Autoimmune polyendocrine syndrome (APS) is a group of rare diseases characterized by autoimmune activity against more than one endocrine organ, although non-endocrine organs can also be affected. There are different types of APS, including APS-1 and APS-2, which have Addison's disease as a prominent component. APS can occur in patients from early infancy to old age, and new components of a given syndrome can appear throughout life. APS has a strong genetic component, with the type 2 syndrome occurring in multiple generations and the type 1 syndrome in siblings1. The syndromes are insidious and are characterized by circulating autoantibodies and lymphocytic infiltration of the affected tissues or organs, eventually leading to organ failure.

Reference

New England Journal of Medicine