The RARS1 antibody targets arginyl-tRNA synthetase (RARS1), a cytoplasmic enzyme critical for protein synthesis. As a member of the aminoacyl-tRNA synthetase (ARS) family, RARS1 catalyzes the attachment of arginine to its cognate tRNA, ensuring translational accuracy. Autoantibodies against RARS1 are primarily studied in the context of autoimmune disorders, particularly idiopathic inflammatory myopathies (IIM) like dermatomyositis (DM) and polymyositis (PM). These autoantibodies are part of the anti-synthetase syndrome (ASS), a clinical subset characterized by myositis, interstitial lung disease (ILD), arthritis, and mechanic's hands. Among anti-ARS autoantibodies, anti-RARS1 (anti-Ro52 or anti-Jo-1 variants) are less common than others but hold diagnostic and prognostic significance. Their presence often correlates with severe ILD and aggressive disease progression. Detection methods include ELISA, immunoprecipitation, or line immunoassays. Research also explores RARS1's role beyond autoimmunity, such as in cancer, where overexpression may influence tumorigenesis. However, its immunogenic mechanisms—whether via molecular mimicry, aberrant enzyme exposure, or dysregulated immune tolerance—remain under investigation. Clinically, RARS1 antibodies aid in stratifying patients for tailored therapies, while ongoing studies aim to unravel their pathogenic contributions or potential as therapeutic targets.