Triple-A syndrome

Triple A syndrome
Classification and external resources
MRI of the brain of 12 year-old boy with triple-A syndrome showing hypoplastic lacrimal glands (yellow arrows.)
ICD-10	E27.4
OMIM	231550
DiseasesDB	32088
eMedicine	ped/71

Triple-A syndrome (AAA), also known as Achalasia-Addisonianism-Alacrimia syndrome or Allgrove syndrome,^[1] is a rare autosomal recessive congenital disorder. In most cases, there is no family history of it.^[2] The syndrome was discovered by Jeremy Allgrove and colleagues in 1978. Triple A stands for achalasia-addisonianism-alacrimasyndrome. Alacrima is usually the earliest manifestation.^[3] It is a progressive disorder that can take years to develop the full blown clinical picture.^[4]

Characteristics

Individuals affected by AAA have adrenal insufficiency/Addison's disease due to ACTH resistance, alacrima (absence of tear secretion), and achalasia (a failure of a ring of muscle fibers, such as a sphincter, to relax) of the lower esophageal sphincter at the cardia which delays food going to the stomach and causes dilation of the thoracic esophagus. There may also be signs of autonomic dysfunction with AAA, such as pupillary abnormalities, an abnormal reaction to intradermal histamine, abnormal sweating, orthostatic hypotension, and disturbances of the heart rate.^[5] Hypoglycemia (low blood sugar) is often mentioned as an early sign.^[4] The disorder has also been associated with mild mental retardation.^[4]

The syndrome is highly variable. Managed effectively, affected individuals can have a normal lifespan and bear children.

Cause and genetics

Triple-A syndrome is associated with mutations in the AAAS gene, which encodes a protein known as ALADIN (ALacrima Achalasia aDrenal Insuffiency Neurologic disorder).^[6][7] In 2000, Huebner et al. mapped the syndrome to a 6 cM interval on human chromosome 12q13 near the type II keratin gene cluster.^[8] Since inheritance and gene for the association is known, early diagnosis can allow genetic counseling.^[3]