Table 1.

Associations of the Myositis-specific and Myositis-associated Autoantibodies.

Autoantibody	Associations and Comments
Myositis-Specific Autoantibody
Anti-synthetase	Acute onset of polymyositis (PM), dermatomyositis (DM) or overlap myositis in the spring with high frequency of symmetric non-erosive arthritis, interstitial lung disease, fever, mechanic's hands, Raynaud's phenomenon; moderate response to therapy, myositis flare with tapering of therapy; seen in 20–25% of adult and 5–10% of juvenile myositis cases; immunogenetic association with HLA A*01, B*08, Cw*0701, DRB1*0301, DQA1*0501(9;15).
Anti-signal recognition particle (SRP)	Very acute onset of severe PM with frequent myalgias, severe weakness and very high creatine kinase levels; some adults more frequently have cardiac involvement and palpitations, and are African American females; poor response to therapy; seen in <5% of adult and juvenile myositis patients (9;13).
Anti-Mi-2	Classic DM; mild to moderate weakness with V and shawl sign rashes, and cuticular overgrowth associated in adults; good response to therapy; seen in 5–10% of adult and 5% of juvenile myositis patients; immunogenetic association with HLA DRB1*0701, DQA1*0201(9;15).
Myositis-Associated Autoantibodies
Anti-p155	A newly identified autoantibody present in 20–30% of adult and juvenile DM patients, including those with DM associated with another connective tissue disease and cancer-associated DM Clinically distinct from patients with anti-synthetase antibodies, but high frequency of V-sign rash and cuticular overgrowth may not make this distinct from other patients with DM; immunogenetic association with HLA DQA1*0301 (12).
Anti-PM-Scl	Scleroderma/myositis overlap syndromes, mild myositis, high incidence of arthritis, Raynaud's, interstitial lung disease, calcinosis, sicca; associated with HLA A*0101, B*08, DRB1*0301, DQA1*0501 (15).
Anti-Ku	Scleroderma/myositis overlap syndromes, frequent Raynaud's, arthralgias, and reflux
Anti-Ro	Seen in 12% of adult idiopathic inflammatory myopathies (IIM) overall, but 17% of subjects with myositis overlap syndromes; associated with anti-Jo-1 antibodies; immunogenetic association is B*0801, Cw*0701, DRB1*0301, DQA1*0501(9;15).
Anti-La	Seen 8% of adult IIM, but 19% of subjects with myositis overlap syndromes; immunogenetic association is B*0801, Cw*0701, DRB1*0301 (9;15).
Anti-U1RNP	Myositis overlap syndromes
Anti-U2RNP	Scleroderma/myositis overlap syndromes
Anti-U3RNP	Myositis overlap syndromes
None of the above	A heterogeneous group of patients requiring further study and classification (myositis-specific and myositis-associated antibody negative)