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Intellectual disability - microarray and sequencing v5.475 | INTS8 | Arina Puzriakova Phenotypes for gene: INTS8 were changed from to ?Neurodevelopmental disorder with cerebellar hypoplasia and spasticity, OMIM:618572 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v5.402 | ACBD6 |
Arina Puzriakova edited their review of gene: ACBD6: Added comment: - PMID: 21937992 (2011) - single individuals with a p.G22fs variant in the ACBD6 gene, presenting with mild ID, microcephaly, facial dysmorphism, spasticity. Limited additional information. - PMID: 32108178 (2020) - two unrelated individuals with neurodevelopmental disorder (moderate ID is noted but otherwise limited clinical information) and carrying homozygous LoF variants in the ACBD6 gene (1 frameshift, 1 canonical splice). One individual also carried an allelic homozygous variant in the PRDX6 gene (unlikely but unknown disease consequence). Skin-derived patient fibroblasts showed reduced ACBD6 expression and N-myristoylation deficiency. - PMID: 36457943 (2023) - two Thai siblings presenting with profound ID, morbid obesity, pancytopenia with severe recurrent infections, diabetes mellitus, cirrhosis, and renal failure, leading to deaths in their early 30s. Sequencing showed a novel homozygous single bp duplication (c.360dup; p.Leu121Thrfs*27) in the ACBD6 gene. Parents were heterozygous carriers. - PMID: 37951597 (2023) - 45 previously undiagnosed individuals from 28 families with a neurodevelopmental syndrome including a complex and progressive movement disorder phenotype. Cardinal clinical features include moderate-to-severe GDD/ID (45/45), facial dysmorphism (38/40), HC <2nd percentile (21/31), weight >50th percentile (20/34), mild cerebellar ataxia (35/41), limb spasticity/hypertonia (31/41), gait abnormalities (33/35), dystonia (30/32) and variable epilepsy (13/29). Homozygous ACBD6 variants were identified by WES in all cases, including 18 predicted LoF, 1 missense and 1 inframe insertion. Knockout studies in zebrafish recapitulate clinical features reported in patients such as movement disorders, seizures, and facial dysmorphology, while inactivation of acbd6 in X. tropicalis predominantly caused embryo death while surviving tadpoles demonstrated microcephaly, reduced movement, eye abnormalities, and brain structure differences.; Changed rating: GREEN; Changed publications to: 21937992, 32108178, 36457943, 37951597; Changed phenotypes to: Neurodevelopmental disorder, MONDO:0700092; Changed mode of inheritance: BIALLELIC, autosomal or pseudoautosomal |
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Intellectual disability - microarray and sequencing v5.389 | CLDN11 |
Achchuthan Shanmugasundram gene: CLDN11 was added gene: CLDN11 was added to Intellectual disability - microarray and sequencing. Sources: Literature Mode of inheritance for gene: CLDN11 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: CLDN11 were set to 33313762 Phenotypes for gene: CLDN11 were set to Leukodystrophy, hypomyelinating, 22, OMIM:619328 Review for gene: CLDN11 was set to GREEN Added comment: PMID:33313762 reported three unrelated individuals with early-onset spastic movement disorder, expressive speech disorder and eye abnormalities including hypermetropia. These patients exhibit global developmental delay, particularly motor and speech delay. Intellectual disability was maximally mild in two of three individuals and the intelligence is in a low-normal range in third individual, although IQ testing was not performed in them. Two different heterozygous de novo stop-loss variants were identified in these patients. One of the variants did not lead to a loss of CLDN11 expression on RNA level in fibroblasts indicating this transcript is not subject to nonsense-mediated decay and most likely translated into an extended protein. This gene has been associated with hypomyelinating leukodystrophy in OMIM, which includes global developmental delay and impaired intellectual development (mild) as clinical presentations. However, this gene has not yet been associated with phenotypes in Gene2Phenotype. Sources: Literature |
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Intellectual disability - microarray and sequencing v5.284 | ESAM |
Achchuthan Shanmugasundram changed review comment from: As reviewed by Julia Baptista, PMID:36996813 reported the identification of biallelic ESAM variants in 13 individuals from eight unrelated families, which included four foetuses. All nine born individuals had profound global developmental delay/ unspecified intellectual disability, epilepsy, absent or severely delayed speech, varying degrees of spasticity, ventriculomegaly, and ICH/ cerebral calcifications, the latter being also observed in the foetuses. This gene has been associated with relevant phenotypes in OMIM (MIM #620371), but not yet in Gene2Phenotype.; to: As reviewed by Julia Baptista, PMID:36996813 reported the identification of biallelic ESAM variants in 13 individuals from eight unrelated families, which included four foetuses. All nine live-born individuals had profound global developmental delay/ unspecified intellectual disability, epilepsy, absent or severely delayed speech, varying degrees of spasticity, ventriculomegaly, and ICH/ cerebral calcifications, the latter being also observed in the foetuses. This gene has been associated with relevant phenotypes in OMIM (MIM #620371), but not yet in Gene2Phenotype. |
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Intellectual disability - microarray and sequencing v5.283 | ESAM | Achchuthan Shanmugasundram Phenotypes for gene: ESAM were changed from severe ID; seizures, spasticity to Neurodevelopmental disorder with intracranial hemorrhage, seizures, and spasticity, OMIM:620371 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v5.281 | ESAM | Achchuthan Shanmugasundram reviewed gene: ESAM: Rating: GREEN; Mode of pathogenicity: None; Publications: 36996813; Phenotypes: Neurodevelopmental disorder with intracranial hemorrhage, seizures, and spasticity, OMIM:620371; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v5.271 | ESAM |
Julia Baptista gene: ESAM was added gene: ESAM was added to Intellectual disability - microarray and sequencing. Sources: Literature,Expert Review Mode of inheritance for gene: ESAM was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: ESAM were set to PMID: 36996813 Phenotypes for gene: ESAM were set to severe ID; seizures, spasticity Review for gene: ESAM was set to GREEN Added comment: Lecca et al 2023 reported thirteen patients from eight unrelated families with biallelic loss of function variants (nonsense, frameshift, canonical splice site, all predicted to result in a transcript targeted for nonsense-mediated decay). Protein staining assays in one of the brain fetal samples confirmed loss the loss of protein. The phenotype reported in this cohort is of a severe neurodevelopmental disorder with brain anomalies (calcifications, hydrocephalus, enlarged ventricles, cerebral atrophy, etc), and dysmorphic features. Sources: Literature, Expert Review |
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Intellectual disability - microarray and sequencing v5.181 | CCDC82 | Achchuthan Shanmugasundram Phenotypes for gene: CCDC82 were changed from Global developmental delay; Intellectual disability; Spastic paraparesis to neurodevelopmental disorder, MONDO:0700092; intellectual disability, MONDO:0001071 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v5.175 | HECTD4 |
Achchuthan Shanmugasundram gene: HECTD4 was added gene: HECTD4 was added to Intellectual disability - microarray and sequencing. Sources: Literature Mode of inheritance for gene: HECTD4 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: HECTD4 were set to 36401616 Phenotypes for gene: HECTD4 were set to Neurodevelopmental disorder with seizures, spasticity, and complete or partial agenesis of the corpus callosum, OMIM:620250 Review for gene: HECTD4 was set to GREEN Added comment: PMID:36401616 reported seven patients from five unrelated families with either homozygous (3 families) or compound heterozygous variants (2 families) in HECTD4 gene and presenting with syndromic neurodevelopmental, seizure, and movement disorders and neurobehavioral phenotypes. All seven patients had severe (4 cases) or moderate (3 cases) intellectual disability. Sources: Literature |
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Intellectual disability - microarray and sequencing v5.123 | ENTPD1 |
Achchuthan Shanmugasundram changed review comment from: As reviewed by Konstantinos Varvagiannis, PMID:35471564 reported 27 cases from 17 families with a complex childhood-onset neurodevelopmental disorder characterised by intellectual disability/ developmental delay and spastic paraplegia in all individuals, white matter abnormalities in 12 individuals and epilepsy in 7 individuals. In addition, this gene has been associated with autosomal recessive intellectual developmental disorder in Gene2phenotype with 'limited' rating and ID has been included as part of the SPG64 phenotype in OMIM. ; to: As reviewed by Konstantinos Varvagiannis, PMID:35471564 reported 27 cases from 17 families with biallelic variants in ENTPD1 and with a complex childhood-onset neurodevelopmental disorder characterised by intellectual disability/ developmental delay and spastic paraplegia in all individuals, white matter abnormalities in 12 individuals and epilepsy in 7 individuals. PMID:35758610 reported two siblings with biallelic variants in ENTPD1. The proband was mildly intellectually disabled and her brother was moderately clinically disabled based on clinical observations. In addition, this gene has been associated with autosomal recessive intellectual developmental disorder in Gene2phenotype with 'limited' rating and ID has been included as part of the SPG64 phenotype in OMIM. |
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Intellectual disability - microarray and sequencing v5.121 | ENTPD1 |
Achchuthan Shanmugasundram changed review comment from: As reviewed by Konstantinos Varvagiannis, PMID35471564 reported 27 cases from 17 families with a complex childhood-onset neurodevelopmental disorder characterised by intellectual disability/ developmental delay and spastic paraplegia in all individuals, white matter abnormalities in 12 individuals and epilepsy in 7 individuals. In addition, this gene has been associated with autosomal recessive intellectual developmental disorder in Gene2phenotype with 'limited' rating and ID has been included as part of the SPG64 phenotype in OMIM. ; to: As reviewed by Konstantinos Varvagiannis, PMID:35471564 reported 27 cases from 17 families with a complex childhood-onset neurodevelopmental disorder characterised by intellectual disability/ developmental delay and spastic paraplegia in all individuals, white matter abnormalities in 12 individuals and epilepsy in 7 individuals. In addition, this gene has been associated with autosomal recessive intellectual developmental disorder in Gene2phenotype with 'limited' rating and ID has been included as part of the SPG64 phenotype in OMIM. |
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Intellectual disability - microarray and sequencing v5.120 | ENTPD1 |
Achchuthan Shanmugasundram changed review comment from: As reviewed by Konstantinos Varvagiannis, PMID35471564 reported 27 cases from 17 families with a complex childhood-onset neurodevelopmental disorder characterised by intellectual disability/ developmental delay and spastic paraplegia in all individuals, white matter abnormalities in 12 individuals and epilepsy in 7 individuals. In addition, this gene has been associated with autosomal recessive intellectual developmental disorder in Gene2phenotype with 'limited' rating and ID has been includes as part of the SPG64 phenotype in OMIM. ; to: As reviewed by Konstantinos Varvagiannis, PMID35471564 reported 27 cases from 17 families with a complex childhood-onset neurodevelopmental disorder characterised by intellectual disability/ developmental delay and spastic paraplegia in all individuals, white matter abnormalities in 12 individuals and epilepsy in 7 individuals. In addition, this gene has been associated with autosomal recessive intellectual developmental disorder in Gene2phenotype with 'limited' rating and ID has been included as part of the SPG64 phenotype in OMIM. |
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Intellectual disability - microarray and sequencing v5.120 | ENTPD1 |
Achchuthan Shanmugasundram changed review comment from: Comment on list classification: As reviewed by Konstantinos Varvagiannis, PMID35471564 reported 27 cases from 17 families with a complex childhood-onset neurodevelopmental disorder characterised by intellectual disability/ developmental delay and spastic paraplegia in all individuals, white matter abnormalities in 12 individuals and epilepsy in 7 individuals. Hence, this gene can be promoted to Green in the next major update.; to: As reviewed by Konstantinos Varvagiannis, PMID35471564 reported 27 cases from 17 families with a complex childhood-onset neurodevelopmental disorder characterised by intellectual disability/ developmental delay and spastic paraplegia in all individuals, white matter abnormalities in 12 individuals and epilepsy in 7 individuals. In addition, this gene has been associated with autosomal recessive intellectual developmental disorder in Gene2phenotype with 'limited' rating and ID has been includes as part of the SPG64 phenotype in OMIM. |
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Intellectual disability - microarray and sequencing v5.119 | ENTPD1 | Achchuthan Shanmugasundram Added comment: Comment on list classification: As reviewed by Konstantinos Varvagiannis, PMID35471564 reported 27 cases from 17 families with a complex childhood-onset neurodevelopmental disorder characterised by intellectual disability/ developmental delay and spastic paraplegia in all individuals, white matter abnormalities in 12 individuals and epilepsy in 7 individuals. Hence, this gene can be promoted to Green in the next major update. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v5.118 | ENTPD1 | Achchuthan Shanmugasundram reviewed gene: ENTPD1: Rating: GREEN; Mode of pathogenicity: None; Publications: 35471564; Phenotypes: Spastic paraplegia 64, autosomal recessive, OMIM:615683; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v5.115 | CHMP3 |
Arina Puzriakova gene: CHMP3 was added gene: CHMP3 was added to Intellectual disability - microarray and sequencing. Sources: Literature Mode of inheritance for gene: CHMP3 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: CHMP3 were set to 35710109 Phenotypes for gene: CHMP3 were set to Complex spastic quadriplegia associated with developmental delay and seizures Added comment: Cohen-Barak et al., 2022 (PMID: 35710109) reported on a consanguineous family, in which five individuals presented with intellectual and progressive motor disabilities, seizures and spastic quadriplegia, associated with a homozygous variant in CHMP3. Patient derived fibroblasts expressed ultrastructural and molecular features of impaired autophagy, partially rescued by ectopic expression of WT-CHMP3. Sources: Literature |
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Intellectual disability - microarray and sequencing v5.91 | PPFIBP1 | Achchuthan Shanmugasundram Phenotypes for gene: PPFIBP1 were changed from Global developmental delay; Intellectual disability; Microcephaly; Seizures; Abnormality of brain morphology; Abnormality of the cerebral white matter; Cerebral calcification; Abnormal cortical gyration; Hypertonia; Spastic tetraplegia; Generalized hypotonia; Small for gestational age; Growth delay; Failure to thrive; Feeding difficulties; abnormal heart morphology; Hearing abnormality; Cryptorchidism; Abnormality of vision to Neurodevelopmental disorder with seizures, microcephaly, and brain abnormalities, OMIM:620024 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v5.17 | SPG7 | Sarah Leigh Phenotypes for gene: SPG7 were changed from Spastic paraplegia 7, autosomal recessive, 607259 to Spastic paraplegia 7, autosomal recessive, OMIM:607259; hereditary spastic paraplegia 7, MONDO:0011803 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v4.72 | ROBO1 |
Achchuthan Shanmugasundram changed review comment from: Comment on gene classification: This gene should be rated green as this gene has been associated with intellectual disability from six unrelated cases. However, the MOI should be set as "BIALLELIC, autosomal or pseudoautosomal" as five of these cases were reported with biallelic variants and only one case was reported with monoallelic variant. PMID:28286008 reported a boy with compound heterozygous variants that was presented with developmental delay in 13 months and had severe intellectual disability and hyperactivity at nine years of age. He was nonverbal and wheelchair dependent because of spastic diplegia and ataxia. PMID:30692597 reported a five year old boy identified with a homozygous ROBO1 variant who had combined pituitary hormone deficiency, psychomotor developmental delay, severe intellectual disability, sensorineural hearing loss, strabismus and characteristic facial features. PMID:35227688 reported eight patients including the boy reported in PMID:30692597. Of the other seven patients, three were presented with intellectual disability. Of these three patients, two harboured compound heterozygous and one harboured homozygous variants. PMID:35348658 reported a patient identified with monoallelic de novo variant (p.D422G) who presented with early-onset epileptic encephalopathy and had severe developmental delay. This gene has not yet been associated with any phenotypes in OMIM or Gene2Phenotype.; to: Comment on gene classification: This gene should be rated green as this gene has been associated with intellectual disability from six unrelated cases. However, the MOI should be set as "BIALLELIC, autosomal or pseudoautosomal" as five of these cases were reported with biallelic variants and only one case was reported with monoallelic variant. PMID:28286008 reported a boy with compound heterozygous variants that was presented with developmental delay in 13 months and had severe intellectual disability and hyperactivity at nine years of age. He was nonverbal and wheelchair dependent because of spastic diplegia and ataxia. PMID:30692597 reported a five year old boy identified with a homozygous ROBO1 variant who had combined pituitary hormone deficiency, psychomotor developmental delay, severe intellectual disability, sensorineural hearing loss, strabismus and characteristic facial features. PMID:35227688 reported eight patients including the boy reported in PMID:30692597. Of the other seven patients, three were presented with intellectual disability. Of these three patients, two harboured compound heterozygous and one harboured homozygous variants. PMID:35348658 reported a patient identified with monoallelic de novo variant (p.D422G) who presented with early-onset epileptic encephalopathy and had severe developmental delay. This gene has not yet been associated with any phenotypes in OMIM or Gene2Phenotype. |
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Intellectual disability - microarray and sequencing v3.1757 | CTNNB1 | Arina Puzriakova Phenotypes for gene: CTNNB1 were changed from Mental retardation, autosomal dominant 19, 615075Colorectal cancer, somatic, 114500Pilomatricoma, somatic, 132600Ovarian cancer, somatic, 167000Hepatocellular carcinoma, somatic, 114550; MENTAL RETARDATION, AUTOSOMAL DOMINANT 19 to Neurodevelopmental disorder with spastic diplegia and visual defects, OMIM:615075 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1713 | ANK3 | Sarah Leigh Phenotypes for gene: ANK3 were changed from ?Mental retardation, autosomal recessive, 37 615493 to Intellectual developmental disorder, autosomal recessive 37, OMIM:615493; intellectual disability-hypotonia-spasticity-sleep disorder syndrome, MONDO:0014210 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1687 | NRCAM | Sarah Leigh edited their review of gene: NRCAM: Added comment: Associated with relevant phenotype in OMIM and as moderate Gen2Phen gene for NRCAM neurodevelopmental disorder with dysmorphic features, hypotonia and spasticity. At least 12 variants have been reported in PMID: 35108495 in 8 unrelated cases (table 1). Global developmental delay / intellectual disabilty was evident in 5/7 unrelated cases (individual 1 was not considered as they also had homozygous loss-of-function variant in CD55 (OMIM: 125240)(PMID: 35108495).; Changed rating: GREEN | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1686 | NRCAM | Sarah Leigh Phenotypes for gene: NRCAM were changed from Hypotonia; Hypertonia; Spasticity; Global developmental delay; Intellectual disability; Microcephaly; Behavioral abnormality; Neuropathy; Hearing abnormality; Abnormality of the eye; Abnormality of the skeletal system; Scoliosis; Abnormality of the face to Neurodevelopmental disorder with neuromuscular and skeletal abnormalities, OMIM:619833 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1656 | TAF8 |
Arina Puzriakova Added comment: Comment on list classification: New gene added by Jana Jezkova. There is sufficient evidence to promote this gene to Green at the next GMS panel update. TAF8 is associated with a relevant phenotype in OMIM (MIM# 619972) but is not yet listed in G2P. 8 individuals from 5 families have been reported in literature (PMIDs: 29648665; 35759269). Four families from different ethnic backgrounds harboured the same c.781-1G>A homozygous variant while sequencing in a sib pair revealed different compound het splice variants (c.45+4A>G and c.489G>A) in the TAF8 gene. Patients presented with an overlapping phenotype including microcephaly (8/8), DD and ID (8/8), spasticity (7/8), and seizures (6/8). Brain MRI have shown hypoplastic corpus callosum, hypomyelination, enlarged ventricles in most subjects, and additionally generalised brain atrophy in two sibs. |
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Intellectual disability - microarray and sequencing v3.1654 | TAF8 | Arina Puzriakova Phenotypes for gene: TAF8 were changed from severe developmental delay; feeding problems; microcephaly; growth retardation; spasticity; epilepsy to Neurodevelopmental disorder with severe motor impairment, absent language, cerebral hypomyelination, and brain atrophy, OMIM:619972 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1649 | SLC38A3 | Catherine Snow Phenotypes for gene: SLC38A3 were changed from Infantile axial hypotonia; Global developmental delay; Intellectual disability; Seizures; Spasticity; Microcephaly; Cerebral atrophy; Cerebellar atrophy; Abnormality of the corpus callosum; Dysphagia; Constipation; Increased serum lactate; Hyperammonemia to Developmental and epileptic encephalopathy 102, 619881 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1643 | OGDHL |
Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is sufficient evidence to promote to Green at the next GMS panel update. The NSRP1 gene is not yet associated with any phenotype in OMIM but has a 'moderate' disease confidence rating in G2P for 'OGDHL-related neurodevelopmental disorder with seizures, hearing loss and gait ataxia'. At least 10 individuals from 9 unrelated families identified with biallelic variants in this gene (PMIDs: 28017472; 34800363). Main clinical features include mild-to-severe DD/ID (9/10), seizures (5/10), gait ataxia (5/10), profound bilateral sensorineural hearing loss (4/10), spasticity (3/10). |
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Intellectual disability - microarray and sequencing v3.1641 | NSRP1 |
Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. There is sufficient evidence to promote to Green at the next GMS panel update. The NSRP1 gene is not yet associated with any phenotype in OMIM but has a 'strong' disease confidence rating in G2P for 'NSRP1-associated developmental delay, epilepsy and microcephaly'. Six individuals from three families with different homozygous LoF NSRP1 variants identified by Calame et al. 2021 (PMID: 34385670). Main clinical features include ID/DD (6/6), epilepsy (6/6, drug-resistant in 3/6), hypotonia (6/6), appendicular spasticity (6/6), microcephaly (5/6, Z-scores −0.95 to −5.60). Brain abnormalities included under-opercularization (3/4), simplified gyral pattern (3/4), superior and/or inferior cerebellar vermian hypoplasia (3/4), corpus callosum dysgenesis (1/4), and thin brainstem (1/4). |
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Intellectual disability - microarray and sequencing v3.1632 | TAF8 |
Jana Jezkova gene: TAF8 was added gene: TAF8 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: TAF8 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: TAF8 were set to PMID: 35759269 Phenotypes for gene: TAF8 were set to severe developmental delay; feeding problems; microcephaly; growth retardation; spasticity; epilepsy Penetrance for gene: TAF8 were set to unknown Review for gene: TAF8 was set to AMBER Added comment: Eight patients reported in total. Six patients are homozygous for a recurrent NM_138572.2, c.781-1G>A variant. In two sibling patients, two novel compound heterozygous TAF8 splice site mutations, c.45+4A > G and c.489G>A were identified, which cause aberrant splicing as well as reduced expression and mislocalization of TAF8. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.1628 | PPFIBP1 |
Konstantinos Varvagiannis gene: PPFIBP1 was added gene: PPFIBP1 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: PPFIBP1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PPFIBP1 were set to 35830857; 30214071 Phenotypes for gene: PPFIBP1 were set to Global developmental delay; Intellectual disability; Microcephaly; Seizures; Abnormality of brain morphology; Abnormality of the cerebral white matter; Cerebral calcification; Abnormal cortical gyration; Hypertonia; Spastic tetraplegia; Generalized hypotonia; Small for gestational age; Growth delay; Failure to thrive; Feeding difficulties; abnormal heart morphology; Hearing abnormality; Cryptorchidism; Abnormality of vision Penetrance for gene: PPFIBP1 were set to Complete Review for gene: PPFIBP1 was set to GREEN Added comment: Consider inclusion with green rating in the ID, epilepsy as well as other likely relevant gene panels (microcephaly, white matter disorders, corpus callosum abnormalities, intracerebral calficication disorders, malformations of cortical development, hereditary spastic paraplegia, growth failure in early childhood, etc) based on the summary below. ---- Rosenhahn et al (2022 - PMID: 35830857) describe the phenotype of 16 individuals - belonging to 12 unrelated families - with biallelic PPFIBP1 pathogenic variants. Most (14/16) were born to consanguineous parents. One of these families was previously reported by Shaheen et al (2019 - PMID: 30214071) who first identified PPFIBP1 as a candidate gene for congenital microcephaly. In the current study, Rosenhahn also identified a fetus homozygous for a missense variant and similar features. All individuals presented global DD/ID (16/16 - in 15 cases profound/severe) and epilepsy (16/16 - onset 1d-4y / median 2m - focal seizures in 11/16, epileptic spams in 7/16, generalized onset in 7/16, myoclonic in 6/16 - drug-resistant : 13/16). Almost all (15/16) had microcephaly, commonly congenital (9/16) and progressive (11/16). Other neurological findings included hypertonia (10/16), spastic tetraplegia (6/16), hypotonia (5/16), dystonic movements (3/16) or nystagmus (4/16). Brain abnormalities were identified in all investigated with MRI and included leukoencephalopathy (11/14) mostly periventricular, abnormal cortex morphology (7/14 - polymicrogyria 1, increased cortical thickness 4, pachygyria 3), cortical atrophy, corpus callosum hypoplasia (7/14). Intracranial calcifications were identified in all (9/9) investigated with CT scan. Abnormal growth was reported for several (SGA in 9/16, FTT 8/16, short stature 7/16) often associated with feeding difficulties (7/16). Other features incl. abnormal hearing (4/16), congenital heart defects (7/16), ophthalmologic findings (8/16), undescended testes (3/10). There were no overlapping facial features. The fetus displayed similar features incl. SGA, microcephaly, intracranial calcifications. Investigations incl. exome/genome sequencing (singleton or trio) with Sanger for confirmation/segregation of variants where necessary. Variable previous investigations incl. metabolic screening, TORCH screening, chromosomal studies (CMA) are mentioned in the supplement and were non-diagnostic. Additional candidate variants were identified in few cases although cases with plausible dual diagnoses (e.g. ind14) were not included in the overall phenotypic description. 9 pLoF variants (nonsense, frameshift, 1 splicing) predicted to lead to NMD were identified. There were no functional studies performed. The missense variant c.2177G>T / p.Gly726Val (NM_003622.4) was predicted deleterious by in silico tools while the AA change causing severe steric problems upon modelling. PPFIBP1 encodes PPFIA-binding protein 1 also known as liprin-β1. As the authors discuss: The liprin family of proteins comprises liprins α1 to 4 and liprin β1 and β2 in mammals. Liprin β1 is known to homodimerize and heterodimerize with α-liprins. In fibroblast cultures liprins β1 and α1 colocalize to cell membrane and periphery of focal adhesions. Members of the liprin-α fam. are scaffold proteins playing a role in synapse formation/signaling and axonal transport. A ko model of the PPFIBP1 ortholog in C.elegans displayed abnormal locomotion behavior. In Drosophila, null-allele mutants resulted in altered axon outgrowth and synapse formation of R7 photoreceptors and reduced neuromuscular junction size (Refs provided in article). Using a PPFIBP1/hlb-1 ko C.elegans model the authors demonstrated defects in spontaneous and light-induced behavior. Sensitivity of the worms to an acetylcholinesterase inhibitor (aldicarb) was suggestive of a presynaptic defect. ---- There is currently no PPFIBP1 - associated phenotype in OMIM / G2P. SysNDD lists PPFIBP1 among the ID genes (limited evidence based on the 3 sibs reported by Shaheen et al, 2019 - PMID: 30214071). In PanelApp Australia the gene is listed with green rating for ID, epilepsy, microcephaly based on the medRxiv pre-print. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.1607 | TMEM63C |
Sarah Leigh gene: TMEM63C was added gene: TMEM63C was added to Intellectual disability. Sources: Literature Q3_22_rating tags were added to gene: TMEM63C. Mode of inheritance for gene: TMEM63C was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: TMEM63C were set to 35718349 Phenotypes for gene: TMEM63C were set to hereditary spastic paraplegia, MONDO:0019064 Review for gene: TMEM63C was set to GREEN Added comment: Not associated with a phenotype in OMIM, Gen2Phen or MONDO. PMID:35718349 reports four TMEM63C variants in seven individuals from three unrelated families with childhood onset hereditary spastic paraplegia, with mild intellectual disability in some cases. Functional studies in PMID:35718349, reveal a role for TMEM63C in regulating both endoplasmic reticulum and mitochondrial morphologies. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.1561 | CCDC82 |
Konstantinos Varvagiannis gene: CCDC82 was added gene: CCDC82 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: CCDC82 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: CCDC82 were set to 27457812; 28397838; 35118659; 35373332 Phenotypes for gene: CCDC82 were set to Global developmental delay; Intellectual disability; Spastic paraparesis Penetrance for gene: CCDC82 were set to Complete Review for gene: CCDC82 was set to AMBER Added comment: The phenotype of individuals with biallelic CCDC82 variants has been reported - in most cases briefly - in the following reports (each summarizing the findings of previous ones): Riazzudin et al (2017 - PMID: 27457812) in a large consanguineous pedigree from Pakistan (PKMR206) identified 4 individuals homozygous for a fs variant [NM_024725.3:c.373delG / p.(Asp125Ilefs*6)] (V3,V4,V5,V10). There was no other variant segregating with the phenotype of ID (Delayed CMS, moderate ID and speech delay probably common to all, V3,4,5 had also mild hypotonia and motor weakness). There was one unaffected sib tested (homozygous for ref. alelle). 2 further affected males (V1, V2) with similar phenotype were not tested. Harripaul et al (2018 - PMID: 28397838) reported 2 sibs with nonsyndromic ID belonging to a consanguineous family (AS17) from the Middle-East. Both were homozygous for NM_024725.3:c.535C>T / p.Arg179*. The variant was confirmed with Sanger sequencing and parents were heterozygous carriers. Two additional affected sibs were probably not tested. Yahia et al (2022 - PMID: 35118659) described 2 sibs belonging to a consanguineous family from Sudan. These presented global DD (last evaluation at 4y and 9m) and spasticity. There was a common history of infantile spasms with the elder developing GTC convulsions with spontaneous resolution. Additionaly, both presented microcephaly (<-2 and <-3SD). Exome sequencing revealed homozygosity for c.535C>T / p.Arg179* (previously reported by Harripaul et al). Sanger sequencing was used for confirmation and demonstration of carrier state of parents. Two similarly affected sibs were not available for testing. Bauer et al (2022 - PMID: 35373332) reported a 21 y.o. male born to consanguineous parents from Pakistan. Features included short stature, ID, spastic paraparesis (at the age of 3y). Gelastic seizures were suspected but not confirmed (repeated normal EEGs). WES revealed homozygosity for a fs CCDC82 variant [NM_001318736.1:c.183del / p.(Phe61Leufs*27)] with Sanger confirmation in proband and heterozygous parents. There was another hmz variant, albeit classified as VUS and not thought to fit the clinical presentation. As proposed by Bauer et al. overlapping features include spastic paraparesis, DD and dysmorphic features. As commented, CCDC82 encodes coiled-coil domain protein 82, a protein with unknown function. Consider inclusion probably with amber rating (>3 individuals/families/variants, role of the gene not known, variant studies not performed to date, animal models not discussed). Sources: Literature |
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Intellectual disability - microarray and sequencing v3.1559 | AFG3L2 | Arina Puzriakova Phenotypes for gene: AFG3L2 were changed from Spastic ataxia 5, autosomal recessive OMIM:614487; spastic ataxia 5 MONDO:0013776; Spinocerebellar ataxia 28 OMIM:610246; spinocerebellar ataxia type 28 MONDO:0012450 to Optic atrophy 12, OMIM:618977; Spinocerebellar ataxia 28, OMIM:610246; Spastic ataxia 5, autosomal recessive, OMIM:614487 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1551 | HSPD1 | Arina Puzriakova Phenotypes for gene: HSPD1 were changed from Spastic paraplegia 13, autosomal dominant, 605280Leukodystrophy, hypomyelinating, 4, 612233; SPASTIC PARAPLEGIA AUTOSOMAL DOMINANT TYPE 13 to Leukodystrophy, hypomyelinating, 4, OMIM:612233 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1529 | SLC38A3 |
Konstantinos Varvagiannis gene: SLC38A3 was added gene: SLC38A3 was added to Intellectual disability. Sources: Literature,Other Mode of inheritance for gene: SLC38A3 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: SLC38A3 were set to 34605855 Phenotypes for gene: SLC38A3 were set to Infantile axial hypotonia; Global developmental delay; Intellectual disability; Seizures; Spasticity; Microcephaly; Cerebral atrophy; Cerebellar atrophy; Abnormality of the corpus callosum; Dysphagia; Constipation; Increased serum lactate; Hyperammonemia Penetrance for gene: SLC38A3 were set to Complete Review for gene: SLC38A3 was set to GREEN Added comment: Marafi et al (2021 - PMID: 34605855) describe the phenotype of 10 individuals, belonging to 7 families (6/7 consanguineous), harboring biallelic deleterious SLC38A3 variants. One subject (from fam3) was previously reported in the context of a larger cohort of consanguineous families investigated with exome sequencing (2017, PMID: 31130284). The phenotype overall corresponded to a DEE and features included axial hypotonia (10/10), severe global DD or ID (10/10), seizures (8/10, onset : 1w-15m, NOT observed in 2/10 aged 1y3m and 4y | s. types: tonic-clonic in 3/8, tonic 2/8, focal 2/8 with secondary generalization, myoclonic 1/8, gelastic 1/8 | EEG burst-suppression, hypsarrhythmia in few). Microcephaly was observed in (8/10) and was more commonly postnatal and/or progressive. Variable abnormalities were observed upon brain imaging incl. cerebral (5/10) or cerebellar atrophy (2/10) and abnormal CC (6/10), abnormal myelination for age (6/10). Other phenotypes included visual impairment (9/10), peripheral hypertonia (8/9) constipation (8/9) and dysphagia (7/9), FTT (4/8), movement disorder (3/10). Metabolic studies indicated (transient) elevation of lactate (7/8 - also pyruvate in 2) and elevated plasma ammonia (4/7). Individuals from the 1st family were investigated with ES, and the SLC38A3 splice site variant (NM_006841.6:c.855+1G>T) was the most likely candidate, additional SNVs not contributing to the NDD phenotype. Other affected subjects were ascertained through GeneMatcher/collaborations. In total, 3 different missense and 4 pLoF (1 fs, 2 nonsense, 1 splicing) variants were identified with individuals from 2 families being hmz or cmd htz for missense variants. Variants were absent/ultrarare with no homozygotes in public/in-house databases with several in silico predictions in favor of a deleterious effect. Regions of AOH (around SLC38A3/total) are provided for some individuals/families. Sanger sequencing was used for confirmation and segregation studies (apart from carrier parents in 7/7 fam, 11 unaffected sibs tested in 6/7 fam). The solute carrier (SLC) superfamily of transmembrane transporters - highly expressed in mammalian brain - is involved in exchange of amino-acids (AAs), nutrients, ions, neurotransmitters and metabolites etc across biological membranes with >100 SLC-encoding genes associated with NDDs. SLC38A3 specifically encodes SNAT3, a sodium-coupled neutral amino-acid transporter, principal transporter of Asn, His, Gln (precursor for GABA and glutamate), expressed in brain, liver, kidney, retina and pancreas. In the brain, it localizes to peri-synaptic astrocytes playing an important role in glutamate/GABA-glutamine cycle. While the pLoF variants are predicted to undergo NMD or result in non-functional protein, protein modelling suggested that missense ones affect protein activity or stability. Biochemical and metabolic screening was carried out for several individuals with plasma AAs reported normal (10/10), urinary OAs normal in 9/9, CSF AAs (incl. GABA/glutamine) normal in 2 sibs, CSF lactate normal in 1 indiv. studied. As discussed above plasma ammonia was elevated in 4/7 (2 fam), and 7/10 had elevated lactate and/or pyruvate (2/7). Untargeted metabolomic profiles performed in biofluids (plasma from 3 subjects, CSF:1, urine:1) were suggestive of altered AA and nitrogen metabolism. In particular, alterations in levels of AA known to be transported by SNAT3 were found. 676 molecules overall showed deviation in plasma samples, 630 in urine and 241 in CSF (albeit with no consistent pattern). Perturbations in several biochemical pathways were shown to occur (incl. Gln-,Asn- and His- pathways). Slc38a3-/- mice have reductions in brain glutamate and GABA neurotransmitters in homogenized brain tissue (GABA analytes being normal in plasma samples or the single CSF sample available from affected subjects). Snat3-deficient mice had elevation of plasma urea and normal ammonia levels (urea was low in all human samples and ranged from -2 to -3.5 SD in plasma, ammonia was elevated in 4/7). Slc38a3-/- mice have impaired growth, lethargy and ataxic gait, altered plasma AAs, normal glutamine in plasma with abundance in brain and exhibit early lethality. Plasma AAs were normal in 4 affected individuals, impaired growth observed in 4 and gait impairment was observed in 9/10. Hypoglycemia, previously reported in Slc38a3-/- mice, was not observed in any of the patients although this is presumably explained by diet/feeding intervals with abnormalities in pentose phosphate pathway in one individual hypothesized to be reflective of abn. glucose metabolism. The human phenotypes of microcephaly and seizures were not observed in mice. For mouse studies PMIDs cited by the authors : 27362266, 26490457. There is currently no SLC38A3-related phenotype reported in OMIM. In G2P this gene is incl. in the DD panel (biallelic, confidence: strong, SLC38A3-associated epileptic encephalopathy). SLC38A3 is listed among the primary ID genes in SysID. In PanelApp Australia, SLC38A3 is included with green rating in the epilepsy, ID and microcephaly panels. Consider inclusion with green rating (10 individuals, 7 families, 7 variants, role of SLCs and SLC38A3, alterations in AA/nitrogen metabolism etc) or amber rating (if discordances with mouse model considered). Please consider inclusion in other panels e.g. for microcephaly, CC abnormalities, metabolic disorders, etc. Sources: Literature, Other |
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Intellectual disability - microarray and sequencing v3.1525 | CACNA2D1 |
Konstantinos Varvagiannis gene: CACNA2D1 was added gene: CACNA2D1 was added to Intellectual disability. Sources: Literature,Other Mode of inheritance for gene: CACNA2D1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: CACNA2D1 were set to 35293990; 28097321 Phenotypes for gene: CACNA2D1 were set to Abnormal muscle tone; Feeding difficulties; Global developmental delay; Intellectual disability; Seizures; Microcephaly; Abnormality of the corpus callosum; Cerebral atrophy; Abnormality of movement; Cortical visual impairment; Pain insensitivity Penetrance for gene: CACNA2D1 were set to Complete Review for gene: CACNA2D1 was set to GREEN Added comment: Consider inclusion in the current panel with green rating. Recent report of 2 unrelated individuals with DEE due to biallelic CACNA2D1 variants. Both referred to neurology/genetics for hypotonia/severe DD prior to onset of seizures. One further individual with hypotonia and severe ID (seizures not discussed, age unknown). Gene with established role, encoding α2δ-1 subunit of Cav channels. Studies for the variants support loss-of-function as the underlying effect. Eventual contribution of monoallelic variants to NDD-phenotypes discussed (and put in question) in Ref [1] below. There is currently no phenotype for CACNA2D1 in OMIM/G2P. In SysID this gene is listed among the candidates for ID, based on a previous report. CACNA2D1 is not currently included in the ID/epilepsy panels in PanelApp Australia. See also relevant review in epilepsy panel (Dr. H. Lord). Please consider also inclusion in other panels (e.g. microcephaly, corpus callosum, movement disorders, etc). [1] ---- Dahimene et al (2022 - PMID: 35293990) describe the phenotype of 2 unrelated individuals with biallelic CACNA2D1 variants. Overall, the phenotype corresponded to an early-onset DEE, characterized by abnormal muscle tone (axial hypotonia 2/2 with spasticity in extremities in 2/2), feeding difficulties (2/2), profound DD and ID (2/2), microcephaly (2/2 - approx. -2 SD in both), seizures (2/2 - 1st : onset 9m with absences and later generalized seizures, 2nd : onset 11m with hemi-clonic seizures and atypical absences). Other features included cortical visual impairment (2/2) and movement disorder (incl. choreiform movements 2/2, orofacial dyskinesia 2/2 and dystonic episodes 1/2). Brain MRI revealed corpus callosum anomalies (2/2) and cerebral atrophy (2/2). Both had echocardiography (abnormal in 1/2 - tiny PFO) and electrocardiography which was normal. Both exhibited insensibility to pain. Presentation is relevant to the current panel as first symptoms in the first 3 months with severe hypotonia and poor head control (2/2) with evaluation in neurology/genetics preceding onset of seizures in both. Trio ES was performed for both individuals and their (healthy) parents and revealed homozygosity for a fs variant in the first [NM_000722.3:c.818_822dup / p.(Ser275Asnfs*13)] and compound htz for a fs and a missense variant [c.13_23dup / p.(Leu9Alafs*5) and c.626G>A / p.(Gly209Asp)] in the second affected individual, respectively. Eventual additional variants were not discussed. Previous investigations are only provided for the 2nd and were all normal (karyotype, CMA, 15q methylation, epilepsy/neurometabolic gene panels). Voltage-gated calcium channels are heteromultimers comprising different subunits incl. an alpha-1 (α1), α2δ (alpha-2/delta), beta (β) and gamma (γ). CACNA2D1 is one of the 4 genes (CACNA2D1-4) encoding the alpha-2/delta subunit. Its product is post-translationally processed into 2 peptides, an alpha-2 and a delta subunit, held by a disulfide bond. Biallelic variants in CACNA2D2 - also encoding an alpha-2/delta subunit - cause cerebellar atrophy with seizures and variable developmental delay (# 618501). Variant studies support loss-of-function effect for the studied variants, notably by NMD for the fs one, and severe impairment of the Cav2 channel function for the missense one : - CACNA2D1 mRNA was reduced to 6-9% compared with control in fibroblasts from the 1st individual. mRNA levels for the 2nd subject were similar to control. - Quantification of the protein in whole-cell lysates from fibroblasts revealed lower α2δ levels compared to control (10-12% and 31-38% applying to the 1st and 2nd individual). - CACNA2D3 mRNA levels in fibroblasts from the 2nd patient were 2-7x higher compared to the 1st or controls suggesting a possible compensatory effect. CACNA2D2/4 mRNA levels were too low for quantification. - Gly209 lies within the gabapentin and amino-acid binding pocket and this residue is invariable in CACNA2D1/CACNA2D2 in all vertebrates and paralogs. - Transfection of tsA-201 cells with either WT or G209D HA-tagged α2δ revealed reduced cell surface expression for this missense variant (~80, for biotinylated form ~86%). - In tsA-201 cells transfected with HA-tagged Cav2.2/β1b and either α2δ-1-WT, no α2δ-1 or α2δ-1-G209D, WT resulted in increased 13x currents with no increase applying to G209D (or in absence of α2δ). Plasma membrane expression of double (GFP/HA) tagged Cav2.2 was increased upon co-expression with WT α2δ-1 which was not the case for α2δ-1-G209D. - In hippocampal neurons, double (GFP/HA)-tagged Cav2.2 could not be detected at the cell surface in the presence of α2δ-1-G209D (or no α2δ) in contrast with strong expression in presence of α2δ-1-WT. α2δ-1-G209D did not promote trafficking of Cav2.2 into hippocampal neurites, as indicated by reduced signals for both HA and GFP (for cell surface and total Cav2.2 respectively). - Co-expression of double (GFP/HA) tagged Cav2.2 with β1b and either HA-α2δ-1-WT or HA-α2δ-1-G209D in tsA-201 cells, revealed reduced complex formation of G209D with Cav2.2 Co-immunoprecipitated HA-α2δ-1-G209D had higher molecular weight compared to HA-α2δ-1-WT which suggests that α2δ-1-G209D remains as the uncleaved immature form (probably in the ER). Mouse model (several Refs in text): Mild cardiac phenotype and reduced ventricular myocyte Ca current density was observed in hmz ko mice. Similarly to the insensibility to pain human phenotype, mice had delayed neuropathic pain-related responses. Overexpression of a2δ-1 resulted in epileptiform EEG and behavioral arrest, overall supporting a critical role of α2δ-1 for mouse brain. The authors underscore that the parents of both patients (htz carriers) were healthy and review previous literature for association of monoallelic variants with epilepsy, ID and arrhythmogenic disorders (in suppl.) [Refs not here reviewed]. As for the NDD phenotype, CACNA2D1 is within a previously defined small region of overlap for 7q21.11 microdeletions associated with ID+/-epilepsy. The same study did not reveal de novo SNVs in any of the 3 contained genes within this SRO (HGF, CACNA2D1, PCLO) in 4293 patients with NDD [cited PMID: 28240412]. A frameshift variant (c.2625del) was identified in a 13-yo girl with infantile spasms and normal intelligence [cited PMID: 25877686]. A 1-bp insertion (c.659-2_659-1insT / not studied at the mRNA level) was identified in another 14-yo female with ID and epilepsy [cited PMID: 34356170]. The authors state that the phenotype (/differences) of these individuals as well as presence of pLoF CACNA2D1 variants in gnomAD [still pLI of 1] put in question pathogenicity of monoallelic variants for these phenotypes. The role of heterozygous missense variants described in relation to arrhythmogenic disorders is also discussed extensively (some downgraded to LB/VUS, others having a relatively high MAF and presence of 1-2 homozygotes in gnomAD). [2] ---- In an article cited by SysID for CACNA2D1 (2017 - PMID: 28097321), Reuter et al studied with WES and autozygosity mapping individuals with NDD belonging to consanguineous families. As in eTables1/3, a male - single affected individual born to consanguineous parents from Turkey (MR150) - was investigated by singleton ES. This individual was homozygous for a missense CACNA2D1 SNV [NM_000722.2:c.1514C>T;p.(Thr505Ile)]. Prior investigations are unavailable (although individuals with previously known P/LP CNVs were excluded). The phenotype - briefly reported - included hypotonia, severe ID, stereotypic behaviors, inguinal hernia and omphalocele. Presence of seizures was not commented on. The age of this individual was not reported. Sources: Literature, Other |
