The GJB6 gene encodes Connexin 30 (Cx30), located ~ 35 kb telomeric to GJB2. Initially identified in autosomal dominant deafness (DFNA3) GJB6 mutations were later shown to participate in digenic inheritance with GJB2 [79,82]. Here, GJB2 is linked to autosomal dominant nonsyndromic hearing loss 3A.