CD4+ T cells differentiate into TH1, TH2, and TH17 cells in response to the specific cytokine milieu present in the microenvironment of inflammation and mediate immune inflammatory responses in respective settings.1, 2, 3, 4 Among these TH subsets, TH17 cells mediate inflammatory responses in patients with many autoimmune diseases, including multiple sclerosis; inflammatory bowel diseases, such as Crohn disease; psoriasis; and rheumatoid arthritis. The gene discussed is CD4; the disease is psoriasis.