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| Intellectual disability syndromic and non-syndromic v1.96 | CDKL2 |
Sarah Milton gene: CDKL2 was added gene: CDKL2 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: CDKL2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: CDKL2 were set to PMID: 40088891 Phenotypes for gene: CDKL2 were set to Neurodevelopmental disorder, MONDO:0700092, CDKL2-related Penetrance for gene: CDKL2 were set to Complete Mode of pathogenicity for gene: CDKL2 was set to Other Review for gene: CDKL2 was set to AMBER Added comment: CDKL2 encodes a cyclin dependent kinase of which there are CDKL1-5 in humans. (CDKL5 has been associated with a neurodevelopmental disorder previously.) Bereshneh et al describe 5 individuals with a neurodevelopmental disorder with de novo variants in CDKL2. 3 variants were missense, 1 was an in frame single amino acid deletion. 2 of the individuals described were monozygotic twins who were born at 30/40 and also had PVL on neuroimaging. Phenotype included GDD (5/5) - severity not described, speech impairment (5/5), motor impairment (4/5), epilepsy (3/5), ID (3/5), IUGR (3/5), poor growth postnatally (3/5), GI/feeding issues (3/5), tone abnormality (3/5) Missense variants were located in the kinase domain and dominant negative mechanism was postulated based on drosophilia studies. Functional studies in drosphilia showed variants seen in probands did not completely rescue a loss of function model, as well as this, overexpression of transcripts containing the variants resulted in a more severe phenotype suggesting dominant negative. Authors also noted the larger than expected number of LOF variants in gnomad for the disease to be caused by this mechanism. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v1.83 | KMT2C | Zornitza Stark edited their review of gene: KMT2C: Added comment: Additional report of >80 individuals suggesting condition is distinct from Kleefstra syndrome and needs to be renamed.; Changed publications: 39013459; Changed phenotypes: Kleefstra syndrome 2, MIM#617768, Neurodevelopmental disorder, MONDO:0700092, KMT2C-related | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v1.62 | ARHGEF40 |
Chirag Patel gene: ARHGEF40 was added gene: ARHGEF40 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: ARHGEF40 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: ARHGEF40 were set to PMID: 39838643 Phenotypes for gene: ARHGEF40 were set to Neurodevelopmental disorder MONDO:0700092 Review for gene: ARHGEF40 was set to RED Added comment: 2 individuals with global developmental delay, hypotonia, short stature, hearing impairment, nystagmus, feeding issues, and dysmorphism (bifid uvula, narrow mouth, high palate, micrognathia). Trio clinical whole exome sequencing identified de novo variants in the ARHGEF40 gene at position p.Arg225, which is fully conserved in mammals and located within the n-terminal keratin binding region (p.Arg225Trp and p.Arg225Gln). Of note, multiple additional probands with rare missense variants at the p.Arg225 residue have been identified by the same laboratory (but there was no consent for publication, providing further evidence of the importance of this residue. The ARHGEF40 gene (aka SOLO) is a member of the Rho guanine nucleotide exchange factor (Rho-GEF) family of proteins, which stimulate Rho signal transduction molecules by converting them from inactive GDP-bound form to the active GTP-bound state. No functional studies to characterise disease-gene relationship or disease mechanism. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.6548 | DHRSX |
Zornitza Stark gene: DHRSX was added gene: DHRSX was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: DHRSX was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: DHRSX were set to 38821050 Phenotypes for gene: DHRSX were set to congenital disorder of glycosylation, MONDO:0015286, DHRSX-related Added comment: PMID:38821050 reported the identification of biallelic missense variants in DHRSX gene in four patients from three unrelated families with a congenital disorder of glycosylation. They displayed distinct facial features, severe neurological involvement including hypotonia, scoliosis, contractures, profound intellectual disability, epilepsy, and sensorineural hearing loss. These patients also experienced severe failure to thrive (requiring tube feeding); variable respiratory insufficiency; and involvement of the eyes, the gastrointestinal system, and other organs. Gene located in PAR. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.6497 | SLC12A5 |
Zornitza Stark changed review comment from: Note LIMITED by ClinGen. However, note functional evidence including mouse model. Ten variants (missense, small in-frame deletions, and splicing) that have been reported in six probands in three publications (PMIDs: 26333769, 27436767, 31618474) are included in this curation. There is some preliminary evidence to suggest that the mechanism of pathogenicity may be loss of function. Electrophysiological studies showed reduced transporter activity of proteins with some variants, although few studies are available at this time (PMIDs: 26333769, 27436767). This gene-disease relationship is also supported by a knockout mouse model in which gentle handling or movement of the mother and littermates triggered seizures (PMID: 12000122). In summary, there is limited evidence to support this gene-disease relationship. Although more evidence is needed to support a causal role, no convincing evidence has emerged that contradicts the gene-disease relationship.; to: LIMITED by ClinGen. However, note functional evidence including mouse model and additional family in 38660387, again with supportive functional data. Ten variants (missense, small in-frame deletions, and splicing) that have been reported in six probands in three publications (PMIDs: 26333769, 27436767, 31618474) are included in this curation. There is some preliminary evidence to suggest that the mechanism of pathogenicity may be loss of function. Electrophysiological studies showed reduced transporter activity of proteins with some variants, although few studies are available at this time (PMIDs: 26333769, 27436767). This gene-disease relationship is also supported by a knockout mouse model in which gentle handling or movement of the mother and littermates triggered seizures (PMID: 12000122). In summary, there is limited evidence to support this gene-disease relationship. Although more evidence is needed to support a causal role, no convincing evidence has emerged that contradicts the gene-disease relationship. |
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| Intellectual disability syndromic and non-syndromic v0.6124 | PNPLA8 |
Chirag Patel gene: PNPLA8 was added gene: PNPLA8 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: PNPLA8 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PNPLA8 were set to PMID: 39082157 Phenotypes for gene: PNPLA8 were set to PNPLA8-related neurological diseases Review for gene: PNPLA8 was set to GREEN gene: PNPLA8 was marked as current diagnostic Added comment: Cohort analysis of clinical features of new and previously reported individuals with biallelic PNPLA8 variants (25 affected individuals across 20 families). They showed that PNPLA8-related neurological diseases manifest as a continuum ranging from variable developmental and/or degenerative epileptic-dyskinetic encephalopathy to childhood-onset neurodegeneration. Complete loss of PNPLA8 was associated with the more profound end of the spectrum. 13/19 individuals (info available) had developmental delay and/or severe intellectual disability. Using cerebral organoids generated from human induced pluripotent stem cells, they found that loss of PNPLA8 led to developmental defects by reducing the number of basal radial glial cells and upper-layer neurons. Neural progenitor cells lacking PNPLA8 showed a reduced amount of lysophosphatidic acid, lysophosphatidylethanolamine and phosphatidic acid. They show that PNPLA8 is crucial to meet phospholipid synthetic needs and to produce abundant basal radial glial cells in human brain development. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.6025 | ATXN7L3 |
Chirag Patel gene: ATXN7L3 was added gene: ATXN7L3 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: ATXN7L3 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: ATXN7L3 were set to PMID: 38753057 Phenotypes for gene: ATXN7L3 were set to Neurodevelopmental disorder, MONDO_0100500 Review for gene: ATXN7L3 was set to GREEN gene: ATXN7L3 was marked as current diagnostic Added comment: This study reports 9 unrelated individuals with de novo heterozygous variants in ATXN7L3 identified through WES testing and GeneMatcher. Core clinical features included: global motor and language developmental delay, hypotonia, and dysmorphic features (hypertelorism, epicanthal folds, blepharoptosis, small nose, small mouth, and low-set posteriorly rotated ears). Variable features included: feeding difficulties, seizures, mild periventricular leukomalacia, and structural cardiac abnormalities. A recurrent nonsense variant [p.(Arg114Ter)] was found in 5/9 individuals. The other variants were 1 frameshift [p.(Ser112LysfsTer12)] and 3 missense variants [p.(Ile71Thr), p.(Ser92Arg), and p.(Leu106Pro)]. They investigated the effects of the recurrent nonsense variant [p.(Arg114Ter)] in fibroblasts of an affected individual. ATXN7L3 protein levels were reduced, and deubiquitylation was impaired (as indicated by an increase in histone H2Bub1 levels). This is consistent with the previous observation of increased H2Bub1 levels in Atxn7l3-null mouse embryos, which have developmental delay and embryonic lethality. Pathogenic variants in deubiquitinating enzymes (DUBs) have been implicated in neurodevelopmental disorders (ND) and congenital abnormalities. ATXN7L3 is a component of the DUB module of the SAGA complex, and two other related DUB modules, and serves as an obligate adaptor protein of 3 ubiquitin-specific proteases (USP22, USP27X or USP51). Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.6001 | SSR4 | Katie Thompson reviewed gene: SSR4: Rating: GREEN; Mode of pathogenicity: None; Publications: PMID: 24218363, 26264460; Phenotypes: intellectual disabilities, hypotonia, microcephaly, seizures, Feeding problems, Facial dysmorphism, Gastrointestinal abnormalities, Failure to thrive, strabismus; Mode of inheritance: X-LINKED: hemizygous mutation in males, monoallelic mutations in females may cause disease (may be less severe, later onset than males) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.5821 | SLC25A15 |
