Despite being the major symptoms in KID syndrome, erythrokeratoderma and deafness are also characteristic for the other disorder caused by mutations in genes coding connexin Cx31 (GJB3; OMIM 603324) and Cx30.3 (GJB4; OMIM 605425)—erythrokeratoderma variabilis of Mendes da Costa; however, keratitis is not part of this syndrome. This evidence concerns the gene GJB4 and erythrokeratoderma.