In addition to characteristics such as eye color, skin color, and body shape, among others, there are a number of other conditions that can be passed on by parents to their children. Familial hypercholesterolemia is one of these and it affects about 1 in 200 to 250 people. It is caused by a gene mutation that leads to elevated levels of bad cholesterol (LDL-C) in the blood from a young age, such as levels higher than 190 mg/dL in adults. While those in this group may have a family history of hypercholesterolemia, such as a parent with the condition, or may have had coronary heart disease from a young age, hypercholesterolemia is generally accompanied by other external and environmental factors as well. As a result, proper planning and thorough knowledge of one’s physical condition and limitations can help to slow the progression of the disease. In the case of familial hypercholesterolemia, the most severe symptoms include heart attack and death, but risk can be reduced with the use of lipid-lowering agents and with genetic testing in order to determine whether an individual has inherited a gene mutation or not.
How does hypercholesterolemia occur?
Hypercholesterolemia is caused by certain genetic mutations that limit the body’s ability to remove LDL cholesterol from the blood, the most common being a mutation in the LDL receptor gene. This abnormal gene in the liver and in the extrahepatic tissue impairs the removal of bad cholesterol from the bloodstream and, as a result, from the body as well, which causes hypercholesterolemia. In addition, bad cholesterol can accumulate in various organs throughout the body, and if this happens in the coronary arteries, it can lead to coronary artery disease or an atheroma, which puts those with familial hypercholesterolemia at risk for developing heart disease at an early age. Familial hypercholesterolemia can be divided into two types:
- Heterozygous FH is caused by a mutation in one of the LDL receptor genes (from either the father or the mother), causing LDL cholesterol concentrations of about 350–500 mg/dl, which are double the concentrations found in the general population. In addition, this leads to a risk of developing coronary artery disease at an average age of 30-40 years.
- Homozygous FH is caused by mutations in both alleles of the LDL receptor (from both parents), causing LDL cholesterol levels of about 600-1,200 mg/dl, which are up to four times higher than those of the normal population. Most patients with this disease will die before the age of 20 if it is left untreated.
What are the benefits of genetic testing for hereditary diseases?
Genetic testing has a number of potential benefits, including:
- Helping to predict severity of a disease, allowing preventative steps to be taken before a disease becomes more severe.
- Allowing for more targeted treatment of diseases.
- Enabling physicians to choose the safest, most effective medications for their patients.
- Providing information helpful for family planning, as parents can find out in advance if there are any hereditary diseases that could be passed on to future children or not.
Who should receive genetic testing?
- People with high levels of LDL cholesterol in the blood
- People who have a family history of high levels of LDL cholesterol in the blood
- Those with a family member having had a heart attack or heart disease, especially at a young age
- People who have xanthomas (small yellow fat masses that have developed under the skin in areas such as the ankles, elbows, knees, or hands—Xanthomas)
- People who have xanthelasmas (yellowish-white lumps of fatty material accumulated under the skin around the eyelid areas)
- People with arcus cornealis (fat deposits deep in the edge of the cornea, causing a white or grey arc or ring around the outer region of the cornea)
How can hypercholesterolemia be prevented?
The risk of heart disease can be minimized and hypercholesterolemia levels can be reduced by leading a healthy lifestyle. For example:
- Eat heart-healthy foods such as fruits, vegetables, and whole grains. Avoid foods high in saturated fats, such as dairy products, fried foods, and palm oil.
- Lose weight if your weight is outside of normal, healthy levels.
- Exercise regularly.
- Don’t smoke.
Why do patients choose genetic testing at Bumrungrad?
The technology we use at the
Preventive Genomics & Family Check-up Services Center is proven to be both effective and accurate, while our laboratories meet international standards and our test results are certified worldwide. Our medical genetics specialists, cardiologists and other multidisciplinary physicians and specialists work together seamlessly with cooperation and teamwork to ensure they deliver the highest standards of care for heart disease patients and their families at every stage of life.
For details on genetic testing packages,
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Compiled by Assist.Prof.Dr. Polakit Teekakirikul
Cardiology and Medical Genetics Specialist
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