Rajkumar Krishnaswamy changed review comment from: Rare genetic disorder representing a heterogeneous disease with high clinical variability. Pyramidal dysfunction, developmental, cognitive and behavioural abnormalities have been reported. ID/mental retardation ranging from mild, moderate to severe have been reported in several cases usually manifesting in the childhood or as adult onset.; to: Rare genetic disorder representing a heterogeneous disease with high clinical variability. Lethargy, feeding difficulties, seizures, pyramidal dysfunction, developmental, cognitive and behavioural abnormalities have been reported with various features exhibited at various stages of life e.g. neonates, infantile/childhood and adults. ID/mental retardation ranging from mild, moderate to severe have been reported in several cases usually manifesting in childhood or adults. |
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| Intellectual disability syndromic and non-syndromic v0.5821 | SLC25A15 | Rajkumar Krishnaswamy reviewed gene: SLC25A15: Rating: GREEN; Mode of pathogenicity: None; Publications: PMID: 18978333, 25874378; Phenotypes: Hyperornithinemia-hyperammonemia-homocitrullinemia syndrome, 238970, hyperammonemia, lethargy, somnolence, refusal to feed, vomiting, tachypnea with respiratory alkalosis, seizures, protein intolerance, developmental delay, spasticity, intellectual disability / mental retardation, dysarthria, learning disabilities, spasticity, liver dysfunction; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.5797 | SPR |
Amy Chiang edited their review of gene: SPR: Added comment: SPR has been classified to have definitive association with dopa-responsive dystonia (reviewed by the Aminoacidopathy Expert Panel on 06/04/2021). Clinical phenotypes are mainly neuromuscular with characteristic features of axial hypotonia, dystonia, delayed psychomotor development, oculogyric crises, diurnal fluctuation with improvement after sleep; though cognitive impairment ranging from mild to severe levels have been reported in patients with sepiapterin reductase deficiency (PMID: 16049044, 17188538) - 7 Maltese patients with the same homozygous spice variants in SPR (founder effect due to relative small Maltese population); note there was no significant improvement in cognitive ability with L-dopa treatment in these patients despite improvement in their motor abilities (PMID: 16049044) - ? other causes to cognitive impairment in these patients other than SPR associated sepiapterin reductase deficiency There are 271 SPR variants registered in ClinVar to date with only 1 submission from a research lab reported 2 affected individuals with intellectual disability + family history (ClinVar # 625209) - no publication available to verify, ? from BRIDGE consortium study: SPEED project cohort A start loss variant detected in 5 affected individuals with ID & epilepsy from a Persian consanguineous family - LOD score = 4.027 (PMID: 29302074); Changed publications: PMID: 29302074, 16049044, 17188538; Changed phenotypes: MONDO #0012994, OMIM #612716, axial hypotonia, dystonia with diurnal fluctuation, oculogyric crises, delayed psychomotor development, sepiapterin reductase deficiency |
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| Intellectual disability syndromic and non-syndromic v0.5796 | SPR |
Amy Chiang changed review comment from: SPR has been classified to have definitive association with dopa-responsive dystonia. This was reviewed by the Aminoacidopathy Expert Panel on 06/04/2021. There are 271 SPR variants registered in ClinVar to date with only 1 submission from a research lab reported 2 affected individuals with intellectual disability + family history (ClinVar # 625209) - no publication available to verify, ? from BRIDGE consortium study: SPEED project cohort A start loss variant detected in 5 affected individuals with ID & epilepsy from a Persian consanguineous family - LOD score = 4.027 (PMID: 29302074); to: SPR has been classified to have definitive association with dopa-responsive dystonia. This was reviewed by the Aminoacidopathy Expert Panel on 06/04/2021. There are 271 SPR variants registered in ClinVar to date with only 1 submission from a research lab reported 2 affected individuals with intellectual disability + family history (ClinVar # 625209) - no publication available to verify, ? from BRIDGE consortium study: SPEED project cohort A start loss variant detected in 5 affected individuals with ID & epilepsy from a Persian consanguineous family - LOD score = 4.027 (PMID: 29302074) |
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| Intellectual disability syndromic and non-syndromic v0.5768 | PURA | Ain Roesley Phenotypes for gene: PURA were changed from Neurodevelopmental disorder with neonatal respiratory insufficiency, hypotonia, and feeding difficulties (OMIM 616158) to Neurodevelopmental disorder with neonatal respiratory insufficiency, hypotonia, and feeding difficulties (OMIM 616158) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.5768 | PURA | Ain Roesley Phenotypes for gene: PURA were changed from Mental retardation, autosomal dominant 31, MIM# 616158 to Neurodevelopmental disorder with neonatal respiratory insufficiency, hypotonia, and feeding difficulties (OMIM 616158) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.5761 | SEPHS1 |
Zornitza Stark gene: SEPHS1 was added gene: SEPHS1 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: SEPHS1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: SEPHS1 were set to 38531365 Phenotypes for gene: SEPHS1 were set to Neurodevelopmental disorder, MONDO:0700092, SEPHS1-related Review for gene: SEPHS1 was set to GREEN Added comment: Nine individuals from eight families with developmental delay, growth and feeding problems, hypotonia, and dysmorphic features, all with heterozygous missense variants in SEPHS1. Eight of these individuals had a recurrent variant at amino acid position 371 of SEPHS1 (p.Arg371Trp, p.Arg371Gln, and p.Arg371Gly); seven of these variants were known to be de novo. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.5591 | ZFHX3 | Chirag Patel edited their review of gene: ZFHX3: Added comment: 41 patients with protein truncating variants (PTVs) or (partial) deletions of ZFHX3. Presentations included (mild) ID and/or behavioural problems, postnatal growth retardation, feeding difficulties, dysmorphism (rarely cleft palate). Nuclear abundance of ZFHX3 increases during human brain development and neuronal differentiation in neural stem cells and SH-SY5Y cells, ZFHX3 interacts with the chromatin remodelling BRG1/Brm-associated factor complex and the cleavage and polyadenylation complex. ZFHX3 haploinsufficiency associates with a specific DNA methylation profile in leukocyte-derived DNA, and participates in chromatin remodelling and mRNA processing.; Changed rating: GREEN; Changed publications: PMID: 37292950; Changed phenotypes: Neurodevelopmental disorder; Changed mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted; Set current diagnostic: yes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.5549 | SMARCA4 |
Claire Fryer-Smith changed review comment from: Coffin-Siris syndrome is a congenital malformation syndrome characterized by developmental delay, intellectual disability, coarse facial features, feeding difficulties, and hypoplastic or absent fifth fingernails and fifth distal phalanges. Missense and an in-frame deletion in SCARCA4 have been observed across 15 CSS patients in the literature (22426308, 23637025, 23929686), suggesting a dominant negative GoF effect. LoF variants in SMARCA4 result in Rhabdoid tumor predisposition syndrome, which does not exhibit ID.; to: Coffin-Siris syndrome is a congenital malformation syndrome characterized by developmental delay, intellectual disability, coarse facial features, feeding difficulties, and hypoplastic or absent fifth fingernails and fifth distal phalanges. Missense and an in-frame deletion in SMARCA4 have been observed across 15 CSS patients in the literature (22426308, 23637025, 23929686), suggesting a dominant negative GoF effect. LoF variants in SMARCA4 result in Rhabdoid tumor predisposition syndrome, which does not exhibit ID. |
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| Intellectual disability syndromic and non-syndromic v0.5250 | RPH3A |
Lucy Spencer gene: RPH3A was added gene: RPH3A was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: RPH3A was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: RPH3A were set to 37403762; 29441694 Phenotypes for gene: RPH3A were set to Neurodevelopmental disorder (MONDO#0700092), RPH3A-related Review for gene: RPH3A was set to GREEN Added comment: PMID: 37403762- 6 patients with RPH3A variant. All 6 have ID, 4 have epilepsy, 2 with obesity, 1 with dysmorphic features. All 6 have missense variants, 3 shown to be de novo, the other 3 parents were not available for testing. I patient also had language and motor impairment, breathing issues and mixed hypo/hypertonia- he also had variants in CUL4B, PRKAG2, SCN4A, none of these genes cause seizures (which he had). Patch clamp studies on 2 of the missense showed they increased either the number of NMDA receptors on neuron membrane surface or increased their conductance. Study suggests that the variants interrupt the normal role of RPH3A activity at the synaptic NMDAR complex which is needed for the induction of synaptic plasticity and NMDAR-dependant behaviours Also previously 1 biallelic patient was reported, PMID: 29441694- 1 girl with learning disabilities, tremors, ataxia, hyperglycemia and muscle fatigability. Chet for 2 RPH3A missense. Functional analysis showed strong and marginal impairment of protein binding for each variant. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.5234 | POU3F2 |
