Taking into consideration that different autoimmune diseases may share some common pathogenetic pathways, we hypothesized that STAT4, a susceptibility gene found to be associated with increased risk for systemic lupus erythematosus, rheumatoid arthritis, type 1 diabetes, Sjögren's syndrome, Wegener's granulomatosis, Crohn's disease, and ulcerative colitis may also have a role in psoriasis.
STAT4, a transcription factor transmitting signals induced by several key cytokines, has recently been identified as a genetic risk factor for rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and Sjögren's disease (SD), thus indicating that multiple autoimmune diseases may share common biochemical pathways that lead to immune deregulation.