A single base deletion mutation, 35delG, in the gene (GJB2/DFNB1)(OMIM 121011/220290) encoding the gap junction protein, connexin 26 is the most important single cause of genetic hearing loss in European and American populations. It is the cause of one of the most common human genetic disorders with a frequency similar to cystic fibrosis. Mutations in this connexin are associated with skin disorders.