Sarah Pantaleo gene: POU3F2 was added gene: POU3F2 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: POU3F2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: POU3F2 were set to PMID: 37207645 Phenotypes for gene: POU3F2 were set to Autism spectrum disorder, NDD, and adolescent-onset obesity Penetrance for gene: POU3F2 were set to unknown Mode of pathogenicity for gene: POU3F2 was set to Other Review for gene: POU3F2 was set to GREEN Added comment: We associate ultra-rare variants in POU3F2, encoding a central nervous system transcription factor, with syndromic obesity and neurodevelopment delay in 12 individuals. Demonstrate variant pathogenicity through in vitro analysis. Used exome sequencing, GeneMatcher and Genomics England 100,000 Genomes Project rare disease database. Both truncating and missense variants in over 10 individuals sharing autism spectrum disorder, NDD, and adolescent-onset obesity (may have had other features eg. CAKUT in 2 individuals, diabetes in two) . Affected individuals presented with low-to-normal birth weight and infantile feeding difficulties but developed insulin resistance and hyperplasia during childhood. With the exception of an early truncating variant, the variants showed adequate nuclear translocation but overall disturbed DNA-binding ability and promoter activation. Variants absent from population and clinical databases. Almost all constituted putatively non-inherited de novo variants (8/10). Functional studies provide evidence for loss of function in eight and gain of function in one obesity-associated POU3F2 variant. One variant did not impact POU3F2-promoter activation, leaving the possibility for further path-mechanisms. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.5127 | SETD2 |
Zornitza Stark edited their review of gene: SETD2: Added comment: PMID 32710489: 12 unrelated patients, ranging from 1 month to 12 years of age, with a multisystemic neurodevelopmental disorder associated with a specific de novo heterozygous mutation in the SETD2 gene (R1740W). Key clinical features: severely impaired global development apparent from infancy, feeding difficulties with failure to thrive, small head circumference, and dysmorphic facial features. Affected individuals have impaired intellectual development and hypotonia; they do not achieve walking or meaningful speech. Other neurologic findings may include seizures, hearing loss, ophthalmologic defects, and brain imaging abnormalities. There is variable involvement of other organ systems, including skeletal, genitourinary, cardiac, and possibly endocrine. Further 3 unrelated patients identified with mild to moderately impaired intellectual development associated with a specific de novo heterozygous mutation in the SETD2 gene (R1740Q). These are distinct clinically from Luscan-Lumish syndrome, which is characterised by overgrowth.; Changed publications: 29681085, 32710489; Changed phenotypes: Luscan-Lumish syndrome, MIM#616831, Rabin-Pappas syndrome,MIM# 620155, Intellectual developmental disorder, autosomal dominant 70, MIM# 620157 |
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| Intellectual disability syndromic and non-syndromic v0.4986 | DPH5 |
Zornitza Stark gene: DPH5 was added gene: DPH5 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: DPH5 was set to BIALLELIC, autosomal or pseudoautosomal Phenotypes for gene: DPH5 were set to Neurodevelopmental disorder with short stature, prominent forehead, and feeding difficulties 620070 Review for gene: DPH5 was set to GREEN Added comment: 5 individuals from 3 unrelated families reported with severe ID, feeding difficulties, dysmorphic features and congenital anomalies, though there was no consistent pattern to these. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.4963 | NAPB |
Paul De Fazio gene: NAPB was added gene: NAPB was added to Intellectual disability syndromic and non-syndromic. 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 |
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| Intellectual disability syndromic and non-syndromic v0.4854 | KMT2B | Zornitza Stark edited their review of gene: KMT2B: Added comment: Nine individuals reported in PMID 33150406 with heterozygous variants in this gene and intellectual disability, speech delay, microcephaly, growth delay, feeding problems, and dysmorphic features, including epicanthic folds, posteriorly rotated ears, syndactyly/clinodactyly of toes, and fifth finger clinodactyly, normal MRIs and NO dystonia.; Changed publications: 33150406; Changed phenotypes: Dystonia 28, childhood-onset 617284, MONDO:0015004, Intellectual developmental disorder, autosomal dominant 68, MIM# 619934 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.4839 | TAF8 |
Zornitza Stark changed review comment from: Further 7 individuals reported from 4 families, three of which were consanguineous. Clinical features included severe psychomotor retardation with almost absent development, feeding problems, microcephaly, growth retardation, spasticity and epilepsy. Five had the previously reported c.781-1G > A variant in homozygous state. This is likely to be a founder variant. One family with different compound heterozygous variants.; to: Further 7 individuals reported from 4 families, three of which were consanguineous. Clinical features included severe psychomotor retardation with almost absent development, feeding problems, microcephaly, growth retardation, spasticity and epilepsy. Five had the previously reported c.781-1G > A variant in homozygous state. Unclear if this is a founder variant, families of different ethnicities. One family with different compound heterozygous variants. |
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| Intellectual disability syndromic and non-syndromic v0.4543 | NACC1 | Zornitza Stark Phenotypes for gene: NACC1 were changed from to Neurodevelopmental disorder with epilepsy, cataracts, feeding difficulties, and delayed brain myelination - MIM#617393 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.4540 | NACC1 | Zornitza Stark reviewed gene: NACC1: Rating: GREEN; Mode of pathogenicity: None; Publications: 28132692; Phenotypes: Neurodevelopmental disorder with epilepsy, cataracts, feeding difficulties, and delayed brain myelination - MIM#617393; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.4102 | CACNA1I |
Kristin Rigbye gene: CACNA1I was added gene: CACNA1I was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: CACNA1I was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: CACNA1I were set to 33704440 Phenotypes for gene: CACNA1I were set to Neurodevelopmental disorder Mode of pathogenicity for gene: CACNA1I was set to Other Review for gene: CACNA1I was set to GREEN Added comment: 4 different missense variants identified and shown to result in a gain of function. 2 individuals with de novo variants (a 3rd also suspected de novo but their father was unavailable for testing) - these patients all had severe neurodevelopmental disorders, involving severe global developmental delay, absence of speech, gross motor delay, muscular hypotonia, early-onset seizures, cortical visual impairment, and feeding difficulties. Variable clinical features include various brain malformations, startle response or seizures, postnatal growth retardation, gastroesophageal reflux, and gastrostomy. 1 family had three affected individuals - variable cognitive impairment in all, involving borderline intellectual functioning or mild or moderate intellectual disability as main clinical feature, with late-onset seizures in the mother and speech retardation in one of the children. This variant had a milder functional effect than the variants in sporadic cases. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.4070 | ZNF699 |
Zornitza Stark gene: ZNF699 was added gene: ZNF699 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: ZNF699 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: ZNF699 were set to 33875846 Phenotypes for gene: ZNF699 were set to DEGCAGS syndrome, MIM# 619488 Review for gene: ZNF699 was set to GREEN Added comment: DEGCAGS syndrome is a neurodevelopmental disorder characterized by global developmental delay, coarse and dysmorphic facial features, and poor growth and feeding apparent from infancy. Affected individuals have variable systemic manifestations often with significant structural defects of the cardiovascular, genitourinary, gastrointestinal, and/or skeletal systems. Additional features may include sensorineural hearing loss, hypotonia, anaemia or pancytopaenia, and immunodeficiency with recurrent infections. 12 unrelated families reported, 5 different homozygous frameshift variants. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.4041 | JAKMIP1 |
Seb Lunke gene: JAKMIP1 was added gene: JAKMIP1 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: JAKMIP1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: JAKMIP1 were set to 29158550; 26627310; 27799067 Phenotypes for gene: JAKMIP1 were set to Intellectual disability; Seizures Review for gene: JAKMIP1 was set to AMBER Added comment: Identified in two independent patients in the literature with a mouse model. Patient 1 (27799067) with developmental delay, speech delay, and cognitive impairment; self-injurious and aggressive behaviour, seizures, dysmorphic features. De-novo missense JAKMIP1 (p.D586H). Patient 2 (29158550) with feeding difficulties, hypotonia, epilepsy, severe ID, no active speech, kyphoscoliosis, constipation, autism, short stature. Splice variant c.1432-2A>G, no segregation or RNA data available. KO mouse model (27799067) displays social deficits, stereotyped activity, abnormal postnatal vocalizations, and other autistic-like behaviors. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.4040 | PIDD1 |
