Molecular pathogenefic mechanism of maternally inherited deafness

摘要

Mutations in the mitochondrial DNA(mtDNA) have been shown to be one of the important causes of deafness.In particular, mutations in mitochondrial DNA(mtDNA)have been found to be associated with both syndromic and non-syndromic forms of sensorineural hearing loss.The deafness-linked mutations often occur in the mitochondrial 12S rRNA gene and the tRNA genes.The mutations in the 12S rRNA gene account for a significant number of cases of aminoglycoside ototoxicity.The other hot spot for mutations associated with hearing impairment is the tRNA Ser(UCN)gene,as five deafness-linked mutations have been identified.Non-syndromic deafness-linked mtDNA mutations are often homoplasmic or at high levels of heteroplasm,indicating a high threshold for pathogenicity.Phenotypic expression of rnthese mtDNA mutations require the contribution of other factors,such as nuclear modifier gene(s),environmental rnfactor(s) and mitochondrial haplotype(s).