| Date | Panel | Item | Activity | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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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 v0.2038 | CPT2 |
Andrew Fennell gene: CPT2 was added gene: CPT2 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: CPT2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: CPT2 were set to PMID: 20301431; 35028265; 36478999 Phenotypes for gene: CPT2 were set to CPT II deficiency, infantile 600649; CPT II deficiency, lethal neonatal 608836; CPT II deficiency, myopathic, stress-induced 255110 Review for gene: CPT2 was set to GREEN Added comment: GeneReviews quotes seizures as a core component of the phenotype in lethal neonatal and severe infantile forms of the disorder. PMID: 36478999 - single report of a 10yo male with CPT2 who developed focal seizures during an acute episode. PMID: 35028265 - single report of a male who presented at 5 months of age with infantile‐onset carnitine palmitoyltransferase 2 (CPT2) deficiency. He also had X‐linked nephrogenic diabetes insipidus. He developed focal seizures at 17yo. Sources: Literature |
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| Genetic Epilepsy v0.2028 | OSTC | Lauren Rogers reviewed gene: OSTC: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Oligosaccharyltransferase complex-congenital disorders of glycosylation; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1911 | COL4A3BP |
Ee Ming Wong gene: COL4A3BP was added gene: COL4A3BP was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: COL4A3BP was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: COL4A3BP were set to PMID: 36976648 Phenotypes for gene: COL4A3BP were set to Intellectual developmental disorder 34 (MIM#616351) Mode of pathogenicity for gene: COL4A3BP was set to Other Review for gene: COL4A3BP was set to GREEN gene: COL4A3BP was marked as current diagnostic Added comment: - current HGNC symbol: CERT1 - Thirty-one unrelated individuals with twenty-two distinct missense variants. The majority of variants were de novo - Several variants transfected into HeLa cells demonstrated gain of CERT activity - CERT gain of function in Drosophila melanogaster led to head and brain size defects and impaired locomotor activity, which was corrected by pharmacological inhibition of CERT Sources: Literature |
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| Genetic Epilepsy v0.1876 | GPRC5B |
Lucy Spencer gene: GPRC5B was added gene: GPRC5B was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: GPRC5B was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: GPRC5B were set to 37143309 Phenotypes for gene: GPRC5B were set to Megalencephalic leukoencephalopathy with subcortical cysts 3 MIM#620447 Review for gene: GPRC5B was set to GREEN Added comment: PMID: 37143309 Cohort of 5 patients with an MRI based diagnosis of megalencephalic leukoencephalopathy with subcortical cysts (MLC). 3 unrelated patients had variants in GPRC5B, 2 have the same inframe dup Ile175dup and the third has an in frame dup of Ala177. All 3 were de novo and unaffected siblings did not have the variants. All patients have macrocephaly, delayed motor development, seizures, all had varying degrees of cognitive deficits. 2 also had spasticity, ataxia and dystonia. MRI showed MLC, abnormal and swollen cerebral white matter. Patient cell lines showed reduced regulatory volume decrease, and western blot showed a strong increase in GRPC5B levels in patient lymphoblasts. Together, these findings indicate disturbed volume regulation in lymphoblasts from patients with GPRC5B variants, potentially due to increased GPRC5B levels. Transfected cells caused increased volume-regulated anion channel activity. Sources: Literature |
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| Genetic Epilepsy v0.1542 | TRAPPC10 |
Naomi Baker gene: TRAPPC10 was added gene: TRAPPC10 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: TRAPPC10 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: TRAPPC10 were set to PMID: 35298461; 30167849 Phenotypes for gene: TRAPPC10 were set to neurodevelopmental disorder (MONDO:0700092), TRAPPC10-related Review for gene: TRAPPC10 was set to GREEN Added comment: PMID: 35298461 – two Pakistani families reported with homozygous variants. Family 1 has frameshift variant in 8 affected individual and family 2 has missense variant in 2 affected individuals. Patients present with microcephaly, short stature, hypotonia, severe ID and behavioural abnormalities. Seizures also reported in 4/10 individuals. Paper also reported brain abnormalities in null mouse model and other functional in transfected cell lines. PMID: 30167849 – initial report of family 2 above. Sources: Literature |
