Both RA and SLE show an association between disease risk and genes that are involved in type I interferon production, signaling, and response, such as IRF5, Interleukin 1 receptor associated kinase 1 (IRAK1), and Signal transducer and activator of promoter 4 (STAT4) (9, 14). Here, STAT4 is linked to systemic lupus erythematosus.