IFNG and psoriasis: This revealed that many cytokines previously associated with the psoriasis gene expression profile (e.g., TNF, IFN-a, IFN-g and IL-1 family) [6, 8, 22, 74] are primarily inducing a gene expression response that is not specific to psoriasis, but is instead associated with a broad spectrum of skin diseases (Figs. 6 and 8).