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| Genetic Epilepsy v0.1317 | OSTC |
Belinda Chong gene: OSTC was added gene: OSTC was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: OSTC was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: OSTC were set to PMID: 32267060 Phenotypes for gene: OSTC were set to Oligosaccharyltransferase complex-congenital disorders of glycosylation Review for gene: OSTC was set to RED Added comment: A patient with microcephaly, dysmorphic facies, congenital heart defect, focal epilepsy, infantile spasms, skeletal dysplasia, and a type 1 serum transferrin isoelectrofocusing due to a novel CDG caused by a homozygous variant in the oligosaccharyltransferase complex noncatalytic subunit (OSTC) gene involved in glycosylation and confirmed by serum transferrin electrophoresis. Patient was homozygous for a canonical splice variant (c.431 + 1G > A), mRNA from patient's fibroblast showed mRNA transcript reduced 80-90%/aberrant splicing - predicting NMD. GnomAD - 10 hets, 0 hom Sources: Literature |
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| 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 v0.1124 | ATP1A3 |
Ee Ming Wong changed review comment from: - sixteen individuals with de novo or inherited variants (1 variant was mosaic) - Mutant constructs transfected into COS-1 cells demonstrated impaired NKA-pump activity; to: - sixteen individuals with de novo or inherited variants (1 variant was mosaic) - Mutant constructs transfected into COS-1 cells demonstrated impaired NKA-pump activity |
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| Genetic Epilepsy v0.1124 | ATP1A3 |
Ee Ming Wong changed review comment from: - six individuals with de novo missense variants - Mutant constructs transfected into COS-1 cells demonstrated impaired NKA-pump activity; to: - sixteen individuals with de novo or inherited variants (1 variant was mosaic) - Mutant constructs transfected into COS-1 cells demonstrated impaired NKA-pump activity |
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| Genetic Epilepsy v0.1121 | PPP2R1A |
Elena Savva gene: PPP2R1A was added gene: PPP2R1A was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: PPP2R1A was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: PPP2R1A were set to PMID: 33106617; 26168268 Phenotypes for gene: PPP2R1A were set to Mental retardation, autosomal dominant 36 MIM#616362 Mode of pathogenicity for gene: PPP2R1A was set to Other Review for gene: PPP2R1A was set to GREEN Added comment: Likely dominant negative. For some variants, binding assays using HEK293T cells transfected with either WT or mutant constructs demonstrated decreased binding to B subunit families or C subunit with corresponding decrease in PP2A activity by affecting the trimeric holoenzyme (hypothesized by authors) ((PMIDs: 26168268, 33106617). 10/26 patients were reported with epilepsy, interestingly none also presented with macrocephaly (otherwise observed in 38% of the cohort) Sources: Literature |
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| Genetic Epilepsy v0.1092 | NSF | Zornitza Stark Phenotypes for gene: NSF were changed from Seizures; EEG with burst suppression; Global developmental delay; Intellectual disability to Developmental and epileptic encephalopathy 96, MIM# 619340; Seizures; EEG with burst suppression; Global developmental delay; Intellectual disability | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.1091 | NSF | Zornitza Stark edited their review of gene: NSF: Changed phenotypes: Developmental and epileptic encephalopathy 96, MIM# 619340, Seizures, EEG with burst suppression, Global developmental delay, Intellectual disability | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.982 | ST3GAL5 | Zornitza Stark Phenotypes for gene: ST3GAL5 were changed from to Salt and pepper developmental regression syndrome 609056; GM3 synthase deficiency, MONDO:0018274; Lactosylceramide alpha-2,3-sialyltransferase deficiency (Disorders of glycosphingolipid and glycosylphosphatidylinositol anchor glycosylation) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.979 | ST3GAL5 | Zornitza Stark reviewed gene: ST3GAL5: Rating: GREEN; Mode of pathogenicity: None; Publications: 23436467, 22990144, 15502825, 27232954, 30691927, 30688114, 30576498; Phenotypes: Salt and pepper developmental regression syndrome 609056, GM3 synthase deficiency, MONDO:0018274, Lactosylceramide alpha-2,3-sialyltransferase deficiency (Disorders of glycosphingolipid and glycosylphosphatidylinositol anchor glycosylation); Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.860 | LMNB1 |
