Anti-SSA autoantibodies (anti–Sjögrens-syndrome-related antigen A autoantibodies, also called anti-Ro, or similar names including anti-SSA/Ro, anti-Ro/SSA, anti–SS-A/Ro, and anti-Ro/SS-A) are a type of anti-nuclear autoantibodies that are associated with many autoimmune diseases, such as systemic lupus erythematosus (SLE), SS/SLE overlap syndrome, subacute cutaneous lupus erythematosus (SCLE), neonatal lupus and primary biliary cirrhosis. They are often present in Sjögrens syndrome (SS). Additionally, Anti-Ro/SSA can be found in other autoimmune diseases such as systemic sclerosis (SSc), polymyositis/dermatomyositis (PM/DM), rheumatoid arthritis (RA), and mixed connective tissue disease (MCTD), and are also associated with heart arrhythmia.
Anti-SSA/Ro autoantibodies are classified as extractable nuclear antigens. The Anti-SSA/Ro autoantibody targets Ro proteins, namely Ro52 and Ro60. Ro52 and Ro60 were originally thought to be one protein, however current findings show that they are two functionally distinct proteins encoded by genes on separate chromosomes. Anti-SSA/Ro autoantibodies are used in clinical settings as a diagnostic tool to identify patients with SLE and Sjögren's syndrome. In clinical tests for autoimmune disease, Anti-Ro antibodies are some of the most consistently and frequently detected among autoantibodies.
Anti-Ro autoantibodies are often found in conjunction with a similar antibody, Anti-La/SSB (also called anti–SS-B or anti–SS-B/La), in patients with SS. These two antibodies share pathological characteristics.