STAT4 and autoimmune disease: Non-MHC genes such as tumor necrosis factor alpha (TNF-α) [3–6], interleukin (IL)-1α, IL-1β [5], interferon (IFN)-γ [7], interferon-induced helicase (IFIH1) [8], mannose-binding lectin 2 (MBL2) [9], protein tyrosine phosphatase N22 (PTPN22) [10], and signal transducer and activator of transcription 4 (STAT4) [11] confer susceptibility to PM/DM, which indicated that PM/DM shared genetic susceptibility with other autoimmune diseases.