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Intellectual disability - microarray and sequencing v3.1518 | NRCAM |
Konstantinos Varvagiannis gene: NRCAM was added gene: NRCAM was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: NRCAM was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: NRCAM were set to 35108495 Phenotypes for gene: NRCAM were set to Hypotonia; Hypertonia; Spasticity; Global developmental delay; Intellectual disability; Microcephaly; Behavioral abnormality; Neuropathy; Hearing abnormality; Abnormality of the eye; Abnormality of the skeletal system; Scoliosis; Abnormality of the face Penetrance for gene: NRCAM were set to Complete Review for gene: NRCAM was set to GREEN Added comment: Kurolap et al (2022 - PMID: 35108495) describe the phenotype of 10 individuals (from 8 families) with biallelic variants in NRCAM. Features included tone abnormalities (hypotonia in 4/10, hypertonia/spasticity in 4/10), DD (8/10 - 7 families) and cognitive impairment (in 7/10 - 6 fam), neuropathy (4/10 - incl. 2 sibs without DD/ID). Other phenotypes incl. FTT (2/8), microcephaly (3/6), variable behavioral issues (3/5), abnormalities from the eyes/vision (6/8 - cataract in 2), abnormal hearing (3/7) or skeletal findings (8/9 - incl. scoliosis in 5). Nonspecific facial features were reported in 5/8. Previous metabolic, genetic (incl. karyotype or CMA, FMR1, testing for Steinert disease or SMA) or other work-up (e.g. muscle biopsy) is reported for several subjects but was normal/non-diagnostic. All were investigated by WES/WGS which revealed biallelic NRCAM variants. Sanger sequencing was used for confirmation and segregation analyses, with compatible results in several affected/unaffected sibs tested. There were no alternative explanations for the NDD phenotype with the exception of one subject with a mosaic functionally characterized LP KRAS variant suspected to contribute to his phenotype. NRCAM encodes neuronal cell adhesion molecule (CAM). CAMs are membrane bound proteins with important role in tissue morphogenesis and maintenance. They mediate interactions between neighboring cells or cells and the extracellular matrix. The L1 subgroup of immunoglobulin CAMS - consisting of L1CAM, neurofascin, NRCAM, CHL1 - is the most abundant in the CNS with several critical functions in CNS development, among others in neural cell differentiation, axonal growth and guidance, myelination, synapse formation. Pathogenic L1CAM (XL) and NFASC variants (AR) are associated with NDD. Different missense (N=7), stopgain/frameshift (N=3), a splice variant (NM_001037132.2:c.2647-2A>G) as well as a deep intronic one (c.230+824G>C / rs575851831). Variants occurred in different domains with a cluster (42%) in the fibronectin III domain. Missense SNVs were ultrarare or not present in gnomAD, occurred in conserved residues, with several in silico predictions in favor of a deleterious effect. Structural modelling suggested that all substitutions occurred at residues exposed to solvent and possible abrogated interaction with other proteins. There were no expression studies performed at the mRNA/protein level. The splice variant is predicted to cause ex22 skipping leading to frameshift. The deep intronic variant is predicted to disrupt a site for spl. regulator SC35 and may cause activation of a cryptic acceptor site with inclusion of a cryptic exon. The zebrafish nrcama gene is the sole ortholog of human NRCAM, with another gene proposed as possible ortholog (nrcamb) mapping upon BLAST analysis to cntn1a. The authors performed CRISPR-Cas9 mutagenesis in zebrafish introducing a partial deletion of ex18 and 19. Mutant zebrafish were viable, displayed altered axonal projections and abnormal swimming behavior (increased movement in darkness). Currently, there is no NRCAM-associated phenotype in OMIM/G2P/SysID. PanelApp Australia includes NRCAM in its ID panel with green rating. Consider inclusion probably with green (>3 individuals/families/variants, segregation, gene in the L1-Ig CAM family causing NDD, zebrafish model) or amber rating (ID not a universal feature, variant effect not studied). Sources: Literature |
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Intellectual disability - microarray and sequencing v3.1497 | GJC2 | Arina Puzriakova Phenotypes for gene: GJC2 were changed from Leukodystrophy, hypomyelinating, 2, 608804Spastic paraplegia 44, autosomal recessive, 613206Lymphedema, hereditary, IC, 613480; LYMPHEDEMA, HEREDITARY, IC to Leukodystrophy, hypomyelinating, 2, OMIM:608804 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1496 | SLC35F1 |
Zornitza Stark gene: SLC35F1 was added gene: SLC35F1 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: SLC35F1 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: SLC35F1 were set to 33821533 Phenotypes for gene: SLC35F1 were set to Neruodevelopmental disorder, MONDO:0700092, SLC35F1-associated; Rett-like syndrome Review for gene: SLC35F1 was set to RED Added comment: WES identified a de novo heterozygous c.1037T>C; p.(I346T) (absent in gnomad v2 and v3) in a female described to have Rett-like syndrome. Global developmental delay, generalized tonic andtonic–clonic seizure, never acquired independent walking and developed spastictetraplegia in adulthood and limited speech No functional data Sources: Literature |
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Intellectual disability - microarray and sequencing v3.1490 | SPATA5L1 | Ivone Leong Phenotypes for gene: SPATA5L1 were changed from Neurodevelopmental disorder with hearing loss and spasticity, MIM# 619616 to Neurodevelopmental disorder with hearing loss and spasticity, OMIM:619616 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1478 | NSRP1 |
Zornitza Stark gene: NSRP1 was added gene: NSRP1 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: NSRP1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: NSRP1 were set to 34385670 Phenotypes for gene: NSRP1 were set to Epilepsy; Cerebral palsy; microcephaly; Intellectual disability Review for gene: NSRP1 was set to GREEN gene: NSRP1 was marked as current diagnostic Added comment: Novel gene regulating splicing. Biallelic LoF pathogenic variants reported in 6 individuals from 3 unrelated families associated with a phenotype characterized by developmental delay, epilepsy, microcephaly, and spastic cerebral palsy. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.1478 | SPATA5L1 |
Zornitza Stark gene: SPATA5L1 was added gene: SPATA5L1 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: SPATA5L1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: SPATA5L1 were set to 34626583 Phenotypes for gene: SPATA5L1 were set to Neurodevelopmental disorder with hearing loss and spasticity, MIM# 619616 Review for gene: SPATA5L1 was set to GREEN gene: SPATA5L1 was marked as current diagnostic Added comment: 47 individuals from 26 unrelated families from various ethnicities with biallelic variants reported. Phenotypes include ID, hearing impairment, movement disorder, abnormal MRI, hypotonia, visual impairment, epilepsy, and microcephaly. ~53% of patients had ID. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.1468 | GPT2 | Arina Puzriakova Phenotypes for gene: GPT2 were changed from Microcephaly; Mental retardation, autosomal recessive 49, 138210; Intellectual disability; Progressive spasticity to Neurodevelopmental disorder with microcephaly and spastic paraplegia, OMIM:616281 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1463 | AP5Z1 | Arina Puzriakova Phenotypes for gene: AP5Z1 were changed from Spastic paraplegia 48, autosomal recessive 613647 to Spastic paraplegia 48, autosomal recessive, OMIM:613647 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1461 | KIDINS220 | Arina Puzriakova Phenotypes for gene: KIDINS220 were changed from Spastic paraplegia, intellectual disability, nystagmus, and obesity, 617296 to Spastic paraplegia, intellectual disability, nystagmus, and obesity OMIM:617296 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1334 | ABHD16A |
Zornitza Stark gene: ABHD16A was added gene: ABHD16A was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: ABHD16A was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: ABHD16A were set to 34587489 Phenotypes for gene: ABHD16A were set to Spastic paraplegia; Intellectual disability Review for gene: ABHD16A was set to GREEN gene: ABHD16A was marked as current diagnostic Added comment: 11 individuals from 6 families with a complicated form of hereditary spastic paraplegia who carry bi-allelic deleterious variants in ABHD16A. Affected individuals present with a similar phenotype consisting of global developmental delay/intellectual disability, progressive spasticity affecting the upper and lower limbs, and corpus callosum and white matter anomalies. Immunoblot analysis on extracts from fibroblasts from four affected individuals demonstrated little to no ABHD16A protein levels compared to controls. In 5 of the families the affected members were homozygous, 3 of these families were consanguineous. 2 families have the same variant- both families are French-Canadian. 4 missense variants, 1 frameshift, 1 nonsense. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.1329 | RNF220 | Ivone Leong Phenotypes for gene: RNF220 were changed from Leukodystrophy; CNS hypomyelination; Ataxia; Intellectual disability; Sensorineural hearing impairment; Elevated hepatic transaminases; Hepatic fibrosis; Dilated cardiomyopathy; Spastic paraplegia; Dysarthria; Abnormality of the corpus callosum to Intellectual disability, MONDO:0001071 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1321 | ARF3 |
Ivone Leong Added comment: Comment on list classification: New gene added by Konstantinos Varvagiannis (Other). This gene is not associated with a phenotype in OMIM or Gene2Phenotype. PMID:34346499, individual 1 also has severe microcephaly (-3.3SD), spasticity, cerebellum atrophy and brainstem atrophy. Individual 2 does not have microcephaly, but has cerebellar hypoplasia. Based on the available evidence, there is currently not enough evidence to support a gene-disease association, therefore this gene has been given an Amber rating. |
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Intellectual disability - microarray and sequencing v3.1311 | EIF2AK2 | Arina Puzriakova edited their review of gene: EIF2AK2: Added comment: A further 5 families reported (PMID: 33236446) harbouring 3 different variants in this gene (including the first homozygous case). Clinical presentation was prominent in all cases for dystonia with onset in infancy or childhood, with subsequent generalisation. 3 unrelated individuals additionally developed mild ID, spasticity, and brain MRI alterations; while 6 individuals from the remaining 2 families had only isolated dystonia.; Changed publications to: 32197074, 33236446 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1292 | AP1G1 |
Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark. Usmani et al., 2021 (PMID: 34102099) identified 9 families with heterozygous and 2 families with homozygous variants in this gene. All individuals (12) had GDD and ID of various severity (mild to severe), except one patient who died at 22 days. Other features include hypotonia (9/10), seizures (6/10) and spasticity (4/10). Some supportive functional data included. There is sufficient evidence to promote this gene to Green at the next GMS panel update, with 'monoallelic' MOI. Biallelic cases would still be picked up by the Genomics England pipeline - but this may be reviewed if additional cases are discovered. |
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Intellectual disability - microarray and sequencing v3.1241 | C12orf65 | Arina Puzriakova Phenotypes for gene: C12orf65 were changed from COMBINED OXIDATIVE PHOSPHORYLATION DEFICIENCY 7 to Combined oxidative phosphorylation deficiency 7, OMIM:613559; Spastic paraplegia 55, autosomal recessive, OMIM:615035 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1240 | WDR45B | Arina Puzriakova Phenotypes for gene: WDR45B were changed from AUTOSOMAL RECESSIVE MENTAL RETARDATION; Neurodevelopmental disorder with spastic quadriplegia and brain abnormalities with or without seizures, 617977 to Neurodevelopmental disorder with spastic quadriplegia and brain abnormalities with or without seizures, OMIM:617977 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1239 | TFG | Arina Puzriakova Phenotypes for gene: TFG were changed from Hereditary motor and sensory neuropathy, proximal type, 604484; ?Spastic paraplegia 57, autosomal recessive, 615658 to Spastic paraplegia 57, autosomal recessive, OMIM:615658 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1236 | KIF1C | Arina Puzriakova Phenotypes for gene: KIF1C were changed from Spastic ataxia 2, autosomal recessive, 611302 to Spastic ataxia 2, autosomal recessive, OMIM:611302 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1224 | ENTPD1 | Arina Puzriakova Phenotypes for gene: ENTPD1 were changed from AUTOSOMAL RECESSIVE MENTAL RETARDATION to Spastic paraplegia 64, autosomal recessive, OMIM:615683 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1223 | ENTPD1 | Arina Puzriakova reviewed gene: ENTPD1: Rating: AMBER; Mode of pathogenicity: None; Publications: 24482476, 29691679, 30652007; Phenotypes: Spastic paraplegia 64, autosomal recessive, OMIM:615683; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1222 | RNF220 |
Konstantinos Varvagiannis gene: RNF220 was added gene: RNF220 was added to Intellectual disability. Sources: Literature,Other Mode of inheritance for gene: RNF220 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: RNF220 were set to 33964137; 10881263 Phenotypes for gene: RNF220 were set to Leukodystrophy; CNS hypomyelination; Ataxia; Intellectual disability; Sensorineural hearing impairment; Elevated hepatic transaminases; Hepatic fibrosis; Dilated cardiomyopathy; Spastic paraplegia; Dysarthria; Abnormality of the corpus callosum Penetrance for gene: RNF220 were set to Complete Review for gene: RNF220 was set to GREEN Added comment: Sferra et al (2021 - PMID: 33964137) provide extensive evidence that biallelic RNF220 mutations cause a disorder characterized by hypomyelinating leukodystrophy, ataxia (9/9 - onset 1-5y), borderline intellectual functioning (3/9) / intellectual disability (5/9 - in most cases mild), sensorineural deafness (9/9) with complete hearing loss in the first decade of life, hepatopathy (9/9) with associated periportal fibrosis, and dilated cardiomyopathy (9/9) which was fatal. Other neurologic manifestations apart from ataxia incl. hyperreflexia (8/8), spastic paraplegia (9/9), dysarthria (9/9), peripheral neuropathy (4/9), seizures in one case (1/9). Upon brain MRI there was thin corpus callosum (9/9) or cerebellar atrophy in some (2/9). The authors identified homozygosity for 2 recurrent missense RNF220 variants in affected members belonging to these 5 broad consanguineous pedigrees (7 families), namely NM_018150.4:c.1094G>A / p.Arg365Gly in 4 Roma families in the context of a shared haplotype (/founder effect) as well as c.1088G>A / p.Arg363Gly in a large pedigree from southern Italy initially reported by Leuzzi et al (2000 - PMID: 10881263). Extensive segregation analyses were carried out including several affected and unaffected members. RNF220 encodes ring finger protein 220, which functions as an E3 ubiquitin ligase. Previous studies have shown among others a role in modulation of Sonic hedgehog/GLI signaling and cerebellar development Evidence for the role of RNF220 included relevant expression, localization within the cell, interaction partners (lamin B1, 20S proteasome), similarities with other laminopathies in terms of phenotype, etc : *RNF220 has a relevant expression pattern in CNS (based on qRT-PCR analyses in human brain, cerebellum, cerebral cortex / mRNA levels in human fetal CNS with higher expression in cerebellum, spinal cord and cortex / previous GTEx data / protein levels in mouse CNS) *The protein displays nuclear localization based on iPSC cells differentiated to motor neurons (also supported by data from the Human Protein Atlas). Transfection of COS-1 cells demonstrated localization primarily to the nucleus (as also previously demonstrated in HEK293T cells) in vesicle like structures with ASF2/SF2 colocalization suggesting enrichment in nuclear speckles. There was also partial co-distribution with the 20S proteasome. R363Q and R365Q additionally coalesced in the cytoplasm forming protein aggregates/inclusions. *Immunofluorescence studies in patient fibroblasts also confirmed abnormal increase of the protein in the cytoplasm and increased fluorescence with the 20S proteasome. *Proteomic identification of RNF220-interacting proteins in transfected HEK293T cells demonstrated enrichment for all members of the lamin protein family (incl . lamin B1, AC, B2). *RNAi-mediated downregulation of RNF222 in Drosophila suggested altered subcellular localization and accumulation of the fly orthologue for human lamin B1. *Immunoprecipitation of lamin B1 from the nuclear matrix of cerebellar cells suggested significant interaction of endogenous lamin B1 with RNF220, while transfection studies in HEK293T cells for wt/mt suggested reduced binding to endogenous lamin B1 for RNF220 mt compared to wt (more prominent for R365Q). RNF220 mutants also reduced ubiquitination of nuclear lamin B1 compared to wt. *Patient fibroblasts immunostained with different nuclear envelope markers displayed abnormal nuclear shapes with multiple invaginations and lobulations, findings also observed in laminopathies. There is currently no associated phenotype in OMIM or G2P. SysID includes RNF220 among the current primary ID genes. Consider inclusion in panels for leukodystrophies, childhood onset ataxia, sensorineural hearing loss, corpus callosum anomalies, cardiomyopathies, hepatopathies, etc in all cases with green rating. Sources: Literature, Other |
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Intellectual disability - microarray and sequencing v3.1222 | ALS2 | Arina Puzriakova Phenotypes for gene: ALS2 were changed from ALS2-RELATED DISORDERS; Amyotrophic lateral sclerosis 2, juvenile, 205100 to Amyotrophic lateral sclerosis 2, juvenile, OMIM:205100; Primary lateral sclerosis, juvenile, OMIM:606353; Spastic paralysis, infantile onset ascending, OMIM:607225 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1215 | KIF1A | Arina Puzriakova Phenotypes for gene: KIF1A were changed from Mental Retardation, Dominant; Spastic paraplegia 30, autosomal recessive, 610357Neuropathy, hereditary sensory, type IIC, 614213Mental retardation, autosomal dominant 9, 614255; MENTAL RETARDATION, AUTOSOMAL DOMINANT 9 to NESCAV syndrome, OMIM:614255; Spastic paraplegia 30, autosomal dominant, OMIM:610357 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1208 | BSCL2 | Arina Puzriakova Phenotypes for gene: BSCL2 were changed from Encephalopathy, progressive, with or without lipodystrophy 615924; Lipodystrophy, congenital generalized, type 2 269700; Neuropathy, distal hereditary motor, type VA 600794; Silver spastic paraplegia syndrome 270685 to Encephalopathy, progressive, with or without lipodystrophy, OMIM:615924; Lipodystrophy, congenital generalized, type 2, OMIM:269700 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1207 | BSCL2 |
Arina Puzriakova Added comment: Comment on mode of inheritance: Monoallelic variants lead to a motor neuropathy (MIM# 619112) or spastic paraplegia (MIM# 270685) presentation, both characterised by motor symptoms, but neither are associated with any cognitive deficits. On the other hand, biallelic variants cause encephalopathy (MIM# 615924) or generalised lipodystrophy (MIM# 269700) which do include cognitive decline and intellectual impairment, respectively. Therefore, the MOI should be changed from 'Both mono- and biallelic' to 'Biallelic' only at the next GMS panel review. |
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Intellectual disability - microarray and sequencing v3.1145 | GEMIN5 |
Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is sufficient evidence to promote this gene to Green at the next GMS panel update (see details below). ----- Kour et al. 2021 (PMID: 33963192) report 30 individuals from 22 unrelated families with biallelic variants in the GEMIN5 gene. All affected individuals displayed predominantly motor DD, although cognitive and speech delays were also seen in most patients (18/19). 23/30 had central hypotonia, and variable appendicular spasticity was observed in 13/30 cases. 8 individuals were nonambulatory, while all ambulatory patients (19) had a gait ataxia. Brain MRI in all cases showed cerebellar atrophy. Variants perturbed the subcellular distribution, stability, and expression of GEMIN5 protein and its interacting partners, and disrupted snRNP complex assembly formation in patient iPSC-derived neurons, suggesting a LoF mechanism. Knockdown in Drosophila lead to developmental defects, motor dysfunction, and a reduced lifespan GEMIN5 is associated with a relevant phenotype in OMIM (Neurodevelopmental disorder with cerebellar atrophy and motor dysfunction, MIM# 619333) but is not yet listed in G2P. |
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Intellectual disability - microarray and sequencing v3.1143 | BCAS3 |
Arina Puzriakova Added comment: Comment on list classification: New gene added by Zornitza Stark (Australian Genomics). There is sufficient evidence to promote this gene to Green at the next GMS panel update (see details below). ----- Hengel et al. 2021 (PMID: 34022130) report 8 unrelated families, all with different biallelic variants in the BCAS3 gene. All affected individuals (15 total, +1 additional proband but with unphased variants but consistent phenotype) had severe GDD and ID, with 10 subjects having minimal vocabulary and 4 never learning to speak. All probands had a severe motor disorder with pyramidal tract involvement resulting in hyperreflexia and spasticity of the lower limbs (15/15). Other variable features observed in the cohort include microcephaly, short stature, seizures, and dysmorphic facial features. |
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Intellectual disability - microarray and sequencing v3.1132 | POLR3B | Arina Puzriakova Phenotypes for gene: POLR3B were changed from Leukodystrophy, hypomyelinating, 8, with or without oligodontia and/or hypogonadotropic hypogonadism, OMIM:614381 to Leukodystrophy, hypomyelinating, 8, with or without oligodontia and/or hypogonadotropic hypogonadism, OMIM:614381; POLR3B-related neurodevelopmental disorder; Ataxia, spasticity, and demyelinating neuropathy | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1120 | GEMIN5 |
