Researchers discovered eight sites of common DNA variation that increase the risk of psoriasis (PS). They also found that variations in one genetic region link psoriasis and psoriatic arthritis (PSA) to other autoimmune disorders.
The study “revealed that the MHC (multiple histocompatibility locus antigen cluster) is truly the most important risk factor for PS and that it plays a very major role in PSA, confirmed recently identified associations with interleukin 23 receptor and interleukin 12B in both PS and PSA, and identified new associations,” wrote the researchers.
The new associations “include a region on chromosome 4q27 that contains genes for interleukin 2 and interleukin 21 that has been recently implicated in other autoimmune diseases and seven additional regions that include chromosome 13q13 and 15q21.”
Using whole-genome association, the investigators scanned more than 300,000 SNPs in the genomes of 223 psoriasis patients including 91 who had psoriatic arthritis. They compared the DNA variations in people with psoriasis to those found in 519 healthy control patients. They then replicated their findings in a larger set of patients—577 with psoriasis and 576 with psoriatic arthritis—and more than 1,200 healthy controls.
The scientists involved in the study were from Washington University School of Medicine, University of California San Francisco, The Rockefeller University, Texas Scottish Rite Hospital for Children, University of Manchester, and Baylor University Medical Center. The results are published in the April 4 issue of PLoS Genetics.