A novel locus for disseminated superficial porokeratosis maps to chromosome 18p11.3.

Disseminated superficial porokeratosis (DSP) is a rare autosomal dominant epidermal keratinization disorder of lesions characterized by cornoid lamella with parakeratosis, hyperkeratosis, and loss of granular layers. The genetic basis for this disease is unknown. Through a proband with a diagnosis of DSP, we identified a large four-generation Chinese family with multiple DSP-affected members from Anhui province in China. After excluding the linkage of the disease phenotype to two known loci for disseminated superficial actinic porokeratosis in this family, we performed a genome-wide linkage analysis using 387 microsatellite markers and identified a novel disease locus for DSP at 18p11.3. Our subsequent fine mapping and haplotype analyses further narrowed down the disease locus into an 18.7 cM region between the telomere and D18S391 with a maximum two-point LOD (logarithm of the odds) score of 4.82 (theta =0.00) at D18S1138. Therefore, this study provides strong linkage evidence for a DSP locus at 18p11.3.