Antisynthetase Syndrome

Antisynthetase syndrome is a systemic autoimmune disorder defined by autoantibodies against an aminoacyl-transfer RNA synthetase enzyme. These enzymes normally attach amino acids to transfer RNA during protein synthesis. Anti-Jo-1, directed against histidyl-tRNA synthetase, is the most frequently identified antibody; other antibodies include anti-PL-7, PL-12, EJ, OJ, and KS. The syndrome is recognised by a pattern rather than by one isolated symptom: inflammatory myositis, interstitial lung disease (ILD), non-erosive inflammatory arthritis, Raynaud phenomenon, unexplained fever, and mechanic's hands. Mechanic's hands are rough, hyperkeratotic, fissured areas over the radial and palmar surfaces of the fingers. They are particularly informative when they occur with ILD, inflammatory arthritis, or proximal weakness. The three most clinically useful domains are muscle, joints, and lungs. They do not always appear together or at the same time. A person may first present with inflammatory arthritis or breathlessness and develop weakness later. In some patients, ILD remains the dominant manifestation, and creatine kinase may be normal because the lung disease is active while clinically apparent muscle injury is minimal. The proposed mechanism helps explain this uneven presentation. Immune recognition...