Autoantibodies in idiopathic inflammatory myopathies (IIM)22,102,103,104,105,106.
| Antibody | Frequency in IIM, % | Clinical Significance and Associations |
|---|---|---|
| Myositis-specific autoantibodies | ||
| Anti-Jo-1 (histidyl-tRNA synthetase) | 15–20 | Antisynthetase syndrome, including juvenile antisynthetase syndrome; sometimes clinically amyopathic |
| Anti-PL-7 (threonyl-) | 5–10 | |
| Anti-PL-12 (alanyl-) | < 5 | |
| Anti-EJ (glycyl-) | 5–10 | |
| Anti-OJ (isoleucyl-) | < 5 | |
| Anti-KS (asparaginyl-) | < 5 | |
| Anti-Zo (phenylalanyl-) | < 1 | |
| Anti-Ha-YRS (tyrosyl-) | < 1 | |
| Anti-SRP | 5–10 | Immune-mediated necrotizing myopathy (generally severe and rapidly evolving with frequent myocardial involvement); rarely in children |
| Anti-200/100 (HMGCR) | 40% of necrotizing myopathy107 | Immune-mediated necrotizing myopathy, frequently associated with prior statin use |
| Anti-Mi-2 | 5–30 | Classical DM, often of sudden onset with erythroderma and shawl sign, generally without ILD or malignancy and good prognosis; occasional juvenile DM |
| Anti-CADM-140 (MDA5) | 50% of CADM | DM, sometimes juvenile, with mild or absent muscle inflammation (CADM) and increased risk of ILD that can be rapidly progressive |
| Anti-SAE | 5% | Adult DM |
| Anti-p155(/p140) (TIF1-α/β/γ) | 15–25% of adult DM, 40–75% of cancer-associated DM, 30% of juvenile DM | DM, especially cancer-associated (Ca in 45–75% of positive anti-TIF1-α/β/γ patients). Common in juvenile DM (without malignancy); rare in PM |
| Anti-MJ (NXP-2) | < 5; 25% of juvenile DM | Juvenile DM exclusively; frequently severe cases with calcinosis |
| Anti-PMS1 | 7.5 | Rare DM and PM |
| Myositis-associated autoantibodies | ||
| Anti-U1RNP | 10 | OM, MCTD |
| Anti-Ku | 20–30 | PM-SSc overlap (Japanese) |
| Anti-PM-Scl | 8–10 | PM-SSc overlap (whites) |
| Sporadic inclusion body myositis (s-IBM)-associated autoantibodies | ||
| Anti-43-kDa muscle autoantigen | 50% of s-IBM22 (needs further confirmation) | s-IBM |
CADM: clinically amyopathic dermatomyositis; MCTD: mixed connective tissue disease; HMGCR: 3-hydroxy-3-methylglutaryl-coenzyme A reductase; ILD: interstitial lung disease; MDA5: melanoma-differentiation-associated gene 5; OM: overlap myositis; NXP-2: nuclear matrix protein 2; SAE: small ubiquitin-like modifier activating enzyme; SRP: signal recognition particle; SSc: systemic sclerosis; TIF1-α/β/γ: transcriptional intermediary factors 1-α, β, and/or γ.