Zornitza Stark gene: GEMIN5 was added gene: GEMIN5 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: GEMIN5 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: GEMIN5 were set to 33963192 Phenotypes for gene: GEMIN5 were set to Neurodevelopmental disorder with cerebellar atrophy and motor dysfunction, MIM# 619333 Review for gene: GEMIN5 was set to GREEN gene: GEMIN5 was marked as current diagnostic Added comment: Neurodevelopmental disorder with cerebellar atrophy and motor dysfunction (NEDCAM) is an autosomal recessive disorder characterized by global developmental delay with prominent motor abnormalities, mainly axial hypotonia, gait ataxia, and appendicular spasticity. Affected individuals have cognitive impairment and speech delay; brain imaging shows cerebellar atrophy. 30 individuals from 22 unrelated families reported. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.1115 | CYP7B1 | Arina Puzriakova Phenotypes for gene: CYP7B1 were changed from Spastic paraplegia 5A, autosomal recessive 270800 to Spastic paraplegia 5A, autosomal recessive , OMIM:270800 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1084 | AFG3L2 | Sarah Leigh Phenotypes for gene: AFG3L2 were changed from Spastic ataxia 5, autosomal recessive, 614487 to Spastic ataxia 5, autosomal recessive OMIM:614487; spastic ataxia 5 MONDO:0013776; Spinocerebellar ataxia 28 OMIM:610246; spinocerebellar ataxia type 28 MONDO:0012450 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1083 | AFG3L2 | Sarah Leigh reviewed gene: AFG3L2: Rating: ; Mode of pathogenicity: None; Publications: ; Phenotypes: Spastic ataxia 5, autosomal recessive OMIM:614487, spastic ataxia 5 MONDO:0013776, Spinocerebellar ataxia 28 OMIM:610246, spinocerebellar ataxia type 28 MONDO:0012450; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.1069 | FBXO31 |
Zornitza Stark edited their review of gene: FBXO31: Added comment: PMIDs 33675180; 32989326: three unrelated individuals with de novo missense variant, (p.Asp334Asn) and spastic-dystonic CP, including ID. AR ID: Single consanguineous family reported with homozygous truncating variant, limited functional evidence.; Changed rating: GREEN; Changed publications to: 24623383, 33675180, 32989326 |
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Intellectual disability - microarray and sequencing v3.1018 | 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 - microarray and sequencing v3.995 | MED27 | Arina Puzriakova Phenotypes for gene: MED27 were changed from Intellectual disability; cerebellar hypoplasia; dystonia to Intellectual disability; Axial hypotonia; Spasticity; Dystonia; Cerebellar hypoplasia; Cataracts; Epilepsy | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.993 | MED27 | Arina Puzriakova reviewed gene: MED27: Rating: GREEN; Mode of pathogenicity: None; Publications: 33443317; Phenotypes: Intellectual disability, Axial hypotonia, Spasticity, Dystonia, Cerebellar hypoplasia, Cataracts, Epilepsy; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.767 | HPDL | Arina Puzriakova reviewed gene: HPDL: Rating: GREEN; Mode of pathogenicity: None; Publications: 32707086, 33188300; Phenotypes: Neurodevelopmental disorder with progressive spasticity and brain white matter abnormalities, OMIM:619026, Neurodevelopmental disorder with progressive spasticity and brain white matter abnormalities, MONDO:0033613; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.767 | HPDL | Arina Puzriakova Phenotypes for gene: HPDL were changed from spastic paraplegia; spastic tetraplegia; microcephaly; brain atrophy; epilepsy; severe intellectual; motor disability to Neurodevelopmental disorder with progressive spasticity and brain white matter abnormalities, OMIM:619026; Neurodevelopmental disorder with progressive spasticity and brain white matter abnormalities, MONDO:0033613 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.762 | B4GALNT1 | Sarah Leigh Phenotypes for gene: B4GALNT1 were changed from ID; Spastic paraplegia 26, autosomal recessive to Spastic paraplegia 26, autosomal recessive OMIM:609195; hereditary spastic paraplegia 26 MONDO:0012213 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.760 | HPDL |
Evan Reid gene: HPDL was added gene: HPDL was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: HPDL was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: HPDL were set to PMID: 32707086; 33188300 Phenotypes for gene: HPDL were set to spastic paraplegia; spastic tetraplegia; microcephaly; brain atrophy; epilepsy; severe intellectual; motor disability Penetrance for gene: HPDL were set to Complete Review for gene: HPDL was set to GREEN Added comment: Newly identified gene that can give a phenotype ranging from infantile epileptic encephalopathy with severe developmental delay/intellectual disability to juvenile onset progressive spastic paraplegia. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.742 | TMX2 | Arina Puzriakova Phenotypes for gene: TMX2 were changed from Global developmental delay; Intellectual disability; Seizures; Microcephaly; Abnormal cortical gyration; Neurodevelopmental disorder with microcephaly, cortical malformations, and spasticity, 618730 to Neurodevelopmental disorder with microcephaly, cortical malformations, and spasticity, OMIM:618730; Neurodevelopmental disorder with microcephaly, cortical malformations, and spasticity, MONDO:0032887 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.716 | TRAPPC12 | Arina Puzriakova Phenotypes for gene: TRAPPC12 were changed from Encephalopathy, progressive, early-onset, with brain atrophy and spasticity, 617669; Developmental delay to Encephalopathy, progressive, early-onset, with brain atrophy and spasticity, OMIM:617669; Early-onset progressive encephalopathy-hearing loss-pons hypoplasia-brain atrophy syndrome, MONDO:0044696 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.714 | TRAPPC12 | Arina Puzriakova reviewed gene: TRAPPC12: Rating: GREEN; Mode of pathogenicity: None; Publications: 32369837; Phenotypes: Encephalopathy, progressive, early-onset, with brain atrophy and spasticity, OMIM:617669, Early-onset progressive encephalopathy-hearing loss-pons hypoplasia-brain atrophy syndrome, MONDO:0044696; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.694 | AP4E1 | Arina Puzriakova Phenotypes for gene: AP4E1 were changed from Spastic paraplegia 51, autosomal recessive, 613744; CEREBRAL PALSY SPASTIC QUADRIPLEGIC TYPE 4 to Spastic paraplegia 51, autosomal recessive, OMIM:613744; Hereditary spastic paraplegia 51, MONDO:0013401 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.693 | AP4B1 | Arina Puzriakova Phenotypes for gene: AP4B1 were changed from Spastic paraplegia 47, autosomal recessive, 614066; CEREBRAL PALSY SPASTIC QUADRIPLEGIC TYPE 5 to Spastic paraplegia 47, autosomal recessive, OMIM:614066; Hereditary spastic paraplegia 47, MONDO:0013551 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.665 | SHMT2 |
Arina Puzriakova Added comment: Comment on list classification: New gene added by Konstantinos Varvagiannis. Sufficient number of unrelated cases (>3) with ID of relevant severity to this panel. Some functional data indicating variants result in impaired SHMT2 enzymatic function. Rating Amber but should be promoted to Green at the next GMS panel update (added 'for-review' tag) SHMT2 is listed in Gene2Phenotype with a 'probable' disease confidence rating for 'SHMT2-related neurodevelopmental syndrome', and is also associated with 'Neurodevelopmental disorder with cardiomyopathy, spasticity, and brain abnormalities, MIM# 619121' in OMIM. |
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Intellectual disability - microarray and sequencing v3.664 | SHMT2 | Arina Puzriakova Phenotypes for gene: SHMT2 were changed from Congenital microcephaly; Infantile axial hypotonia; Spastic paraparesis; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum; Abnormal cortical gyration; Hypertrophic cardiomyopathy; Abnormality of the face; Proximal placement of thumb; 2-3 toe syndactyly to Neurodevelopmental disorder with cardiomyopathy, spasticity, and brain abnormalities, OMIM:619121 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.510 | DHX32 |
Zornitza Stark gene: DHX32 was added gene: DHX32 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: DHX32 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: DHX32 were set to 32989326 Phenotypes for gene: DHX32 were set to Intellectual disability, spastic diplegia, dystonia, brain abnormalities Review for gene: DHX32 was set to AMBER Added comment: PMID: 32989326 - Large cohort study of cerebral palsy cases identified two de novo variants in two unrelated patients with intellectual disability, one with spastic diplegia, and the other characterised as generalised dystonia. Brain abnormalities were identified also. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.510 | FBXO31 | Zornitza Stark edited their review of gene: FBXO31: Changed phenotypes: Mental retardation, autosomal recessive 45, MIM#615979, Intellectual disability, spasticity, autosomal dominant | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.510 | FBXO31 |
Zornitza Stark gene: FBXO31 was added gene: FBXO31 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: FBXO31 was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal Publications for gene: FBXO31 were set to 24623383; 32989326 Phenotypes for gene: FBXO31 were set to Mental retardation, autosomal recessive 45, MIM#615979; Intellectual disability, autosomal dominant Review for gene: FBXO31 was set to AMBER Added comment: Bi-allelic variants: Single consanguineous family reported with homozygous truncating variant, limited functional evidence. Mono-allelic variants: 2 unrelated probands reported as part of a 'cerebral palsy' cohort harbouring the same de novo missense variant (p.Asp334Asn). The variant affects the cyclin D interaction site, leading to an apparent gain of function of cyclin D degradation, supported by Western blots from patient fibroblasts which showed decreased cyclin D expression. Patient phenotypes: Spastic diplegia, with esotropia, ID, dysarthria, mixed receptive/expressive language disorder, ADHD, cleft palate, intestinal malrotation and midgut volvulus (patient 1); Spastic paraplegia with ventricular dilation and thin corpus callosum, ID, attention deficit, anxiety, language impairments, strabismus, severe constipation (patient 2). Sources: Literature |
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Intellectual disability - microarray and sequencing v3.497 | MFSD2A | Arina Puzriakova Phenotypes for gene: MFSD2A were changed from NA to Neurodevelopmental disorder with progressive microcephaly, spasticity, and brain imaging abnormalities, 616486 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.494 | MFSD2A | Arina Puzriakova reviewed gene: MFSD2A: Rating: GREEN; Mode of pathogenicity: None; Publications: 26005868, 26005865, 29302074, 30043326, 32572202; Phenotypes: Neurodevelopmental disorder with progressive microcephaly, spasticity, and brain imaging abnormalities, 616486; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.420 | SHMT2 |
Konstantinos Varvagiannis gene: SHMT2 was added gene: SHMT2 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: SHMT2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: SHMT2 were set to 33015733 Phenotypes for gene: SHMT2 were set to Congenital microcephaly; Infantile axial hypotonia; Spastic paraparesis; Global developmental delay; Intellectual disability; Abnormality of the corpus callosum; Abnormal cortical gyration; Hypertrophic cardiomyopathy; Abnormality of the face; Proximal placement of thumb; 2-3 toe syndactyly Penetrance for gene: SHMT2 were set to Complete Review for gene: SHMT2 was set to GREEN Added comment: García‑Cazorla et al. (2020 - PMID: 33015733) report 5 individuals (from 4 families) with a novel brain and heart developmental syndrome caused by biallelic SHMT2 pathogenic variants. All affected subjects presented similar phenotype incl. microcephaly at birth (5/5 OFC < -2 SD though in 2/5 cases N OFC was observed later), DD and ID (1/5 mild-moderate, 1/5 moderate, 3/5 severe), motor dysfunction in the form of spastic (5/5) paraparesis, ataxia/dysmetria (3/4), intention tremor (in 3/?) and/or peripheral neuropathy (2 sibs). They exhibited corpus callosum hypoplasia (5/5) and perisylvian microgyria-like pattern (4/5). Cardiac problems were reported in all, with hypertrophic cardiomyopathy in 4/5 (from 3 families) and atrial-SD in the 5th individual (1/5). Common dysmorphic features incl. long palpebral/fissures, eversion of lateral third of lower eylids, arched eyebrows, long eyelashes, thin upper lip, short Vth finger, fetal pads, mild 2-3 toe syndactyly, proximally placed thumbs. Biallelic variants were identified following exome sequencing in all (other investigations not mentioned). Identified variants were in all cases missense SNVs or in-frame del, which together with evidence from population databases and mouse model might suggest a hypomorphic effect of variants and intolerance/embryonic lethality for homozygous LoF ones. SHMT2 encodes the mitohondrial form of serine hydroxymethyltransferase. The enzyme transfers one-carbon units from serine to tetrahydrofolate (THF) and generates glycine and 5,10,methylene-THF. Mitochondrial defect was suggested by presence of ragged red fibers in myocardial biopsy of one patient. Quadriceps and myocardial biopsies of the same individual were overall suggestive of myopathic changes. While plasma metabolites were within N range and SHMT2 protein levels not significantly altered in patient fibroblasts, the authors provide evidence for impaired enzymatic function eg. presence of the SHMT2 substrate (THF) in patient but not control (mitochondria-enriched) fibroblasts , decrease in glycine/serine ratios, impared folate metabolism. Patient fibroblasts displayed impaired oxidative capacity (reduced ATP levels in a medium without glucose, diminished oxygen consumption rates). Mitochondrial membrane potential and ROS levels were also suggestive of redox malfunction. Shmt2 ko in mice was previously shown to be embryonically lethal attributed to severe mitochondrial respiration defects, although there was no observed brain metabolic defect. The authors performed Shmt2 knockdown in motoneurons in Drosophila, demonstrating neuromuscular junction (# of satellite boutons) and motility defects (climbing distance/velocity). Overall this gene can be considered for inclusion with (probably) green rating in gene panels for ID, metabolic / mitochondrial disorders, cardiomyopathy, congenital microcephaly, corpus callosum anomalies, etc. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.360 | CYP2U1 | Eleanor Williams Added comment: Comment on list classification: Leaving this gene as green for now, but after consultation with the Genomics England clinical team it was felt that it should be considered for downgrade to amber at the next GMS review. It is a spastic paraplegia gene and seems to mainly present in that manner. Amber rating would be appropriate as cognitive impairment is a feature and new cases may emerge which support that as a primary presentation. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.335 | CYP2U1 | Eleanor Williams reviewed gene: CYP2U1: Rating: AMBER; Mode of pathogenicity: None; Publications: 23176821; Phenotypes: Spastic paraplegia 56, autosomal recessive, 615030; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.325 | AFG3L2 | Arina Puzriakova Phenotypes for gene: AFG3L2 were changed from SPINOCEREBELLAR ATAXIA 28 to Spastic ataxia 5, autosomal recessive, 614487 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.314 | LMNB1 |
Konstantinos Varvagiannis gene: LMNB1 was added gene: LMNB1 was added to Intellectual disability. 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 Loss-of-function variants (as defined in pop up message) DO NOT cause this phenotype - please provide details in the comments Review for gene: LMNB1 was set to GREEN 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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Intellectual disability - microarray and sequencing v3.274 | ADARB1 | Arina Puzriakova edited their review of gene: ADARB1: Added comment: PMID: 32719099 (2020) - Three additional patients from two consanguineous families with novel biallelic variants in the ADARB1 gene. All affected individuals presented global DD, severe-profound ID, intractable early infantile-onset seizures, severe microcephaly, axial hypotonia and progressive appendicular spasticity. In vitro RNA editing assays showed that both variants resulted in severe impairment or loss of ADAR2 enzymatic activity.; Changed publications: 32220291, 32719099 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.255 | TAF1C |
Konstantinos Varvagiannis gene: TAF1C was added gene: TAF1C was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: TAF1C was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: TAF1C were set to 32779182 Phenotypes for gene: TAF1C were set to Global developmental delay; Intellectual disability; Spasticity; Strabismus; Seizures; Abnormality of nervous system morphology Penetrance for gene: TAF1C were set to Complete Review for gene: TAF1C was set to AMBER Added comment: Knuutinen et al (2020 - PMID: 32779182) report on 2 individuals from 2 consanguineous families, homozygous for TAF1C missense variants. Both presented with an early onset neurological phenotype with severe global DD, ID (2/2 - moderate and profound), spasticity (2/2), ophthalmic findings (strabismus 2/2, nystagmus 1/2). Epilepsy, abnormal brain MRI (cerebral and cerebellar atrophy and white matter hyperintensities) as well and additional findings were reported in one (always the same individual). Following a normal CMA, exome in the first case revealed a homozygous missense SNV (NM_005679.3:c.1165C>T / p.Arg389Cys) supported by in silico predictions. mRNA and protein levels were substantially reduced in fibroblasts from this subject. Only the patient and parents were tested for the variant but not 3 unaffected sibs (fig1). The second individual was homozygous for another missense variant (p.Arg405Cys) also supported by in silico predictions. The girl was the single affected person within the family with an unaffected sib and parents heterozygous for the variant. Several other unaffected relatives in the extended pedigree were either carriers for this variant or homozygous for the wt allele. TAF1C encodes the TATA-box binding protein associated factor (TAF) RNA polymerase I subunit. RNA polymerase I (Pol I) transcribes genes to produce rRNA. For Pol I to initiate transcription, two transcription factors are required : UBF (upstream binding factor encoded by UBTF) and SL1 (selectivity factor 1). The latter is formed by TBP (TATA-binding protein) and 3 Pol I-specific TBP-associated factors (TAFs). A recurrent de novo missense variant in UBTF (encoding the other Pol I transcription factor) causes a disorder with highly similar features. The specific variant acts through a gain-of-function mechanism (and not by LoF which appears to apply for TAF1C based on expression data). The authors hypothesize that altered Pol I activity and resulting ribosomal stress could cause the microcephaly and leukodystrophy (both reported in 1 - the same - individual). As a result, TAF1C may be considered for inclusion in the ID panel with amber rating pending further evidence. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.219 | NARS |
Konstantinos Varvagiannis changed review comment from: [Please note that HGNC Approved Gene Symbol for this gene is NARS1] Manole et al (2020 - PMID: 32738225) provide evidence that both biallelic and monoallelic (de novo) pathogenic NARS1 variants cause a neurodevelopmental disorder. In total 32 individuals from 21 families are reported, with biallelic variants identified in individuals from 13 families and de novo in 8 families. Similar features were reported for AR/AD occurrences of the disorder and included of microcephaly (90% - most often primary), epilepsy (23/32 or 74% - variable semiology incl. partial/myoclonic/generalized tonic-clonic seizures), DD and ID (as a universal feature), abnormal tone in several (hypotonia/spasticity), ataxia, demyelinating peripheral neuropathy (in 3 or more for each inheritance mode - or a total of 25%). Some individuals had dysmorphic features. NARS1 encodes an aminoacyl-tRNA synthetase (ARS) [asparaginyl-tRNA synthetase 1]. Aminoacyl-tRNA synthetases constitute a family of enzymes catalyzing attachment of amino-acids to their cognate tRNAs. As the authors comment, mutations in genes encoding several other ARSs result in neurological disorders ranging from peripheral neuropathy to severe multi-systemic NDD. Dominant, recessive or both modes for inheritance for mutations in the same gene (e.g. AARS1, YARS1, MARS1, etc) have been reported. Some variants were recurrent, e.g. the c.1600C>T / p.Arg534* which occurred in 6 families as a de novo event or c.1633C>T p.Arg545Cys (homozygous in 6 families). 3 different variants were reported to have occured de novo (c.965G>T - p.Arg322Leu, c.1525G>A - p.Gly509Ser, p.Arg534*) with several other variants identified in hmz/compound htz individuals. A single SNV (c.1067A>C - p.Asp356Ala) was suggested to be acting as modifier and pathogenic only when in trans with a severe variant. [NM_004539.4 used as RefSeq for all]. The authors provide several lines of evidence for a partial loss-of-function effect (e.g. reduction in mRNA expression, enzyme levels and activity in fibroblasts or iNPCs) underlying pathogenicity of the variants identified in individuals with biallelic variants. A gain-of-function (dominant-negative) effect is proposed for de novo variants (such effect also demonstrated for the p.Arg534* in a zebrafish model). As also Manole et al suggest, NARS1 can be considered for inclusion in gene panels for DD/ID, epilepsy and/or demyelinating neuropathy. Sources: Literature; to: [Please note that HGNC Approved Gene Symbol for this gene is NARS1] Manole et al (2020 - PMID: 32738225) provide evidence that both biallelic and monoallelic (de novo) pathogenic NARS1 variants cause a neurodevelopmental disorder. In total 32 individuals from 21 families are reported, with biallelic variants identified in individuals from 13 families and de novo in 8 families. Similar features were reported for AR/AD occurrences of the disorder and included microcephaly (90% - most often primary), epilepsy (23/32 or 74% - variable semiology incl. partial/myoclonic/generalized tonic-clonic seizures), DD and ID (as a universal feature), abnormal tone in several (hypotonia/spasticity), ataxia, demyelinating peripheral neuropathy (in 3 or more for each inheritance mode - or a total of 25%). Some individuals had dysmorphic features. NARS1 encodes an aminoacyl-tRNA synthetase (ARS) [asparaginyl-tRNA synthetase 1]. Aminoacyl-tRNA synthetases constitute a family of enzymes catalyzing attachment of amino-acids to their cognate tRNAs. As the authors comment, mutations in genes encoding several other ARSs result in neurological disorders ranging from peripheral neuropathy to severe multi-systemic NDD. Dominant, recessive or both modes for inheritance for mutations in the same gene (e.g. AARS1, YARS1, MARS1, etc) have been reported. Some variants were recurrent, e.g. the c.1600C>T / p.Arg534* which occurred in 6 families as a de novo event or c.1633C>T p.Arg545Cys (homozygous in 6 families). 3 different variants were reported to have occured de novo (c.965G>T - p.Arg322Leu, c.1525G>A - p.Gly509Ser, p.Arg534*) with several other variants identified in hmz/compound htz individuals. A single SNV (c.1067A>C - p.Asp356Ala) was suggested to be acting as modifier and pathogenic only when in trans with a severe variant. [NM_004539.4 used as RefSeq for all]. The authors provide several lines of evidence for a partial loss-of-function effect (e.g. reduction in mRNA expression, enzyme levels and activity in fibroblasts or iNPCs) underlying pathogenicity of the variants identified in individuals with biallelic variants. A gain-of-function (dominant-negative) effect is proposed for de novo variants (such effect also demonstrated for the p.Arg534* in a zebrafish model). As also Manole et al suggest, NARS1 can be considered for inclusion in gene panels for DD/ID, epilepsy and/or demyelinating neuropathy. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.219 | NARS |
