Autoimmune polyendocrine syndrome

In medicine, autoimmune polyendocrine syndromes are a heterogeneous group^[1] of rare diseases characterised by autoimmune activity against more than one endocrine organs, although non-endocrine organs can be affected.

There are three "autoimmune polyendocrine syndromes", and a number of other diseases which have endocrine autoimmunity as one of their features.

The syndromes

• Autoimmune polyendocrine syndrome type 1 (APECED or Whitaker's syndrome)
• Autoimmune polyendocrine syndrome type 2 (Schmidt's syndrome)
• The most serious but rarest form is the X-linked polyendocrinopathy, immunodeficiency and diarrhea-syndrome, also called XLAAD (X-linked autoimmunity and allergic dysregulation) or IPEX (immune dysfunction, polyendocrinopathy, and enteropathy, X-linked). This is due to mutation of the FOXP3 gene on the X chromosome.^[2] Most patients develop diabetes and diarrhea as neonates and many die due to autoimmune activity against many organs. Boys are affected, while girls are carriers and might suffer mild disease.

Other diseases

Other diseases featuring polyendocrine autoimmunity:

• Chromosomal abnormalities (Down's syndrome) increase the risk of endocrine autoimmunity
• POEMS syndrome - the E is for endocrinopathy; the cause is a paraprotein excreted by a plasmacytoma or multiple myeloma; other features are polyneuropathy, organomegaly (hepatomegaly and splenomegaly), M-protein (paraprotein) and skin changes.
• Several^[which?] very rare diseases.

Management

In principle, the component diseases are managed as usual. The challenge is to detect the possibility of any of the above syndromes, and to anticipate other manifestations. For example, in a patient with known Type 2 autoimmune polyendocrine syndrome but no features of Addison's disease, regular screening for antibodies against 21-hydroxylase (a feature of Addison's) may prompt early intervention and hydrocortisone replacement to prevent characteristic crises.

References