Frequency of the common mitochondrial DNA (mtDNA) mutations in non-syndromic hearing impairment in southwest subpopulations of Iran

Although، most hereditary non-syndromic hearing impairment (NSHI) is due to mutation in nuclear genes، role of mtDNA mutations in causing deafness becoming much more clear in recent years. The aim of the present study was to screen the A1555G، C1494T، A3243G and A7445G mutations in non-syndromic hearing impairment patients in two provinces of southwest of Iran. In this descriptive laboratory study، 150 subjects with acquired and prelingual autosomal recessive NSHI from Chaharmahal va Bakhtiari province and 46 unrelated probands with postlingual NSHI from Bushehr province (negative for GJB2 mutations) were screened for the presence of the common mtDNA mutations using PCR-RFLP method that followed by direct sequencing for confirming the observed mtDNA mutations. None of these mutations was found in subjects with acquired and prelingual autosomal recessive NSHI from Chaharmahal va Bakhtiari province، but mutation A1555G with frequency of 4. 35% was found in postlingual NSHI patients in Bushehr province. This investigation shows that apparently، mtDNA mutations play a more significant role role in the etiology of postlingual NSHI in comparison with prelingual NSHI