Konstantinos Varvagiannis gene: NARS was added gene: NARS was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: NARS was set to BOTH monoallelic and biallelic, autosomal or pseudoautosomal Publications for gene: NARS were set to 32738225 Phenotypes for gene: NARS were set to Abnormal muscle tone; Microcephaly; Global developmental delay; Intellectual disability; Seizures; Ataxia; Abnormality of the face; Demyelinating peripheral neuropathy Penetrance for gene: NARS were set to Complete Review for gene: NARS was set to GREEN Added comment: [Please note that HGNC Approved Gene Symbol for this gene is NARS1] Manole et al (2020 - PMID: 32738225) provide evidence that both biallelic and monoallelic (de novo) pathogenic NARS1 variants cause a neurodevelopmental disorder. In total 32 individuals from 21 families are reported, with biallelic variants identified in individuals from 13 families and de novo in 8 families. Similar features were reported for AR/AD occurrences of the disorder and included of microcephaly (90% - most often primary), epilepsy (23/32 or 74% - variable semiology incl. partial/myoclonic/generalized tonic-clonic seizures), DD and ID (as a universal feature), abnormal tone in several (hypotonia/spasticity), ataxia, demyelinating peripheral neuropathy (in 3 or more for each inheritance mode - or a total of 25%). Some individuals had dysmorphic features. NARS1 encodes an aminoacyl-tRNA synthetase (ARS) [asparaginyl-tRNA synthetase 1]. Aminoacyl-tRNA synthetases constitute a family of enzymes catalyzing attachment of amino-acids to their cognate tRNAs. As the authors comment, mutations in genes encoding several other ARSs result in neurological disorders ranging from peripheral neuropathy to severe multi-systemic NDD. Dominant, recessive or both modes for inheritance for mutations in the same gene (e.g. AARS1, YARS1, MARS1, etc) have been reported. Some variants were recurrent, e.g. the c.1600C>T / p.Arg534* which occurred in 6 families as a de novo event or c.1633C>T p.Arg545Cys (homozygous in 6 families). 3 different variants were reported to have occured de novo (c.965G>T - p.Arg322Leu, c.1525G>A - p.Gly509Ser, p.Arg534*) with several other variants identified in hmz/compound htz individuals. A single SNV (c.1067A>C - p.Asp356Ala) was suggested to be acting as modifier and pathogenic only when in trans with a severe variant. [NM_004539.4 used as RefSeq for all]. The authors provide several lines of evidence for a partial loss-of-function effect (e.g. reduction in mRNA expression, enzyme levels and activity in fibroblasts or iNPCs) underlying pathogenicity of the variants identified in individuals with biallelic variants. A gain-of-function (dominant-negative) effect is proposed for de novo variants (such effect also demonstrated for the p.Arg534* in a zebrafish model). As also Manole et al suggest, NARS1 can be considered for inclusion in gene panels for DD/ID, epilepsy and/or demyelinating neuropathy. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.183 | EIF2AK1 | Arina Puzriakova reviewed gene: EIF2AK1: Rating: RED; Mode of pathogenicity: ; Publications: 32197074; Phenotypes: Leukoencephalopathy, motor delay, spasticity, and dysarthria syndrome, 618878, ADHD; Mode of inheritance: MONOALLELIC, autosomal or pseudoautosomal, imprinted status unknown | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.183 | ADD3 | Arina Puzriakova reviewed gene: ADD3: Rating: GREEN; Mode of pathogenicity: ; Publications: 23836506, 29768408; Phenotypes: Cerebral palsy, spastic quadriplegic, 617008, Intellectual disability, Microcephaly; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.175 | ATL1 | Zornitza Stark edited their review of gene: ATL1: Changed publications: 21336785, 28736820, 29180453, 29691679, 31236401; Changed phenotypes: Neuropathy, hereditary sensory, type ID, MIM# 613708, Spastic paraplegia 3A, autosomal dominant, MIM# 182600 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.175 | ATL1 | Sarah Leigh changed review comment from: Associated with phenotype in OMIM, not in G2P. Mild late onset mental retardation in 10 members of a three generation family with Spastic paraplegia 3A, autosomal dominant 182600; to: Associated with phenotype in OMIM, not in G2P. Mild to severe late onset mental retardation in 10 members of a three generation family with Spastic paraplegia 3A, autosomal dominant 182600 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.175 | ATL1 | Sarah Leigh commented on gene: ATL1: Associated with phenotype in OMIM, not in G2P. Mental retardation has been reported in a second family (PMID 31236401). In this publication, the 9 year old proband and his maternal grandfather had hereditary spastic paraplegia and intellectual disability, however, proband's mother had hereditary spastic paraplegia, but no intelectual disability. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.174 | PTPN23 | Eleanor Williams Phenotypes for gene: PTPN23 were changed from Developmental epileptic encephalopathy with hypomyelination and brain atrophy; Intellectual disability; Severe developmental delay, to Developmental epileptic encephalopathy with hypomyelination and brain; Neurodevelopmental disorder and structural brain anomalies with or without seizures and spasticity MIM#618890 atrophy; Intellectual disability; Severe developmental delay, | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.170 | EXOC2 |
Konstantinos Varvagiannis gene: EXOC2 was added gene: EXOC2 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: EXOC2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: EXOC2 were set to 32639540 Phenotypes for gene: EXOC2 were set to Global developmental delay; Intellectual disability; Abnormality of the face; Abnormality of brain morphology Penetrance for gene: EXOC2 were set to Complete Review for gene: EXOC2 was set to AMBER Added comment: Van Bergen et al (2020 - PMID: 32639540) report on 3 individuals from 2 families, harboring biallelic EXOC2 mutations. Clinical presentation included DD, ID (severe in 2 subjects from fam1, borderline intellectual functioning in fam2), dysmorphic features and brain abnormalities. Cerebellar anomalies were common to all with a molar tooth sign observed in one (1/3). Other findings limited to subjects from one family included acquired microcephaly, congenital contractures, spastic quadriplegia (each observed 2/3). Previous investigations were in all cases non-diagnostic. WES identified biallelic EXOC2 mutations in all affected individuals. EXOC2 encodes an exocyst subunit. The latter is an octameric complex, component of the membrane transport machinery, required for tethering and fusion of vesicles at the plasma membrane. As discussed ,vesicle transport is important for the development of brain and the function of neurons and glia. Exocyst function is also important for delivery of Arl13b to the primary cilium (biallelic ARL13B mutations cause Joubert syndrome 8) and ciliogenesis. Affected subjects from a broader consanguineous family (fam1) were homozygous for a truncating variant. Fibroblast studies revealed mRNA levels compatible with NMD (further restored in presence of CHX) as well as reduced protein levels. The female belonging to the second non-consanguineous family was found to harbor 2 missense variants in trans configuration. An exocytosis defect was demonstrated in fibroblasts from individuals belonging to both families. Ciliogenesis appeared to be normal, however Arl13b localization/recruitment to the cilia was reduced compared with control cells with the defect rescued upon exogenous expression of wt EXOC2. Mutations in other genes encoding components of the exocyst complex have been previously reported in individuals with relevant phenotypes (e.g. EXOC8 in a boy with features of Joubert s. or EXOC4 in nephrotic syndrome). The authors discuss on the essential role of EXOC2 based on model organism studies (e.g. impaired neuronal membrane traffic, failure of neuronal polarization and neuromuscular junction expansion seen in Drosophila Sec5 (EXOC2) null mutants). Sources: Literature |
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Intellectual disability - microarray and sequencing v3.169 | SEC31A | Sarah Leigh Phenotypes for gene: SEC31A were changed from Neurodevelopmental disorder with spastic quadriplegia, optic atrophy, seizures, and structural brain anomalies, OMIM #618651 to Neurodevelopmental disorder with spastic quadriplegia, optic atrophy, seizures, and structural brain anomalies 618651 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.151 | NOVA2 | Sarah Leigh Phenotypes for gene: NOVA2 were changed from Intellectual disability; autism; hypotonia; spasticity; ataxia to Neurodevelopmental disorder with or without autistic features and/or structural brain abnormalities 618859 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.68 | TRAPPC4 | Rebecca Foulger Phenotypes for gene: TRAPPC4 were changed from Feeding difficulties; Progressive microcephaly; Intellectual disability; Seizures; Spastic tetraparesis; Abnormality of the face; Scoliosis; Cortical visual impairment; Hearing impairment to Neurodevelopmental disorder with epilepsy, spasticity, and brain atrophy, 618741 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.67 | WDR45B | Rebecca Foulger Phenotypes for gene: WDR45B were changed from AUTOSOMAL RECESSIVE MENTAL RETARDATION to AUTOSOMAL RECESSIVE MENTAL RETARDATION; Neurodevelopmental disorder with spastic quadriplegia and brain abnormalities with or without seizures, 617977 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.62 | TMX2 | Eleanor Williams Phenotypes for gene: TMX2 were changed from Global developmental delay; Intellectual disability; Seizures; Microcephaly; Abnormal cortical gyration to Global developmental delay; Intellectual disability; Seizures; Microcephaly; Abnormal cortical gyration; Neurodevelopmental disorder with microcephaly, cortical malformations, and spasticity, 618730 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.57 | PCYT2 | Rebecca Foulger Phenotypes for gene: PCYT2 were changed from Global developmental delay; Developmental regression; Intellectual disability; Spastic paraparesis; Seizures; Spastic tetraparesis; Cerebral atrophy; Cerebellar atrophy to Spastic paraplegia 82, autosomal recessive, 618770; Global developmental delay; Developmental regression; Intellectual disability; Spastic paraparesis; Seizures; Spastic tetraparesis; Cerebral atrophy; Cerebellar atrophy | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.35 | UGDH |
Konstantinos Varvagiannis gene: UGDH was added gene: UGDH was added to Intellectual disability. 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 - microarray and sequencing v3.35 | YIF1B |
Konstantinos Varvagiannis gene: YIF1B was added gene: YIF1B was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: YIF1B was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: YIF1B were set to 32006098 Phenotypes for gene: YIF1B were set to Central hypotonia; Failure to thrive; Microcephaly; Global developmental delay; Intellectual disability; Seizures; Spasticity; Abnormality of movement Penetrance for gene: YIF1B were set to Complete Review for gene: YIF1B was set to GREEN Added comment: AlMuhaizea et al (2020 - PMID: 32006098) report on the phenotype of 6 individuals (from 5 families) with biallelic YIF1B truncating variants. Affected subjects presented hypotonia, failure to thrive, microcephaly (5/6), severe global DD and ID (as evident from best motor/language milestones achieved - Table S1) as well as features suggestive of a motor disorder (dystonia/spasticity/dyskinesia). Seizures were reported in 2 unrelated individuals (2/6). MRI abnormalities were observed in some with thin CC being a feature in 3. Variable initial investigations were performed including SNP CMA, MECP2, microcephaly / neurotransmitter disorders gene panel testing did not reveal P/LP variants. YIF1B variants were identified in 3 families within ROH. Following exome sequencing, affected individuals were found to be homozygous for truncating variants (4/5 families being consanguineous). The following 3 variants were identified (NM_001039672.2) : c.186dupT or p.Ala64fs / c.360_361insACAT or p.Gly121fs / c.598G>T or p.Glu200*. YIF1B encodes an intracellular transmembrane protein. It has been previously demonstrated that - similarly to other proteins of the Yip family being implicated in intracellular traffic between the Golgi - Yif1B is involved in the anterograde traffic pathway. Yif1B KO mice demonstrate a disorganized Golgi architecture in pyramidal hippocampal neurons (Alterio et al 2015 - PMID: 26077767). The rat ortholog interacts with serotonin receptor 1 (5-HT1AR) with colocalization of Yif1BB and 5-HT1AR in intermediate compartment vesicles and involvement of the former in intracellular trafficing/modulation of 5-HT1AR transport to dendrites (PMID cited: 18685031). Available mRNA and protein expression data (Protein Atlas) suggest that the gene is widely expressed in all tissues incl. neuronal cells. Immunochemistry data from the Human Brain Atlas also suggest that YIF1B is found in vesicles and localized to the Golgi apparatus. Immunohistochemistry in normal human brain tissue (cerebral cortex) demonstrated labeling of neuronal cells (Human Protein Atlas). Functional/network analysis of genes co-regulated with YIF1B based on available RNAseq data, suggest enrichement in in genes important for nervous system development and function. Please consider inclusion in other panels that may be relevant (e.g. microcephaly, etc). Sources: Literature |
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Intellectual disability - microarray and sequencing v3.31 | GSX2 |
Zornitza Stark gene: GSX2 was added gene: GSX2 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: GSX2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: GSX2 were set to 31412107 Phenotypes for gene: GSX2 were set to Diencephalic-mesencephalic junction dysplasia syndrome 2 618646; Intellectual disability; Dystonia; Spastic tetra paresis Review for gene: GSX2 was set to AMBER Added comment: Two unrelated families, some functional data. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.29 | NOVA2 |
Zornitza Stark gene: NOVA2 was added gene: NOVA2 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: NOVA2 was set to MONOALLELIC, autosomal or pseudoautosomal, NOT imprinted Publications for gene: NOVA2 were set to 32197073 Phenotypes for gene: NOVA2 were set to Intellectual disability; autism; hypotonia; spasticity; ataxia Review for gene: NOVA2 was set to GREEN gene: NOVA2 was marked as current diagnostic Added comment: Six individuals with de novo frameshift variants resulting in C-terminal extension suggesting partial LoF as mechanism. Sources: Literature |
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Intellectual disability - microarray and sequencing v3.29 | GAD1 | Sarah Leigh Phenotypes for gene: GAD1 were changed from ?Cerebral palsy, spastic quadriplegic, 1; Developmental and epileptic encephalopathies, cleft palate, joint contractures and/or omphalocele to ?Cerebral palsy, spastic quadriplegic, 1 603513; Developmental and epileptic encephalopathies, cleft palate, joint contractures and/or omphalocele | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.26 | GAD1 | Sarah Leigh Phenotypes for gene: GAD1 were changed from ?Cerebral palsy, spastic quadriplegic, 1 to ?Cerebral palsy, spastic quadriplegic, 1; Developmental and epileptic encephalopathies, cleft palate, joint contractures and/or omphalocele | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.3 | TNR |
Zornitza Stark gene: TNR was added gene: TNR was added to Intellectual disability. Sources: Expert list Mode of inheritance for gene: TNR was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: TNR were set to 32099069 Phenotypes for gene: TNR were set to Spastic para- or tetraparesis; Axial muscular hypotonia; Intellectual disability; Transient opisthotonus Review for gene: TNR was set to GREEN gene: TNR was marked as current diagnostic Added comment: 13 individuals from 8 unrelated families reported. Sources: Expert list |
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Intellectual disability - microarray and sequencing v3.3 | TRAPPC4 | Zornitza Stark reviewed gene: TRAPPC4: Rating: GREEN; Mode of pathogenicity: None; Publications: 31794024; Phenotypes: intellectual disability, epilepsy, spasticity, microcephaly; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.3 | SEC31A |
Zornitza Stark gene: SEC31A was added gene: SEC31A was added to Intellectual disability. Sources: Expert list Mode of inheritance for gene: SEC31A was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: SEC31A were set to 30464055 Phenotypes for gene: SEC31A were set to Neurodevelopmental disorder with spastic quadriplegia, optic atrophy, seizures, and structural brain anomalies, OMIM #618651 Review for gene: SEC31A was set to AMBER Added comment: Single family with two affected sibs with functional data (drosophila), one to watch. Sources: Expert list |
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Intellectual disability - microarray and sequencing v3.0 | GBA2 | Zornitza Stark reviewed gene: GBA2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spastic paraplegia 46, autosomal recessive, MIM#614409; Mode of inheritance: None | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.0 | CYP7B1 | Zornitza Stark reviewed gene: CYP7B1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spastic paraplegia 5A, autosomal recessive, MIM# 270800; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.0 | CYP2U1 | Zornitza Stark reviewed gene: CYP2U1: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spastic paraplegia 56, autosomal recessive, MIM#615030; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.0 | CCT5 | Zornitza Stark reviewed gene: CCT5: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Neuropathy, hereditary sensory, with spastic paraplegia, MIM# 256840; Mode of inheritance: None | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.0 | AFG3L2 | Zornitza Stark reviewed gene: AFG3L2: Rating: RED; Mode of pathogenicity: None; Publications: ; Phenotypes: Spastic ataxia 5, autosomal recessive, MIM#614487; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v3.0 | ADD3 |
Zornitza Stark gene: ADD3 was added gene: ADD3 was added to Intellectual disability. Sources: Expert list Mode of inheritance for gene: ADD3 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: ADD3 were set to 29768408; 23836506 Phenotypes for gene: ADD3 were set to Cerebral palsy, spastic quadriplegic, 3, MIM#617008 Review for gene: ADD3 was set to GREEN gene: ADD3 was marked as current diagnostic Added comment: Four families reported in the literature with bi-allelic variants in this gene causing intellectual disability. Sources: Expert list |
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Intellectual disability - microarray and sequencing v3.0 | MTHFS |
Konstantinos Varvagiannis changed review comment from: Biallelic pathogenic MTHFS variants cause Neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination (# 618367). The gene encodes 5,10-Methenyltetrahydrofolate synthetase which catalyzes conversion of 5-formyltetrahydrofolate (5-FTHF or folinic acid) to 5,10-methenyltetrahydrofolate (5,10-MTHF). At least 3 unrelated individuals have been reported. The phenotype appears to be relevant to both epilepsy and ID gene panels and the role of variants/the gene supported by enzymatic activity studies, 5-FTHF accumulation, 5,10-MTHF levels (low/low-normal), the role of folate metabolism pathway overall and some supporting (metabolic) evidence from the mouse model. --- Rodan et al (2018 - PMID: 30031689) reported on 2 individuals both presenting with microcephaly, severe global DD, epilepsy, progressive spasticity and cerebral hypomyelination upon MRI imaging. Short stature was also feature in both. The 1st patient was an 8-year-old male who following exome sequencing was found to harbor 2 missense variants each inherited from a carrier parent. (NM_006441.3:c.434G>A / p.R145Q and c.107T>C / p.L36P). A further AFG3L2 indel was not felt to fit with his phenotype (and the onset of the related disorder appears to occur later). Previous investigations included extensive metabolic testing, CMA, Angelman syndrome methylation analysis, GFAP, POLG1, TYMP sequencing, mitochondrial genome analysis and an XL-ID gene panel (further suggesting relevance of this gene to the current panel) were all non-diagnostic. CSF 5-MTHF levels were initially on the low-normal range, subsequently found to be decreased (upon folinic acid supplementation) and later normalized upon use of another regimen. MTHFS activity was measured in control fibroblasts as well as fibroblasts from this individual, with the latter demonstrating no enzyme activity. Accumulation (30x elevation) of 5-FTHF (the substrate of MTHFS) was demonstrated in patient fibroblasts. The 2nd patient was a 11-year-old male with similar features incl. global DD (standing/walking/single words at/after 4 years of age, limited vocabulary and articulation upon last examination). Extensive metabolic work-up as well as genetic testing for an epilepsy panel, vanishing white matter disease gene panel, mitochondrial genome as well as specific gene sequencing (LAMA2, POLR3A, POLR3B) were all non-diagnostic. Trio exome revealed 2 MTHFS variants in trans configuration (c.484C>T / p.Q162X and c.434G>A / p.R145Q). --- Romero et al (2019 - PMID: 31844630) reported on a 4-year-old female with congenital microcephaly, severe global DD (nonverbal/nonambulatory at the age of 4), spasticity, epilepsy and cerebral hypomyelination. Extensive investigations prior to exome sequencing revealed macrocytic anemia, decreased CSF 5-MTHF and elevated neopterin, 2 CNVs of uncertain significance upon CMA with additional long ROH on chr15. Methylation studies were negative. The child was homozygous for c.220C>T / p.R74X (RefSeq is probably NM_006441.3. MTHFS lies on chr15. The parents were unrelated but came from the same town). There were no other candidate variants from the exome analysis. Both articles discuss extensively the role of the folate metabolism pathway overall in nucleic acid synthesis, AA metabolism, neurotransmitter synthesis, methylation as well as 5-FTHF / 5,10-MTHF in particular in myelin stabilization and DNA synthesis (eg. according to Romero et al. a defect in MTHFS would impair myelin production and also lead to decreased myelin stability). --- A book chapter cited by Rodan et al (in N. Blau et al. (eds.), Physician’s Guide to the Diagnosis, Treatment, and Follow-Up of Inherited Metabolic Diseases - DOI: 10.1007/978-3-642-40337-8_10) included limited details on a patient with 'MTHFS gene mutation'. This individual had early speech delay, seizures beginning in infancy, ID, autistic features, recurrent infections and was found to have very low CSF 5-MTHF levels. [Details in p169 and table 10.6 - p173]. --- In a mouse model reported by Field et al (2011 - PMID: 22303332), Mthfs was disrupted through insertion of a gene trap vector between the first 2 exons. Heterozygous [Mthfs(gt/+)] mice were fertile and viable. Mthfs protein levels were slightly but not statistically significantly reduced in tissues measured. No homozygous embryos were recovered following intercrosses of heterozygous mice, suggesting that Mthfs is an essential gene. Mouse embryonic fibroblasts from heterozygous mice [Mthfs (gt/+)] exhibited reduced de novo purine biosynthesis, but did not exhibit altered de novo thymidylate biosynthesis. Plasma folate levels were altered in heterozygous mice on a standard (/control) diet. Sources: Literature; to: Biallelic pathogenic MTHFS variants cause Neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination (# 618367). The gene encodes 5,10-Methenyltetrahydrofolate synthetase which catalyzes conversion of 5-formyltetrahydrofolate (5-FTHF or folinic acid) to 