RNPC3 and myositis disease: ANA: antinuclear antibodies, MI-2: myositis-specific autoantibody, RNP: ribonucleoprotein, SS-A: anti–Sjögren's syndrome-related antigen A autoantibodies, SS-B: anti–Sjögren's syndrome-related antigen B autoantibodies, Ro-52: associated with systemic lupus erythematosus and Sjögren's syndrome, anti Scl-70: anti-topoisomerase I in scleroderma, dsDNA: double-stranded DNA, anti-Jo-1: anti-histidyl-tRNA synthetase, AMA-M2: anti-mitochondrial M2 antibody, DFS-70: anti-dense fine speckled 70, Ku: rare autoantibody seen in scleroderma-polymyositis overlap syndrome, Sm: anti-Smith antibody