Antisynthetase Syndrome

Antisynthetase syndrome is a systemic autoimmune rheumatic disease associated with autoantibodies to aminoacyl-transfer RNA synthetases. Anti-Jo-1 targets histidyl-transfer RNA synthetase; other recognized antisynthetase antibodies include PL-7, PL-12, EJ, OJ, and KS. Antibody assays vary in availability and performance, so a laboratory result must be interpreted with the clinical phenotype rather than used alone. The hallmark pattern spans inflammatory myositis, interstitial lung disease (ILD), inflammatory arthritis, mechanic's hands, Raynaud phenomenon, and otherwise unexplained fever. Mechanic's hands are rough, hyperkeratotic, fissured areas along the fingers. The CLASS cohort found that joint, muscle, lung, skin, and cardiac involvement were more prevalent in antisynthetase syndrome than in control diseases, while arthritis, muscle weakness or enzyme elevation, ILD, mechanic's hands, Raynaud phenomenon, and unexplained fever contributed useful clinical information. The muscle, joint, and lung manifestations need not begin together. A person may initially present with arthritis or respiratory symptoms and develop weakness later. ILD may dominate the presentation even when clinically apparent myositis is limited. This variation is why normal muscle enzymes do not exclude important pulmonary disease and why respiratory assessment cannot be replaced...