TNF‐α, IL‐1β, IL‐23, IL‐17, IL‐22, Cox2, and iNOS are all inflammatory cytokines involved in the pathogenesis of psoriasis,32, 33 and CXCL1, CXCL8, and CCL20 are antimicrobial peptides and chemokines produced by keratinocytes.34 This evidence concerns the gene CCL20 and psoriasis.