Identification of a locus for porokeratosis palmaris et plantaris disseminata to a 6.9-cM region at chromosome 12q24.1-24.2.

BACKGROUND: Porokeratosis palmaris et plantaris disseminata (PPPD) is a rare autosomal dominant dyskeratotic disorder characterized by a cornoid lamella with parakeratosis, hyperkeratosis and loss of granular layers. The genetic basis of this disease is still unknown. Two loci for disseminated superficial actinic porokeratosis (DSAP) were found to be located on 12q23.2-24.1 and 15q25.1-26.1. Both PPPD and DSAP are disseminated types of porokeratosis.

OBJECTIVES: To locate the locus for PPPD, thereby facilitating the identification of this disease gene and leading to an understanding of the pathogenesis of porokeratosis.

METHODS: Genotyping was performed in a Chinese family with PPPD using polymorphic microsatellite markers on 12q and 15q.

RESULTS: The locus for PPPD is located within a 6.9-cM region between markers D12S1613 and D12S1341, with a maximum two-point LOD score of 8.14 (theta = 0.00) at D12S1335.

CONCLUSIONS: This study provides a map location for isolation of a gene causing PPPD.