What Is Abetalipoproteinemia (ABL)?
Abetalipoproteinemia (ABL) is an inherited condition that prevents the body from completely absorbing certain dietary fats. Without treatment, it can cause vitamin deficiencies that may have long-term effects on your health. Dietary fats and the vitamins they contain are important for the growth and development of many of your body’s organs and tissues, including the brain.
ABL is also known as Bassen-Kornzweig syndrome, acanthocytosis, or apolipoprotein B deficiency. It’s the result of a defective gene and runs in families. It’s not contagious.
Causes Abetalipoproteinemia (ABL)
ABL is the result of problems with a gene that tells your body how to combine fat with protein to make something called a lipoprotein. When the gene doesn’t work, it’s harder for your body to digest certain types of fat and vitamins.
ABL is an autosomal recessive condition. You must inherit the defective gene from both parents to have the condition.
ABL is a rare disorder. The U.S. National Library of Medicine’s Genetics Home Reference notes that there only 100 cases reported worldwide.
Symptoms of Abetalipoproteinemia (ABL)
The symptoms of ABL vary greatly. This reflects the many important roles that fats and vitamins play in the body. Symptoms range from problems with growth and development in infancy to slurred speech and coordination issues in adults. According to the National Organization for Rare Disorders (NORD), symptoms often affect the:
- nervous system
- gastrointestinal tract
Specific symptoms of ABL include:
- abnormal growth patterns in infants, such as developmental milestone delays or failure to thrive
- abnormal curvature of the spine
- problems with balance and dexterity
- problems with coordination
- muscle weakness
- a protruding abdomen
- problems with vision
- speech disorders
- slurring of speech
- fatty, frothy, foul-smelling, or otherwise irregular stools
If you or your child have any of the symptoms of ABL, it’s important to talk to your doctor. ABL is treatable, but treatment delays can have lasting effects.
Diagnosis of Abetalipoproteinemia (ABL)
Your doctor can use several different types of tests to diagnose ABL.
Metabolic Blood Tests
One of the ways that doctors diagnose ABL is to look for changes in your metabolism. Tests for deficiencies in the following vitamins are common:
- vitamin A
- vitamin D
- vitamin E
- vitamin K
Doctors may also test your levels of apolipoprotein B. Apolipoprotein B metabolism can be different in people with ABL and other lipid disorders.
Your doctor may also run a complete blood count and a cholesterol study.
Genetic Blood Tests
If you have a family history of ABL, your doctor may test you to see if you have mutations in your MTP gene. This is the gene responsible for causing ABL. Knowing whether you have the mutation is not only useful for figuring out if you have the condition. It can also help you decide whether your partner needs testing before you have children.
Other Diagnostic Tests
In addition to testing your blood, your doctor may perform other exams to see how ABL is affecting your body. A few examples of such tests are:
- an eye exam
- a stool sample test
It may take several visits to the doctor to diagnose ABL. It can sometimes be difficult to determine whether symptoms are due to ABL or another condition.
Treatments of Abetalipoproteinemia (ABL)
A common treatment for ABL is high doses of fat-soluble vitamins. You may also receive other supplements, including linoleic acid, which is an omega-6 fatty acid.
Diet can be an important part of treating ABL. Your doctor may recommend speaking to a nutritionist who can help you lower your fat intake. This might involve changing to skim milk or eating smaller servings of meat and other fatty foods.
NORD notes that investigative treatments may soon be available for those with ABL. Ask your doctor for information on ongoing clinical trials for new therapies.
Complications of Abetalipoproteinemia (ABL)
There are several potentially severe complications of ABL. Visual problems may become worse over time and lead to blindness. Muscle function changes may produce tremors and lead to trouble walking or performing regular activities. Some people with ABL may also experience mental deterioration.
The good news is that treatments for these complications are available. Your doctors may not be able to restore perfect health. However, if you experience these symptoms, they can work with you to regain as much mental clarity, vision, and muscle function as possible.
Long-Term Outlook of Abetalipoproteinemia (ABL)
The specific complications of ABL can vary depending on the person, and your outlook depends on the extent of your illness. While many people do well with treatment, ABL can cause serious problems in the muscles and nervous system.
Medically reviewed by Steve Kim, MD on February 3, 2016 — Written by Seth Stoltzfus and Elizabeth Boskey, PhD