Alternative Names
Abetalipoproteinemia neuropathy; Apolipoprotein B deficiency; Bassen-Kornzweig Syndrome; Betalipoprotein Deficiency Disease; Congenital betalipoprotein deficiency syndrome; Familial hypobetalipoproteinemia; Microsomal Triglyceride Transfer Protein Deficiency Disease
Symptoms & Characteristics
Abetalipoproteinemia (also called Bassen-Kornzweig Syndrome) is an inherited disorder that affects the absorption of dietary fats, cholesterol, and certain vitamins. People affected by this disorder are not able to make certain lipoproteins, which are molecules that consist of proteins combined with cholesterol and particular fats called triglycerides. These lipoproteins, referred to as beta-lipoproteins, include low-density lipoproteins (LDL), very-low-density lipoproteins (VLDL), and chylomicrons. A lack of beta-lipoproteins prevents absorption through the digestive tract of dietary fats and fat-soluble vitamins such as vitamins E, A, and sometimes K. 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. Common symptoms may include:
- failure to gain weight and grow at the expected rate (called failure to thrive)
- abnormal star-shaped red blood cells (called acanthocytosis)
- fatty, foul-smelling stools (called steatorrhea)
Many of the signs and symptoms of abetalipoproteinemia result from a severe vitamin deficiency, especially vitamin E deficiency, which can lead to nerve problems. These symptoms may develop later in childhood and may include:
- difficulty with balance and movement (called ataxia)
- progressive degeneration of the retina at the back of the eye that can progress to near-blindness
Treatment
There is currently no cure for Abetalipoproteinemia. However, early diagnosis, routine surveillance and treatment can help manage some of the symptoms and sometimes prevent related problems.
How Common Is It?
Abetalipoproteinemia is a rare disorder with approximately 100 cases described worldwide.
Genetics & Inheritance
Mutations in the MTTP gene cause abetalipoproteinemia.
- More than 15 mutations have been identified in the MTTP gene.
- Two specific mutations are more commonly found in people of Ashkenazi (eastern and central European) Jewish ancestry.
Abetalipoproteinemia 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. Two carriers have a 25% chance with each pregnancy to have an affected child.
Tests
Clinical genetic testing for abetalipoproteinemia can be broken down into two categories: diagnostic testing and carrier testing.
- Diagnostic testing may be used to confirm or rule out a diagnosis in a person suspected to have the disorder.
- Carrier testing is typically offered after a clinical diagnosis/and or mutations have already been identified in an affected family member(s) first. Carrier testing is also available for people of high risk ethnic groups.
Carrier testing for the Ashkenazi-specific mutations that cause abetalipoproteinemia is available online (over the internet) or through an in person genetic consultation. This testing is available individually or as part of an Ashkenazi Jewish panel. Go to the Tests tab to link to the best providers, compare providers and read provider reviews.
Diagnostic testing and carrier testing for people who are not of Ashkenazi Jewish ancestry is available through an in person genetic consultation for people who are considered at risk. Use our find a genetic professional directory to locate a trained genetic professional in your area.
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