Konstantinos Varvagiannis gene: PIDD1 was added gene: PIDD1 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: PIDD1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PIDD1 were set to 28397838; 29302074; 33414379; 34163010 Phenotypes for gene: PIDD1 were set to Global developmental delay; Intellectual disability; Seizures; Autism; Behavioral abnormality; Psychosis; Pachygyria; Lissencephaly; Abnormality of the corpus callosum Penetrance for gene: PIDD1 were set to Complete Review for gene: PIDD1 was set to GREEN Added comment: There is enough evidence to include this gene in the current panel with green rating. Biallelic PIDD1 pathogenic variants have been reported in 26 individuals (11 families) with DD (all), variable degrees of ID (mild to severe), behavioral (eg. aggression/self-mutilation in several, ADHD) and/or psychiatric abnormalities (ASD, psychosis in 5 belonging to 3 families), well-controlled epilepsy is some (9 subjects from 6 families) and MRI abnormalities notably abnormal gyration pattern (pachygyria with predominant anterior gradient) as well as corpus callosum anomalies (commonly thinning) in several. Dysmorphic features have been reported in almost all, although there has been no specific feature suggested. The first reports on the phenotype associated with biallelic PIDD1 mutations were made by Harripaul et al (2018 - PMID: 28397838) and Hu et al (2019 - PMID: 29302074) [both studies investigating large cohorts of individuals with ID from consanguineous families]. Sheikh et al (2021 - PMID: 33414379) provided details on the phenotype of 15 individuals from 5 families including those from the previous 2 reports and studied provided evidence on the role of PIDD1 and the effect of variants. Zaki et al (2021 - PMID: 34163010) reported 11 additional individuals from 6 consanguineous families, summarize the features of all subjects published in the literature and review the neuroradiological features of the disorder. PIDD1 encodes p53-induced death domain protein 1. The protein is part of the PIDDosome, a multiprotein complex also composed of the bipartite linker protein CRADD (also known as RAIDD) and the proform of caspase-2 and induces apoptosis in response to DNA damage. There are 5 potential PIDD1 mRNA transcript variants with NM_145886.4 corresponding to the longest. Similar to the protein encoded by CRADD, PIDD1 contains a death domain (DD - aa 774-893). Constitutive post-translational processing gives PIDD1-N, PIDD1-C the latter further processed into PIDD1-CC (by auto-cleavage). Serine residues at pos. 446 and 588 are involved in this autoprocessing generating PIDD1-C (aa 446-910) and PIDD1-CC (aa 774-893). The latter is needed for caspase-2 activation. Most (if not all) individuals belonged to consanguineous families of different origins and harbored pLoF or missense variants. Variants reported so far include : c.2587C>T; p.Gln863* / c.1909C>T ; p.Arg637* / c.2443C>T / p.Arg815Trp / c.2275-1G>A which upon trap assay was shown to lead to skipping of ex15 with direct splicing form exon14 to the terminal exon 16 (resulting to p.Arg759Glyfs*1 with exlcusion of the entire DD) / c.2584C>T; p.Arg862Trp / c.1340G>A; p.Trp447* / c.2116_2120del; p.Val706His*, c.1564_1565del; p.Gly602fs*26 Evidence so far provided includes: - Biallelic CRADD variants cause a NDD disorder and a highly similar gyration pattern. - Confirmation of splicing effect (eg. for c.2275-1G>A premature stop in position 760) or poor expression (NM_145886.3:c.2587C>T; p.Gln863*). Arg815Trp did not affect autoprocessing or protein stability. - Abnormal localization pattern, loss of interaction with CRADD and failure to activate caspase-2 (MDM2 cleavage assay) [p.Gln863* and Arg815Trp] - Available expression data from GTEx (PIDD1 having broad expression in multiple tissues, but higher in brain cerebellum) as well as BrainSpan and PsychEncode studies suggesting high coexpression of PIDD1, CRADD and CASP2 in many regions in the developing human brain. - Variants in other genes encoding proteins interacting with PIDD1 (MADD, FADD, DNAJ, etc) are associated with NDD. Pidd-1 ko mice (ex3-15 removal) lack however CNS-related phenotypes. These show decreased anxiety but no motor anomalies. This has also been the case with Cradd-/- mice displaying no significant CNS phenotypes without lamination defects. There is currently no associated phenotype in OMIM, PanelApp Australia. PIDD1 is listed in the DD panel of G2P (PIDD1-related NDD / biallelic / loss of function / probable) . SysID includes PIDD1 among the current primary ID genes. Overall the gene appears to be relevant for the epilepsy panel, panels for gyration and/or corpus callosum anomalies etc. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.4020 | CLCN3 |
Zornitza Stark gene: CLCN3 was added gene: CLCN3 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: CLCN3 was set to BOTH monoallelic and biallelic (but BIALLELIC mutations cause a more SEVERE disease form), autosomal or pseudoautosomal Publications for gene: CLCN3 were set to 34186028 Phenotypes for gene: CLCN3 were set to Neurodevelopmental disorder Mode of pathogenicity for gene: CLCN3 was set to Other Review for gene: CLCN3 was set to GREEN Added comment: 11 individuals reported, 9 that carried 8 different rare heterozygous missense variants in CLCN3, and 2 siblings that were homozygous for an NMD-predicted frameshift variant likely abolishing ClC-3 function. All missense variants were confirmed to be de novo in eight individuals for whom parental data was available. The 11 individuals in the cohort share clinical features of variable severity. All 11 have GDD or ID and dysmorphic features, and a majority has mood or behavioural disorders and structural brain abnormalities: - Structural brain abnormalities on MRI (9/11) included partial or full agenesis of the corpus callosum (6/9), disorganized cerebellar folia (4/9), delayed myelination (3/9), decreased white matter volume (3/9), pons hypoplasia (3/9), and dysmorphic dentate nuclei (3/9). Six of those with brain abnormalities also presented with seizures. - Nine have abnormal vision, including strabismus in four and inability to fix or follow in the two with homozygous loss-of-function variants. - Hypotonia ranging from mild to severe was reported in 7 of the 11 individuals. - Six have mood or behavioural disorders, particularly anxiety (3/6). - Consistent dysmorphic facial features included microcephaly, prominent forehead, hypertelorism, down-slanting palpebral fissures, full cheeks, and micrognathia. The severity of disease in the two siblings with homozygous disruption of ClC-3 is consistent with the drastic phenotype seen in Clcn3 KO mice. The disease was more severe in two siblings carrying homozygous loss-of-function variants with the presence of GDD, absent speech, seizures, and salt and pepper fundal pigmentation in both individuals, with one deceased at 14 months of age. The siblings also had significant neuroanatomical findings including diffusely decreased white matter volume, thin corpora callosa, small hippocampi, and disorganized cerebellar folia. Supporting biallelic inheritance for LoF variants, disruption of mouse Clcn3 results in drastic neurodegeneration with loss of the hippocampus a few months after birth and early retinal degeneration. Clcn3−/− mice display severe neurodegeneration, whereas heterozygous Clcn3+/− mice appear normal. Patch-clamp studies were used to investigate four of the missense variants. These suggested a gain of function in two variants with increased current in HEK cells, however they also showed reduced rectification of voltage and a loss of transient current, plus decreased current amplitude, glycosylation and surface expression when expressed in oocytes, and were suspected to interfere with channel gating and a negative feedback mechanism. These effects were also shown to vary depending on pH levels. The current of the remaining two variants did not differ from WT. For heterozygous missense variants, the disruption induced may be at least partially conferred to mutant/WT homodimers and mutant/ClC-4 heterodimers. Both loss and gain of function in this gene resulted in the same phenotype. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.3968 | RNF2 |
Zornitza Stark gene: RNF2 was added gene: RNF2 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: RNF2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: RNF2 were set to 33864376 Phenotypes for gene: RNF2 were set to epilepsy; intellectual disability; intrauterine growth retardation Review for gene: RNF2 was set to AMBER Added comment: Not associated with any phenotype in OMIM. PMID:33864376 (Luo et al 2021) report 2 cases of children with de novo missense variants (p.R70H and p.S82R) in RNF2 and a phenotype of intrauterine growth retardation, severe intellectual disabilities, behavioral problems, seizures, feeding difficulties and dysmorphic features. Seizures started in infancy. Both variants are absent from gnomad. Functional studies in Drosophila showed that the disease-linked variants (p.R70H and p.S82R) behave as LoF alleles. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.3847 | PGM2L1 |
