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Triple A syndrome
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Reviewed February 2010
What is triple A syndrome?
Triple A syndrome is an inherited condition characterized by three specific features: achalasia, Addison disease, and alacrima. Achalasia is a disorder that affects the ability to move food through the esophagus, the tube that carries food from the throat to the stomach. It can lead to severe feeding difficulties and low blood sugar (hypoglycemia). Addison disease, also known as primary adrenal insufficiency, is caused by abnormal function of the small hormone-producing glands on top of each kidney (adrenal glands). The main features of Addison disease include fatigue, loss of appetite, weight loss, low blood pressure, and darkening of the skin. The third major feature of triple A syndrome is a reduced or absent ability to secrete tears (alacrima). Most people with triple A syndrome have all three of these features, although some have only two.
Many of the features of triple A syndrome are caused by dysfunction of the autonomic nervous system. This part of the nervous system controls involuntary body processes such as digestion, blood pressure, and body temperature. People with triple A syndrome often experience abnormal sweating, difficulty regulating blood pressure, unequal pupil size (anisocoria), and other signs and symptoms of autonomic nervous system dysfunction (dysautonomia).
People with this condition may have other neurological abnormalities, such as developmental delay, intellectual disability, speech problems (dysarthria), and a small head size (microcephaly). In addition, affected individuals commonly experience muscle weakness, movement problems, and nerve abnormalities in their extremities (peripheral neuropathy). Some develop optic atrophy, which is the degeneration (atrophy) of the nerves that carry information from the eyes to the brain. Many of the neurological symptoms of triple A syndrome worsen over time.
People with triple A syndrome frequently develop a thickening of the outer layer of skin (hyperkeratosis) on the palms of their hands and the soles of their feet. Other skin abnormalities may also be present in people with this condition.
Alacrima is usually the first noticeable sign of triple A syndrome, as it becomes apparent early in life that affected children produce little or no tears while crying. They develop Addison disease and achalasia during childhood or adolescence, and most of the neurologic features of triple A syndrome begin during adulthood. The signs and symptoms of this condition vary among affected individuals, even among members of the same family.
How common is triple A syndrome?
Triple A syndrome is a rare condition, although its exact prevalence is unknown.
What genes are related to triple A syndrome?
Mutations in the AAAS gene cause triple A syndrome. This gene provides instructions for making a protein called ALADIN whose function is not well understood. Within cells, ALADIN is found in the nuclear envelope, the structure that surrounds the nucleus and separates it from the rest of the cell. Based on its location, ALADIN is thought to be involved in the movement of molecules into and out of the nucleus.
Mutations in the AAAS gene change the structure of ALADIN in different ways; however, almost all mutations prevent this protein from reaching its proper location in the nuclear envelope. The absence of ALADIN in the nuclear envelope likely disrupts the movement of molecules across this membrane. Researchers suspect that DNA repair proteins may be unable to enter the nucleus if ALADIN is missing from the nuclear envelope. DNA damage that is not repaired can cause the cell to become unstable and lead to cell death. Although the nervous system is particularly vulnerable to DNA damage, it remains unknown exactly how mutations in the AAAS gene lead to the signs and symptoms of triple A syndrome.
Some individuals with triple A syndrome do not have an identified mutation in the AAAS gene. The genetic cause of the disorder is unknown in these individuals.
Read more about the AAAS gene.
How do people inherit triple A syndrome?
This condition is inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene, but they typically do not show signs and symptoms of the condition.
Where can I find information about diagnosis or management of triple A syndrome?
These resources address the diagnosis or management of triple A syndrome and may include treatment providers.
General information about the diagnosis and management of genetic conditions is available in the Handbook. Read more about genetic testing, particularly the difference between clinical tests and research tests.
To locate a healthcare provider, see How can I find a genetics professional in my area? in the Handbook.
Where can I find additional information about triple A syndrome?
You may find the following resources about triple A syndrome helpful. These materials are written for the general public.
You may also be interested in these resources, which are designed for healthcare professionals and researchers.
What other names do people use for triple A syndrome?
What if I still have specific questions about triple A syndrome?
Where can I find general information about genetic conditions?
The Handbook provides basic information about genetics in clear language.
These links provide additional genetics resources that may be useful.
What glossary definitions help with understanding triple A syndrome?
adrenal glands ; atrophy ; autonomic nervous system ; autosomal ; autosomal recessive ; cell ; developmental delay ; digestion ; DNA ; DNA damage ; DNA repair ; dysarthria ; esophagus ; gene ; hormone ; hypoglycemia ; involuntary ; kidney ; microcephaly ; mutation ; nervous system ; neurologic ; neurological ; neuropathy ; nuclear envelope ; nucleus ; optic atrophy ; peripheral ; peripheral neuropathy ; prevalence ; protein ; pupil ; recessive ; sign ; stomach ; syndrome
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (8 links)
The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.