Familial combined hyperlipidemia

Familial combined hyperlipidemia

Definition:

An inherited disorder of high serum cholesterol and/or high blood triglycerides associated with an increased risk of cardiovascular disease and characterized by multiple types of elevated lipoproteins within one family.

Alternative Names:

Multiple lipoprotein-type hyperlipidemia

Causes, incidence, and risk factors:

This disease is genetic and is inherited in an autosomal dominant manner but the specific defective gene(s) have not been identified. Elevations in the cholesterol and/or triglyceride levels appear during the teenage years and continue throughout life. Types of elevated lipoproteins may vary between affected family members. Cholesterol deposits in the skin, called xanthomas, that are seen in other disorders of elevated lipoproteins are rarely seen in this disorder. This disorder predisposes the person to increased risk of early coronary artery disease and therefore, heart attacks. The incidence of obesity and glucose intolerance is increased. The condition is worsened by diabetes, alcoholism, and hypothyroidism. Risk factors are a family history of high cholesterol and early coronary artery disease. The incidence is up to 1% of people making this the most common disorder of increased blood fats that cause early heart attacks. The rare person (1 in 10,000) who gets 2 defective genes is at markedly increased risk for early heart attack due to very high blood fat (cholesterol or triglyceride) levels.

Symptoms:

obesity may coexist
early onset of chest pain (angina)
family history of early heart attack or increased blood fats

Note: There may be no symptoms.

Signs and tests:

elevated serum LDL or VLDL
elevated total cholesterol
decreased or normal serum HDL cholesterol
elevated triglycerides
elevated apolipoprotein B100 test
pedigree analysis may show parent or child with high blood fat

Treatment:

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

Diet modification is the initial phase of treatment and is tried for several months before drug therapy is added. Diet modifications 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, chicken, pork, and lamb; substituting low-fat dairy products for full-fat ones; and eliminating coconut and palm oil. Cholesterol intake is reduced by eliminating egg yolks and organ meats. 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. Weight loss and regular exercise may also aid in lowering cholesterol levels.

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

bile acid-sequestering resins (cholestyramine and colestipol)
nicotinic acid
lovastatin and other 'statin' drugs
gemfibrozil
probucol

Expectations (prognosis):

The probable outcome is related to early diagnosis and treatment and compliance with therapy. Untreated people are at risk for shortened life span due to heart attack and stroke. The person with 2 defective genes has such high lipids that they are unlikely to be able to reduce their risk of coronary artery disease to normal. Therefore, they are at increased risk of heart attack despite medical therapy.

Complications:

A complication is early atherosclerotic heart disease or myocardial tissue death due to lack of blood (infarction). The fatty deposits can affect the blood vessels to the brain causing an increase risk for stroke.

Calling your health care provider:

Call your health care provider if you experience warning symptoms of myocardial infarction or your screening total cholesterol or triglycerides was found to be high.

Prevention:

A low-cholesterol, low-saturated fat diet in high risk individuals may help to control LDL levels. Screening of family members of people with familial combined hyperlipidemia should be undertaken to facilitate early treatment. It is important to control other risk factors for early heart attacks such as smoking if you have this disease. Sometimes younger children may have mild hyperlipidemia. Genetic counseling is recommended for family members.

Review Date: 11/20/2001
Reviewed By: David G. Brooks, M.D., Ph.D., Division of Medical Genetics, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.

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