Abstract Background and aim: The frequency of hearing impairment is one out of 500 newborn babies, worldwide. However, in Iran, due to the high prevalence of consanguineous marriages, this amount is estimated to be two to three times higher. So far, more than 120 genes causing non-syndromic Hearing loss (NSHL) have been identified in the world, of which GJB2 gene mutations are the most common c...