The right answer is autoimmune disease.
Autoimmune diseases are the result of a reversal of the immune system of an individual against some of its own cells, even against all of one or more organs. Little known by this scholarly name, autoimmune diseases represent the third cause of morbidity in developed countries (after cardiovascular diseases and cancers); we will be less surprised when we learn that among them are widespread diseases such as type 1 diabetes, rheumatoid arthritis or multiple sclerosis.