5,10-methenyltetrahydrofolate (5,10-MTHF). At least 3 unrelated individuals have been reported. The phenotype appears to be relevant to both epilepsy and ID gene panels and the role of variants/the gene supported by enzymatic activity studies, 5-FTHF accumulation, 5,10-MTHF levels (low/low-normal), the role of folate metabolism pathway overall and some supporting (metabolic) evidence from the mouse model. --- Rodan et al (2018 - PMID: 30031689) reported on 2 individuals both presenting with microcephaly, severe global DD, epilepsy, progressive spasticity and cerebral hypomyelination upon MRI imaging. Short stature was also feature in both. The 1st patient was an 8-year-old male who following exome sequencing was found to harbor 2 missense variants each inherited from a carrier parent. (NM_006441.3:c.434G>A / p.R145Q and c.107T>C / p.L36P). A further AFG3L2 indel was not felt to fit with his phenotype (and the onset of the related disorder appears to occur later). Previous investigations included extensive metabolic testing, CMA, Angelman syndrome methylation analysis, GFAP, POLG1, TYMP sequencing, mitochondrial genome analysis and an XL-ID gene panel (further suggesting relevance of this gene to the current panel) were all non-diagnostic. CSF 5-MTHF levels were initially on the low-normal range, subsequently found to be decreased (upon folinic acid supplementation) and later normalized upon use of another regimen. MTHFS activity was measured in control fibroblasts as well as fibroblasts from this individual, with the latter demonstrating no enzyme activity. Accumulation (30x elevation) of 5-FTHF (the substrate of MTHFS) was demonstrated in patient fibroblasts. The 2nd patient was a 11-year-old male with similar features incl. global DD (standing/walking/single words at/after 4 years of age, limited vocabulary and articulation upon last examination). Extensive metabolic work-up as well as genetic testing for an epilepsy panel, vanishing white matter disease gene panel, mitochondrial genome as well as specific gene sequencing (LAMA2, POLR3A, POLR3B) were all non-diagnostic. Trio exome revealed 2 MTHFS variants in trans configuration (c.484C>T / p.Q162X and c.434G>A / p.R145Q). --- Romero et al (2019 - PMID: 31844630) reported on a 4-year-old female with congenital microcephaly, severe global DD (nonverbal/nonambulatory at the age of 4), spasticity, epilepsy and cerebral hypomyelination. Extensive investigations prior to exome sequencing revealed macrocytic anemia, decreased CSF 5-MTHF and elevated neopterin, 2 CNVs of uncertain significance upon CMA with additional long ROH on chr15. Methylation studies were negative. The child was homozygous for c.220C>T / p.R74X (RefSeq is probably NM_006441.3. MTHFS lies on chr15. The parents were unrelated but came from the same town). There were no other candidate variants from the exome analysis. Both articles discuss extensively the role of the folate metabolism pathway overall in nucleic acid synthesis, AA metabolism, neurotransmitter synthesis, methylation as well as 5-FTHF / 5,10-MTHF in particular in myelin stabilization and DNA synthesis (eg. according to Romero et al. a defect in MTHFS would impair myelin production and also lead to decreased myelin stability). --- A book chapter cited by Rodan et al (in N. Blau et al. (eds.), Physician’s Guide to the Diagnosis, Treatment, and Follow-Up of Inherited Metabolic Diseases - DOI: 10.1007/978-3-642-40337-8_10) included limited details on a patient with 'MTHFS gene mutation'. This individual had early speech delay, seizures beginning in infancy, ID, autistic features, recurrent infections and was found to have very low CSF 5-MTHF levels. [Details in p169 and table 10.6 - p173]. --- In a mouse model reported by Field et al (2011 - PMID: 22303332), Mthfs was disrupted through insertion of a gene trap vector between the first 2 exons. Heterozygous [Mthfs(gt/+)] mice were fertile and viable. Mthfs protein levels were slightly but not statistically significantly reduced in tissues measured. No homozygous embryos were recovered following intercrosses of heterozygous mice, suggesting that Mthfs is an essential gene. Mouse embryonic fibroblasts from heterozygous mice [Mthfs (gt/+)] exhibited reduced de novo purine biosynthesis, but did not exhibit altered de novo thymidylate biosynthesis. Plasma folate levels were altered in heterozygous mice on a standard (/control) diet. [Please consider inclusion in other possibly relevant panels e.g. for metabolic disorders] Sources: Literature |
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Intellectual disability - microarray and sequencing v3.0 | MTHFS |
Konstantinos Varvagiannis gene: MTHFS was added gene: MTHFS was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: MTHFS was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: MTHFS were set to 30031689; 31844630; 22303332; https://doi.org/10.1007/978-3-642-40337-8_10 Phenotypes for gene: MTHFS were set to Neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination, 618367 Penetrance for gene: MTHFS were set to Complete Review for gene: MTHFS was set to GREEN Added comment: Biallelic pathogenic MTHFS variants cause Neurodevelopmental disorder with microcephaly, epilepsy, and hypomyelination (# 618367). The gene encodes 5,10-Methenyltetrahydrofolate synthetase which catalyzes conversion of 5-formyltetrahydrofolate (5-FTHF or folinic acid) to 5,10-methenyltetrahydrofolate (5,10-MTHF). At least 3 unrelated individuals have been reported. The phenotype appears to be relevant to both epilepsy and ID gene panels and the role of variants/the gene supported by enzymatic activity studies, 5-FTHF accumulation, 5,10-MTHF levels (low/low-normal), the role of folate metabolism pathway overall and some supporting (metabolic) evidence from the mouse model. --- Rodan et al (2018 - PMID: 30031689) reported on 2 individuals both presenting with microcephaly, severe global DD, epilepsy, progressive spasticity and cerebral hypomyelination upon MRI imaging. Short stature was also feature in both. The 1st patient was an 8-year-old male who following exome sequencing was found to harbor 2 missense variants each inherited from a carrier parent. (NM_006441.3:c.434G>A / p.R145Q and c.107T>C / p.L36P). A further AFG3L2 indel was not felt to fit with his phenotype (and the onset of the related disorder appears to occur later). Previous investigations included extensive metabolic testing, CMA, Angelman syndrome methylation analysis, GFAP, POLG1, TYMP sequencing, mitochondrial genome analysis and an XL-ID gene panel (further suggesting relevance of this gene to the current panel) were all non-diagnostic. CSF 5-MTHF levels were initially on the low-normal range, subsequently found to be decreased (upon folinic acid supplementation) and later normalized upon use of another regimen. MTHFS activity was measured in control fibroblasts as well as fibroblasts from this individual, with the latter demonstrating no enzyme activity. Accumulation (30x elevation) of 5-FTHF (the substrate of MTHFS) was demonstrated in patient fibroblasts. The 2nd patient was a 11-year-old male with similar features incl. global DD (standing/walking/single words at/after 4 years of age, limited vocabulary and articulation upon last examination). Extensive metabolic work-up as well as genetic testing for an epilepsy panel, vanishing white matter disease gene panel, mitochondrial genome as well as specific gene sequencing (LAMA2, POLR3A, POLR3B) were all non-diagnostic. Trio exome revealed 2 MTHFS variants in trans configuration (c.484C>T / p.Q162X and c.434G>A / p.R145Q). --- Romero et al (2019 - PMID: 31844630) reported on a 4-year-old female with congenital microcephaly, severe global DD (nonverbal/nonambulatory at the age of 4), spasticity, epilepsy and cerebral hypomyelination. Extensive investigations prior to exome sequencing revealed macrocytic anemia, decreased CSF 5-MTHF and elevated neopterin, 2 CNVs of uncertain significance upon CMA with additional long ROH on chr15. Methylation studies were negative. The child was homozygous for c.220C>T / p.R74X (RefSeq is probably NM_006441.3. MTHFS lies on chr15. The parents were unrelated but came from the same town). There were no other candidate variants from the exome analysis. Both articles discuss extensively the role of the folate metabolism pathway overall in nucleic acid synthesis, AA metabolism, neurotransmitter synthesis, methylation as well as 5-FTHF / 5,10-MTHF in particular in myelin stabilization and DNA synthesis (eg. according to Romero et al. a defect in MTHFS would impair myelin production and also lead to decreased myelin stability). --- A book chapter cited by Rodan et al (in N. Blau et al. (eds.), Physician’s Guide to the Diagnosis, Treatment, and Follow-Up of Inherited Metabolic Diseases - DOI: 10.1007/978-3-642-40337-8_10) included limited details on a patient with 'MTHFS gene mutation'. This individual had early speech delay, seizures beginning in infancy, ID, autistic features, recurrent infections and was found to have very low CSF 5-MTHF levels. [Details in p169 and table 10.6 - p173]. --- In a mouse model reported by Field et al (2011 - PMID: 22303332), Mthfs was disrupted through insertion of a gene trap vector between the first 2 exons. Heterozygous [Mthfs(gt/+)] mice were fertile and viable. Mthfs protein levels were slightly but not statistically significantly reduced in tissues measured. No homozygous embryos were recovered following intercrosses of heterozygous mice, suggesting that Mthfs is an essential gene. Mouse embryonic fibroblasts from heterozygous mice [Mthfs (gt/+)] exhibited reduced de novo purine biosynthesis, but did not exhibit altered de novo thymidylate biosynthesis. Plasma folate levels were altered in heterozygous mice on a standard (/control) diet. Sources: Literature |
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Intellectual disability - microarray and sequencing v2.1138 | FA2H | Rebecca Foulger Phenotypes for gene: FA2H were changed from Spastic paraplegia 35, autosomal recessive, 612319 to Spastic paraplegia 35, autosomal recessive, 612319; spastic paraplegia with ID; cognitive defects; Seizures | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.1136 | FA2H | Rebecca Foulger Added comment: Comment on list classification: Upgraded from Amber to Green based on Green review by Alistair Pagnamenta: PMID:31135052 analysed a cohort of 19 cases with biallelic FA2H variants. Phenotype includes spastic paraplegia associated with ID: mild cognitive deficits were noted from childhood in 93% of cases, and were considered progressive in all but two cases. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.1135 | TRAPPC4 |
Konstantinos Varvagiannis gene: TRAPPC4 was added gene: TRAPPC4 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: TRAPPC4 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: TRAPPC4 were set to 31794024 Phenotypes for gene: TRAPPC4 were set to Feeding difficulties; Progressive microcephaly; Intellectual disability; Seizures; Spastic tetraparesis; Abnormality of the face; Scoliosis; Cortical visual impairment; Hearing impairment Penetrance for gene: TRAPPC4 were set to Complete Review for gene: TRAPPC4 was set to GREEN Added comment: Van Bergen et al. (2019 - PMID: 31794024) report on 7 affected individuals from 3 famillies (only 1 of which consanguineous), all homozygous for a TRAPPC4 splicing variant. Overlapping features included feeding difficulties, progressive microcephaly, severe to profound developmental disability (7/7 - DD also prior to the onset of seizures / regression also reported in 3), epilepsy (7/7 - onset in the first year), spastic quadriparesis. Other findings in some/few incl. scoliosis, cortical visual and hearing impairment. Some facial features were shared (eg. bitemporal narrowing, long philtrum, open mouth with thin tented upper lip, pointed chin, etc). Brain imaging demonstrated abnormalities in those performed (among others cerebral with/without cerebellar atrophy). Work-up prior to exome sequencing was normal (highly variable incl. metabolic testing, CMA, MECP2, CDKL5, mitochondrial depletion studies, etc). Exome of affected individuals (and parents +/- affected sibs in some families) revealed a homozygous TRAPPC4 splicing variant [NM_016146.5:c.454+3A>G / chr11:g.118890966A>G (hg19)]. Sanger sequencing confirmed variant in affecteds, heterozygosity in parents and compatible genotypes with disease status in sibs/other members. Families were of Caucasian/Turkish and French-Canadian ethnicities. SNP array to compare haplotypes between affecteds in 2 families did not reveal a shared haplotype (/founder effect) and the variant is present in gnomAD (68/281054 - no hmz) in many populations (European/Asian/African/Latino) [https://gnomad.broadinstitute.org/variant/11-118890966-A-G]. mRNA studies in fibroblasts from an affected individual confirmed the splicing defect (2 RT-PCR products corresponding to wt and a shorter due to skipping of exon 3, the latter further confirmed by Sanger sequencing. The shorter transcript is not present in controls). qPCR revealed that the normal transript in patient fibroblasts was present at 6% of the level observed in control fibroblasts (or 54% in the case of a heterozygote parent compared to controls). Western blot in patient fibroblasts, revealed presence of full-length protein in significantly reduced levels compared to fibroblasts from carrier parents or controls. There was no band using an antibody targeting the N-terminal region of the protein prior to exon 3, suggesting that NMD applies (skipping of ex3 is also predicted to lead to frameshift). TRAPPC4 encodes one of the core proteins of the TRAPP complex. Use of different accessory proteins leads to formation of 2 distinct complexes (TRAPPII / III). The complex has an important role in intracellular trafficking. Both TRAPPII & TRAPPIII have a function in the secretory pathway, while complex III has a role also in autophagy. Core proteins are important for the complex stability. The TRAPP complex serves as a GEF for Ypt/Rab GTPases [several refs in article]. Mutations in genes for other proteins of the complex lead to neurodevelopmental disorders with associated ID ('TRAPPopathies' used by the authors / TRAPPC12, C6B, C9 green in the current panel). Western blot suggested that levels of other TRAPP subunits (TRAPPC2 or C12) under denaturing conditions, although PAGE/size exclusion chromatography suggested that the levels of fully-assembled TRAPP complexes were lower in affected individuals. Studies in patient fibroblasts showed a secretory defect (between ER, Golgi and the plasma membrane) which was restored upon lentiviral transduction with wt TRAPPC4 construct. Basal and starvation-induced autophagy were also impaired in patient fibroblasts (increased LC3 marker and LC3-positive structures / impaired co-localization with lysosomes) partly due to defective autophagosome formation (/sealing). TRAPPC4 is the human orthologue of the yeast Trs23. In a yeast model of reduced Trs23 (due to temperature instability) the authors demonstrated impaired assembly of the TRAPP core. The yeast model recapitulated the autophagy as well as well as the secretory defect observed in patient fibroblasts. Sources: Literature |
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Intellectual disability - microarray and sequencing v2.1135 | SLC5A6 |
Konstantinos Varvagiannis changed review comment from: SLC5A6 encodes the sodium dependent multivitamin transporter (SMVT), a transporter of biotin, pantothenate and lipoate. The transporter has a major role in vitamin uptake in the digestive system (among others is the sole transporter for intestinal uptake of biotin which is not synthesized and but must be obtained from exogenous sources) as well as transport across the blood-brain barrier (SMVT being responsible for 89% of biotin transport) [several refs provided by Subramanian et al and Byrne et al]. 4 affected individuals from 3 families have been reported. Subramanian et al (2017 - PMID: 27904971) et al reported on a girl with feeding difficulties and failure to thrive (requiring nasogastric tube placement), microcephaly, DD (at 15m developmental age corresponding to 6m with features suggestive of spastic cerebral palsy), occurrence of multiple infections, osteoporosis and pathologic bone fractures. MRIs suggested brain atrophy, thin CC and hypoplasia of the pons. Metabolic (AA, OA) investigations and array-CGH were normal. Whole exome sequencing revealed presence of a missense (Arg123Leu - RefSeq not provided) and a nonsense (Arg94Ter) SLC5A6 variant. Serum biotin was normal although - at the time - the child was on parenteral and G-T nutrition. Following administration of biotin, pantothenic acid and lipoic acid the child demonstrated among others improved motor and verbal skills, head growth and normalization of immunoglobulin levels. Transfection of mutants in human derived intestinal HuTu-80 cells and brain U87 cells was carried out and a 3H-biotin assay showed no induction in biotin uptake confirming impaired functionality of the transporter. While wt protein displayed normal expression/membrane localization, Arg94Ter was poorly expressed with ectopic localization (cytoplasm). Arg123Leu was retained predominantly intracellularly, probably in the ER as was further supported by colocalization with DsRed-ER. Evidence from the literature is provided that deficiencies of the specific vitamins explain the clinical features (DD, microcephaly, immunological defect, osteopenia, etc). Schwantje et al (2019 - PMID: 31392107) described a girl with severe feeding problems, vomiting with blood (suspected Mallory-Weiss syndrome), poor weight gain and delayed gross motor development. The child presented an episode of gastroenteritis associated with reduced consciousness, circulatory insufficiency and metabolic derangement (hypoglycemia, severe metabolic acidosis, hyperammonemia, mild lactate elevation, ketonuria). Investigations some months prior to the admission (?) were suggestive of a metabolic disorder due to elevated plasma C3-carnitine, C5-OH-carnitine and elevated urinary excretion of 3-OH-isovaleric acid (biotinidase deficiency was considered in the DD but enzymatic activity was only marginally decreased). Biotin supplementation was initiated. Trio-exome sequencing (at 3yrs) demonstrated compound heterozygosity for 2 frameshift variants [NM_021095.2:c.422_423del / p.(Val141Alafs*34) and c.1865_1866del]. Following this result, increase of biotin supplementation and introduction of pantothenic acid, GI symptoms (incl. chronic diarrhea) resolved and the child displayed improved appetite and growth, yet a stable motor delay. The authors cite previous studies of conditional ko mice, displaying intestinal mucosal abnormalities and growth defects (similar to the child's problems), prevented by biotin and pantothenic acid supplementation. Byrne et al (2019 - PMID: 31754459) reported on a sibling pair with severe motor/speech developmental regression following a plateau (at 12m and 14m), development of ataxia and dyskinetic movements (both), seizures (one). Feeding difficulties, reflux and failure to thrive required N-G/gastrostomy feeding while both presented GI hemorrhage (in the case of the older sib, lethal). Other features in the youngest sib included brain MRI abnormalities (cerebral/cerebellar atrophy, thin CC, etc) and IgG deficiency. Biochemical, single-gene testing and mtDNA sequencing were not diagnostic. Exome in one, revealed presence of a frameshift [c.422_423del as above] and a missense variant (Arg400Thr). Sanger sequencing confirmed variants in both sibs and heterozygosity in parents. HeLa cells transfected with empty vector, wt or mut expression constructs confirmed significantly decreased 3H-biotin uptake for mut constructs compared to wt (and similar to empty vector). Parenteral triple vitamin replacement at the age of ~7 years resulted in improved overall condition, regain of some milestones, attenuation of vomiting, and resolution of peripheral neuropathy. Seizure were well-controlled (as was the case before treatment) despite persistence of epileptiform discharges. Again the authors cite studies of conditional (intestine-specific) SLC5A6 ko mice, with those viable (~1/3) demonstrating growth retardation, decreased boned density and GI abnormalities (similar to affected individuals). The phenotype could be rescued by oversupplementation of biotin and pantothenic acid (PMIDs cited: 23104561, 29669219). [Please consider inclusion in other relevant panels eg. metabolic disorders] Sources: Literature; to: SLC5A6 encodes the sodium dependent multivitamin transporter (SMVT), a transporter of biotin, pantothenate and lipoate. The transporter has a major role in vitamin uptake in the digestive system (among others is the sole transporter for intestinal uptake of biotin which is not synthesized but must be obtained from exogenous sources) as well as transport across the blood-brain barrier (SMVT being responsible for 89% of biotin transport) [several refs provided by Subramanian et al and Byrne et al]. 4 affected individuals from 3 families have been reported. Subramanian et al (2017 - PMID: 27904971) et al reported on a girl with feeding difficulties and failure to thrive (requiring nasogastric tube placement), microcephaly, DD (at 15m developmental age corresponding to 6m with features suggestive of spastic cerebral palsy), occurrence of multiple infections, osteoporosis and pathologic bone fractures. MRIs suggested brain atrophy, thin CC and hypoplasia of the pons. Metabolic (AA, OA) investigations and array-CGH were normal. Whole exome sequencing revealed presence of a missense (Arg123Leu - RefSeq not provided) and a nonsense (Arg94Ter) SLC5A6 variant. Serum biotin was normal although - at the time - the child was on parenteral and G-T nutrition. Following administration of biotin, pantothenic acid and lipoic acid the child demonstrated among others improved motor and verbal skills, head growth and normalization of immunoglobulin levels. Transfection of mutants in human derived intestinal HuTu-80 cells and brain U87 cells was carried out and a 3H-biotin assay showed no induction in biotin uptake confirming impaired functionality of the transporter. While wt protein displayed normal expression/membrane localization, Arg94Ter was poorly expressed with ectopic localization (cytoplasm). Arg123Leu was retained predominantly intracellularly, probably in the ER as was further supported by colocalization with DsRed-ER. Evidence from the literature is provided that deficiencies of the specific vitamins explain the clinical features (DD, microcephaly, immunological defect, osteopenia, etc). Schwantje et al (2019 - PMID: 31392107) described a girl with severe feeding problems, vomiting with blood (suspected Mallory-Weiss syndrome), poor weight gain and delayed gross motor development. The child presented an episode of gastroenteritis associated with reduced consciousness, circulatory insufficiency and metabolic derangement (hypoglycemia, severe metabolic acidosis, hyperammonemia, mild lactate elevation, ketonuria). Investigations some months prior to the admission (?) were suggestive of a metabolic disorder due to elevated plasma C3-carnitine, C5-OH-carnitine and elevated urinary excretion of 3-OH-isovaleric acid (biotinidase deficiency was considered in the DD but enzymatic activity was only marginally decreased). Biotin supplementation was initiated. Trio-exome sequencing (at 3yrs) demonstrated compound heterozygosity for 2 frameshift variants [NM_021095.2:c.422_423del / p.(Val141Alafs*34) and c.1865_1866del]. Following this result, increase of biotin supplementation and introduction of pantothenic acid, GI symptoms (incl. chronic diarrhea) resolved and the child displayed improved appetite and growth, yet a stable motor delay. The authors cite previous studies of conditional ko mice, displaying intestinal mucosal abnormalities and growth defects (similar to the child's problems), prevented by biotin and pantothenic acid supplementation. Byrne et al (2019 - PMID: 31754459) reported on a sibling pair with severe motor/speech developmental regression following a plateau (at 12m and 14m), development of ataxia and dyskinetic movements (both), seizures (one). Feeding difficulties, reflux and failure to thrive required N-G/gastrostomy feeding while both presented GI hemorrhage (in the case of the older sib, lethal). Other features in the youngest sib included brain MRI abnormalities (cerebral/cerebellar atrophy, thin CC, etc) and IgG deficiency. Biochemical, single-gene testing and mtDNA sequencing were not diagnostic. Exome in one, revealed presence of a frameshift [c.422_423del as above] and a missense variant (Arg400Thr). Sanger sequencing confirmed variants in both sibs and heterozygosity in parents. HeLa cells transfected with empty vector, wt or mut expression constructs confirmed significantly decreased 3H-biotin uptake for mut constructs compared to wt (and similar to empty vector). Parenteral triple vitamin replacement at the age of ~7 years resulted in improved overall condition, regain of some milestones, attenuation of vomiting, and resolution of peripheral neuropathy. Seizure were well-controlled (as was the case before treatment) despite persistence of epileptiform discharges. Again the authors cite studies of conditional (intestine-specific) SLC5A6 ko mice, with those viable (~1/3) demonstrating growth retardation, decreased boned density and GI abnormalities (similar to affected individuals). The phenotype could be rescued by oversupplementation of biotin and pantothenic acid (PMIDs cited: 23104561, 29669219). [Please consider inclusion in other relevant panels eg. metabolic disorders] Sources: Literature |
