Condition or diseases caused by an over active immune system attacking the body's own tissues and organs. Prominent examples include celiac disease, diabetes mellitus type 1, systemic lupus erythematosus, Sjögrens syndrome, multiple sclerosis (MS), Hashimoto's thyroiditis, Graves' disease, idiopathic thrombocytopenic purpura, and rheumatoid arthritis (RA). Many different organs can be damaged depending on the specific disease.