A novel locus (DSAP2) for disseminated superficial actinic porokeratosis maps to chromosome 15q25.1-26.1

Background: Disseminated superficial actinic porokeratosis (DSAP) is a chronic cutaneous disorder characterized by multiple superficial keratotic lesions surrounded by a slightly raised keratotic border. It develops in teenagers in sun-exposed areas of skin and usually follows an autosomal dominant inheritance pattern. The first locus for DSAP was localized to chromosome 12q23.2-24.1, but no gene responsible for porokeratosis has been identified to date. Objectives: To determine whether DSAP is a genetically heterogeneous disorder and to identify the disease gene locus in a three-generation Chinese family with DSAP. Methods: Genetic linkage analysis was carried out in this family using 15 microsatellite markers between D12S1671 and D12S369 on chromosome 12q, followed by a genome-wide scan with 382 microsatellite markers from the autosomes. Results: Genetic linkage analysis with chromosome 12q markers suggested that the locus in this family is not linked to chromosome 12q. A genome-wide scan and fine mapping finally localized the locus for DSAP in this family to a 6.4-cM region between markers D15S1023 and D15S1030 at chromosome 15q25.1-26.1. This DSAP locus was named DSAP2. Conclusions: The previous results and this study have shown that DSAP is a genetically heterogeneous disorder: a novel locus for DSAP, termed DSAP2, was mapped to a 6.4-cM region between markers D15S1023 and D15S1030.