In the differential diagnostics of KID syndrome, other disorders should also be considered: the classic form of Vohwinkel syndrome (OMIM 124500) with congenital deafness, keratopachydermia, constrictions of fingers and toes, and palmoplantar keratoderma with deafness (OMIM 148350), which are also caused by GJB2 mutations. The gene discussed is GJB2; the disease is hereditary palmoplantar keratoderma.