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Intellectual disability - microarray and sequencing v2.1135 | SLC5A6 |
Konstantinos Varvagiannis gene: SLC5A6 was added gene: SLC5A6 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: SLC5A6 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: SLC5A6 were set to 27904971; 31392107; 31754459; 23104561; 29669219 Phenotypes for gene: SLC5A6 were set to Feeding difficulties; Failure to thrive; Global developmental delay; Developmental regression; Intellectual disability; Seizures; Microcephaly; Cerebral atrophy; Abnormality of the corpus callosum; Vomiting; Chronic diarrhea; Gastrointestinal hemorrhage; Abnormal immunoglobulin level; Osteopenia; Abnormality of metabolism/homeostasis Penetrance for gene: SLC5A6 were set to Complete Review for gene: SLC5A6 was set to GREEN Added comment: SLC5A6 encodes the sodium dependent multivitamin transporter (SMVT), a transporter of biotin, pantothenate and lipoate. The transporter has a major role in vitamin uptake in the digestive system (among others is the sole transporter for intestinal uptake of biotin which is not synthesized and but must be obtained from exogenous sources) as well as transport across the blood-brain barrier (SMVT being responsible for 89% of biotin transport) [several refs provided by Subramanian et al and Byrne et al]. 4 affected individuals from 3 families have been reported. Subramanian et al (2017 - PMID: 27904971) et al reported on a girl with feeding difficulties and failure to thrive (requiring nasogastric tube placement), microcephaly, DD (at 15m developmental age corresponding to 6m with features suggestive of spastic cerebral palsy), occurrence of multiple infections, osteoporosis and pathologic bone fractures. MRIs suggested brain atrophy, thin CC and hypoplasia of the pons. Metabolic (AA, OA) investigations and array-CGH were normal. Whole exome sequencing revealed presence of a missense (Arg123Leu - RefSeq not provided) and a nonsense (Arg94Ter) SLC5A6 variant. Serum biotin was normal although - at the time - the child was on parenteral and G-T nutrition. Following administration of biotin, pantothenic acid and lipoic acid the child demonstrated among others improved motor and verbal skills, head growth and normalization of immunoglobulin levels. Transfection of mutants in human derived intestinal HuTu-80 cells and brain U87 cells was carried out and a 3H-biotin assay showed no induction in biotin uptake confirming impaired functionality of the transporter. While wt protein displayed normal expression/membrane localization, Arg94Ter was poorly expressed with ectopic localization (cytoplasm). Arg123Leu was retained predominantly intracellularly, probably in the ER as was further supported by colocalization with DsRed-ER. Evidence from the literature is provided that deficiencies of the specific vitamins explain the clinical features (DD, microcephaly, immunological defect, osteopenia, etc). Schwantje et al (2019 - PMID: 31392107) described a girl with severe feeding problems, vomiting with blood (suspected Mallory-Weiss syndrome), poor weight gain and delayed gross motor development. The child presented an episode of gastroenteritis associated with reduced consciousness, circulatory insufficiency and metabolic derangement (hypoglycemia, severe metabolic acidosis, hyperammonemia, mild lactate elevation, ketonuria). Investigations some months prior to the admission (?) were suggestive of a metabolic disorder due to elevated plasma C3-carnitine, C5-OH-carnitine and elevated urinary excretion of 3-OH-isovaleric acid (biotinidase deficiency was considered in the DD but enzymatic activity was only marginally decreased). Biotin supplementation was initiated. Trio-exome sequencing (at 3yrs) demonstrated compound heterozygosity for 2 frameshift variants [NM_021095.2:c.422_423del / p.(Val141Alafs*34) and c.1865_1866del]. Following this result, increase of biotin supplementation and introduction of pantothenic acid, GI symptoms (incl. chronic diarrhea) resolved and the child displayed improved appetite and growth, yet a stable motor delay. The authors cite previous studies of conditional ko mice, displaying intestinal mucosal abnormalities and growth defects (similar to the child's problems), prevented by biotin and pantothenic acid supplementation. Byrne et al (2019 - PMID: 31754459) reported on a sibling pair with severe motor/speech developmental regression following a plateau (at 12m and 14m), development of ataxia and dyskinetic movements (both), seizures (one). Feeding difficulties, reflux and failure to thrive required N-G/gastrostomy feeding while both presented GI hemorrhage (in the case of the older sib, lethal). Other features in the youngest sib included brain MRI abnormalities (cerebral/cerebellar atrophy, thin CC, etc) and IgG deficiency. Biochemical, single-gene testing and mtDNA sequencing were not diagnostic. Exome in one, revealed presence of a frameshift [c.422_423del as above] and a missense variant (Arg400Thr). Sanger sequencing confirmed variants in both sibs and heterozygosity in parents. HeLa cells transfected with empty vector, wt or mut expression constructs confirmed significantly decreased 3H-biotin uptake for mut constructs compared to wt (and similar to empty vector). Parenteral triple vitamin replacement at the age of ~7 years resulted in improved overall condition, regain of some milestones, attenuation of vomiting, and resolution of peripheral neuropathy. Seizure were well-controlled (as was the case before treatment) despite persistence of epileptiform discharges. Again the authors cite studies of conditional (intestine-specific) SLC5A6 ko mice, with those viable (~1/3) demonstrating growth retardation, decreased boned density and GI abnormalities (similar to affected individuals). The phenotype could be rescued by oversupplementation of biotin and pantothenic acid (PMIDs cited: 23104561, 29669219). [Please consider inclusion in other relevant panels eg. metabolic disorders] Sources: Literature |
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Intellectual disability - microarray and sequencing v2.1133 | PCYT2 | Ellen McDonagh Added comment: Comment on list classification: This gene was added by an external reviewer and rated Green. This is currently Green on the Hereditary spastic paraplegia gene panel (Version 1.210), and confirmed with Zerin Hyder (Genomics England Clinical Team) that this is appropriate to be Green on the ID panel. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.1098 | PCYT2 |
Konstantinos Varvagiannis gene: PCYT2 was added gene: PCYT2 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: PCYT2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PCYT2 were set to 31637422 Phenotypes for gene: PCYT2 were set to Global developmental delay; Developmental regression; Intellectual disability; Spastic paraparesis; Seizures; Spastic tetraparesis; Cerebral atrophy; Cerebellar atrophy Penetrance for gene: PCYT2 were set to Complete Review for gene: PCYT2 was set to GREEN Added comment: Vaz et al. (2019 - PMID: 31637422 - DDD study among the co-authors) report on 5 individuals - from 4 families - with biallelic PCYT2 mutations. The phenotype corresponded to a complex hererditary paraplegia with global DD, regression (4/5), ID (mild in 3/5, severe in 2/5), spastic para-/tetraparesis, epilepsy (5/5 - variable onset 2-16 yrs - focal or tonic-clonic seizures) and progressive cerebral and cerebellar atrophy. Exome sequencing in all revealed biallelic PCYT2 variants, confirmed with Sanger s. in probands and their parents (NM_001184917.2 - corresponding to the canonical transcript used as Ref below): - P1 (Fam1) : 2 missense SNVs in trans configuration, c.730C>T or p.His244Tyr and c.920C>T or p.Pro307Leu - P2 (Fam2 - consanguineous of White British origin), P3 (Fam3 - Consanguineous of Turkish origin), P4,5 (Fam4 - consanguineous, unspecified origin) : homozygosity for c.1129C>T or p.Arg377Ter) affecting the last exon of 8/12 transcripts, including the canonical one. Individuals with the same genotype displayed variable degrees of ID (eg P3 - severe / P2, P4,5 - mild ID). For sibs in Fam4, homozygosity for a missense SACS variant led to consideration of the respective disorder (AR spastic ataxia of Charlevoix-Saguenay) though the variant was predicted to be tolerated in silico and notably the MRI images not suggestive. All variants were absent from / had extremely low AF in public databases, with no homozygotes. Posphatidylethanolamine (PE) is a membrane lipid, particularly enriched in human brain (45% of phospholypid fraction). PE is synthesized either via the CDP-ethanolamine pathway or by decarboxylation of phosphatidylserine in mitochondria. PCYT2 encodes CTP:phosophoethanolamine cytidyltransferase (ET) which is an ubiquitously expressed rate-limiting enzyme for PE biosynthesis in the former pathway. In silico, the 2 missense variants - localizing in the CTP catalytic domain 2 - were predicted to be damaging, as well as to affect protein stability. Fibroblasts of 3 patients (P1, P2, P3) representing all variants were studied: - Enzymatic activity was shown to be significantly reduced (though not absent) compared to controls. Abnormalities were noted upon Western Blot incl. absence in all 3 patients studied of one of the 2 bands normally found in controls (probably representing the longer isoform), reduced intensity in all 3 of another band probably corresponding to a shorter isoform, and presence of an additional band of intermediate molec. mass in patients with the truncating variant. - RT-PCR on mRNA from patient fibroblasts did not reveal (significant) reduction compared to controls. - Lipidomic profile of patient fibroblasts was compatible with the location of the block in the phospholipid biosynthesis pathway and different from controls. The lipidomic profile had similarities with what has been reported for EPT1 deficiency, the enzyme directly downstream of ET. The SELENO1-related phenotype (/EPT1 deficiency) is also highly overlapping. CRISPR-Cas9 was used to generate pcyt2 partial or complete knockout (ko) zebrafish, targeting either the final (ex13) or another exon (ex3) respectively. mRNA expression was shown to be moderately reduced in the first case and severely reduced/absent in the second, compared to wt. Similarly, complete-ko (ex3) led to significantly lower survival, with impaired though somewhat better survival of partial-ko (ex13) zebrafish. Complete knockout of Pcyt2 in mice is embryonically lethal (PMID cited: 17325045) while heterozygous mice develop features of metabolic syndrome (PMID cited: 22764088). Given lethality in knockout zebrafish / mice and the residual activity (15-20%) in patient fibroblasts, the variants reported were thought to be hypomorphic and complete loss of function possibly incompatible with life. PCYT2 is not associated with any phenotype in OMIM/G2P/SysID and not commonly included in gene panels for ID. As a result this gene could included in the ID / epilepsy panels with green (~/>3 indiv/fam/variants with the nonsense found in different populations, consistent phenotype, lipidomics, in silico/in vitro/in vivo evidence) or amber rating. [Please consider inclusion in other possibly relevant panels eg. for metabolic disorders, etc]. Sources: Literature |
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Intellectual disability - microarray and sequencing v2.1092 | SVBP | Alistair Pagnamenta reviewed gene: SVBP: Rating: GREEN; Mode of pathogenicity: None; Publications: PMID: 31363758, 30607023; Phenotypes: brain abnormalities, microcephaly, intellectual disability, delayed gross motor development, spasticity, delayed speech development; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.1082 | PCDH12 | Catherine Snow Phenotypes for gene: PCDH12 were changed from intellectual disability; microcephaly; epilepsy; perithalamic hyperechogenicity; periventricular hyperechogenicity; midbrain abnormalities; hypothalamic abnormalities to intellectual disability; microcephaly; epilepsy; perithalamic hyperechogenicity; periventricular hyperechogenicity; midbrain abnormalities; hypothalamic abnormalities; Microcephaly, seizures, spasticity, and brain calcification, 251280 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.1062 | PCDH12 | Konstantinos Varvagiannis reviewed gene: PCDH12: Rating: ; Mode of pathogenicity: None; Publications: 27164683, 28804758, 29556033, 30178464, 30459466, 18477666; Phenotypes: Microcephaly, seizures, spasticity, and brain calcification, 251280; Mode of inheritance: None; Current diagnostic: yes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.1046 | PMPCA |
Konstantinos Varvagiannis gene: PMPCA was added gene: PMPCA was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen Mode of inheritance for gene: PMPCA was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: PMPCA were set to 25808372; 26657514; 27148589; 30617178 Phenotypes for gene: PMPCA were set to Spinocerebellar ataxia, autosomal recessive 2 (MIM 213200) Penetrance for gene: PMPCA were set to Complete Review for gene: PMPCA was set to GREEN gene: PMPCA was marked as current diagnostic Added comment: Biallelic pathogenic PMPCA variants cause Spinocerebellar ataxia, autosomal recessive 2 (SCAR2 - MIM 213200). More than 20 individuals from several unrelated families have been reported. At least 6 different pathogenic variants have been identified. Loss of PMPCA function is the suggested mechanism. ID is a feature of the disorder. PMPCA encodes the α-subunit of mitochondrial processing peptidase (αMPP), a heterodimeric enzyme responsible for the cleavage of nuclear-encoded mitochondrial precursor proteins after import in the mitochondria (summary by Jobling et al and OMIM). Arguments for involvement of the gene include the highly similar phenotype, segregation studies, expression of the gene in fetal and relevant adult tissues (in brain/cerebellum/cerebellar vermis), lower protein levels demonstrated for some variants, abnormal processing of frataxin (in line with the role of αMPP) demonstrated in most cases, rescue of the maturation defect upon transduction of wt PMPCA cDNA, disruption of REDOX balance in patient cells, etc. Relevant studies are summarized below. PMPCA is included in gene panels for ID offered by several diagnostic laboratories (incl. Radboud UMC, GeneDx, etc) and listed as a confirmed ID gene in SysID. It is not associated with any phenotype in G2P. As a result, this gene can be considered for inclusion in the current panel probably as green (or amber). ---- [1] - Jobling et al. (2015 - PMID: 25808372) described the phenotype of 17 individuals from 4 families, all presenting with non-progressive cerebellar ataxia and the majority with ID of variable severity (15/17 - relevant to the current panel). Individuals from 3 of the families - all of Lebanese origin - were homozygous for NM_015160.3:c.1129G>A (p.Ala377Thr). A further similarly affected subject was compound heterozygous for c.287C>T (p.Ser96Leu) and c.1543G>A (p.Gly515Arg). The homozygous variant in the first family was found within a 2.85 Mb linkage region on chr 9q34. An additional variant within this region (in CAMSAP1) was discarded following results in other families of the same origin. Semi-quantitative RT-PCR demonstrated fetal expression of the PMPCA as well as relatively higher expression in adult brain, cerebellum and cerebellar vermis. As for Ala377Thr, protein levels were shown to be lowest in affected individuals (LCLs, fibroblasts) and low - though somewhat higher - in carrier parents (LCL) compared to controls. RT-PCR on total RNA from LCLs did not show evidence of abnormal transcripts/additional splicing defect. Localization of mutant protein and morphology of mitochondrial reticulum was similar to controls. Maturation of frataxin - the protein depleted in Friedreich ataxia - was shown to be abnormal in patient lymphoblasts, compatible with the role of αMPP. In line with abnormal mitochondrial function, REDOX balance was increased in patient cells. [2] - Choquet et al. (2016 - PMID: 26657514) reported on 2 sibs - born to distantly related parents. The authors noted a phenotype corresponding to SCAR2 although the presentation was somewhat milder, intellectual disability was not a feature (despite some learning difficulties in one) and ataxia was progressive. WES demonstrated homozygosity for NM_015160:c.766G>A (p.Val256Met). Western blot in patient lymphoblasts showed αMPP levels similar to carriers and controls. Abnormal maturation (accumulation of specific isoforms) was shown for frataxin. [3] - Joshi et al. (2016 - PMID: 27148589) described the phenotype of 2 cousins belonging to a large Lebanese pedigree. Presentation in both was compatible with multisystem involvement incl. profound global DD, severe hypotonia, weakness, respiratory insufficiency, blindness suggestive of mitochondrial disorder. mtDNA, analyses of mitochondrial focused nuclear gene panel and aCGH were non-diagnostic. Both subjects were compound heterozygous for NM_015160.3:c.1066G>A (p.Gly356Ser) and c.1129G>A (p.Ala377Thr) following WES, with compatible segregation studies within the family. Western blot revealed PMPCA levels similar to control. Reduction of PMPCA staining and abnormally enlarged mitochondria were observed upon immunofluorescence in patient fibroblasts. Frataxin processing was abnormal. Lentiviral transduction of patient fibroblasts with wt PMPCA cDNA, led to increased PMPCA levels and correction of frataxin processing. [4] - Rubegni et al. (2019 - PMID: 30617178) report on a 7-y.o. boy with global DD, spastic-ataxic gait and 'low IQ'. MRI images were suggestive of cerebellar atrophy with hyperintensity in the striatum. The child was homozygous for c.553C>T / p.Arg185Trp (reference not specified, although the variant would be compatible with NM_015160.3). Sources: Literature, Radboud University Medical Center, Nijmegen |
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Intellectual disability - microarray and sequencing v2.1046 | TIMM50 |
Konstantinos Varvagiannis gene: TIMM50 was added gene: TIMM50 was added to Intellectual disability. Sources: Literature,Radboud University Medical Center, Nijmegen Mode of inheritance for gene: TIMM50 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: TIMM50 were set to 27573165; 30190335; 31058414; Serajee et al. (ASHG conference 2015 - abstract Nr. 2299T) Phenotypes for gene: TIMM50 were set to 3-methylglutaconic aciduria, type IX (MIM 617698) Penetrance for gene: TIMM50 were set to Complete Review for gene: TIMM50 was set to GREEN gene: TIMM50 was marked as current diagnostic Added comment: Biallelic pathogenic TIMM50 variants cause 3-methylglutaconic aciduria, type IX (MIM 617698). At least 9 affected individuals from 5 unrelated (but often consanguineous) families of variable origin have been reported (based on a conference abstract and PMIDs : 27573165, 30190335, 31058414). TIMM50 encodes encodes a subunit of the mitochondrial presequence import machinery called the TIM23 complex. TIMM50 serves as a major receptor in the intermembrane space that binds to proteins on their way to cross the mitochondrial inner membrane (summary by Shahrour et al., 2017 and OMIM). The highly overlapping patient clinical features [seizures, DD and ID - the latter in all age-appropriate individuals (5 from 3 families - refs 2,4)], metabolic investigations (lactate elevations in many, elevated urinary 3MGA in almost all, variable mitochondrial complex deficiencies in some), additional extensive functional evidence of mitochondrial dysfunction or the similar phenotypes in other types of 3-methylglutaconic aciduria all support a role for the gene. [AUH- / CLPB- / DNAJC19- / HTRA2- / OPA3- / SERAC1-related methylglutaconic acidurias are all included as relevant disorders in the ID panel, with the respective genes rated green.] TIMM50 is included in gene panels for ID offered by some diagnostic laboratories (incl. Radboudumc and GeneDx). The gene is not associated with any phenotype in G2P As a result this gene could be considered for inclusion/upgrade as green in both ID and epilepsy panels respectively. --------- [1] - Serajee et al. (ASHG conference 2015 - abstract Nr. 2299T) reported on a patient born to consanguineous parents of South Asian ancestry with intractable epilepsy, microcephaly, DD and spastic quadriplegia. Metabolic investigations revealed increased urinary 3MGA. Two similarly affected sisters with demonstrated increase of 3MGA, were deceased following an infection. WES in the affected child, 2 unaffected sibs and the parents suggested a homozygous missense variant as the likely cause of the disorder in the proband (c.1114G>A / p.G372S - Reference not specified though the variant probably corresponds to ENST00000314349.4 and ClinVar's entry VCV000208697.1 - www.ncbi.nlm.nih.gov/clinvar/variation/208697/). [2] - Shahroor et al. (2017, PMID: 27573165) reported on 2 consanguineous families, each with 2 affected individuals. Two sibs from the 1st family (of Bedouin origin) presented with seizures (onset at 3m and 4m respectively), DD and ID with slightly elevated plasma lactate and increased urinary 3MGA upon metabolic investigations. Enzymatic activities of mitochondrial complex I-V were carried out for 1 sib and were normal also after normalization for citrate synthase. Following a SNP array, WES was carried out in affected children and their parents. Both sibs were homozygous for a missense SNV [NM_001001563.1:c.755C>T / p.Thr252Met]. Segregation studies - also in 3 unaffected sibs - supported a role for the variant. Two sibs from the 2nd family (of Muslim origin) presented with seizures (myoclonic jerks at 3m, generalized tonic movements at 2m - respectively) with DD and ID. Urinary 3MGA was elevated for both, with CSF lactate also elevated in one. WES revealed homozygosity for p.Arg217Trp (NM_001001563.1:c.649C>T) and segregation studies in parents and an unaffected sib were again compatible. The authors could not demonstrate pathogenicity of the variants in a yeast based system although - as also commented on in Ref 4 - the human TIMM50 could not rescue the yeast ΔΤim50 growth defect and global conservation between the two proteins is poor. [3] - Reyes et al. (2018, PMID: 30190335) reported on one individual with onset of infantile spasms at the age of 2m with hypsarrythmia upon EEG and psychomotor regression. Leigh-like features were noted upon brain MRI. Lactate was elevated in both plasma and CSF. Urinary 3MGA was normal. WES, Sanger confirmation and segregation studies demonstrated compound htz for 2 variants (NM_001001563:c.335C>A or p.S112* and c.569G>C or p.G190A). Functional studies demonstrated among others decrease in all components of the TIM23 complex and decreased mitochondrial membrane potential. Patient fibroblasts grown in glucose had lower levels of all complex II and IV subunits and one complex I subunit (due to the impairment in import system) with decreased mitochondrial respiration and increase in ROS production. Growth in galactose - shifting energy production toward OxPhos - caused massive cell death. The phenotype was rescued/substantially improved following complementation of patient fibroblasts with wt TIMM50. [4] - Tort et al. (2019, PMID: 31058414) reported on a boy with seizures and ID (diagnosis of West syndrome), Leigh-like MRI anomalies, cardiomyopathy with elevated plasma and CSF lactate and persistent urinary elevation of 3MGA. The proband was found to be compound heterozygous for 2 TIMM50 variants [NM_001001563.5:c.341 G>A (p.Arg114Gln) in trans with c.805 G>A (p.Gly269Ser)] following WES and Sanger confirmation/segregation studies. In patient fibroblasts TIMM50 protein levels were severely reduced upon WB although mRNA levels were similar to control. Muscle biopsy revealed decreased activity of the complexes I-IV, when normalized to the citrate synthase activity. Accumulation of lipidic material in muscle fibers was shown to be associated with mitochondria upon EM. Expression and sublocalization of mitochondria-targeted proteins were not found to be affected in patient fibroblasts. In extracts from muscle biopsy reduced protein levels of SDHA, COX4L and MTCO1 were demonstrated, in line with the disruptions in the activities of the MRC. Mitochondrial morphology and network were shown to be altered in patient fibroblasts. Patient fibroblasts showed marked reduction of max respiratory capacity. Similar reduction was noted in CRISPR/Cas9 generated TIMM50-ko HEK293T cells, but rescued upon transient transfection with a plasmid encoding for wt TIMM50. (Functional studies better summarized in the respective articles). Sources: Literature, Radboud University Medical Center, Nijmegen |
