IL17A and psoriasis vulgaris: The genes whose polymorphisms confer susceptibility to plaque psoriasis are related to antigen presentation (ERAP1 and MHC), interferon signaling pathway (IL-28RA and IFIH1), NFkB pathway (ZNF313, REL, TNIP1, TNFAIP3, NFkB1A),15 of IL-17 (TRAF3IP2), of IL-23 (TYK2, IL-23R, IL-23A, IL-12B) and to the epidermal barrier (LCE3D).16