Laboratory tests showed a creatine phosphokinase (CPK) of 3539 U/L (reference range: 30-200 U/L), a positive antinuclear antibody with a cytoplasmic pattern of 1/320; myositis-specific autoantibodies (anti-Jo-1, anti-OJ, anti-EJ, anti-PL-7, anti-PL-12, anti-Mi-2, and anti-SRP) and myositis-associated autoantibodies (anti-PM/Scl75, anti-Ku, and anti-PM/Scl100) were negative, except for a positive anti-Ro52, according to a commercially available line blot test kit (Myositis Profile Euroline Blot test kit, Euroimmun, Lübeck, Germany). Here, TRIM21 is linked to myositis disease.