Detection of Deafness-Causing Mutations in the Greek Mitochondrial Genome

Abstract

Mitochondrion harbors its own DNA, known as mtDNA, encoding certain essential components of the mitochondrial respiratory chain and protein synthesis apparatus. mtDNA mutations have an impact on cellular ATP production and many of them are undoubtedly a factor that contributes to sensorineural deafness, including both syndromic and non-syndromic forms. Hot spot regions for deafness mutations are theMTRNR1gene, encoding the 12S rRNA, theMTTS1gene, encoding the tRNA for Ser(UCN), and theMTTL1gene, encoding the tRNA for Leu(UUR). We investigated the impact of mtDNA mutations in the Greek hearing impaired population, by testing a cohort of 513 patients suffering from childhood onset prelingual or postlingual, bilateral, sensorineural, syndromic or non-syndromic hearing loss of any degree for six mitochondrial variants previously associated with deafness. Screening involved theMTRNR1961delT/insC and A1555G mutations, theMTTL1A3243G mutation, and theMTTS1A7445G, 7472insC and T7510C mutations. Although two patients were tested positive for the A1555G mutation, we failed to identify any subject carrying the 961delT/insC, A3243G, A7445G, 7472insC, or T7510C mutations. Our findings strongly support our previously raised conclusion that mtDNA mutations are not a major risk factor for sensorineural deafness in the Greek population.