Keratitis–ichthyosis–deafness (KID) syndrome is a rare ectodermal dysplasia caused by mutations in the GJB2 gene, which is responsible for the production of the Cx26 protein, a protein present in the epithelial gap junctions that is postulated to be associated with the differentiation of ectodermally derived tissues. Here, GJB2 is linked to ectodermal dysplasia syndrome.