Konstantinos Varvagiannis gene: LMNB1 was added gene: LMNB1 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: LMNB1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: LMNB1 were set to 32910914 Phenotypes for gene: LMNB1 were set to Global developmental delay; Intellectual disability; Microcephaly; Short stature; Seizures; Abnormality of the corpus callosum; Cortical gyral simplification; Feeding difficulties; Scoliosis Penetrance for gene: LMNB1 were set to unknown Mode of pathogenicity for gene: LMNB1 was set to Other Review for gene: LMNB1 was set to AMBER Added comment: Cristofoli et al (2020 - PMID: 32910914) report 7 individuals (from 5 families) harboring mostly de novo LMNB1 variants. The common phenotype consisted of primary microcephaly (7/7 ranging from -4.4 to -10 SD), DD/ID (7/7), relative short stature in most (+0.7 to -4 SD). Additional features included brain MRI abnormalities (abnormal CC in 3, simplified gyral pattern in 3, small structurally normal brain, etc), seizures (4 individuals from 2 families), limb spasticity (1/7), cortical visual impairment (in 3), feeding difficulties (5/7), scoliosis (4/7). Non-overlapping dysmorphic features were reported in some. Variants were identified by WES or custom-designed gene panel and included 3 missense variants, 1 in-frame deletion and a splice variant. The in-frame deletion was inherited from a similarly affected parent in whom the variant occurred as a dn event. The splice SNV(NM_005573.3:c.939+1G>A) occurred in 3 sibs and was present as mosaic variant (15%) in the parent. This variant was predicted to result to extension of exon 5 by 6 amino-acids (samples were unavailable for mRNA studies). LMNB1 encodes a B-type lamin (the other being encoded by LMNB2). A- and B- type lamins are major components of the nuclear lamina. As the authors comment, LMNB1 is expressed in almost all cell types beginning at the earliest stages of development. Lamin-deficient mouse models support an essential role of B-type lamins in organogenesis, neuronal migration, patterning during brain development. Functional studies performed, demonstrated impaired formation of LMNB1 nuclear lamina in LMNB1-null HeLa cells transfected with cDNAs for 3 missense variants. Two variants (Lys33Glu/Arg42Trp) were shown to result in decreased nuclear localization with increased abundance in the cytosolic fraction. In patient derived LCLs these variants led to abnormal nuclear morphology. A missense variant in another domain (Ala152Gly - 1st coil domain) resulted also in lower abundance of lamin B1, irregular lamin A/C nuclear lamina, as well as more condensed nuclei (HeLa cells). LMNB1 duplications or missense mutations increasing LMNB1 expression are associated with a different presentation of AD leuodystrophy. A variant previously associated with leukodystrophy (Arg29Trp) was shown to behave differently (present in the nuclear extract but not in the cytosol, lamin B1 to A/C ratio in nuclear extract was not significantly altered compared to wt as was the case for Arg42Trp, Lys33Glu). Given the pLI score of 0.55 as well as the phenotype of individuals with deletions (not presenting microcephaly) the authors predict that a dominant-negative effect applies (rather than haploinsufficiency). Consider inclusion in the following panels : DD/ID (green), epilepsy (amber - 4 of 7 patients belonging to 2 families), primary microcephaly (green), callosome (amber/green - 3 individuals belonging to 3 families), mendeliome (green), etc. Sources: Literature |
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| Genetic Epilepsy v0.776 | KAT5 |
Konstantinos Varvagiannis gene: KAT5 was added gene: KAT5 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: KAT5 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: KAT5 were set to 32822602 Phenotypes for gene: KAT5 were set to Severe global developmental delay; Intellectual disability; Seizures; Microcephaly; Behavioral abnormality; Sleep disturbance; Morphological abnormality of the central nervous system; Short stature; Oral cleft; Abnormality of the face Penetrance for gene: KAT5 were set to unknown Mode of pathogenicity for gene: KAT5 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: KAT5 was set to GREEN Added comment: Humbert el al (2020 - PMID: 32822602) report 3 individuals with de novo missense KAT5 variants. Features included severe DD (3/3) and ID (2/2 - the 3rd was 18m on last examination), microcephaly (2/3), behavioral anomalies (3/3) including severe sleep disorder (3/3 - table S1 / night walking, sleep onset delay, excessive daytime sleepiness), seizures (3/3 - variable type and age of onset), brain MRI abnormalities (3/3 - CC, cerebellar atrophy each in 2 subjects, focal polymicrogyria in 1), various genitourinary anomalies (3/3). All had moderately short stature (-1.95 SD to -2.9SD). Cleft LP and submucous cleft P were observed in 2/3. Facial features included round face, flat profile, depressed nasal bridge, downturned corners of mouth and prognathism (each in at least 2 subjects). KAT5 encodes a lysine acetyltransferase involved in gene expression, DNA repair, chromatine remodeling, apoptosis and cell proliferation. It is part of the NuA4 histone acetyltransferase (HAT) complex also called TIP60/p400 (TIP60 being another name for KAT5). Regulation by histone acetylation is important for proper development. 