Th17 has been shown to play an important role in many inflammatory and autoimmune diseases, especially atopic dermatitis, psoriasis, Behçet’s disease, and systemic lupus erythematosus.31 In recent studies, IL-17 and IL-23 produced by Th17 are shown to contribute to the pathogenesis of IBD. The gene discussed is IL17A; the disease is psoriasis.