Familial lipid disorders

A familial lipid disorder is an inherited condition that causes very high levels of cholesterol and, in some cases, triglycerides. Familial lipid disorders often result in the premature onset of coronary artery disease (CAD). Because familial lipid disorders are rare, your doctor may only suspect one if you have:

• Extremely high cholesterol levels.
• A family history of high cholesterol.
• A family history of early CAD.
• Specific findings on physical exam.

Because familial lipid disorders are so rare, your primary care doctor may not have a great deal of experience in dealing with them. In this case, you may need to see a doctor who specializes in these conditions. Because familial lipid disorders often result in early CAD, a number of cardiologists specialize in lipid disorders as well as heart problems.

Types of familial lipid disorders

Disorder	Cholesterol level	Distinguishing characteristics
Familial combined hyperlipidemia (FCHL)	Elevated, usually with high triglycerides High triglyceride and low HDL	Appears in adulthood Common in families with obesity, hypertension, and diabetes Estimated prevalence in the U.S.: 1 in 50
Familial defective apolipoprotein B-100	Elevated LDL
Familial dysbetalipoproteinemia (type 3 hyperlipoproteinemia)	Total cholesterol of 300–600 mg/dL Triglyceride of 400–800 mg/dL	Estimated prevalence in U.S.: 1 in 5,000 Premature CAD, heart attack, and stroke Xanthomas (common)
Familial hypertriglyceridemia	Very high triglycerides	Risk for even higher triglycerides from secondary causes
Heterozygous familial hypercholesterolemia	Total cholesterol of 325–450 mg/dL	CAD before age 50 Estimated prevalence in the U.S.: 1 in 500 Small, pale ring around the iris of the eye Xanthomas on tendons in young adults
Homozygous familial hypercholesterolemia	Total cholesterol of 500–1,000 mg/dL	CAD before age 20 Estimated prevalence in the U.S.: 1 in 1 million Xanthomas on tendons within the first few months of life