A collection of conditions in which the body's immune system (see IMMUNITY) attacks its own tissues, identifying them as foreign substances. Genetic factors may play a part in this abnormal function, but the causes are not clear. The disorder may affect one organ (organ-specific) or type of cell, or several (non-organ-specific). Among the autoimmune disorders are ADDISON'S DISEASE; autoimmune haemolytic anaemia and pernicious anaemia (see under ANAEMIA); autoimmune chronic active HEPATITIS; DIABETES MELLITUS; MYASTHENIA GRAVIS; RHEUMATOID ARTHRITIS; and SYSTEMIC LUPUS ERYTHEMATOSUS (SLE).