Antisynthetase Syndrome RN

Antisynthetase syndrome is an autoimmune inflammatory myopathy defined by an autoantibody against an aminoacyl-tRNA synthetase. These enzymes attach each amino acid to its transfer RNA (tRNA) during protein synthesis. Autoantibodies against eight of these enzymes have been linked to the syndrome. Anti-Jo-1 (against histidyl-tRNA synthetase) is the most common, found in roughly 30-60% of patients depending on the group studied. The others are anti-PL-7, anti-PL-12, anti-EJ, anti-OJ, anti-KS, anti-Zo and anti-Ha. Core features: myositis (muscle inflammation), interstitial lung disease (ILD), inflammatory arthritis, Raynaud phenomenon, mechanic's hands and fever. A patient does not need every feature at once, and ILD can come first, before any muscle, joint or skin signs. Pathophysiology (the leading model, not yet proven): in a genetically susceptible person, inhaled environmental antigens injure the lung lining. The immune system then targets the synthetase enzymes, producing autoantibodies and inflammation in the lungs, skeletal muscle, joints and skin. In the lungs, ongoing inflammation can progress to fibrosis (scarring), which reduces gas exchange. Epidemiology: women are affected more than twice as often as men (greater than 2:1). Mean age at onset...