Baseline substudy serum samples from patients with psoriasis (n = 118) contained significantly (all P < .01) higher concentrations of IL-17A, IL-17F, IL-22, IL-8, CCL22/macrophage-derived chemokine (MDC), and CCL4/MIP-1β than an independent, healthy control serum cohort (n = 25) (Figure 1 and Table 2). This evidence concerns the gene IL17A and psoriasis.