Familial chylomicronemia syndrome

Other Names:Familial lipoprotein lipase deficiency; Hyperlipoproteinemia type 1 ;Burger-Grutz syndrome;endogenous hypertriglyceridaemia;familial fat-induced hypertriglyceridemia ;familial hyperchylomicronemia;familial LPL deficiency;hyperlipoproteinemia type Ia;lipase D deficiency;LIPD deficiency;lipoprotein lipase deficiency, familial

Hyperlipoproteinemia type 1 is an inherited condition that disrupts the normal breakdown of fats in the body, causing a large amount of fat to build up in the blood. This condition is characterized by inflammation of the pancreas (pancreatitis), abdominal pain, enlargement of the liver and spleen (hepatosplenomegaly), and small yellow skin lesions called eruptive xanthomas.

Onset

People with familial lipoprotein lipase deficiency typically develop signs and symptoms before age 10, with one-quarter showing symptoms by age 1.

Epidemiology

This condition affects about 1 per million people worldwide. It is much more common in certain areas of the province of Quebec, Canada.

Cause

Mutations in the LPL gene cause familial lipoprotein lipase deficiency. The LPL gene provides instructions for producing an enzyme called lipoprotein lipase, which is found primarily on the surface of cells that line tiny blood vessels (capillaries) within muscles and fatty (adipose) tissue. This enzyme helps break down fats called triglycerides, which are carried by molecules called lipoproteins.

Mutations that cause familial lipoprotein lipase deficiency lead to a reduction or elimination of lipoprotein lipase activity, which prevents the enzyme from effectively breaking down triglycerides. As a result, triglycerides attached to lipoproteins build up in the blood and tissues, leading to the signs and symptoms of familial lipoprotein lipase deficiency.

Inheritance

Autosomal recessive inheritance, a 25% chance

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.

Researchers speculate that if family members of affected individuals have a mutation in one copy of the LPL gene in each cell, they may have a mild increase in fat levels in the blood, which could increase their risk of health problems such as heart disease or diabetes. However, studies have not clearly demonstrated whether these individuals are more prone to develop these health problems than individuals in the general population.

Signs and symptoms

The signs and symptoms of hyperlipoproteinemia type 1 usually begin during childhood. Approximately 25 percent of affected individuals develop symptoms before age 1. The characteristic features of hyperlipoproteinemia type 1 include:

• Abdominal pain (may manifest as colic in infancy)
• Nausea, vomiting, loss of appetite
• Failure to thrive in infancy
• Musculoskeletal pain (pain in the muscles and bones)
• Xanthomas (small, yellow, fat deposits in the skin)
• Pancreatitis
• Enlarged liver and spleen (hepatosplenomegaly)

In some cases, neurological features develop, including depression, memory loss, and mild intellectual decline (dementia). These symptoms typically go away once dietary fat levels are lowered.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 100% of people have these symptoms

• Hypertriglyceridemia(Increased plasma triglycerides)
• Increased circulating chylomicron concentration

80%-99% of people have these symptoms

• Acute pancreatitis(Acute pancreatic inflammation)
• Episodic abdominal pain
• Hepatosplenomegaly(Enlarged liver and spleen)
• Lipemia retinalis
• Recurrent pancreatitis(Recurring pancreas inflammation)

30%-79% of people have these symptoms

• Eruptive xanthomas
• Hepatic steatosis(Fatty infiltration of liver)

5%-29% of people have these symptoms

• Failure to thrive(Faltering weight)
• Nausea and vomiting

1%-4% of people have these symptoms

• Abnormal emotion/affect behavior
• Dementia(Dementia, progressive)
• Depressivity(Depression)
• Diabetes mellitus
• Jaundice(Yellow skin)
• Memory impairment(Forgetfulness)
• Perianal abscess
• Pulmonary embolism(Blood clot in artery of lung)

Diagnosis

Clinical findings

• Recurrent acute pancreatitis
• Eruptive cutaneous xanthomata
• Hepatosplenomegaly

Supportive laboratory findings

• Impaired clearance of chylomicrons from plasma causing the plasma to have a milky (lactescent or lipemic) appearance
• Plasma triglyceride concentrations greater than 2000 mg/dL in the untreated state, regardless of fasting status.

The diagnosis of LPL deficiency is established in a proband by the identification of biallelic pathogenic variants in LPL on molecular genetic testing.

Treatment

Treatment for hyperlipoproteinemia type 1 is intended to control blood triglyceride levels with a very low-fat diet. It is recommended that individuals with this condition eat no more than 20 grams of fat per day.

Medium-chain fatty acids (such as coconut oil) can be incorporated into the diet, as they are absorbed by the body in a different manner. Dietary counseling may be helpful to maintain adequate calorie and nutrient intake.

NIH genetic and rare disease info

• NIH info on Familial chylomicronemia syndrome

Familial chylomicronemia syndrome is a rare disease.

Familial chylomicronemia syndrome Resources
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