Autoimmune diseases are caused by the body's loss of tolerance to self-antigens, and the immune system attacks its own tissues or cells, causing tissue, organ or cell damage and a series of clinical manifestations. AID can affect virtually all organs and systems in the body. Diagnosis of AID requires a variety of clinical and laboratory evidence. Some AID-associated autoantibodies appear earlier than clinical manifestations, such as those associated with systemic lupus erythematosus, rheumatoid arthritis, antiphospholipid syndrome, and type 1 diabetes, which may exist for many years before clinical diagnosis.