TRIM21 and idiopathic inflammatory myopathy: Autoantibodies directed against Ro/SSA and La/SSB autoantigens were originally identified in patients with Sjögren syndrome and systemic lupus erythematosus (SLE).[19] Subsequent studies showed that anti-Ro/SSA antibodies may be present in patients with other autoimmune diseases, including systemic sclerosis, idiopathic inflammatory myopathies, primary biliary cholangitis, and rheumatoid arthritis.