ClinVar Miner

Submissions for variant NC_012920.1(MT-TH):m.12201T>C

dbSNP: rs387906733
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Total submissions: 3
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Submitter RCV SCV Clinical significance Condition Last evaluated Review status Method Comment
ClinGen Mitochondrial Disease Nuclear and Mitochondrial Variant Curation Expert Panel, ClinGen RCV003319172 SCV004023278 likely pathogenic Mitochondrial disease 2023-04-17 reviewed by expert panel curation The m.12201T>C variant in MT-TH has been reported in three families with features of primary mitochondrial disease (PS4_supporting). The first family reported was 5-generation Han Chinese family with late-onset non-syndromic deafness (PMIDs: 21931169, 24920829, 31819004, 32169613). A second case was reported in a Vietnamese cohort of children with non-syndromic hearing loss (https://www.ojhas.org/issue65/2018-1-6.html). The third case was reported in a cohort of individuals with dilated cardiomyopathy (PMID: 34991096). Seventeen of 35 matrilineal relatives in the first reported family exhibited variable severity and age at onset of sensorineural hearing loss and blood heteroplasmy levels correlated with both onset age and symptom severity (PP1_moderate). There are no reported de novo occurrences of this variant to our knowledge. Although there are several occurrences in population databases, the frequency is still low (PM2_supporting). The computational predictor MitoTIP suggests this variant is pathogenic (67th percentile) and HmtVAR predicts it to be pathogenic score of 0.5 (PP3). Cybrid studies show different classes of function defects including a decrease in the steady-state level of tRNAHis, diminished respiratory capacity, marked decreases in mtATP levels and membrane potential, increased reactive oxygen species (ROS) production, decreased melting temperature, conformational changes, and instability of the mutated tRNA, and HARS2 overexpression corrected the mitochondrial dysfunction (PS3_moderate; PMIDs: 24920829, 31819004). In summary, this variant meets criteria to be classified as likely pathogenic for primary mitochondrial disease inherited in a mitochondrial manner. This classification was approved by the NICHD/NINDS U24 ClinGen Mitochondrial Disease Variant Curation Expert Panel on April 17, 2023. Mitochondrial DNA-specific ACMG/AMP criteria applied (PMID: 32906214): PS4_supporting, PP1_moderate, PM2_supporting, PP3, PS3_moderate.
Wong Mito Lab, Molecular and Human Genetics, Baylor College of Medicine RCV000851039 SCV000993273 uncertain significance MELAS syndrome 2019-07-12 criteria provided, single submitter clinical testing The NC_012920.1:m.12201T>C variant in MT-TH gene is interpreted to be a Unknown Significance variant based on the modified ACMG guidelines (unpublished). This variant meets the following evidence codes reported in the guidelines: PP3, BP6
OMIM RCV000022899 SCV000044190 pathogenic Mitochondrial non-syndromic sensorineural hearing loss 2011-10-01 no assertion criteria provided literature only

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