EVIDENCE FOR 2 PSORIASIS SUSCEPTIBILITY LOCI (HLA AND 17Q) AND 2 NOVEL CANDIDATE REGIONS (16Q AND 20P) BY GENOME-WIDE SCAN

In a 12.5 cM genome-wide scan for psoriasis susceptibility loci, recom bination-based tests revealed linkage to the HLA region (Z(max) = 3.52 ), as well as suggestive linkage to two novel regions: chromosome 16q (60-83.1 cM from pter, Z(max) = 2.50), and chromosome 20p (7.5-25 cM f rom pter, Z(max) = 2.62), All three regions yielded P values less than or equal to 0.01 by non-parametric analysis, Recombination-based and allele sharing methods also confirmed a previous report of a dominant susceptibility locus on distal chromosome 17q (108.2 cM from pter, Z(m ax) = 2.09, GENEHUNTER P = 0.0056), We could not confirm a previously reported locus on distal chromosome 4q; however, a broad region of unc lear significance was identified proximal to this proposed locus (153. 6-178.4 cM from pter, Z(max) = 1.01), Taken together with our recent r esults demonstrating linkage to HLA-B and -C, this genome-wide scan id entifies a psoriasis susceptibility locus at HLA, confirms linkage to 17q, and recommends two novel genomic regions for further scrutiny. On e of these regions (16q) overlaps with a recently-identified susceptib ility locus for Crohn's disease, Psoriasis is much more common in pati ents with Crohn's disease than in controls, suggesting that an immunom odulatory locus capable of influencing both diseases may reside in thi s region.