In the past decade, Th1 cytokines such as interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) were considered to play a major role in this disease [10], but recent evidence points toward a central role of IL-23 and IL-17A in the physiopathogenesis of psoriasis [11–13]. Here, IL17A is linked to psoriasis.