Fine genetic mapping of diffuse non-epidermolytic palmoplantar keratodermato chromosome 12q11-q13: exclusion of the mapped type II keratins

Diffuse non-epidermolytic palmoplantar keratoderma (NEPPK) belongs to the h eterogeneous group of skin diseases characterized by thickening of the stra tum corneum of the palms and soles (1). This autosomal dominant PPK is char acterized by a diffuse pattern of palmar and plantar hyperkeratosis giving the affected areas a thickened yellowish appearance with a marked erythemat ous edge. Linkage of diffuse NEPPK to chromosome 12q11-q13 has been demonst rated in two independent reports (2, 3), In this study, we describe detaile d haplotyping with microsatellite markers mapping to this chromosomal regio n in three diffuse NEPPK pedigrees from the south of England. Fine mapping of a previously identified recombination event and the identification of a common disease haplotype segregating in the three pedigrees places the diff use NEPPK locus proximal to the type II keratin gene cluster.