3 missense KAT5 SNVs were identified, one within the chromobarrel domain (aa 7-65 / NM_006388.3) and 2 in the acetyl-CoA binding domain (aa 365-420). Following generation of K562 cells expressing either WT or variants, it was demonstrated that wt/mt KAT5 assemble normally into NuA4/TIP60 complexes. Histone acetyltransferase activity was however impaired for all variants, suggesting a partial loss of function mechanism. As Humbert et al comment, it is possible that KAT5 haploinsufficiency does not lead to a syndrome. Over 10 high-confidence LoF variants are listed in gnomAD. Heterozygous Kat5 ko mice have normal development, growth and fertility. Homozygous ko mice are embryonic lethal. In haploinsufficient mice, reduction of mRNA to 50% has been shown to be compensated at the protein level in adipose and/or other tissues (several studies cited). RNA-Seq in fibroblasts from 2 affected individuals revealed dysregulation of highly relevant genes (e.g. for neurodevelopment, circadian clock, etc). Mutations in KAT6A/B, encoding two other acetyltransferases cause neurodevelopmental disorders with features overlapping those observed in individuals with KAT5 variants (e.g. DD/ID, microcephaly, seizures, sleep disturbance, clefts, CC or genital anomalies). Consider inclusion in the ID and epilepsy panels with green rating as well as the gene panel for clefting with amber. 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 v0.578 | NSF | Zornitza Stark Marked gene: NSF as ready | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.578 | NSF | Zornitza Stark Gene: nsf has been classified as Amber List (Moderate Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.578 | NSF | Zornitza Stark Classified gene: NSF as Amber List (moderate evidence) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.578 | NSF | Zornitza Stark Gene: nsf has been classified as Amber List (Moderate Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.577 | NSF |
Zornitza Stark gene: NSF was added gene: NSF was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: NSF was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: NSF were set to 31675180 Phenotypes for gene: NSF were set to Seizures; EEG with burst suppression; Global developmental delay; Intellectual disability Review for gene: NSF was set to AMBER Added comment: Two individuals reported with de novo missense variants in this gene. Sources: Literature |
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| Genetic Epilepsy v0.575 | KAT8 |
Zornitza Stark gene: KAT8 was added gene: KAT8 was added to Genetic Epilepsy. Sources: Literature Mode of inheritance for gene: KAT8 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: KAT8 were set to 31794431 Phenotypes for gene: KAT8 were set to Intellectual disability; seizures; autism; dysmorphic features Review for gene: KAT8 was set to GREEN Added comment: Eight unrelated individuals reported with de novo variants in this gene and a mouse model. All variants missense, in the chromobarrel domain or the acetyltransferase domain; three individuals had the same variant p.Tyr90Cys . One more individual reported with bi-allelic variants: one missense and one frameshift; carrier parents were normal suggesting that may be haploinsuffiency is not the mechanism. Sources: Literature |
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| Genetic Epilepsy v0.429 | PSAT1 | Zornitza Stark Phenotypes for gene: PSAT1 were changed from Phosphoserine aminotransferase deficiency, MIM#610992 to Phosphoserine aminotransferase deficiency, MIM#610992 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.428 | PSAT1 | Zornitza Stark Phenotypes for gene: PSAT1 were changed from to Phosphoserine aminotransferase deficiency, MIM#610992 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Genetic Epilepsy v0.424 | PSAT1 | Zornitza Stark reviewed gene: PSAT1: Rating: AMBER; Mode of pathogenicity: None; Publications: 17436247, 26610677, 26960553; Phenotypes: Phosphoserine aminotransferase deficiency, MIM#610992; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||