While the disease was initially considered an epidermal disorder in which various mediators like cyclic adenosine monophosphate, protein kinase C, phospholipase C, eicosanoids, transforming growth factor (TGF)-α had a central role [6,7], in later years the role of T-cells was recognized and interferon (IFN)-γ and interleukin (IL)-12 were considered key players in the pathogenesis of psoriasis [12]. This evidence concerns the gene IFNG and psoriasis.