The gene for diffuse palmoplantar keratoderma of the type found in northern Sweden is localized to chromosome 12q11-q13.

Hereditary palmoplantar keratoderma is characterized by hyperkeratosis of the skin of palms and soles. An autosomal dominant form of diffuse non-epidermolytic palmoplantar keratoderma, frequently complicated by fungal infections, is encountered in northern Sweden with a prevalence of 0.3-0.55%. We have examined two families with this type of palmoplantar keratoderma and localized the causative genetic defect to a 14 cM interval on chromosome 12q11-q13, a region known to contain the keratin type II gene cluster as well as the retinoic acid receptor gamma gene. The palmoplantar keratoderma variant investigated in this study is thus genetically different from epidermolytic palmoplantar keratoderma, which recently has been shown to result from mutations in the gene for the type I keratin 9.