Single-stranded DNA (ssDNA) autoantibodies are found in 80-90% of SLE patients during the administration of certain drugs (e.g., procainamide or quinidine) and other autoimmune diseases including rheumatoid arthritis, scleroderma, linear localized scleroderma, polymyositis- polymyositis-dermatomyositis, Sjogren syndrome, mixed connective tissue disease (MCTD) and overlap syndromes, myasthenia gravis, chronic active hepatitis, infectious mononucleosis, chronic glomerulonephritis, and biliary cirrhosis.