According to the Familial Hypercholesterolemia Foundation, an estimated 1 in 300-500 people in the United States have pure hypercholesterolemia. However, an estimated 90 percent of people remain undiagnosed with the condition.
While high cholesterol is often the result of eating a high-fat diet, pure hypercholesterolemia is unrelated to lifestyle or diet.
However, pure hypercholesterolemia is no less dangerous to a person's overall health. Whatever the cause, excess cholesterol can increase a person's risk of heart disease.
Pure hypercholesterolemia is unrelated to lifestyle or diet and is inherited genetically by a person from their parents.
Pure hypercholesterolemia is passed down to a person by their parents because of a genetic mutation on chromosome 19.
The condition affects a person's liver. The liver is responsible for producing cholesterol, which helps create healthy cell walls. However, when a person has pure hypercholesterolemia, the liver is unable to recycle cholesterol and regulate cholesterol levels. As a result, the amount of cholesterol builds up in the body.
Two forms of the condition exist: heterozygous familial hypercholesterolemia (HeFH) and homozygous familial hypercholesterolemia (HoFH).
The HeFH condition occurs when a person inherits pure hypercholesterolemia from one parent.
The HoFH condition occurs when a person inherits pure hypercholesterolemia from both parents. This form of the condition is very rare and occurs in only 1 in 160,000-1 million people in the world, according to the Familial Hypercholesterolemia Foundation. The HoFH form of the condition often results in more severe symptoms than the HeFH form.
The major risk factor for developing pure hypercholesterolemia is having one or both parents with a history of the condition.
If a person has pure hypercholesterolemia or has a parent with the condition, it's important they have their children's cholesterol levels tested. This testing should occur when the children are between the ages of 2 and10 years.
If a parent has pure hypercholesterolemia, there is a 50 percent chance they will pass the condition on to their child. Genetic counselors can help a person more closely examine the chances of passing the condition on to their child.
People of certain ethnicities are at a higher risk of experiencing the condition. These include:
- Ashkenazi Jews
- French Canadians
- South African Afrikaners
Symptoms of pure hypercholesterolemia are rare, but chest pain may be experienced.
Traditionally, a person experiences high cholesterol later in life when they have, perhaps, led a less-than-healthful lifestyle for many years.
However, pure hypercholesterolemia occurs from birth and unfortunately high cholesterol does not often present many symptoms in its early stages.
A blood test will usually reveal the levels of low-density lipoprotein (LDL), often called "bad" cholesterol, in the blood. Doctors would consider levels of 190 milligrams per deciliter (mg/dL) or higher in adults, and 160 mg/dL or higher in children, as very high.
Although symptoms rarely occur, some people who have pure hypercholesterolemia may experience:
- chest pain
- small bumps on the skin, usually on the hands, elbows, knees, or around the eyes
- xanthomas, which are waxy cholesterol deposits in the skin or tendons
- small, yellow deposits of cholesterol that build up under the eyes or around the eyelids
When a person receives mutated genes for pure hypercholesterolemia from both parents, they are more likely to develop xanthomas at an early age. Sometimes they will even have the xanthomas in infancy.
People need a small amount of cholesterol in their body to maintain healthy cell function and produce hormones. However, excess cholesterol can be very harmful to a person's health.
Excess cholesterol can start to deposit and build up in the arteries, causing them to become narrower. As a result, the heart has to work harder to pump blood through the body.
If a piece of the cholesterol breaks off, it can lodge itself in the heart's arteries, causing a heart attack.
According to the National Human Genome Research Institute, men with familial hypercholesterolemia have heart attacks at ages 40 to 50. An estimated 85 percent of men with the condition will have a heart attack by 60 years of age.
Women with the condition are also at an increased risk for heart attack, most commonly in their 50s and 60s.
If a person receives mutated genes for pure hypercholesterolemia from both parents, they have a significantly higher chance of heart attack and death before they reach 30 years.
In addition to an increased risk of narrowed arteries, a person who has pure hypercholesterolemia may also experience aortic stenosis. This is a condition where the opening of the aortic valve, which opens and closes to pump oxygenated blood through the body, is very constricted. This can be a major health concern for someone with pure hypercholesterolemia.
Doctors will diagnose the condition by finding out about the person's symptoms and by taking a family history. A doctor may note any cholesterol deposits that have built up in the body, especially on or around the eyes.
A doctor will probably order blood tests to find out what a person's total cholesterol levels are. Results that show total cholesterol levels higher than 300 mg/dL or higher than 250 mg/dL in children, will be cause for concern.
Genetic testing can reveal the genetic mutation on chromosome 19 that would indicate pure hypercholesterolemia.
A doctor may also order tests to determine the overall impact that pure hypercholesterolemia has had on a person's health. This could include a cardiac stress test or an echocardiogram.
Treatments for pure hypercholesterolemia often depend upon how severe the cholesterol levels and symptoms are. Almost all people with the condition will need to take a prescription medication to reduce overall cholesterol levels.
The most common medications are called "statins." An example is atorvastatin.
A blood test may be used to detect a person's cholesterol levels. Genetic testing may be used to determine pure hypercholesterolemia.
Sometimes doctors will prescribe additional medications known to lower cholesterol, such as:
- bile acid sequestrant resins
- nicotinic acid (niacin)
People with severely high cholesterol levels may also need to undergo a procedure called LDL-apheresis. This process involves the removal of excess cholesterol from the blood. It is performed on a weekly or twice-weekly basis.
In very rare and extreme cases, a person may require a liver transplant.
Lifestyle changes can also help to keep cholesterol levels as low as possible. Examples of healthy lifestyle measures include:
- Controlling other risk factors known for making cholesterol levels worse. Examples include managing high blood pressure and diabetes.
- Eating at least 10–20 grams of soluble fiber a day.
- Eating a healthy diet low in saturated and trans fats, usually by limiting fats to no more than 30 percent of a person's total daily calories.
- Being as physically active as possible.
- Limiting the amount of high-fat foods in the diet. These include butter, whole milk, high-fat cheeses, and high-fat beef, pork, and lamb.
- Stopping smoking is one of the most important lifestyle changes a person can make.
However, current guidelines no longer recommend this for most people, as it can increase the risk of bleeding.
Researchers are currently conducting clinical trials and studies regarding medications in a new class of drugs called proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors.
The amount of LDL in the body is normally controlled by specialist receptors. When a person has hypercholesterolemia, these receptors do not function properly. These medications help these receptors to continue working and as a result, the body is better able to process LDL cholesterol.
The U.S. Food and Drug Administration (FDA) have approved evolocumab (Repatha), a PCSK9 medication to treat patients with familial hypercholesterolemia where the genetic mutation was passed down by one parent. The medication isn't considered a first-line treatment, however.
Doctors will typically only prescribe the evolocumab if a person isn't responding to statin therapy, according to the American Pharmacists Association.
The drug is administered anywhere from one to three times a month. The drug is very expensive, however, costing an estimated $14,100 on an annual basis for a person who receives an injection of the medication every 2 weeks.