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Reviewed November 2008
What is abetalipoproteinemia?
Abetalipoproteinemia is an inherited disorder that affects the absorption of dietary fats, cholesterol, and fat-soluble vitamins. People affected by this disorder are not able to make certain lipoproteins, which are particles that carry fats and fat-like substances (such as cholesterol) in the blood. Specifically, people with abetalipoproteinemia are missing a group of lipoproteins called beta-lipoproteins. An inability to make beta-lipoproteins causes severely reduced absorption (malabsorption) of dietary fats and fat-soluble vitamins (vitamins A, D, E, and K) from the digestive tract into the bloodstream. Sufficient levels of fats, cholesterol, and vitamins are necessary for normal growth, development, and maintenance of the body's cells and tissues, particularly nerve cells and tissues in the eye.
The signs and symptoms of abetalipoproteinemia appear in the first few months of life. They can include failure to gain weight and grow at the expected rate (failure to thrive); diarrhea; abnormal star-shaped red blood cells (acanthocytosis); and fatty, foul-smelling stools (steatorrhea). Other features of this disorder may develop later in childhood and often impair the function of the nervous system. Disturbances in nerve function may cause affected people to eventually develop poor muscle coordination and difficulty with balance and movement (ataxia). Individuals with this condition may also develop an eye disorder called retinitis pigmentosa, in which progressive degeneration of the light-sensitive layer (retina) at the back of the eye can cause vision loss. Adults in their thirties or forties may have increasing difficulty with balance and walking. Many of the signs and symptoms of abetalipoproteinemia result from a severe vitamin deficiency, especially a deficiency of vitamin E.
How common is abetalipoproteinemia?
Abetalipoproteinemia is a rare disorder with approximately 100 cases described worldwide.
What genes are related to abetalipoproteinemia?
Mutations in the MTTP gene cause abetalipoproteinemia. The MTTP gene provides instructions for making a protein called microsomal triglyceride transfer protein, which is essential for creating beta-lipoproteins. These lipoproteins are necessary for the absorption of fats, cholesterol, and fat-soluble vitamins from the diet and the efficient transport of these substances in the bloodstream. Most of the mutations in the MTTP gene lead to the production of an abnormally short microsomal triglyceride transfer protein, which prevents the normal creation of beta-lipoproteins in the body. A lack of beta-lipoproteins causes the nutritional and neurological problems seen in people with abetalipoproteinemia.
Read more about the MTTP gene.
How do people inherit abetalipoproteinemia?
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 abetalipoproteinemia?
These resources address the diagnosis or management of abetalipoproteinemia 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 abetalipoproteinemia?
You may find the following resources about abetalipoproteinemia 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 abetalipoproteinemia?
What if I still have specific questions about abetalipoproteinemia?
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 abetalipoproteinemia?
apolipoprotein ; ataxia ; autosomal ; autosomal recessive ; beta-lipoproteins ; cell ; cholesterol ; congenital ; deficiency ; digestive ; failure to thrive ; gene ; hypolipoproteinemia ; malabsorption ; nervous system ; neurological ; neuropathy ; protein ; recessive ; retina ; soluble ; steatorrhea ; syndrome ; vitamins
You may find definitions for these and many other terms in the Genetics Home Reference Glossary.
See also Understanding Medical Terminology.
References (5 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.