Frequency of the Mitochondrial A1555G Mutation in Iranian Patients with Non-syndromic Hearing Impairment

Mitochondrial 12S rRNA gene mutations account for non-syndromic hearing impairment (NSHI). The A1555G substitution is the most common mitochondrial DNA mutation and is associated with both aminoglycoside-induced HI and NSHI. Its frequency is variable among populations of different ethnic background. The purpose of the present survey was to determine the frequency of the A1555G mutation in the Iranian probands with NSHI. We have screened 152 unrelated Iranian probands with NSHI with childhood onset and 548 normal hearing controls for the occurrence of the A1555G mutation using PCR-RFLP method. Totally, 2 patients carrying the homoplasmic A1555G mutation were identified with a total frequency of 1.3% in Iran. Mutation A1555G had a variable frequency among subpopulations of different ethnic origins in Iran: Azeri Turkish (4.16%), Lure (0.0%), Fars (0.0%) and Bushehri (2.86%). The A1555G mutation was not found in any member of the controls. Our study shows that the frequency of the A1555G mutation in Azeri Turkish and Bushehri hearing impaired patients is compatible with that reported for Caucasian populations.