More than two hundred mutations in GJB2 (DFNB1, MIM220290) have been found to be related to autosomal recessive non-syndromic hearing loss2, whereas only nineteen GJB2 mutations have been associated with hereditary autosomal dominant non-syndromic deafness (DFNA3, MIM601544). The gene discussed is GJB2; the disease is autosomal dominant nonsyndromic hearing loss 3A.