The term “anti-synthetase syndrome” refers to a group of conditions characterized by the presence of autoantibodies against aminoacyl-tRNA synthetases, which are enzymes involved in protein synthesis. These autoantibodies are associated with a distinct clinical phenotype, typically including myositis (muscle inflammation), interstitial lung disease, non-erosive arthritis, Raynaud’s phenomenon, and certain skin manifestations such as “mechanic’s hands.”
There are several different anti-synthetase antibodies, each one targeting a specific aminoacyl-tRNA synthetase enzyme. Anti-Jo-1 is the most common and best-characterized anti-synthetase antibody.
Diseases/conditions associated with positive anti-synthetase antibodies include:
- Polymyositis: An inflammatory muscle disease.
- Dermatomyositis: A condition characterized by skin rash and muscle inflammation.
- Interstitial Lung Disease: Especially nonspecific interstitial pneumonia and usual interstitial pneumonia.
- Overlap Syndromes: These are conditions where features of multiple connective tissue diseases coexist, and patients might have features of both myositis and another rheumatic condition.
It’s important to recognize that while the presence of anti-synthetase antibodies can support a diagnosis of one of these conditions, clinical evaluation, and other diagnostic tests are crucial. The presence of these antibodies can also have prognostic implications, particularly regarding the risk of interstitial lung disease.