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Intellectual disability - microarray and sequencing v2.978 | UFC1 |
Catherine Snow Added phenotypes Neurodevelopmental disorder with spasticity and poor growth, 618076 for gene: UFC1 Publications for gene UFC1 were changed from 29868776; 27431290; 30237576 to 30914295 |
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Intellectual disability - microarray and sequencing v2.978 | FARS2 |
Catherine Snow Source Expert Review Green was added to FARS2. Source Expert Review was added to FARS2. Added phenotypes Spastic paraplegia 77, autosomal recessive, 617046; Combined oxidative phosphorylation deficiency 14, 614946 for gene: FARS2 Rating Changed from No List (delete) to Green List (high evidence) |
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Intellectual disability - microarray and sequencing v2.965 | DEGS1 | Rebecca Foulger commented on gene: DEGS1: PMID:30620338: Karsai et al., 2019 identified a homozygous p.Ala280Val variant in DEGS1 in a Turkish patient of consanguineous parents. Both parents and healthy siblings were heterozygous carriers of the variant. Leading symptoms were early-onset developmental delay, movement disorder, progressive spasticity, and epilepsy. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.965 | DEGS1 | Rebecca Foulger commented on gene: DEGS1: PMID:31186544: Dolgin et al., 2019 describe four individuals from a consanguineous family. All four had mild to severe ID, spastic quadriplegia, scoliosis and epilepsy in most. WES identified a homozygous missense variant in DEGS1 (in isoforms N219S, N255S). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.953 | DEGS1 |
Konstantinos Varvagiannis gene: DEGS1 was added gene: DEGS1 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: DEGS1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: DEGS1 were set to 30620337; 30620338; 31186544 Phenotypes for gene: DEGS1 were set to Leukodystrophy hypomyelinating 18, MIM 618404) Penetrance for gene: DEGS1 were set to Complete Review for gene: DEGS1 was set to GREEN Added comment: Several individuals with biallelic pathogenic DEGS1 variants have been reported to date, in the following studies : [1] Pant et al. 2019 (PMID: 30620337) : 19 patients from 13 unrelated families [2] Karsai et al. 2019 (PMID: 30620338) : 1 individual [3] Dolgin et al. 2019 (PMID: 31186544) : 4 individuals belonging to a large consanguineous kindred As summarized in the first article and OMIM, affected individuals may have very poor psychomotor development, dystonia, spasticity, seizures with hypomyelinating leukodystrophy upon brain imaging and/or progressive atrophy of corpus callosum, thalami and cerebellum. Although a severe form overall was reported for many individuals in the first study, variable severity (eg. mild to severe ID) was reported among individuals belonging to the same kindred in the report by Dolgin et al. DEGS1 encodes Δ4-dehydroceramide desaturase which catalyzes conversion of dihydroceramide (DhCer) to ceramide (Cer) in the de novo ceramide biosynthetic pathway. Ceramide is the central unit of all sphingolipids, which are components of cellular membranes and play key roles in several processes incl. cell differentiation, neuronal signaling and myelin sheath formation. Sphingolipid balance is important for the CNS as demonstrated in the case of lysosomal disorders (eg. Gaucher, Niemann Pick, Farber) one enzymatic step away from DEGS1. Variants of all types (missense, stopgain, frameshift) have been reported with the majority/almost all located in the fatty acid desaturase (FAD) domain. Extensive studies have been carried out and demonstrated: - impaired DEGS1 activity in patients' fibroblasts and muscle suggested by increased DhCer/Cer ratio and compatible broader biochemical effects (higher levels of dihydrosphingosine, dihydrosphingomyelins, etc. and lower levels of sphingosine, monohexosylceramides, etc). - increased ROS production in patient fibroblasts (similar to a Drosophila model of excess DhCer), - high expression of the gene in child and adult CNS tissues from control individuals (evaluated by RT-qPCR in Ref. 1). A previous study has suggested that DEGS1 expression is upregulated during the 4-9th week of human embryogenesis (PMID cited: 20430792) which may suggest an important role for neural system development. - decreased expression for some variants either evaluated at the mRNA (RT-qPCR) / protein level (by Western Blot) - In zebrafish loss of Degs1 resulted in increased DhCer/Cer ratio, locomotor disability and impaired myelination similar to the patients' phenotype. Fingolimod, a sphingosine analog inhibiting Cer synthase (one step prior to DEGS1 in the de novo ceramide biosynthesis pathway, and converting sphingosine to ceramide in the salvage pathway) reduced the DhCer/Cer imbalance, ameliorated the locomotor phenotype and increased the number of myelinating oligodendrocytes in zebrafish, while it reduced the ROS levels in patient fibroblasts. Previous animal models: Apart from the zebrafish model (Pant et al.), higher DhCer/Cer ratios have been shown in homozygous Degs1 -/- mice similar to what is also observed in D. melanogaster. As summarized in MGI (and the previous studies as well) "mice homozygous for a knock-out allele exhibit premature death, decreased to absent ceramide levels, decreased body weight, scaly skin, sparse hair, tremors, hematological and blood chemistry abnormalities, decreased bone mineral content and density and decreased liver function." (PMIDs cited: 17339025, 28507162). ---- The respective OMIM entry is Leukodystrophy, hypomyelinating, 18 (#618404). DEGS1 is not associated with any phenotype in G2P. ---- As a result, DEGS1 can be considered for inclusion in the ID and epilepsy panels probably as green (relevant phenotype, sufficient number of individuals, supportive expression and biochemical studies, animal models, etc). Sources: Literature |
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Intellectual disability - microarray and sequencing v2.923 | TRAPPC12 | Louise Daugherty Phenotypes for gene: TRAPPC12 were changed from Encephalopathy, progressive, early-onset, with brain atrophy and spasticity, 617669 to Encephalopathy, progressive, early-onset, with brain atrophy and spasticity, 617669; Developmental delay | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.922 | TRAPPC12 | Louise Daugherty Phenotypes for gene: TRAPPC12 were changed from to Encephalopathy, progressive, early-onset, with brain atrophy and spasticity, 617669 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.920 | TRAPPC12 | Louise Daugherty reviewed gene: TRAPPC12: Rating: GREEN; Mode of pathogenicity: None; Publications: 28777934; Phenotypes: Encephalopathy, progressive, early-onset, with brain atrophy and spasticity, 617669; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.845 | ACTL6B | Rebecca Foulger commented on gene: ACTL6B: Bell et al., 2019 (PMID:31031012) identified 11 individuals (from 10 families) with biallelic variants in ACTL6B and global developmental delay, epileptic encephalopathy, and spasticity. They also identified 10 unrelated individuals with de novo heterozygous variants with ID, developmental delay, hypotonia, Rett-like stereotypies (e.g. handwringing), and minor facial dysmorphisms: 9/10 of these individuals had the identical de novo c.1027G>A (p.Gly343Arg) mutation. Engineered knock-out of ACTL6B in wild-type human neurons resulted in profound deficits in dendrite development. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.841 | UFC1 | Rebecca Foulger Phenotypes for gene: UFC1 were changed from Neurodevelopmental disorder with spasticity and poor growth, 618076 to Neurodevelopmental disorder with spasticity and poor growth, 618076; global developmental delay with progressive microcephaly | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.800 | ACTL6B | Konstantinos Varvagiannis reviewed gene: ACTL6B: Rating: GREEN; Mode of pathogenicity: None; Publications: 31031012, 30656450, 26539891, 27171548, 30237576; Phenotypes: Global developmental delay, Intellectual disability, Seizures, Spasticity, Global developmental delay, Intellectual disability, Stereotypic behavior, Abnormality of the face; Mode of inheritance: BOTH monoallelic and biallelic, autosomal or pseudoautosomal; Current diagnostic: yes | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.784 | FARS2 |
Konstantinos Varvagiannis gene: FARS2 was added gene: FARS2 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: FARS2 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: FARS2 were set to 30869852 Phenotypes for gene: FARS2 were set to Combined oxidative phosphorylation deficiency 14, 614946; Spastic paraplegia 77, autosomal recessive, 617046 Penetrance for gene: FARS2 were set to Complete Review for gene: FARS2 was set to GREEN gene: FARS2 was marked as current diagnostic Added comment: PMID: 30869852 (Almannai et al, 2019) is a review on FARS2 deficiency. DD/ID and seizures are observed in both infantile- and later-onset forms of the disorder (FARS2-related infantile-onset epileptic mitochondrial encephalopathy and FARS2-related later-onset spastic paraplegia respectively). The phenotype of 26 individuals (from 19 families) and 11 individuals (from 6 families) with infantile and later-onset FARS2 deficiency is summarized in table 2. As commented by the authors, pathogenic variants may include missense, nonsense, splice-site variants, small indels as well as larger deletions/duplications (table 1 and footnote). The relevant OMIM entries are the following: Combined oxidative phosphorylation deficiency 14 (MIM 614946) and Spastic paraplegia 77, autosomal recessive (MIM 617046). FARS2 is included in the DD panel of G2P, associated with Neurometabolic disorder due to FARS2 deficiency (disease confidence: confirmed). This gene is included in gene panels for ID offered by some diagnostic laboratories. As a result, FARS2 can be considered for inclusion in the ID panel as green (or amber) Sources: Literature |
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Intellectual disability - microarray and sequencing v2.705 | ASNS | Louise Daugherty Phenotypes for gene: ASNS were changed from Asparagine synthetase deficiency, 615574; congenital microcephaly, severe developmental delay, and axial hypotonia followed by spastic quadriplegia to Asparagine synthetase deficiency, 615574; congenital microcephaly, intellectual disability, progressive cerebral atrophy, intractable seizures | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.703 | ASNS | Louise Daugherty Phenotypes for gene: ASNS were changed from Asparagine synthetase deficiency, 615574 to Asparagine synthetase deficiency, 615574; congenital microcephaly, severe developmental delay, and axial hypotonia followed by spastic quadriplegia | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.700 | AIMP2 | Louise Daugherty Phenotypes for gene: AIMP2 were changed from Leukodystrophy, hypomyelinating, 17, 618006; neurodevelopmental disorder with microcephaly, seizures, and spastic quadriparesis to Leukodystrophy, hypomyelinating, 17, 618006; neurodevelopmental disorder with microcephaly, seizures, and spastic quadriparesis | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.698 | AIMP2 | Louise Daugherty Phenotypes for gene: AIMP2 were changed from Leukodystrophy, hypomyelinating, 17 (MIM 618006) to Leukodystrophy, hypomyelinating, 17, 618006; neurodevelopmental disorder with microcephaly, seizures, and spastic quadriparesis | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.597 | DHPS |
Konstantinos Varvagiannis gene: DHPS was added gene: DHPS was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: DHPS was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: DHPS were set to 21389784; 21850436 Phenotypes for gene: DHPS were set to Abnormal muscle tone; Global developmental delay; Intellectual disability; Seizures; EEG abnormality; Behavioral abnormality; Abnormality of head or neck Penetrance for gene: DHPS were set to Complete Review for gene: DHPS was set to GREEN Added comment: Ganapathi et al. (doi.org/10.1016/j.ajhg.2018.12.017 - PMID : NA) report on 5 individuals from 4 unrelated families with biallelic pathogenic variants in DHPS. The phenotype consisted of DD/ID (5/5), tone abnormalities (hypotonia/hypertonia/spasticity - 5/5), seizures (5/5 - in one case though unclear staring spells) with EEG abnormalities (5/5). Additionally most individuals displayed behavioral issues, or some common facial features. Several other disorders had been ruled prior to the diagnosis, in all cases by exome sequencing. All individuals harbored a specific missense variant (c.518A>G or p.Asn173Ser) in trans with various other variants incl. a splice site mutation (c.1014+1G>A), an in-frame deletion of 2 amino acids (c.912_917delTTACAT or p.Tyr305_Ile306del) or a variant abolishing the translation initiation codon (c.1A>G or p.Met1?) [All variants using NM_001930.3 as a reference]. Deoxyhypusine synthase (encoded by DHPS) is an enzyme participating in the first step of hypusine synthesis, an amino-acid which is specific to eukaryotic initiation factor 5A (eIF5A) and its homolog (eIF5A2). eIF5A, its hypusinated form and DHPS have all been previously implicated in cellular proliferation/differentiation. eIF5A has also been proposed to be a mRNA translation elongation factor. A role of eIF5A in neuronal growth and survival has been proposed previously (all ref. in present article). Neither eIF5A, nor DHPS or DOHH (an enzyme required for the second step of hypusination) have been associated to any disorders previously. Mutations in genes encoding other eukaryotic elongator factors (eg. EEF1A2, EEF2) have been associated with neurodevelopmental disorders. Concerning the DHPS variants reported: cDNA studies suggested that the c.1014+1G>A variant is translated but results in aberrant splicing and truncation of the protein before its active site. The in-frame deletion as well as the missense variant were shown to have absent or partial (20%) enzyme activity in vitro respectively compared to wild-type (following expression in E.coli BL21(DE3) cells). In line with this, reduced hypusination of eIF5A was observed for these 2 variants when compared to wild-type DHPS, upon co-transfection of constructs overexpressing DHPS (wt or mut.) and eIF5A in HEK293T cells. Absence of homozygous DHPS LoF variants in population databases might suggest that complete deficiency is incompatible with normal embryonic development. Mice heterozygous for Dhps deletion do not demonstrate severe phenotypes, though homozygosity is embryonically lethal (PMIDs: 21389784, 21850436). --------- DHPS is not associated with any phenotype in G2P, nor in OMIM. This gene is not - at least commonly - included in gene panels for ID offered by diagnostic laboratories. --------- As a result, DHPS can be considered for inclusion in this panel as green (or amber). Sources: Literature |
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Intellectual disability - microarray and sequencing v2.584 | ZBTB11 |
Konstantinos Varvagiannis gene: ZBTB11 was added gene: ZBTB11 was added to Intellectual disability. Sources: Literature Mode of inheritance for gene: ZBTB11 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: ZBTB11 were set to 29893856; 28382966 Phenotypes for gene: ZBTB11 were set to Intellectual disability Penetrance for gene: ZBTB11 were set to Complete Review for gene: ZBTB11 was set to AMBER Added comment: Fattahi et al. (PMID: 29893856) report on 9 individuals from 2 broader consanguineous pedigrees with biallelic ZBTB11 mutations. Features in the first family (from Iran) consisted of moderate ID, microcephaly, ataxic gait, and spasticity with MRI findings of cerebellar atrophy and ventriculomegaly. Individuals from the second family (from Pakistan) presented with moderate ID and variable features. Homozygosity for missense ZBTB11 variants, private to each family was shown (NM_014415.3:c.2185C>T / p.H729Y and c.2640T>G / p.H880Q for the first and second family respectively). As the authors note, ZBTB11 is predicted to be a zinc finger transcriptional regulator and one of the hypotheses emitted suggests possible disruption of DNA binding. Functional studies performed demonstrated that the mutant proteins were excluded from the nucleolus where the (wt) protein localizes. Previous zebrafish models (PMID: 28382966) suggested CNS degeneration among other phenotypes in Zbtb11 mutants. Knockdown of the drosophila ZBTB11-ortholog (CkIIα-i1) resulted in recognizable shrinking of the mushroom body with significant reduction in the number of neurons compared to controls. Other Zinc Finger and BTB Domain-Containing proteins cause disorders with ID as a prominent feature (eg. ZBTB16, ZBTB20, etc.). ZBTB11 is not associated with any phenotype in OMIM nor in G2P. As a result, this gene can be considered for inclusion in this panel probably as amber (2 pedigrees only) or green (given the supportive functional studies). Sources: Literature |
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Intellectual disability - microarray and sequencing v2.545 | UFC1 |
Konstantinos Varvagiannis gene: UFC1 was added gene: UFC1 was added to Intellectual disability. Sources: Literature,Expert Review Mode of inheritance for gene: UFC1 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: UFC1 were set to 29868776 Phenotypes for gene: UFC1 were set to Neurodevelopmental disorder with spasticity and poor growth, 618076 Penetrance for gene: UFC1 were set to Complete Review for gene: UFC1 was set to GREEN Added comment: Biallelic UFC1 mutations cause Neurodevelopmental disorder with spasticity and poor growth, MIM 618076. PMID: 29868776 describes 7 individuals (most) born to consanguineous Saudi families (in one case the parents were not consanguineous but originated from the same tribe) as well as a further individual born to distantly related Swiss parents. One of these patients was previously briefly published by the same authors (PMID: 27431290). The phenotype consisted of developmental delay (8/8 - usually profound), failure to thrive (8/8), short stature and microcephaly (both observed in 7/8), seizures (4/8) and variable brain MRI anomalies in some of these subjects. Overall, two UFC1 missense variants are reported [NM_016406.3:c.317C>T or p.(Thr106Ile) and c.68G>A or p.(Arg23Gln) the former in the Saudi individuals]. Functional studies demonstrated the hypomorphic nature of the variants. UFC1 (as well as UFM1 also discussed in the same article) participate in ufmylation, with mutations in other enzymes of the same process (notably UBA5 - gene rated Green in the ID and epilepsy panels) having already been described in neurodevelopmental disorders. As a result this gene can be considered for inclusion in the ID panel as green (or amber). Sources: Literature, Expert Review |
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Intellectual disability - microarray and sequencing v2.516 | SLC1A4 |
Louise Daugherty gene: SLC1A4 was added gene: SLC1A4 was added to Intellectual disability. Sources: Expert Review Mode of inheritance for gene: SLC1A4 was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: SLC1A4 were set to 29989513; 27193218; 26138499; 26041762; 25930971 Phenotypes for gene: SLC1A4 were set to Spastic tetraplegia, thin corpus callosum, and progressive microcephaly, 616657; Intellectual disability Review for gene: SLC1A4 was set to GREEN Added comment: From review left on the Genetic Epilepsy Syndromes panel by Zornitza Stark (Australian Genomics) 4 Sep 2018, 3:29 a.m. Multiple affected individuals reported in the literature, seizures/EE are part of the phenotype. While initial reports identified a recurrent missense variant in individuals of Ashkenazi Jewish ancestry, there have been more recent reports of individuals from other ethnic backgrounds with different variants. Gene is also relevant to the ID panel. Sources: Expert Review |
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Intellectual disability - microarray and sequencing v2.498 | SPAST | Louise Daugherty Classified gene: SPAST as Red List (low evidence) | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.498 | SPAST | Louise Daugherty Added comment: Comment on list classification: Changed rating of gene from Amber to Red. This gene was rated as Red in v2.467 and incorrectly automatically demoted to Amber in v2.468. This was due to a defect in the automatic PanelApp uploading tool where a reference gene list was added as a new Source (Victorian Clinical Genetics Services), and under certain conditions associated to previous sources listed, resulted in the rating of the gene being automatically changed when it should not have been. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.498 | SPAST | Louise Daugherty Gene: spast has been classified as Red List (Low Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.468 | SPAST | Louise Daugherty Source Victorian Clinical Genetics Services was added to SPAST. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.417 | KIF5A | Louise Daugherty Added comment: Comment on phenotypes: removed Spastic paraplegia 10, autosomal dominant, 604187, this is not a relevant phenotype on this panel. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing v2.417 | KIF5A | Louise Daugherty Phenotypes for gene: KIF5A were changed from Spastic paraplegia 10, autosomal dominant, 604187 to Myoclonus, intractable, neonatal, 617235; intellectual disability | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing | SPAST | BRIDGE consortium edited their review of SPAST | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing | SPAST | BRIDGE consortium edited their review of SPAST | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing | SPAST | Louise Daugherty classified SPAST as amber | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing | SPAST | Louise Daugherty commented on SPAST | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Intellectual disability - microarray and sequencing | SPAST | BRIDGE consortium reviewed SPAST |