Familial chylomicronemia
Key points
- Familial lipoprotein lipase deficiency is a group of rare genetic disorders characterized by deficient activity of an enzyme (lipoprotein lipase) that breaks down fat molecules, causing the accumulation of large quantities of fat (lipoproteins) in the blood.
- A defective gene is usually the cause of this disorder, which is inherited in an autosomal recessive manner.
- Signs and tests A physical examination may reveal xanthomas, an enlarged liver, an enlarged spleen, and jaundice.
- Treatment is intended to control the symptoms and blood triglyceride levels with a very low fat diet.
Alternative names
Type I hyperlipoproteinemia; Familial lipoprotein lipase deficiency
Definition
Familial lipoprotein lipase deficiency is a group of rare genetic disorders characterized by deficient activity of an enzyme (lipoprotein lipase) that breaks down fat molecules, causing the accumulation of large quantities of fat (lipoproteins) in the blood.
Causes, incidence, and risk factors
A defective gene is usually the cause of this disorder, which is inherited in an autosomal recessive manner. Blood tests show a high level of chylomicrons, a lipoprotein that carries fats from digested food into the blood stream. The chylomicrons are not broken down properly because of the deficiency of the lipoprotein lipase enzyme. This results in a build up of fat-laden chylomicrons in blood. Skin lesions (xanthomas) form as a result of deposits of these chylomicrons in the skin. There is inflammation of the pancreas and resulting abdominal pain.
Risk factors are a family history of lipoprotein lipase deficiency, very high triglycerides in the blood, multiple unexplained episodes of pancreatitis, and failure to thrive in infancy. The incidence is 1 out of 1,000,000 people. The disease usually shows up in infancy or early childhood.
Symptoms
- Abdominal pain (may manifest as colic in infancy)
- Nausea, vomiting, loss of appetite
- Failure to thrive in infancy
- Musculoskeletal pain
- Skin lesions - xanthomas (fatty deposits in the skin)
Signs and tests
A physical examination may reveal xanthomas, an enlarged liver, an enlarged spleen, and jaundice. An eye examination reveals pale retinas and whitish retinal vessels.
Tests or observations that may indicate this disorder is present include:
- Milky appearing serum or plasma from blood
- A special test showing little or no lipoprotein lipase activity in blood collected after treatment with intravenous heparin
- High triglycerides in blood
- Elevation of cholesterol and total fat in blood
- Failure to remove chylomicrons from blood more than 12 hours after a meal
- An overnight icebox test showing chylomicrons in blood serum taken after fasting
- A test for apolipoprotein CII deficiency, which may cause a rare subset of this disease in people with normal lipoprotein lipase activity
Written and revised by
Gerald Hurowitz, M.D.
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