The Antisynthetase Syndrome

The antisynthetase syndrome (ASS) was first described by Marguerie and coworkers in 1990 as a triad of polymyositis, diffuse interstitial lung disease (ILD) and serum autoantibodies to aminoacyl transfer RNA synthetases (anti-ARS) (1). Later, cohort studies have indicated that 20-25 % of patients diagnosed with polymyositis (PM) or dermatomyositis (DM) have antiARS antibodies (2-4). In most cases, these anti-ARS+ PM/DM patients also have ILD. The ILD is, in fact, the major determinant of morbidity and mortality in the ASS. The most common of the anti-ARS, anti-Jo-1, was first described in 1980. Three years later, the Jo-1 antigen was identified as histidyl-tRNA synthetase (5;6). In recent case series, the anti-Jo-1 antibody accounts for 68-87% of the anti-ARS observed in ASS (7-9). The seven other anti-ARS identified (Table 1) are all rare, but their relative frequencies have not been extensively studied (7;8). With very few exceptions, each patient has only one anti-ARS antibody (10). More than half of the anti-ARS+ patients also possess anti-SSA autoantibodies (8;9;11) and then most frequently anti-Ro52 (11).