TNF and psoriasis: Recently, a genome wide association study of psoriasis cases revealed susceptibility loci with confirmed association to the disease, including human leukocyte antigen (HLA)-C, three genes involved in IL-23 signaling (IL23A, IL23R, IL12B), two genes acting downstream of tumor necrosis factor-alpha (TNFα) and regulating nuclear factor-kappa B (NF-κB) signaling (TNIP1, TNFAIP3), and two genes involved in the modulation of T helper 2 (Th2) immune responses (IL4, IL13) [1].