In line with the key role of IL-17A, the main gene variants associated with psoriasis outside the MHC locus are single nucleotide polymorphisms, belonging to the IL-23/IL-17A axis (IL23R, IL12B, and IL23A) and the NF-κB pathway (TNFAIP3) (44, 59). The gene discussed is IL23A; the disease is psoriasis.