These cytokines cause changes in epidermal cells, including hyperproliferation, dysregulated maturation, and epidermal production of cytokines, chemokines, and antimicrobial peptides, which are critical for protection against extracellular bacterial and fungal infection.2, 3 However, the IL-23/IL-17 axis can also drive psoriasis, a common, incurable chronic inflammatory skin disease, as demonstrated by the efficacy of biologics targeting this pathway.4 The gene discussed is IL17A; the disease is psoriasis.