Chern Lim gene: PGM2L1 was added gene: PGM2L1 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: PGM2L1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PGM2L1 were set to 33979636 Phenotypes for gene: PGM2L1 were set to Neurodevelopmental disorder Review for gene: PGM2L1 was set to GREEN gene: PGM2L1 was marked as current diagnostic Added comment: PMID: 33979636: - Hom/chet PTVs in 4 unrelated individuals. All four affected individuals had severe developmental and speech delay, dysmorphic facial features, ear anomalies, high arched palate, strabismus, hypotonia, and keratosis pilaris. Early obesity and seizures were present in three individuals. - Studies on patient fibroblasts and cell lines indicated that PGM2L1 deficiency causes a decrease, but not a disappearance, of the sugar bisphosphates needed for the formation of NDP-sugars and that there is no evidence that this leads to a glycosylation defect. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.3668 | FAR1 | Zornitza Stark edited their review of gene: FAR1: Added comment: PMID 33239752: 12 patients with paediatric onset spastic paraparesis and bilateral congenital/juvenile cataracts. Most also had speech and gross motor developmental delay and truncal hypotonia. Exome sequencing identified de novo variants affecting the Arg480 residue in FAR1 (p.Arg480Cys/His/Leu). Further functional studies in fibroblasts showed that these variants cause a disruption of the plasmalogen-dependent feedback regulation of FAR1 protein levels leading to uncontrolled ether lipid production.; Changed rating: GREEN; Changed publications: 25439727, 33239752; Changed phenotypes: Peroxisomal fatty acyl-CoA reductase 1 disorder, MIM#616154, spastic paraparesis and bilateral cataracts; Changed mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3538 | SATB1 |
Zornitza Stark edited their review of gene: SATB1: Added comment: Kohlschutter-Tonz syndrome-like (KTZSL) is characterized by global developmental delay with moderately to severely impaired intellectual development, poor or absent speech, and delayed motor skills. Although the severity of the disorder varies, many patients are nonverbal and have hypotonia with inability to sit or walk. Early-onset epilepsy is common and may be refractory to treatment, leading to epileptic encephalopathy and further interruption of developmental progress. Most patients have feeding difficulties with poor overall growth and dysmorphic facial features, as well as significant dental anomalies resembling amelogenesis imperfecta. This phenotype was reported in 28 patients (patients 13 to 40, PMID 33513338), including 9 patients from 3 families. Most variants were de novo, though some were inherited, suggestive of incomplete penetrance and variable expressivity. Developmental delay with dysmorphic facies and dental anomalies (DEFDA) is characterized by generally mild global developmental delay with variably impaired intellectual development, walking by 2 to 3 years, and slow language acquisition. The severity of the disorder ranges from moderate cognitive deficits to mild learning difficulties or behavioral abnormalities. Most patients have dysmorphic facial features, often with abnormal dentition and nonspecific visual defects, such as myopia, astigmatism, and strabismus. Although rare, involvement of other systems, such as skeletal, cardiac, and gastrointestinal, may be present. 12 individuals from 11 families reported (one inherited variant, affected parent).; Changed phenotypes: Kohlschutter-Tonz syndrome-like, MIM# 619229, Developmental delay with dysmorphic facies and dental anomalies, MIM# 619228, Developmental disorders |
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| Intellectual disability syndromic and non-syndromic v0.3457 | LMNB1 | Zornitza Stark Phenotypes for gene: LMNB1 were changed from Global developmental delay, Intellectual disability, Microcephaly, Short stature, Seizures, Abnormality of the corpus callosum, Cortical gyral simplification, Feeding difficulties, Scoliosis; Leukodystrophy, adult-onset, autosomal dominant, MIM#169500 to Microcephaly 26, primary, autosomal dominant, MIM# 619179; Global developmental delay, Intellectual disability, Microcephaly, Short stature, Seizures, Abnormality of the corpus callosum, Cortical gyral simplification, Feeding difficulties, Scoliosis; Leukodystrophy, adult-onset, autosomal dominant, MIM#169500 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3394 | EED | Zornitza Stark Marked gene: EED as ready | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3394 | EED | Zornitza Stark Gene: eed has been classified as Green List (High Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3394 | EED | Zornitza Stark Phenotypes for gene: EED were changed from to Cohen-Gibson syndrome, MIM# 617561 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3393 | EED | Zornitza Stark Publications for gene: EED were set to | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3392 | EED | Zornitza Stark Mode of inheritance for gene: EED was changed from Unknown to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3391 | EED | Zornitza Stark reviewed gene: EED: Rating: GREEN; Mode of pathogenicity: None; Publications: 25787343, 27193220, 27868325, 28229514; Phenotypes: Cohen-Gibson syndrome, MIM# 617561; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3251 | VPS4A |
Elena Savva changed review comment from: Comment when marking as ready: PMID: 33186543 - 2x de novo hetorozygous missense variants in the AAA (large ATPase) domain. 1x homozygous missense in the MIT domain (milder phenotype and unaffected parents - possibly just a simple LoF mechanism for AR inheritance). Demonstrated defective CD71 trafficking in all 3 patients. PMID: 33186545 - 6x probands with de novo missense variants in the AAA domain. 5 of the variants were at amino acid position 284 (changes to Trp and Gly). Demonstrated that the variants had a dominant-negative effect on VPS4A function. "The six probands with de novo substitutions affecting Glu206 or Arg284 had a consistent phenotype characterized by severe DD, profound ID, and dystonia. Children were very delayed in establishing head control and none achieved independent walking. Other common findings were cerebellar hypoplasia (five individuals out of six, the other showing uncharacterized severe cerebral atrophy) with a variable degree of corpus callosum hypoplasia. One individual also had bilateral polymicrogyria. Epilepsy was present in three and dystonia in five subjects. Eye involvement was also a common finding, including congenital cataract, retinal dystrophy, and in one case congenital Leber amaurosis. Four individuals were diagnosed with hepatosplenomegaly and/or steatosis. Three subjects had anemia, which was characterized as dyserythropoietic in two. Severe feeding difficulties were present in four individuals, requiring assisted feeding in three. Two had sensorineural deafness. Severe growth retardation, generally for all parameters, was present in most cases. Notably, severe microcephaly (typically with Z scores < −5) was universal. Overall, the disorder seems to have a poor prognosis as two affected individuals died in childhood or early adult life."; to: PMID: 33186543 - 2x de novo hetorozygous missense variants in the AAA (large ATPase) domain. 1x homozygous missense in the MIT domain (milder phenotype and unaffected parents - possibly just a simple LoF mechanism for AR inheritance). Demonstrated defective CD71 trafficking in all 3 patients. PMID: 33186545 - 6x probands with de novo missense variants in the AAA domain. 5 of the variants were at amino acid position 284 (changes to Trp and Gly). Demonstrated that the variants had a dominant-negative effect on VPS4A function. "The six probands with de novo substitutions affecting Glu206 or Arg284 had a consistent phenotype characterized by severe DD, profound ID, and dystonia. Children were very delayed in establishing head control and none achieved independent walking. Other common findings were cerebellar hypoplasia (five individuals out of six, the other showing uncharacterized severe cerebral atrophy) with a variable degree of corpus callosum hypoplasia. One individual also had bilateral polymicrogyria. Epilepsy was present in three and dystonia in five subjects. Eye involvement was also a common finding, including congenital cataract, retinal dystrophy, and in one case congenital Leber amaurosis. Four individuals were diagnosed with hepatosplenomegaly and/or steatosis. Three subjects had anemia, which was characterized as dyserythropoietic in two. Severe feeding difficulties were present in four individuals, requiring assisted feeding in three. Two had sensorineural deafness. Severe growth retardation, generally for all parameters, was present in most cases. Notably, severe microcephaly (typically with Z scores < −5) was universal. Overall, the disorder seems to have a poor prognosis as two affected individuals died in childhood or early adult life." |
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| Intellectual disability syndromic and non-syndromic v0.3251 | VPS4A | Elena Savva Added comment: Comment when marking as ready: PMID: 33186543 - 2x de novo hetorozygous missense variants in the AAA (large ATPase) domain. 1x homozygous missense in the MIT domain (milder phenotype and unaffected parents - possibly just a simple LoF mechanism for AR inheritance). Demonstrated defective CD71 trafficking in all 3 patients. PMID: 33186545 - 6x probands with de novo missense variants in the AAA domain. 5 of the variants were at amino acid position 284 (changes to Trp and Gly). Demonstrated that the variants had a dominant-negative effect on VPS4A function. "The six probands with de novo substitutions affecting Glu206 or Arg284 had a consistent phenotype characterized by severe DD, profound ID, and dystonia. Children were very delayed in establishing head control and none achieved independent walking. Other common findings were cerebellar hypoplasia (five individuals out of six, the other showing uncharacterized severe cerebral atrophy) with a variable degree of corpus callosum hypoplasia. One individual also had bilateral polymicrogyria. Epilepsy was present in three and dystonia in five subjects. Eye involvement was also a common finding, including congenital cataract, retinal dystrophy, and in one case congenital Leber amaurosis. Four individuals were diagnosed with hepatosplenomegaly and/or steatosis. Three subjects had anemia, which was characterized as dyserythropoietic in two. Severe feeding difficulties were present in four individuals, requiring assisted feeding in three. Two had sensorineural deafness. Severe growth retardation, generally for all parameters, was present in most cases. Notably, severe microcephaly (typically with Z scores < −5) was universal. Overall, the disorder seems to have a poor prognosis as two affected individuals died in childhood or early adult life." | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3250 | VPS4A |
