Lipids are various types of body fats, including cholesterol, triglycerides, HDL-cholesterol, LDL-cholesterol and others. Fats have many vital roles, ranging from facilitating transmission of nerve impulses to serving as building blocks for essential hormones. Lipid metabolism encompasses numerous chemical reactions that enable healthy production and use of fats. Several types of inherited lipid diseases interfere with normal lipid metabolism, often increasing the risk for the early development of heart disease.
Familial Hypercholesterolemia
Familial hypercholesterolemia is a genetic disorder characterized by elevated total cholesterol and LDL-cholesterol. People with this disorder have a defect in the LDL receptor, which reduces the normal rate of removal of cholesterol from the bloodstream. Cholesterol levels in people with familial hypercholesterolemia are elevated from birth.
The medical reference text "Harrison’s Principles of Internal Medicine" reports that approximately one in every 500 people in the United States is affected by familial hypercholesterolemia. Adults with this disorder frequently exhibit small fat deposits under the skin along the tendons, with the Achilles tendon and finger tendons most commonly affected. Minute fat deposits called xanthelasmas also characteristically develop on the eyelids. People with familial hypercholesterolemia are at significantly increased risk for coronary heart disease and heart attack at a young age.
Familial Hypertriglyceridemia
Familial hypertriglyceridemia causes an elevated blood triglyceride level without a significant elevation in blood cholesterol. A form of blood fat known as VLDL, or very low density lipoprotein, is significantly increased in people with familial hypertriglyceridemia. MedlinePlus notes that approximately one in every 500 people in the United States has this inherited condition, which increases the risk for early coronary artery disease.
Familial Combined Hyperlipidemia
Elevated levels of cholesterol and triglycerides occur with familial combined hyperlipidemia. Several different genetic abnormalities can lead to this metabolic lipid disorder. "Harrison’s Principles of Internal Medicine" estimates that up to one percent of the population in the United States is affected by familial combined hyperlipidemia. People with this disorder have a markedly increased risk for coronary heart disease at a young age. MedlinePlus reports that familial combined hyperlipidemia is the most prevalent genetic lipid disorder associated with heart attack at an early age.
Familial Dysbetalipoproteinemia
Familial dysbetalipoproteinemia, also known as type III hyperlipoproteinemia, is an uncommon inherited disorder characterized by elevated cholesterol, triglycerides and VLDL. Fat deposits within the skin commonly occur with familial dysbetalipoproteinemia.
"Harrison’s Principles of Internal Medicine" reports that people with this disorder are at significantly increased risk for early-onset coronary heart disease, stroke and peripheral arterial disease. With peripheral arterial disease, fatty deposits called plaques accumulate in the arteries of the extremities, partially obstructing blood flow. People with peripheral arterial disease characteristically develop pain in the legs with physical activity due to decreased blood supply to the leg muscles.
References
- "Harrison’s Principles of Internal Medicine, 16th Edition"; Dennis L. Kasper, M.D., et al., Editors; 2004
- MedlinePlus: Familial Hypercholesterolemia
- MedlinePlus: Familial Hypertriglyceridemia
- MedlinePlus: Familial Combined Hyperlipidemia
- MedlinePlus: Familial Dysbetalipoproteinemia
