chrM-12201-T-C
Variant summary
Our verdict is Likely pathogenic. Variant got 7 ACMG points: 7P and 0B. PP3PS3_ModeratePS4_SupportingPM2_SupportingPP1_Moderate
This summary comes from the ClinGen Evidence Repository: 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. LINK:https://erepo.genome.network/evrepo/ui/classification/CV30004/MONDO:0044970/014
Frequency
Consequence
ENST00000387441.1 non_coding_transcript_exon
Scores
Clinical Significance
Conservation
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ACMG classification
Verdict is Likely_pathogenic. Variant got 7 ACMG points.
Transcripts
RefSeq
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | MANE | UniProt |
---|---|---|---|---|---|---|---|
TRNH | TRNH.1 use as main transcript | n.64T>C | non_coding_transcript_exon_variant | 1/1 | |||
TRNS2 | TRNS2.1 use as main transcript | upstream_gene_variant |
Ensembl
Gene | Transcript | HGVSc | HGVSp | Effect | #exon/exons | TSL | MANE | Appris | UniProt |
---|---|---|---|---|---|---|---|---|---|
MT-TH | ENST00000387441.1 | n.64T>C | non_coding_transcript_exon_variant | 1/1 | |||||
MT-TS2 | ENST00000387449.1 | upstream_gene_variant |
Frequencies
GnomAD4 exome Cov.: 0
Mitomap
ClinVar
Submissions by phenotype
Mitochondrial disease Pathogenic:1
Likely pathogenic, reviewed by expert panel | curation | ClinGen Mitochondrial Disease Nuclear and Mitochondrial Variant Curation Expert Panel, ClinGen | Apr 17, 2023 | 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. - |
Mitochondrial non-syndromic sensorineural hearing loss Pathogenic:1
Pathogenic, no assertion criteria provided | literature only | OMIM | Oct 01, 2011 | - - |
Juvenile myopathy, encephalopathy, lactic acidosis AND stroke Uncertain:1
Uncertain significance, criteria provided, single submitter | clinical testing | Wong Mito Lab, Molecular and Human Genetics, Baylor College of Medicine | Jul 12, 2019 | 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 - |
Computational scores
Source:
Splicing
Find out detailed SpliceAI scores and Pangolin per-transcript scores at