Familial hypercholesterolemia Health Article

Definition

Familial hypercholesterolemia is a condition passed down through families in which a person has high levels of "bad" cholesterol (low density lipoprotein, or LDL) beginning at birth. The condition can cause heart attacks at an early age.

See also:

• Familial combined hyperlipidemia
• Familial hypertriglyceridemia
• Familial dysbetalipoproteinemia

Alternative Names

Type II hyperlipoproteinemia; Hypercholesterolemic xanthomatosis; Low density lipoprotein receptor mutation

Causes, incidence, and risk factors

Familial hypercholesterolemia is caused by a gene defect on chromosome 19. The defect makes the body unable to remove LDL cholesterol from the bloodstream. This results in consistently high levels of LDL in the blood, which leads to atherosclerosis at an early age.

The condition is typically passed down through families in an autosomal dominant manner. That means you only need to get the abnormal gene from one parent in order to inherit the disease. An individual who inherits one copy of the gene is considered "heterozygous."

In rare cases, a child may inherit the gene from both parents. Individuals who inherit both genes are considered "homozygous." Homozygous familial hypercholesterolemia is much more severe. Cholesterol levels may exceed 600mg/dL, greatly increasing the risk for heart attacks and heart disease.

Symptoms

Symptoms that may occur include:

• Fatty, cholesterol-rich skin deposits (xanthomas)
• Cholesterol deposits in the eyelids (xanthelasmas)
• Chest pain (angina) associated with coronary artery disease
• Obesity

Persons with either one or two copies of the defective gene can develop fatty skin deposits over their elbows, knees, buttocks, tendons, and around the cornea of the eye.

Signs and tests

A physical examination may reveal fatty skin growths called xanthomas and cholesterol deposits in the eye (corneal arcus).

Other signs include:

• A strong family history of familial hypercholesterolemia or early heart attacks
• High levels of LDL in either or both parents

Individuals from families with a strong history of early heart attacks should have blood tests done to determine lipid levels. Blood tests may show:

• High levels of total cholesterol
  • Greater than 300 mg/dL in adults
  • Greater than 250 mg/dL in children
• LDL greater than 200 mg/dL
• High level of triglycerides

Other tests that may be done include:

• Heart function (stress) test
• Studies of cells called fibroblasts to see how the body absorbs LDL cholesterol
• Genetic test for the defect associated with this condition