The detection of antibodies in the serum of individuals in whom a diagnosis of autoimmune disease is suspected confers great diagnostic assistance in many conditions—examples include the detection of ANA in systemic lupus erythematosus (SLE), anti-cyclic citrullinated peptide (anti-CCP) in rheumatoid arthritis, and tissue transglutaminase (tTG) antibodies in coeliac. Here, TGM2 is linked to autoimmune disease.