Screening of three common mtDNA mutations among subjects with autosomal recessive non-syndromic hearing loss in Sistan va Baluchestan province, Iran

Non-syndromic hearing loss may be induced by mutations in both nuclear and mitochondrial genes. Mutations in mtDNA are present in less than 1% of the children with pre-lingual deafness but are more prevalent later. Most of the molecular defects responsible for mitochondrial disorder, associated with hearing loss may be induced by mutations in the 12SrRNA and tRNA genes. This aim of this study was to investigate the frequency of three common mtDNA mutations including A1555G, A3243G and A7445G in a cohort of autosomal recessive non-syndromic hearing loss (ARNSHL) subjects in Sistan va Baluchestan province. In this descriptive- experimental based study, a total of 110. ARNSHL subjects from Sistan va Baluchestan province were investigated for three common mtDNA mutations using PCR-RFLP procedure. The possible mutations were confirmed by direct sequencing. None of the A1555G and A7445G mutations were detected in this study. However, we found one sample to carry A3243G mutation (0.9%). Moreover abolishing a MTTL1 restriction site close to A3243G mutation revealed a G3316A allelic variant in 0.9% of patients studied. This study showed that mtDNA mutations are responsible for less than 1% of pre-lingual ARNSHL associated subjects. The present study will improve the genetic counseling of hearing impaired patients in Sistan va Baluchestan province, Iran.