From the UK adult myositis cohort, 51 (5%) patients were anti-TIF1γ autoantibody positive, 88% White, 84% DM, 80% female, and median (IQR) age at onset 49.3 (37.5–62.7) years (Supplementary Table S1A, available at Rheumatology online). This evidence concerns the gene TRIM33 and dermatomyositis.