Department of Medicine, University of Toronto, Ontario, Canada.
Familial keratosis palmaris et plantaris (KPPF) is characterized by extreme keratinization and desquamation of the skin of the palmar and plantar surfaces of the hands and feet. We have mapped the causative genetic defect to an 8 cM interval on 17q12-24 in or close to the acidic keratin (type I) gene cluster. We show that KPPF co-segregates with a rare, high molecular weight allele of an insertion-deletion polymorphism in the C-terminal coding region of the keratin 10 gene (Z = 8.36 at theta = 0.00) and segrates as a true autosomal dominant trait. Some pedigrees with familial hyperkeratosis of the palms and soles have co-inherited diseases such as congenital malformations and familial cancers. Our analysis provide a region which should be investigated for contiguous gene syndromes in such pedigrees.