Heterozygous familial hypercholesterolemia (HeFH) is a genetic disorder a person can inherit from a parent. It can cause a person to develop dangerously high cholesterol levels.

HeFH affects how a person processes cholesterol. Cholesterol is a waxy substance present in a person’s blood and is important for certain bodily processes. However, high levels of cholesterol can cause a person to develop health issues, such as coronary artery disease (CAD).

Lipoproteins in the blood transport cholesterol through the bloodstream to cells. The two main lipoproteins are low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Some people may refer to LDL as “bad” cholesterol, and HDL as “good” cholesterol. A person who has HeFH has increased levels of LDL cholesterol. This can put them at risk of serious health conditions.

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HeFH causes a person to have high levels of LDL cholesterol from birth. These levels continue to increase over time.

High levels of cholesterol can cause a buildup of plaque inside a person’s arteries. Plaque is a sticky substance that consists of cholesterol, fat, blood cells, and other substances. Plaque buildup can result in atherosclerosis. This refers to a narrowing of the arteries and the restriction of blood flow.

The American Heart Association (AHA) notes people with untreated familial hypercholesterolemia (FH) may be 20 times more likely to develop heart disease.

HeFH is one of two forms of familial hypercholesterolemia. The other form is known as homozygous familial hypercholesterolemia (HoFH).

HeFH is more common than HoFH. The Centers for Disease Control and Prevention (CDC) states that HeFH occurs in around 1 in 250 people. HoFH is very rare and occurs in around 1 in 250,000 people.

A person may develop HeFH if they inherit a gene variation from one of their parents. Genes are units of information that determine specific traits. A person receives two copies of each gene, one from each parent. If a person has a parent who is a carrier of HeFH, they have a 50% chance of developing the condition.

To develop HoFH, a person must inherit an FH gene alteration from both parents. HoFH is more serious than HeFH. It can cause a person to develop extremely high cholesterol levels. Untreated, HoFH can commonly cause death before a person reaches 30 years old.

HeFH may develop if a person inherits a gene variation from one of their parents. It generally occurs due to alterations in the LDLR, APOB, or PCSK9 genes. These genes affect a protein called a low-density lipoprotein receptor. These receptors help remove LDL from a person’s bloodstream.

The variations that cause HeFH affect the low-density lipoprotein receptors. These alterations may cause the receptors to function incorrectly or reduce in number. This may allow LDL cholesterol to build up inside a person’s bloodstream.

However, certain people with HeFH do not have variations in any of these genes. The causes of these forms of HeFH are currently unknown.

The CDC notes one of the main signs of HeFH is an LDL cholesterol level of over 190 milligrams per deciliter (mg/dL) in adults and over 160 mg/dL in children. The AHA states that an LDL cholesterol level of 100 mg/dL or less is ideal.

The CDC also notes that not all people who have HeFH will develop physical symptoms. If physical symptoms occur, they may include:

  • lumps around the knees, knuckles, or elbows
  • a swollen or painful Achilles tendon
  • yellowish areas around the eyes
  • a white-gray arc around a person’s cornea, which is the outer layer at the front of the eye

A person who has HeFH may also develop CAD symptoms, including chest pain or heart attack.

A person who has HeFH may not have physical symptoms of the disease. The AHA notes that people over 20 years old should have their cholesterol screened every 4 to 6 years. This allows a doctor to check for unusually high levels of LDL cholesterol.

A doctor may test a person for HeFH if they have high cholesterol levels or have a family member with FH. They may ask a person if they have a family history of FH, early heart attacks, or CAD.

A doctor may also perform a genetic test, using a tissue sample to check a person’s genes for HeFH-causing variations. Tissue samples may include blood, hair, or skin. If a doctor discovers a person has HeFH, they may recommend testing for other members of the person’s family.

If a person notices any signs of HeFH, they should speak with a doctor. The CDC states that early diagnosis and treatment can reduce a person’s chance of CAD by 80%.

The AHA notes that FH may be treated with the use of statins. Statins are drugs that help lower cholesterol levels. A doctor may also prescribe a person with other cholesterol-lowering drugs.

In addition to medication, a person may use lifestyle changes to manage their HeFH. These changes may include:

  • restricting foods containing saturated fat
  • eliminating food containing trans fats
  • reducing dietary cholesterol
  • increasing soluble fiber intake
  • increasing intake of vegetables, fruits, whole grains, nuts, and legumes
  • eating seafood, lean poultry, and low fat dairy
  • maintaining a moderate weight
  • exercising regularly
  • stopping smoking cigarettes if applicable

Heterozygous familial hypercholesterolemia (HeFH) is a condition that causes high levels of LDL cholesterol. It can drastically increase a person’s risk of coronary artery disease (CAD). HeFH occurs due to an alteration in a person’s genes. A person inherits the gene variation from at least one of their parents.

Certain people who have HeFH will have no physical symptoms. A person should make sure they attend cholesterol screenings every 4 to 6 years to check their levels. A person can treat their HeFH using lifestyle changes and medications.