Although autoantibodies against CN1A are known to be a biomarker for sporadic inclusion body myositis (IBM) and are widely detected in other autoimmune diseases (e.g. Sjögren’s syndrome, or systemic lupus erythematosus), none of the CN1A/GAD65 antibody-positive patients presented such syndrome. The gene discussed is GAD2; the disease is systemic lupus erythematosus.