Mitochondrial tRNAIle A4317G mutation may be associated with hearing impairment in a Han Chinese family.

Abstract	Mutations in the mitochondrial genome have been identified to be associated with hearing loss. The aim of the present study was to investigate the role of mitochondrial DNA (mtDNA) variants in a Chinese family with hearing loss. Polymerase chain reaction (PCR)‑Sanger sequencing was used to screen the mtDNA variants and nuclear genes [gap junction protein β2 (GJB2) and transfer (t)RNA 5‑methylaminomethyle‑2‑thiouridylate methyltransferase (TRMU)]; in addition, the mtDNA copy number was determined by quantitative PCR. The present study characterized the molecular features of a Chinese family with maternally‑inherited hearing loss and identified mtDNA A1555G and tRNAIle A4317G mutations. The A4317G mutation was localized at the TΨC arm of tRNAIle (position 59) and created a novel base‑pairing (G59‑C54), which may alter the secondary structure of the tRNA. In addition, patients carrying the A4317G mutation exhibited a lower mtDNA copy number compared with the controls, suggesting that this mutation may cause mitochondrial dysfunction that is responsible for the deafness. However, no functional variants in the GJB2 and TRMU genes were detected. mtDNA A1555G and A4317G mutations may contribute to the clinical manifestation of hearing loss in this family.
Authors	Yong Cui, Duan-Jun He
Journal	Molecular medicine reports (Mol Med Rep) Vol. 18 Issue 6 Pg. 5159-5165 (Dec 2018) ISSN: 1791-3004 [Electronic] Greece
PMID	30272361 (Publication Type: Journal Article)
Chemical References	Connexins DNA, Mitochondrial GJB2 protein, human Mitochondrial Proteins RNA, Transfer, Ile Connexin 26 tRNA Methyltransferases TRMU protein, human
Topics	Adult Asian People (genetics) China Connexin 26 Connexins (genetics) DNA Copy Number Variations DNA, Mitochondrial Genes, Mitochondrial Genetic Association Studies Genetic Predisposition to Disease Genome, Mitochondrial Genotype Hearing Loss (diagnosis, genetics) Humans Middle Aged Mitochondrial Proteins (genetics) Mutation Pedigree Phenotype Phylogeny RNA, Transfer, Ile (chemistry, genetics) Severity of Illness Index tRNA Methyltransferases (genetics)

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