[Clinical phenotypes and prognosis of antisynthetase syndrome]

Antisynthetase syndrome (ASS) was first described in 1989 as an inflammatory myopathy associated with the presence of specific auto-antibodies, namely the anti-tRNA-synthetase antibodies (ASA). To date, the ASA family comprises eight different auto-antibodies, among which anti-hystidyl-tRNA-synthetase (anti-Jo1) is the most prevalent. In addition to myositis, a constellation of clinical features has also been described in ASS, including interstitial lung disease, Raynaud's phenomenon, polyarthritis, fever and mechanic's hands. Large variations in the distribution and the severity of each of these symptoms are reported from one patient to another, and also over the course of the disease. The heterogeneity of this autoimmune connective tissue disease has led to difficulties in the early identification of patients with a poor outcome (those who will require the most intensive treatments). Additionally, very few prospective trials have so far compared the efficacy of the different immunosuppressive drugs available, and evidence is lacking to help adapting therapeutic strategies to all of the different ASS clinical situations. We will review the different characteristics of ASS (namely biological, clinical, functional, and morphological ASS parameters) that have recently been shown to correlate with patients' outcome, our aim being to discuss the usefulness of patient stratification for elaborating targeted therapeutic trials for ASS in the future.