MORC3 and myositis disease: Myositis‐specific autoantibodies (MSAs) have been identified in both adult‐onset DM and juvenile DM, and include anti–Mi‐2, anti–melanoma differentiation–associated gene 5 (anti‐MDA5), anti–transcription intermediary factor 1γ (anti–TIF‐1γ, p155/140), and anti–nuclear matrix protein 2 (anti–NXP‐2, p140; also identified as the anti‐MJ autoantibody).