Identification of a Psoriasis Susceptibility Candidate Gene by Linkage Disequilibrium Mapping with a Localized Single Nucleotide Polymorphism Map

Abstract Psoriasisis a chronic inflammatory disease of the skin with both genetic and environmental risk factors. Here we describe the creation of a single-nucleotide polymorphism (SNP) map spanning 900–1200 kb of chromosome 3q21, which had been previously recognized as containing a psoriasissusceptibility locus, PSORS5 . We genotyped 644 individuals, from 195 Swedish psoriatic families, for 19 polymorphisms. Linkage disequilibrium(LD) between marker and disease was assessed using the transmission/disequilibrium test(TDT). In the TDT analysis, alleles of three of these SNPs showed significant association with disease ( P P value of 3.8 −5 . We have called this gene SLC12A8 , coding for a member of the solute carrier family12 proteins. It belongs to a class of genes that were previously unrecognized as playing a role in psoriasispathogenesis.