How Abetalipoproteinemia Affects the Body

Abetalipoproteinemia (also known as Bassen-Kornzweig syndrome) is an inherited disorder that affects how fats are made and used in the body. Our bodies need fats in order to maintain healthy nerves, muscles, and digestion. Like oil and water, fats can't travel around our bodies by themselves. Instead, they attach to special proteins called lipoproteins and travel to wherever they're needed.

Because of a genetic mutation, people with abetalipoproteinemia don't produce the protein needed to make lipoproteins. Without enough lipoproteins, fats can't be digested properly or travel to where they are needed. This leads to serious health problems that can affect the stomach, blood, muscles, and other body systems.

Because of the problems caused by abetalipoproteinemia, signs of the conditions are often seen in infancy. Males are affected more—about 70-percent more—than females. The condition is an autosomal inherited condition, meaning both parents must have the faulty MTTP gene for their child to inherit it. Abetalipoproteinemia is very rare, only 100 cases have been reported.

Babies born with abetalipoproteinemia have stomach problems due to their inability to digest fats properly. Bowel movements are often abnormal and may be pale-colored and foul-smelling. Children with abetalipoproteinemia may also experience vomiting, diarrhea, bloating, and difficulty gaining weight or growing (also sometimes known as the failure to thrive).

Those with the condition also have with problems relating to the vitamins stored in fats—vitamins A, E, and K. Symptoms caused by the lack of fats and fat-soluble vitamins typically develop within the first decade of life. These may include:

• Sensory disturbances: This includes problems with sensing temperature and touch—especially in the hands and feet (hypesthesia)
• Trouble walking (ataxia): Approximately 33 percent of children will have difficulty walking by the time they turn 10 years. Ataxia gets worse over time.
• Movement disorders: Tremors, shaking (chorea), trouble reaching for things (dysmetria), trouble talking (dysarthria)
• Muscle problems: Weakness, shortening (contraction) of muscles in the back that causes the spine to curve (kyphoscoliosis)
• Blood problems: Low iron (anemia), problems with clotting, abnormal red blood cells (acanthocytosis)
• Eye problems: Night blindness, poor eyesight, problems with eye control (ophthalmoplegia), cataracts

Abetalipoproteinemia can be detected through stool samples. Bowel movements, when tested, will show a high level of fat since the fat is being eliminated rather than being used by the body. Blood tests can also help diagnosis the condition. The abnormal red blood cells present in abetalipoproteinemia can be seen under a microscope. There will also be very low levels of fats like cholesterol and triglycerides in the blood. If your child has abetalipoproteinemia, tests for clotting time and iron levels will also come back abnormal. An eye exam might show inflammation of the back of the eye (retinitis). Testing of muscle strength and contractions may have abnormal results as well.

A specific diet for people with abetalipoproteinemia has been developed. There are several requirements in the diet, including avoiding eating certain types of fats (long-chain triglycerides) in favor of eating other types (medium-chain triglycerides). Another requirement is adding doses of vitamin supplements containing vitamins A, E, and K, as well as iron. A nutritionist with a background treating genetic conditions can help you design a meal plan that will meet your child's special dietary needs.