What Is Pure Hypercholesterolemia?

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Pure—or familial—hypercholesterolemia (FH) is a common inherited disorder associated with elevated low-density lipoprotein (LDL) cholesterol levels and premature coronary heart disease.

According to the Familial Hypercholesterolemia Foundation, an estimated one in 250 people worldwide have pure hypercholesterolemia, but the condition remains largely under-diagnosed in the general population. As a result, many patients with FH are diagnosed only at the time of their first coronary event.

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Types of Pure Hypercholesterolemia

Every person inherits two copies of the genes involved in cholesterol regulation, one from your mother and one from your father. A mutation in only one copy of one of the genes is enough to cause FH. If either your mother or father has a mutation that causes FH, they have a 50% chance of passing it on to you.

Most people with FH only have one FH-causing mutation, called heterozygous FH. Those with heterozygous FH have a defective gene that is offset by a non-defective gene, which often results in manageable increases in cholesterol levels.

In very rare cases, a person can inherit two FH-causing mutations, which results in a much more serious form of FH called homozygous FH.

People with homozygous FH have extremely high levels of cholesterol and can have heart attacks in childhood. This rare group must be placed on cholesterol-lowering medications right away, sometimes as young as 2 or 3 years old, to avoid life-threatening complications.

Pure Hypercholesterolemia Symptoms

High cholesterol levels are usually detected with a blood test in the absence of symptoms. 

Without prompt treatment, you are at increased risk of experiencing a heart attack and stroke, which may be signaled by one or more of the following symptoms:

  • Chest pain: High cholesterol levels can cause atherosclerotic plaque formation and vessel narrowing.
  • Xanthomas: These are fatty, yellow deposits of cholesterol under the skin, most commonly appearing as bumps over the elbows or knees, under the eyes, or around the eyelids.

Causes

Familial hypercholesterolemia is an inherited condition that results in increased LDL cholesterol levels. It is caused by mutations in the LDLR, APOB, and PCSK9 genes, which affect how your body regulates and removes cholesterol from your blood.

While 60% to 80% of people with FH have a mutation in one of these three genes, there are many other mutations that have yet to be discovered, therefore the true risk of FH is unknown.

FH genes are passed down from one or both parents. Defects can increase atherosclerosis risk and lead to massive buildups of cholesterol in the arteries, which puts you at higher risk of heart attack and heart disease. 

Pure Hypercholesterolemia Is Genetic

Familial hypercholesterolemia is caused by one or more abnormal genes that are passed down from one or both parents. People who have this condition are born with it. This defect prevents the body from ridding itself of the type of cholesterol that can build up in your arteries and cause heart disease. 

Diagnosis

Parents with FH will pass on the trait for the disease to their children about 50% of the time. Therefore, any child born to a parent with FH should have their cholesterol checked between the ages of 2 to 10 years old, especially if they are experiencing any of the aforementioned symptoms.

The symptoms, family history, and physical exam may lead to a heightened suspicion of familial hypercholesterolemia. As a result, a healthcare provider may use a blood test to measure serum cholesterol levels.

According to the American Heart Association, an LDL cholesterol greater than 190 mg/dL in adults (160 mg/dL in children) and a family history of a first-degree relative with premature coronary heart disease is required for a diagnosis of pure hypercholesterolemia. Genetic testing may be used to confirm the diagnosis if blood tests are inconclusive, but the additional testing is not usually needed.

If you are experiencing heart symptoms, you may be asked to undergo an echocardiogram and a cardiac stress test to further elucidate how your high cholesterol levels are affecting your heart’s ability to function properly. 

Treatment

The primary and most essential treatment for FH is aggressive cholesterol-lowering drug therapy, but lifestyle modifications may also be put to use.

Healthy lifestyle measures include:

  • Lowering blood pressure
  • Managing diabetes by keeping blood sugar levels within appropriate ranges
  • Exercising: The Centers for Disease Control and Prevention and the U.S. Preventive Services Task Force recommend 150 minutes of moderate-intensity exercise per week.
  • Eating a heart-healthy diet, which includes 10-20 grams of soluble fiber, low sodium meals, and a diet high in fruits and vegetables
  • Quitting smoking and limiting alcohol use

Intensive drug therapy is always indicated for FH, while lifestyle modifications are, at best, supplemental treatment.

Treatments for Extreme Cases

If you have extremely high cholesterol levels that are hard to manage, other more extreme treatments may take place, including:

  • A procedure called LDL-apheresis: During this procedure your excess cholesterol is removed from the blood through a filtration process one to two times a week or as needed depending on the severity and effectiveness of the treatment.
  • A liver transplant: This is extremely rare and often considered a last resort. 

Prognosis

If you have FH, finding the disorder early and treating it can reduce your risk of heart disease by about 80%. Moreover, studies have shown that life expectancy can be increased by as much as 15 to 30 years with treatment. In people with homozygous familial hypercholesterolemia—the most severe form of the disease—the life expectancy may only be 20 years or less even with treatment.

Still, for most people, pure hypercholesterolemia can be managed adequately with medication. Due to medical advances and more knowledge on how to adequately treat familial hypercholesterolemia, it is not uncommon for people with FH to have a normal life expectancy. 

Of note, people with a history of coronary artery disease or a recent cardiovascular event have a worse prognosis than those who have not had either. A recent study also found that those with FH and acute coronary syndrome are twice as likely to have a repeat coronary event within their first year after discharge compared to those without FH, despite use of a high-intensity statin.

Summary

Pure—or familial—hypercholesterolemia (FH) is a common inherited disorder associated with elevated low-density lipoprotein (LDL) cholesterol levels and premature coronary heart disease. It is a highly treatable condition that requires a combination of lifestyle changes and medication adherence.

A Word From Verywell

Learning that you have familial hypercholesterolemia can be a scary thing, but it is not a death sentence.

If you are diagnosed with FH, you may want to look at this as an opportunity to make lifestyle changes, like quitting smoking and starting an exercising routine, which will provide health benefits well beyond the management of your high cholesterol levels. It is important, however, to remember the importance of intensive drug therapy as the focus of your treatment.

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