Mutations in Cx26 causing PPK–deafness syndrome mostly cluster in the EC1 domain of Cx26 (with the exception of p.G130V located in the IC2 domain), but also mutation involved in other phenotypes BPS, Vohwinkel and Clouston syndromes are located in the same domains; so, further studies are necesary to determine if there is a clear correlation domain-involved and phenotype-associated. This evidence concerns the gene GJB2 and Clouston syndrome.