Familial hypercholesterolemia

Definition

A dominantly inherited genetic condition that results in markedly elevated LDL (low-density lipoprotein) cholesterol levels beginning at birth, and cause heart attacks at an early age.

Alternative Names

Causes

Affected people have consistently high levels of low-density lipoprotein (LDL or "bad" cholesterol), which leads to premature atherosclerosis of the coronary arteries. Typically in affected men, heart attacks occur in their 40s to 50s, and 85% of men with this disorder have experienced a heart attack by age 60. The incidence of heart attacks in women with this disorder is also increased, but happens 10 years later than in men.

Individuals from families with a strong history of early heart attacks should be evaluated with a lipid screen. Proper diet, exercise, and the use of newer drugs can bring lipids (fats in the blood) down to safer levels.

The mutation that causes this genetic abnormality occurs on chromosome 19. It is possible for a person to inherit copies of the mutated gene for this disorder (one from each parent, making them genetically "homozygous").

In homozygous individuals the condition is more severe, and cholesterol values may exceed 600 mg/dL. These individuals develop waxy plaques (xanthomas) beneath the skin over their elbows, knees, buttocks. These are deposits of cholesterol in the skin. In addition, they develop deposits in tendons and around the cornea of the eye. Atherosclerosis begins before puberty and heart attacks and death may occur before age 30, or they may require highly invasive surgery such as a liver transplant.

Those who have inherited only one copy of the mutated gene (from one parent) are called heterozygous. These individuals may respond well to diet modifications combined with statin drugs.

Symptoms

• A strong family history of familial hypercholesterolemia or early heart attack
• Elevated and therapy-resistant levels of LDL in either or both parents
• Xanthomas (lesions caused by cholesterol rich lipoprotein deposits)
• Cholesterol deposits in the eyelids (xanthelasmas)
• Chest pain (angina) associated with coronary artery disease
• Evidence of obesity

Exams and Tests

A physical examination may reveal xanthomas, xanthelasmas and cholesterol-laden deposits called a corneal arcus.

Laboratory testing may show:

• Elevated triglycerides
• Protein electrophoresis may show abnormal results
• Total plasma cholesterol that is greater than 300 mg/dL (adult)
• Total plasma cholesterol that is greater than 250 mg/dL (children)
• Serum LDL that is higher than 200
• Studies of heart function, such as a stress test, may be abnormal
• Special studies of patient cells (fibroblasts) may show decreased uptake of LDL cholesterol
• Genetic testing for mutations in the LDL receptor gene

Treatment

The goal of treatment is to reduce the risk of atherosclerotic heart disease

The first step is to change what you eat. This is tried for several months before drug therapy is added. Diet changes include reducing total fat intake to less than 30% of the total calories consumed.

Saturated fat intake is reduced by decreasing the amounts of beef, pork, and lamb; substituting low-fat dairy products; and eliminating coconut and palm oil. Cholesterol intake is reduced by eliminating egg yolks, organ meats, and sources of animal-derived saturated fat.

Further reductions in the percentage of fat in the diet may be recommended after the initial trial period. Dietary counseling is often recommended to assist people with these adjustments to their eating habits.

Exercise, especially to induce weight loss, may also aid in lowering cholesterol levels.

Drug therapy may be initiated if diet, exercise, and weight-loss efforts have not reduced the cholesterol levels after an adequate trial period. Various cholesterol-reducing agents are available including:

• Bile acid sequestrant resins (cholestyramine and colestipol)
• Nicotinic acid (niacin)
• Statin drugs
• Gemfibrozil
• Fenofibrate

Support Groups

MEDPED (Make Early Diagnosis to Prevent Early Death)

www.medped.org

University of Utah

1-888-244-2465

Outlook (Prognosis)

The outcome is likely to be poor in people with the homozygote type of familial hypercholesterolemia because it causes early heart attacks and is resistant to treatment.

The outcome of other types of familial hypercholesterolemia depends in part on the patient's compliance with treatment, but reduction in serum cholesterol levels can be achieved and may be significant in delaying a heart attack.

Possible Complications

• Heart attack at an early age
• Cholesterol-rich deposits in skin, eyelids

When to Contact a Medical Professional

• Call your health care provider or go to the emergency room if you have crushing chest pain or other warning signs of heart attacks.
• Call for an appointment with your health care provider if you or family members are found to have elevated total cholesterol levels.

Prevention

Families with a history of familial hypercholesterolemia may benefit from counseling, especially if both parents are affected. Prevention of early heart attacks requires recognition of existing elevated LDL levels, and a low-cholesterol, low-saturated fat, high-unsaturated fat diet in high-risk people may help to control LDL levels.