Some types of high cholesterol — such as familial hypercholesterolemia (FH) — are genetic. People with FH inherit changes in LDLR, ABOP, and other genes that affect how the body regulates and removes cholesterol from the blood.
Cholesterol plays an important role in the body, but high levels of low-density lipoprotein (LDL) cholesterol can increase the risk of cardiovascular diseases.
This article describes the link between genetics and high cholesterol. It provides an overview of familial hypercholesterolemia (FH), including its symptoms, diagnosis, treatment, and outlook. We also outline some other causes of high cholesterol and list some steps people can take to prevent high cholesterol levels.
Estimates suggest that 1 in 250 people have FH. According to the
FH also appears to be more prevalent among people of certain ethnicities. According to the American College of Cardiology, the prevalence of the condition among people of different ethnic groups is as follows:
- Black people: 1 in 211 people
- white people: 1 in 249 people
- Mexican Americans: 1 in 414 people
- other ethnicities: 1 in 343 people
Lipoproteins are proteins that transport cholesterol throughout the body. There are
- LDL cholesterol, or “bad cholesterol“: This type can accumulate in the arteries, impairing blood flow and increasing the risk of cardiovascular diseases.
- HDL cholesterol, or “good cholesterol“: This type absorbs cholesterol and transports it back to the liver, which then removes it from the body. In this way, HDL helps prevent LDL from becoming too high.
FH impairs the body’s ability to clear LDL cholesterol from the blood. The excess cholesterol builds up in the arteries, forming plaques that impair blood flow. In this way, FH significantly increases the risk of cardiovascular diseases, such as heart attack and stroke.
According to the CDC,
- LDLR gene: Provides the instructions for making LDL receptors on the outside of certain cell types. The LDL receptors pick up circulating LDLs in the blood and bring them in for the cell to use.
- APOB gene: Allows LDLs to attach to LDL receptors, particularly those on liver cells.
- PCSK9 gene: Regulates the number of LDL receptors, making it important for controlling blood cholesterol levels.
According to the National Organization for Rare Disorders, males who do not receive treatment for FH have a 50% risk of having a heart attack by the age of 50 years, while females who do not receive treatment have a 30% risk of having one by the age of 60 years. Additionally, these risks increase for people who smoke or have diabetes.
However, it is important to note that a person who has FH will not necessarily go on to have a heart attack.
Having obesity can
Type 2 diabetes can occur as a result of a diet lacking in nutritious foods and a lack of physical activity. However, it can also have a genetic component. The more family members who have type 2 diabetes, the higher a person’s chances of developing the condition.
Not everyone with FH experiences symptoms. However, the
- bumps or lumps around the knees, knuckles, or elbows
- swelling or pain in the Achilles tendons
- yellowing around the eyes
- a whitish gray half-moon on the outside of the cornea, which is the protective layer of the eye
The above signs are due to the buildup of cholesterol in the relevant parts of the body.
Doctors may consider a diagnosis of FH when the following factors are present:
- LDL greater than 160 milligrams per deciliter (mg/dl)
- a family history of FH or premature heart disease
- LDL greater than 190 mg/dl
- a personal or family history of CAD at a younger age than expected
- physical signs or symptoms
In addition, most people with FH have a family health history of early heart disease or heart attacks.
Both children and adults can experience the above symptoms of FH.
Doctors can also order genetic testing to clarify whether a person has FH. These tests check for variations in one of three genes: LDLR, APOB, and PCSK9. However, the
Dietary and lifestyle modifications for people with FH include:
- avoiding smoking or vaping, if applicable
- eating a diet high in fresh fruits, vegetables, and fiber
- limiting saturated fats, trans fats, salt, and foods with added sugar
- limiting alcohol consumption
- taking part in regular exercise
- maintaining a moderate body weight
- regularly checking and controlling blood pressure and cholesterol levels
Additionally, people with FH should receive treatment for any accompanying cardiometabolic conditions, such as high blood pressure or type 2 diabetes.
- Making nutritious dietary choices: This includes:
- Maintaining a moderate weight: Excess body fat slows the body’s ability to clear LDL cholesterol.
- Engaging in regular physical activity: Regular exercise can help a person maintain a moderate weight.
- Quitting smoking, if applicable: Smoking damages the blood vessels and leads to hardening and stiffening of the arteries, increasing the risk of cardiovascular disease.
- Avoiding or limiting alcohol: Alcohol can contribute to raised cholesterol levels.
According to a 2019 study, people with undiagnosed FH may have a life expectancy around 16 years lower than those who have received a diagnosis of FH. The most likely cause of death is a cardiac event due to a buildup of cholesterol in the arteries.
The outlook for a person with FH also depends on the form of the condition they have. People with heterozygous FH inherit an FH genetic mutation from one biological parent. According to the National Organization for Rare Disorders, people with heterozygous FH have around a 10- to 20-fold increased risk of developing CAD.
Individuals with homozygous FH inherit an FH genetic mutation from both biological parents and tend to develop symptoms in childhood. Without treatment, these individuals are at risk of dying before the age of 30 years.
Therefore, it is important that people discuss their cholesterol levels with a doctor. This is especially true for those with a family history of FH and for individuals with other risk factors for high cholesterol.
High cholesterol levels can have various causes. One possible cause is the genetic condition familial hypercholesterolemia. People with this condition have a genetic mutation that impedes their body’s ability to clear cholesterol from the blood. This can lead to cardiovascular disease and an increased risk of heart attacks.
People with FH can make certain dietary and lifestyle modifications to help manage their cholesterol but will also likely need to take cholesterol-lowering medications, such as statins and PCSK9 inhibitors.
A person with concerns about their cholesterol levels should speak with their doctor, particularly if they have a personal or family history of high cholesterol or other risk factors for high cholesterol.