Hypercholesterolemia is a condition characterized by very high levels
of cholesterol in the blood. Cholesterol is a waxy, fat-like substance
that is produced in the body and obtained from
foods that come from animals (particularly egg yolks, meat, poultry,
fish, and dairy products). The body needs this substance to build cell
membranes, make certain hormones, and produce compounds that aid in fat
digestion. Too much cholesterol, however, increases a person's risk of
developing heart disease.
People with hypercholesterolemia have
a high risk of developing a form of heart disease called coronary
artery disease. This condition occurs when excess cholesterol in the
bloodstream is deposited in the walls of blood vessels, particularly in
the arteries that supply blood to the heart (coronary arteries). The
abnormal buildup of cholesterol forms clumps (plaque) that narrow and
harden artery walls. As the clumps get bigger, they can clog the
arteries and restrict the flow of blood to the heart. The buildup of
plaque in coronary arteries causes a form of chest pain called angina
and greatly increases a person's risk of having a heart attack.
Inherited forms of hypercholesterolemia can also cause health problems
related to the buildup of excess cholesterol in other tissues. If
cholesterol accumulates in tendons, it causes characteristic growths
called tendon xanthomas. These growths most often affect the Achilles
tendons and tendons in the hands and fingers. Yellowish cholesterol
deposits under the skin of the eyelids are known as xanthelasmata.
Cholesterol can also accumulate at the edges of the clear, front surface
of the eye (the cornea), leading to a gray-colored ring called an arcus
cornealis. How common is hypercholesterolemia?
34 million American adults have elevated blood cholesterol levels
(higher than 240 mg/dL). Inherited forms of hypercholesterolemia, which
cause even higher levels of cholesterol, occur less frequently. The most
common inherited form of high cholesterol is called familial
hypercholesterolemia. This condition affects about 1 in 500 people in
most countries. Familial hypercholesterolemia occurs more frequently in
certain populations, including Afrikaners in South Africa, French
Canadians, Lebanese, and Finns. What genes are related to hypercholesterolemia?
Mutations in the APOB, LDLR, LDLRAP1, and PCSK9 genes cause hypercholesterolemia.