We evaluated possible associations between genetic factors and PP predisposition by genotyping IBD and psoriatic patients for 6 SNPs, including HLA-Cw0602 rs10484554, IL23R rs11209026, and rs10789229, TNF-α rs1799964, and rs1800629 and IFIH1 rs1990760, selected for their possible role in PP [23,32,34,35,36,37,52]. This evidence concerns the gene TNF and inflammatory bowel disease.