Kristin Rigbye gene: VPS4A was added gene: VPS4A was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: VPS4A was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: VPS4A were set to 33186543; 33186545 Phenotypes for gene: VPS4A were set to Neurodevelopmental disorder Review for gene: VPS4A was set to GREEN Added comment: PMID: 33186543 - 2x de novo hetorozygous missense variants in the AAA (large ATPase) domain. 1x homozygous missense in the MIT domain (milder phenotype and unaffected parents - possibly just a simple LoF mechanism for AR inheritance). Demonstrated defective CD71 trafficking in all 3 patients. PMID: 33186545 - 6x probands with de novo missense variants in the AAA domain. 5 of the variants were at amino acid position 284 (changes to Trp and Gly). Demonstrated that the variants had a dominant-negative effect on VPS4A function. "The six probands with de novo substitutions affecting Glu206 or Arg284 had a consistent phenotype characterized by severe DD, profound ID, and dystonia. Children were very delayed in establishing head control and none achieved independent walking. Other common findings were cerebellar hypoplasia (five individuals out of six, the other showing uncharacterized severe cerebral atrophy) with a variable degree of corpus callosum hypoplasia. One individual also had bilateral polymicrogyria. Epilepsy was present in three and dystonia in five subjects. Eye involvement was also a common finding, including congenital cataract, retinal dystrophy, and in one case congenital Leber amaurosis. Four individuals were diagnosed with hepatosplenomegaly and/or steatosis. Three subjects had anemia, which was characterized as dyserythropoietic in two. Severe feeding difficulties were present in four individuals, requiring assisted feeding in three. Two had sensorineural deafness. Severe growth retardation, generally for all parameters, was present in most cases. Notably, severe microcephaly (typically with Z scores < −5) was universal. Overall, the disorder seems to have a poor prognosis as two affected individuals died in childhood or early adult life." Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.3078 | CSNK1G1 |
Konstantinos Varvagiannis changed review comment from: Gold et al (2020 - PMID: 33009664) report 5 individuals with CSNK1G1 variants, including updated information on a previously reported subject (Martin et al 2014 - PMID: 24463883). Features included DD (5/5) with associated expressive language delay, ASD (in at least 3/5), seizures (2/5), dysmorphic facial features (4/5 arched eyebrows, 3/5 prominent central incisors, 2/5 epicanthus) and limb anomalies (2/5 - proximally placed thumb, 5th f. clinodactyly, asymmetric overgrowth - the other individual had tapering fingers). GI problems were observed in 4/5. Two individuals had macrocephaly and one had microcephaly. There was no formal developmental assessment although ID might be implied in at least 3 individuals (p1: 20y - single words/regression in walking following a seizure episode, p2: 8y - first words at 5y, assistance to feed, dress and bathe, ASD, p4: 13y - regression, assistance to feed and dress). CSNK1G1 encodes the gamma-1 isoform of casein kinase 1, a protein involved in growth and cell morphogenesis. The gene has ubiquitous expression, incl. brain. As commented, in brain it regulates phosphorylation of NMDA receptors, playing a role in synaptic transmission (4 articles cited). One individual had a 1.2 kb deletion spanning exon 3 of CSNK1G1 [chr15:64550952-64552120 - GRCh37]. Parental samples were unavailable for this individual. Four individuals were found to harbor de novo CSNK1G1 variants [NM_022048.3: c.688C>T - p.(Arg230Trp) dn | c.1255C>T - p.(Gln419*) dn | c.1214+5G>A dn with in silico predictions in favor of splice disruption | c.419C>T - p.(Thr140Met) dn]. Arg230Trp is however present once in gnomAD. The stopgain variant is located in the last exon and predicted to skip NMD. There were no variant studies performed. The Drosophila gish gene encodes a CK1γ homolog with preferential expression in the mushroom body. Heterozygous and homozygous mutants exhibit impairment in memory retention, more severe in homozygous flies. gish was also identified as a seizure modifier in a fly epilepsy model (heterozygous para mt flies). The authors also speculate that impaired transduction of LRP6 (and WNT signaling) might be implicated. Finally the authors discuss the phenotype of individuals in Decipher one of whom (327861) harbors a frameshift variant and presenting ID, epilepsy and progressive spasticity. [NB. Inheritance of this variant is not specified, while this individual has a further inherited SCN2A missense SNV]. Two further Decipher cases with microdeletions spanning CSNK1G1 (and additional variants) are also discussed. Overall, this gene can be considered for inclusion with probably amber rating. Sources: Literature; to: Gold et al (2020 - PMID: 33009664) report 5 individuals with CSNK1G1 variants, including updated information on a previously reported subject (Martin et al 2014 - PMID: 24463883). Features included DD (5/5) with associated expressive language delay, ASD (in at least 3/5), seizures (2/5), dysmorphic facial features (4/5 arched eyebrows, 3/5 prominent central incisors, 2/5 epicanthus) and limb anomalies (2/5 - proximally placed thumb, 5th f. clinodactyly, asymmetric overgrowth - the other individual had tapering fingers). GI problems were observed in 4/5. Two individuals had macrocephaly and one had microcephaly. There was no formal developmental assessment although ID might be implied in at least 3 individuals (p1: 20y - single words/regression in walking following a seizure episode, p2: 8y - first words at 5y, assistance to feed, dress and bathe, ASD, p4: 13y - regression, assistance to feed and dress). CSNK1G1 encodes the gamma-1 isoform of casein kinase 1, a protein involved in growth and cell morphogenesis. The gene has ubiquitous expression, incl. brain. As commented, in brain it regulates phosphorylation of NMDA receptors, playing a role in synaptic transmission (4 articles cited). One individual had a 1.2 kb deletion spanning exon 3 of CSNK1G1 [chr15:64550952-64552120 - GRCh37]. Parental samples were unavailable for this individual. Four individuals were found to harbor de novo CSNK1G1 variants [NM_022048.3: c.688C>T - p.(Arg230Trp) dn | c.1255C>T - p.(Gln419*) dn | c.1214+5G>A dn with in silico predictions in favor of splice disruption | c.419C>T - p.(Thr140Met) dn]. Arg230Trp is however present once in gnomAD. The stopgain variant is located in the last exon and predicted to skip NMD. There were no variant studies performed. The Drosophila gish gene encodes a CK1γ homolog with preferential expression in the mushroom body. Heterozygous and homozygous mutants exhibit impairment in memory retention, more severe in homozygous flies. gish was also identified as a seizure modifier in a fly epilepsy model (heterozygous para mt flies). The authors also speculate that impaired transduction of LRP6 (and WNT signaling) might be implicated. Finally the authors discuss the phenotype of individuals in Decipher one of whom (327861) harbors a frameshift variant and presented ID, epilepsy and progressive spasticity. [NB. Inheritance of this variant is not specified, while this individual has a further inherited SCN2A missense SNV]. Two further Decipher cases with microdeletions spanning CSNK1G1 (and additional variants) are also discussed. Overall, this gene can be considered for inclusion with probably amber rating. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.3078 | CSNK1G1 |
Konstantinos Varvagiannis changed review comment from: Gold et al (2020 - PMID: 33009664) report 5 individuals with CSNK1G1 variants, including updated information on a previously reported subject (Martin et al 2014 - PMID: 24463883). Features included DD (5/5) with associated expressive language delay, ASD (in at least 3/5), seizures (2/5), dysmorphic facial features (4/5 arched eyebrows, 3/5 prominent central incisors, 2/5 epicanthus) and limb anomalies (2/5 - proximally placed thumb, 5th f. clinodactyly, asymmetric overgrowth - the other individual had tapering fingers). GI problems were observed in 4/5. Two individuals had macrocephaly and one had microcephaly. There was no formal developmental assessment although ID might be implied in at least 3 individuals (p1: 20y - single words/regression in walking following a seizure episode, p2: 8y - first words at 5y, assistance to feed, dress and bathe, ASD, p4: 13y - regression, assistance to feed and dress). CSNK1G1 encodes the gamma-1 isoform of casein kinase 1, a protein involved in growth and cell morphogenesis. The gene has ubiquitous expression, incl. brain. As commented, in brain it regulates phosphorylation of NMDA receptors, playing a role in synaptic transmission (4 articles cited). One individual had a 1.2 kb deletion spanning exon 3 of CSNK1G1 [chr15:64550952-64552120 - GRCh37]. Parental samples were unavailable for this individual. Four individuals were found to harbor de novo CSNK1G1 variants [NM_022048.3: c.688C>T - p.