When the Th1/Th2 paradigm dominated the understanding of the pathogenesis of autoimmune diseases, RA was defined as a Th1-driven disease because CD4+ T cells identified to be enriched in synovial fluids from RA patients were prone to secrete IFN-γ but not IL-4 (93, 94). The gene discussed is CD4; the disease is rheumatoid arthritis.