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| Intellectual disability syndromic and non-syndromic v0.2750 | TBC1D2B |
Konstantinos Varvagiannis gene: TBC1D2B was added gene: TBC1D2B was added to Intellectual disability syndromic and non-syndromic. Sources: Literature Mode of inheritance for gene: TBC1D2B was set to BIALLELIC, autosomal or pseudoautosomal Publications for gene: TBC1D2B were set to 32623794 Phenotypes for gene: TBC1D2B were set to Global developmental delay; Intellectual disability; Seizures; Gingival overgrowth; Behavioral abnormality; Abnormality of the mandible; Abnormality of brain morphology; Abnormality of the eye; Hearing abnormality Penetrance for gene: TBC1D2B were set to Complete Review for gene: TBC1D2B was set to AMBER Added comment: Harms et al (2020 - PMID: 32623794) report on 3 unrelated individuals with biallelic pLoF TBC1D2B variants. Features included cognitive impairment (mild ID in one case, regression at the age of 12y in another, hypotonia and delayed milestones in a third aged 8m), seizures (3/3 - variable age of onset) and/or gingival overgrowth (2/3 - prior to initiation of AEDs). Other findings included behavioral abnormalities, mandibular anomalies, abnormal brain imaging and ophthalmologic or (rarely) audiometric evaluations. All were born to non-consanguineous couples and additional investigations were performed in some. Variants were identified by WES or trio WGS, with Sanger confirmation/compatible segregation analyses. In line with the pLoF variants, mRNA studies in fibroblasts from 2 unrelated affected individuals demonstrated significantly reduced (~80-90%) TBC1C2D mRNA levels compared to controls, restored following cycloheximide treatment. Protein was absent in patient fibroblasts. TBC-domain containing GTPase activating proteins are known as key regulators of RAB GTPase activity. TBC1D2B was shown to colocalize with RAB5-positive endocytic vesicles. CRISPR/Cas9-mediated ko of TBC1D2B in HeLa cells suggested a role in EGF receptor endocytosis and decreased cell viability of TBC1D2B-deficient HeLa cells upon serum deprivation. Genes encoding other TBC domain-containg GTPase-activating proteins, e.g. TBC1D7 and TBC1D20, TBC1D24 are associated with recessive neurodevelopmental disorders (with ID and/or seizures) and the pathophysiological defect in TBC1D2B-related disorder (deficit in vesicle trafficking and/or cell survival) is proposed to be similar to that of TBC1D24. Overall this gene can be considered for inclusion with amber/green rating in the ID panel and green in epilepsy panel. Sources: Literature |
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| Intellectual disability syndromic and non-syndromic v0.1548 | TBC1D20 | Zornitza Stark Marked gene: TBC1D20 as ready | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.1548 | TBC1D20 | Zornitza Stark Gene: tbc1d20 has been classified as Green List (High Evidence). | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.1153 | TBC1D20 | Chirag Patel Deleted their comment | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.1153 | TBC1D20 | Chirag Patel edited their review of gene: TBC1D20: Added comment: Liegel et al. (2013) analyzed the candidate gene TBC1D20 and identified homozygous mutations in 7 patients diagnosed with Warburg Micro syndrome from 5 families of different ethnic origins. Evaluation of human fibroblasts deficient in TBC1D20 function identified aberrant lipid droplet formation.; Changed rating: GREEN | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.1153 | TBC1D20 |
Chirag Patel Source Genetic Health Queensland was removed from TBC1D20. Source Expert list was added to TBC1D20. Mode of inheritance for gene TBC1D20 was changed from Unknown to BIALLELIC, autosomal or pseudoautosomal Phenotypes for gene: TBC1D20 were changed from to Warburg micro syndrome 4; OMIM #615663 Publications for gene TBC1D20 were changed from PubMed: 24239381 to PubMed: 24239381 |
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| Intellectual disability syndromic and non-syndromic v0.1152 | TBC1D20 | Chirag Patel reviewed gene: TBC1D20: Rating: RED; Mode of pathogenicity: None; Publications: PubMed: 24239381; Phenotypes: Warburg micro syndrome 4, OMIM #615663; Mode of inheritance: BIALLELIC, autosomal or pseudoautosomal | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| Intellectual disability syndromic and non-syndromic v0.0 | TBC1D20 |
Zornitza Stark gene: TBC1D20 was added gene: TBC1D20 was added to Intellectual disability, syndromic and non-syndromic_GHQ. Sources: Expert Review Green,Genetic Health Queensland Mode of inheritance for gene: TBC1D20 was set to Unknown |
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