MAAs occur in myositis but also in other autoimmune diseases. They help identify overlap syndromes and predict complications.
| Autoantibody | ||
| Associated Conditions | Features | Management |
| Anti‑PM/Scl | ||
| Polymyositis–scleroderma overlap | ILD, Raynaud, mechanic’s hands, calcinosis | Monitor lungs; overlap responds to immunosuppression |
| Anti Ku | ||
| Myositis + systemic sclerosis | ILD, arthritis, esophageal involvement | Treat both muscle and connective tissue disease |
| Anti U3 RNP (Fibrillarin) | ||
| Myositis + diffuse systemic sclerosis | Severe systemic involvement | Requires multi system monitoring |
| Anti Ro/SSA | ||
| Myositis, Sjögren’s, lupus | Often co occurs with antisynthetase antibodies | May increase ILD risk; monitor lungs |
| Anti U1 RNP | ||
| Mixed connective tissue disease (MCTD) | Raynaud, arthritis, mild myositis | Treat overlap features; generally good prognosis |
| Anti RNP70 | ||
| MCTD spectrum | Raynaud, arthritis, mild myositis | Overlap focused care |
| Anti La/SSB | ||
| Sjögren’s, lupus, overlap myositis | Sicca symptoms, mild myositis | Supportive care + immunosuppression as needed |
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