In summary, the literature on the genes involved in immune system that participate in the pathogenesis of psoriasis indicates that IL23R, IL10, TNFα, IL12B, GBP6, IL6, IL13, TNFAIP3, TNIP1, IL1RN, HLA-C, NF-κBIA, APOE, VDR, IFNγ, IL2, IL4, IL15, TNFRSF1B, MCP1, CTLA4, DEFB4, STAT4, IL18, IL19, IL20, IL20RA, ERAP1, IL1B, TRAF3IP2, IL28RA, TYK2, IFIH1, LCE, and ZNF313 play an important role in the development of this disease. The gene discussed is IL20; the disease is psoriasis.