(Arg230Trp) dn | c.1255C>T - p.(Gln419*) dn | c.1214+5G>A dn with in silico predictions in favor of splice disruption | c.419C>T - p.(Thr140Met) dn]. Arg230Trp is however present once in gnomAD. The stopgain variant is located in the last exon and predicted to skip NMD. There were no variant studies performed. The Drosophila gish gene encodes a CK1γ homolog with preferential expression in the mushroom body. Heterozygous and homozygous mutants exhibit impairment in memory retention, more severe in homozygous flies. gish was also identified as a seizure modifier in a fly epilepsy model (heterozygous para mt flies). The authors also speculate that impaired transduction of LRP6 (and WNT signaling) might be implicated. Finally the authors discuss the phenotype of individuals in Decipher one of whom (327861) harbors a frameshift variant and presenting ID, epilepsy and progressive spasticity. [NB. Inheritance of this variant is not specified, while this individual has a further inherited SCN2A missense SNV]. Two further Decipher cases with microdeletions spanning CSNK1G1 (and additional variants) also discussed. Overall, this gene can be considered for inclusion with probably amber rating. Sources: Literature; to: Gold et al (2020 - PMID: 33009664) report 5 individuals with CSNK1G1 variants, including updated information on a previously reported subject (Martin et al 2014 - PMID: 24463883). Features included DD (5/5) with associated expressive language delay, ASD (in at least 3/5), seizures (2/5), dysmorphic facial features (4/5 arched eyebrows, 3/5 prominent central incisors, 2/5 epicanthus) and limb anomalies (2/5 - proximally placed thumb, 5th f. clinodactyly, asymmetric overgrowth - the other individual had tapering fingers). GI problems were observed in 4/5. Two individuals had macrocephaly and one had microcephaly. There was no formal developmental assessment although ID might be implied in at least 3 individuals (p1: 20y - single words/regression in walking following a seizure episode, p2: 8y - first words at 5y, assistance to feed, dress and bathe, ASD, p4: 13y - regression, assistance to feed and dress). CSNK1G1 encodes the gamma-1 isoform of casein kinase 1, a protein involved in growth and cell morphogenesis. The gene has ubiquitous expression, incl. brain. As commented, in brain it regulates phosphorylation of NMDA receptors, playing a role in synaptic transmission (4 articles cited). One individual had a 1.2 kb deletion spanning exon 3 of CSNK1G1 [chr15:64550952-64552120 - GRCh37]. Parental samples were unavailable for this individual. Four individuals were found to harbor de novo CSNK1G1 variants [NM_022048.3: c.688C>T - p.(Arg230Trp) dn | c.1255C>T - p.(Gln419*) dn | c.1214+5G>A dn with in silico predictions in favor of splice disruption | c.419C>T - p.(Thr140Met) dn]. Arg230Trp is however present once in gnomAD. The stopgain variant is located in the last exon and predicted to skip NMD. There were no variant studies performed. The Drosophila gish gene encodes a CK1γ homolog with preferential expression in the mushroom body. Heterozygous and homozygous mutants exhibit impairment in memory retention, more severe in homozygous flies. gish was also identified as a seizure modifier in a fly epilepsy model (heterozygous para mt flies). The authors also speculate that impaired transduction of LRP6 (and WNT signaling) might be implicated. Finally the authors discuss the phenotype of individuals in Decipher one of whom (327861) harbors a frameshift variant and presenting ID, epilepsy and progressive spasticity. [NB. Inheritance of this variant is not specified, while this individual has a further inherited SCN2A missense SNV]. Two further Decipher cases with microdeletions spanning CSNK1G1 (and additional variants) are also discussed. Overall, this gene can be considered for inclusion with probably amber rating. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.3078 | CSNK1G1 |
Konstantinos Varvagiannis gene: CSNK1G1 was added gene: CSNK1G1 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: CSNK1G1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: CSNK1G1 were set to 33009664 Phenotypes for gene: CSNK1G1 were set to Global developmental delay; Intellectual disability; Autism; Seizures; Abnormality of the face; Abnromality of limbs Penetrance for gene: CSNK1G1 were set to unknown Review for gene: CSNK1G1 was set to AMBER Added comment: Gold et al (2020 - PMID: 33009664) report 5 individuals with CSNK1G1 variants, including updated information on a previously reported subject (Martin et al 2014 - PMID: 24463883). Features included DD (5/5) with associated expressive language delay, ASD (in at least 3/5), seizures (2/5), dysmorphic facial features (4/5 arched eyebrows, 3/5 prominent central incisors, 2/5 epicanthus) and limb anomalies (2/5 - proximally placed thumb, 5th f. clinodactyly, asymmetric overgrowth - the other individual had tapering fingers). GI problems were observed in 4/5. Two individuals had macrocephaly and one had microcephaly. There was no formal developmental assessment although ID might be implied in at least 3 individuals (p1: 20y - single words/regression in walking following a seizure episode, p2: 8y - first words at 5y, assistance to feed, dress and bathe, ASD, p4: 13y - regression, assistance to feed and dress). CSNK1G1 encodes the gamma-1 isoform of casein kinase 1, a protein involved in growth and cell morphogenesis. The gene has ubiquitous expression, incl. brain. As commented, in brain it regulates phosphorylation of NMDA receptors, playing a role in synaptic transmission (4 articles cited). One individual had a 1.2 kb deletion spanning exon 3 of CSNK1G1 [chr15:64550952-64552120 - GRCh37]. Parental samples were unavailable for this individual. Four individuals were found to harbor de novo CSNK1G1 variants [NM_022048.3: c.688C>T - p.(Arg230Trp) dn | c.1255C>T - p.(Gln419*) dn | c.1214+5G>A dn with in silico predictions in favor of splice disruption | c.419C>T - p.(Thr140Met) dn]. Arg230Trp is however present once in gnomAD. The stopgain variant is located in the last exon and predicted to skip NMD. There were no variant studies performed. The Drosophila gish gene encodes a CK1γ homolog with preferential expression in the mushroom body. Heterozygous and homozygous mutants exhibit impairment in memory retention, more severe in homozygous flies. gish was also identified as a seizure modifier in a fly epilepsy model (heterozygous para mt flies). The authors also speculate that impaired transduction of LRP6 (and WNT signaling) might be implicated. Finally the authors discuss the phenotype of individuals in Decipher one of whom (327861) harbors a frameshift variant and presenting ID, epilepsy and progressive spasticity. [NB. Inheritance of this variant is not specified, while this individual has a further inherited SCN2A missense SNV]. Two further Decipher cases with microdeletions spanning CSNK1G1 (and additional variants) also discussed. Overall, this gene can be considered for inclusion with probably amber rating. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.3011 | LMNB1 | Zornitza Stark Phenotypes for gene: LMNB1 were changed from Leukodystrophy, adult-onset, autosomal dominant, MIM#169500 to Global developmental delay, Intellectual disability, Microcephaly, Short stature, Seizures, Abnormality of the corpus callosum, Cortical gyral simplification, Feeding difficulties, Scoliosis; Leukodystrophy, adult-onset, autosomal dominant, MIM#169500 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.3007 | LMNB1 | Konstantinos Varvagiannis reviewed gene: LMNB1: Rating: GREEN; Mode of pathogenicity: Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments; Publications: 32910914; Phenotypes: Global developmental delay, Intellectual disability, Microcephaly, Short stature, Seizures, Abnormality of the corpus callosum, Cortical gyral simplification, Feeding difficulties, Scoliosis; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.2803 | MAPK1 |
Konstantinos Varvagiannis gene: MAPK1 was added gene: MAPK1 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: MAPK1 was set to MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown Publications for gene: MAPK1 were set to 32721402 Phenotypes for gene: MAPK1 were set to Global developmental delay; Intellectual disability; Behavioral abnormality; Growth delay; Abnormality of the face; Abnormality of the neck; Abnormality of the cardiovascular system; Abnormality of the skin Penetrance for gene: MAPK1 were set to unknown Mode of pathogenicity for gene: MAPK1 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: MAPK1 was set to GREEN Added comment: Motta et al (2020 - PMID: 32721402) report on 7 unrelated individuals harboring de novo missense MAPK1 pathogenic variants. The phenotype corresponded to a neurodevelopmental disorder and - as the authors comment - consistently included DD, ID , behavioral problems. Postnatal growth delay was observed in approximately half. Hypertelorism, ptosis, downslant of palpebral fissures, wide nasal bridge as low-set/posteriorly rotated ears were among the facial features observed (each in 3 or more subjects within this cohort). Together with short/webbed neck and abnormalities of skin (lentigines / CAL spots) and growth delay these led to clinical suspicion of Noonan s. or disorder of the same pathway in some. Congenital heart defects (ASD, mitral valve insufficiency, though not cardiomyopathy) occurred in 4/7. Bleeding diathesis and lymphedema were reported only once. MAPK1 encodes the mitogen-activated protein kinase 1 (also known as ERK2) a serine/threonine kinase of the RAS-RAF-MEK-(MAPK/)ERK pathway. MAPK1 de novo variants were identified in all individuals following trio exome sequencing (and extensive previous genetic investigations which were non-diagnostic). The distribution of variants, as well as in silico/vitro/vivo studies suggest a GoF effect (boosted signal through the MAPK cascade. MAPK signaling also upregulated in Noonan syndrome). The authors comment that screening of 267 additional individuals with suspected RASopathy (without mutations in previously implicated genes) did not reveal other MAPK1 variants. Overall this gene can be considered for inclusion in the ID panel with green rating. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.2750 | CNPY3 |
