IFNA1 and polymyositis: Most patients with SLE (or related diseases) have elevated levels of type I IFNs (3, 4, 109), which is best detected as the high expression of IFN-stimulated genes (ISGs), now referred to as the “IFN signature” and seen in 70-90% of SLE patient populations world-wide (5, 110–113), as well as in patients with pSS (10, 113), systemic sclerosis (114, 115), polymyositis (PM) and DM (7, 116), and in a small subset of rheumatoid arthritis (RA) (117, 118).