introduction: with prevalence figures close to 0.2% at birth, hearing loss (hl) is the most frequent sensory impairment in childhood. in developed countries, genetic causes account for more than 60% of congenital hl, most often resulting in non-syndromic deafness, which is usually autosomal recessive. hereditary nonsyndromic hearing loss (nshl) in iran is highly heterogeneous, rendering molecul...