Konstantinos Varvagiannis gene: CNPY3 was added gene: CNPY3 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: CNPY3 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: CNPY3 were set to 29394991; 30237576 Phenotypes for gene: CNPY3 were set to Epileptic encephalopathy, early infantile, 60 (MIM 617929) Penetrance for gene: CNPY3 were set to Complete Review for gene: CNPY3 was set to GREEN Added comment: Biallelic CNPY3 mutations cause Epileptic encephalopathy, early infantile, 60 (MIM 617929). The phenotype including among others hypotonia, intractable seizures, DD and ID has been first reported by Mutoh et al (2018 - PMID: 29394991) in 3 subjects from 2 families. Evidence was provided for the role of the gene (incl. mouse model) and pathogenicity of the identified variants (resulting in LoF). Another subject with similar features of hypotonia, DD, intractable epilepsy, feeding problems has been described briefly by Maddirevula et al (2019 - PMID: 30237576). Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.2659 | TTC5 |
Konstantinos Varvagiannis gene: TTC5 was added gene: TTC5 was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: TTC5 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: TTC5 were set to 29302074; 32439809 Phenotypes for gene: TTC5 were set to Central hypotonia; Global developmental delay; Intellectual disability; Abnormality of nervous system morphology; Microcephaly; Abnormality of the face; Behavioral abnormality; Abnormality of the genitourinary system Penetrance for gene: TTC5 were set to Complete Review for gene: TTC5 was set to GREEN Added comment: Hu et al (2019 - PMID: 29302074) reported briefly on 3 individuals from 2 consanguineous families (from Turkey and Iran) with biallelic TTC5 variants. Features included DD (3/3), ID (severe in 2/2 with relevant age), microcephaly (3/3), brain abnormalities, etc. A nonsense and a variant affecting splice site were identified by WES/WGS. --- In a recent report, Rasheed et al (2020 - PMID: 32439809) report on the phenotype of 8 individuals - belonging to 5 consanguineous families - all 8 harboring homozygous TTC5 mutations. Frequent features included hypotonia (6/8), motor and speech delay, moderate to severe ID (10/10 of relevant age - inclusion of less severely affected subjects was not considered by study design), brain MRI abnormalities (8/8). Other findings included microcephaly in some (6/11), behavioral abnormalities in few (autistic behavior in 2/8, aggression in 2/8), genitourinary anomalies (2/8), seizures (1/11). Facial phenotype incl. thin V-shaped upper lip, low-set ears (in most) and/or additional features. TTC5 encodes a 440 aa protein, functioning as a scaffold to stabilise p300-JMY interactions. Apart from this role in nucleus, it has functions in the cytoplasm (inhibiting actin nucleataion, autophagosome formation, etc). The gene has ubiquitous expression, highest in brain. All variants were identified following WES - as the best candidates - in affected individuals with compatible Sanger studies in all affected family members and carrier parents. 2 missense and 2 nonsense variants were identified with the 2 missense SNVs localizing within TPR domains. qRT-PCR studies for a nonsense variant localizing 19 nt before the last exon, revealed fourfold decreased expression in affected individuals compared to carriers. Families from Egypt shared a homozygous ~6.3 Mb haplotype block spanning TTC5, suggesting that p.(Arg263Ter) is likely a founder mutation. The authors underscore some phenotypic (though not facial) similarities with Rubinstein-Taybi syndrome 2 due to EP300 mutations (in line with the role of TTC5). Biallelic variants in genes encoding other members of the TTC family (containing a TPR motif), e.g. TTC8 or TTC15 cause disorders with neurologic manifestations (and DD/ID). Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.2627 | UGDH |
Konstantinos Varvagiannis gene: UGDH was added gene: UGDH was added to Intellectual disability syndromic and non-syndromic. 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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| Intellectual disability syndromic and non-syndromic v0.2491 | AGTPBP1 |
Zornitza Stark gene: AGTPBP1 was added gene: AGTPBP1 was added to Intellectual disability syndromic and non-syndromic. Sources: NHS GMS Mode of inheritance for gene: AGTPBP1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: AGTPBP1 were set to 30420557 Phenotypes for gene: AGTPBP1 were set to Early onset cerebellar atrophy, developmental delay, and feeding and respiratory difficulties, severe motor neuronopathy; Neurodegeneration, childhood-onset, with cerebellar atrophy, 618276 Review for gene: AGTPBP1 was set to GREEN Added comment: Thirteen individuals reported, clinical presentation was with developmental delay, though six went on to have a progressive neurological course. Other features include cerebellar atrophy and neuropathy. Sources: NHS GMS |
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| Intellectual disability syndromic and non-syndromic v0.2380 | NDUFAF3 | Zornitza Stark changed review comment from: Three unrelated families reported.; to: Three unrelated families reported, severe neonatal presentation with lactic acidosis, seizures, and need for respiratory support. ID is unlikely to be the presenting or main feature. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.2115 | ZNF148 |
Chirag Patel gene: ZNF148 was added gene: ZNF148 was added to Intellectual disability syndromic and non-syndromic. Sources: Expert list Mode of inheritance for gene: ZNF148 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: ZNF148 were set to PMID: 27964749 Phenotypes for gene: ZNF148 were set to Global developmental delay, absent or hypoplastic corpus callosum, and dysmorphic facies; OMIM #617260 Review for gene: ZNF148 was set to GREEN Added comment: 4 patients with de novo heterozygous nonsense or frameshift mutations in the ZNF148 gene. Patients characterized by underdevelopment of the corpus callosum, mild to moderate developmental delay and ID, variable microcephaly or mild macrocephaly, short stature, feeding problems, facial dysmorphisms, and cardiac and renal malformations. No functional evidence. Sources: Expert list |
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| Intellectual disability syndromic and non-syndromic v0.1298 | SMARCC2 |
Chirag Patel gene: SMARCC2 was added gene: SMARCC2 was added to Intellectual disability, syndromic and non-syndromic_GHQ_VCGS. Sources: Literature Mode of inheritance for gene: SMARCC2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: SMARCC2 were set to PMID: 30580808 Phenotypes for gene: SMARCC2 were set to Coffin-Siris syndrome 8; OMIM #618362 Review for gene: SMARCC2 was set to GREEN Added comment: 15 individuals with variable degrees of neurodevelopmental delay, growth retardation, prominent speech impairment, hypotonia, feeding difficulties, behavioral abnormalities, and dysmorphic features. They found heterozygous de novo SMARCC2 variants, but no functional evidence of specific variants. Transcriptomic analysis of fibroblasts from affected individuals highlighted a group of differentially expressed genes with possible roles in regulation of neuronal development and function, namely H19, SCRG1, RELN, and CACNB4. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.1296 | SMARCD1 |
Chirag Patel gene: SMARCD1 was added gene: SMARCD1 was added to Intellectual disability, syndromic and non-syndromic_GHQ_VCGS. Sources: Literature Mode of inheritance for gene: SMARCD1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: SMARCD1 were set to PMID: 30879640 Phenotypes for gene: SMARCD1 were set to no OMIM number yet Review for gene: SMARCD1 was set to GREEN Added comment: 5 individuals with heterozygous SMARCD1 variants (4 de novo, 1 unk), and developmental delay, intellectual disability, hypotonia, feeding difficulties, dysmorphisms, and small hands and feet. No functional evidence of some variants was not conclusive with immunoblot or co-immunoprecipitation studies. Targeted knockdown of Drosophila ortholog Bap60 in the mushroom body of adult flies causes defects in long-term memory. Mushroom-body-specific transcriptome analysis revealed that Bap60 is required for context-dependent expression of genes involved in neuron function and development in juvenile flies when synaptic connections are actively being formed in response to experience. T Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.1227 | SNAP25 |
Chirag Patel gene: SNAP25 was added gene: SNAP25 was added to Intellectual disability, syndromic and non-syndromic_GHQ_VCGS. Sources: Expert list Mode of inheritance for gene: SNAP25 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: SNAP25 were set to PMID: 25003006; 29100083; 28135719 Phenotypes for gene: SNAP25 were set to ?Myasthenic syndrome, congenital, 18; OMIM #616330 Review for gene: SNAP25 was set to GREEN Added comment: ID neurodevelopmental disorder rather than muscle disorder, so OMIM entry needs to be edited. > 5 patients reported. Sources: Expert list |
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| Intellectual disability syndromic and non-syndromic v0.0 | EED |
Zornitza Stark gene: EED was added gene: EED was added to Intellectual disability, syndromic and non-syndromic_GHQ. Sources: Expert Review Green,Genetic Health Queensland Mode of inheritance for gene: EED was set to Unknown |
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