Identification of a locus for punctate palmoplantar keratodermas at chromosome 8q24.13-8q24.21

Punctate palmoplantar keratodermas (PPK) is a rare autosomal dominant cutaneous disorder characterized by numerous hyperkeratotic papules that are irregularly distributed on the palms and soles. The genetic basis for this disease is unknown. We performed a genome-wide search in two Chinese families with punctate PPK to map the chromosome location of the responsible gene. We identified a locus at chromosome 8q24.13-8q24.21 with a cumulative maximum two-point LOD score of 5.41 at markers D8S1793 and D8S1774 (at recombination fraction theta=0.00). Haplotype analysis indicated that the disease gene is located within 9.20 cM region between markers D8S1804 and D8S1720. It is the first locus identified for the punctate PPK. This study provides a map location for isolation of a disease gene-causing punctate PPK.