IL17A and psoriasis: In addition to known psoriasis susceptibility loci encoding proteins engaged in the TNF-alpha, IL-23, and IL-17 signaling pathways (including HLA-Cw6, IL23R, IL12B, IL23A, and TNFAIP3 genes), IL6 and STAT3 polymorphisms have been linked with hereditary predisposition of developing psoriasis and response to TNF-alpha inhibitors [33, 86–89].