested to be acting as modifier and pathogenic only when in trans with a severe variant. [NM_004539.4 used as RefSeq for all]. The authors provide several lines of evidence for a partial loss-of-function effect (e.g. reduction in mRNA expression, enzyme levels and activity in fibroblasts or iNPCs) underlying pathogenicity of the variants identified in individuals with biallelic variants. A gain-of-function (dominant-negative) effect is proposed for de novo variants (such effect also demonstrated for the p.Arg534* in a zebrafish model). As also Manole et al suggest, NARS1 can be considered for inclusion in gene panels for DD/ID, epilepsy and/or demyelinating neuropathy. Sources: Literature |
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| Genetic Epilepsy v0.734 | EXOC7 |
Chirag Patel gene: EXOC7 was added gene: EXOC7 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: EXOC7 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: EXOC7 were set to PMID: 32103185 Phenotypes for gene: EXOC7 were set to brain atrophy; seizures; developmental delay; microcephaly Review for gene: EXOC7 was set to GREEN Added comment: 4 families with 8 affected individuals with brain atrophy, seizures, and developmental delay, and in more severe cases microcephaly and infantile death. Four novel homozygous or comp.heterozygous variants found in EXOC7, which segregated with disease in the families. They showed that EXOC7, a member of the mammalian exocyst complex, is highly expressed in developing human cortex. In addition, a zebrafish model of Exoc7 deficiency recapitulates the human disorder with increased apoptosis and decreased progenitor cells during telencephalon development, suggesting that the brain atrophy in human cases reflects neuronal degeneration. Sources: Literature |
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| Genetic Epilepsy v0.694 | UGDH |
Konstantinos Varvagiannis gene: UGDH was added gene: UGDH was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: UGDH was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: UGDH were set to 32001716 Phenotypes for gene: UGDH were set to Epileptic encephalopathy, early infantile, 84 - MIM #618792 Penetrance for gene: UGDH were set to Complete Review for gene: UGDH was set to GREEN Added comment: Hengel et al (2020 - PMID: 32001716) report on 36 individuals with biallelic UGDH pathogenic variants. The phenotype corresponded overall to a developmental epileptic encephalopathy with hypotonia, feeding difficulties, severe global DD, moderate or commonly severe ID in all. Hypotonia and motor disorder (incl. spasticity, dystonia, ataxia, chorea, etc) often occurred prior to the onset of seizures. A single individual did not present seizures and 2 sibs had only seizures in the setting of fever. Affected subjects were tested by exome sequencing and UGDH variants were the only/best candidates for the phenotype following also segregation studies. Many were compound heterozygous or homozygous (~6 families were consanguineous) for missense variants and few were compound heterozygous for missense and pLoF variants. There were no individuals with biallelic pLoF variants identified. Parental/sib studies were all compatible with AR inheritance mode. UGDH encodes the enzyme UDP-glucose dehydrogenase which converts UDP-glucose to UDP-glucuronate, the latter being a critical component of the glycosaminoglycans, hyaluronan, chondroitin sulfate, and heparan sulfate [OMIM]. Patient fibroblast and biochemical assays suggested a LoF effect of variants leading to impairment of UGDH stability, oligomerization or enzymatic activity (decreased UGDH-catalyzed reduction of NAD+ to NADH / hyaluronic acid production which requires UDP-glucuronate). Attempts to model the disorder using an already developped zebrafish model (for a hypomorphic LoF allele) were unsuccessful as fish did not exhibit seizures spontaneously or upon induction with PTZ. Modelling of the disorder in vitro using patient-derived cerebral organoids demonstrated smaller organoids due to reduced number of proliferating neural progenitors. Sources: Literature |
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| Genetic Epilepsy v0.0 | BRAF |
Zornitza Stark gene: BRAF was added gene: BRAF was added to Genetic Epilepsy_AustralianGenomics_VCGS. Sources: Australian Genomics Health Alliance Epilepsy Flagship,Expert Review Green,Victorian Clinical Genetics Services Mode of inheritance for gene: BRAF was set to Unknown |
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