Cardiovascular Genetics

Is heart disease hereditary?

Sometimes. Some changes in our genes can increase our risk for certain heart conditions, and can be passed down through families. Heart conditions can be caused by a number of factors — some we have control over, like diet and exercise, and others we don’t, like genetic changes.

Because of their complex nature, current genetic testing is generally not very useful in guiding medical care for individuals with a personal or family history of many cardiovascular conditions, and family history is often the best guide. There are instances, however, in which a heart condition can be attributed to a change in one specific gene. For these conditions, genetic testing can be extremely useful in informing treatment plans and educating family members about their personal heart health risks.

When should genetic testing be considered?

If you think your family may have an inherited heart condition, it is important to collect information about your family medical history. Consider whether any family members have had heart conditions, died suddenly or unexpectedly, or had other major medical problems. Specifically, consider whether you or any family members have experienced:

• Heart conditions present at birth
• Irregular heartbeat (arrhythmia)
• Sudden and unexplained cardiac arrest
• Unexplained fainting during exercise or emotional stress
• Heart failure under 60 years of age
• ICD/pacemaker installed under 50 years of age
• Early heart attack, coronary heart disease, or stroke (men under 55, women under 60)
• Untreated high cholesterol levels
• Enlarged heart, enlarged aorta, or aortic aneurysm before age 55

The individual in the family who is most seriously affected is typically the ideal candidate for testing, as this is the person for whom there is usually the highest likelihood of identifying a related genetic change.

Common hereditary heart diseases

Familial Hypercholesterolemia (FH)

Familial Hypercholesterolemia is an inherited condition affecting an individual’s ability to process LDL (“bad”) cholesterol. When untreated, FH can cause dangerously high LDL levels, leading to atherosclerotic plaques and an increased risk for coronary artery disease, heart attack, or stroke. For individuals with FH, heart attacks or strokes may occur at young ages, and cholesterol may be high even without other risk factors.

FH is fairly common from a genetics perspective, occurring in about 1 in every 250 people. It is estimated that 9 out of 10 individuals with FH do not know they have it. An early diagnosis is important because there are effective treatments available that can significantly reduce cardiovascular risks. FH is typically inherited in an autosomal dominant pattern: if one parent has FH, there is a 50% chance their child will inherit it.

Hypertrophic Cardiomyopathy (HCM)

Familial Hypertrophic Cardiomyopathy is characterized by thickening of the heart muscle, which can keep the heart from beating properly or impede blood flow. Individuals with HCM are at increased risk for irregular heartbeats, sudden cardiac arrest, or heart failure. HCM is one of the most common genetic heart diseases, affecting about 1 in 500 people. Like FH, it is inherited in an autosomal dominant pattern.

Long QT Syndrome

Long QT Syndrome affects the heart’s electrical conduction system and can cause fast, chaotic heartbeats that lead to fainting, seizures, or in some cases sudden death. Cardiac events can be triggered by certain medications, loud noises, emotional distress, or exercise. If an individual knows they have Long QT, however, there are ways to manage the condition effectively. Long QT is inherited in an autosomal dominant pattern and is estimated to occur in 1 in every 2,000 people.

How can genetic counseling help?

A cardiovascular genetics consultation includes review of your family health history, with a focus on known cardiovascular diagnoses as well as signs and symptoms that may be associated with hereditary conditions. Your genetic counselor will discuss the possibility of a hereditary cardiovascular condition that could be diagnosed with genetic testing, how a clinical diagnosis (such as a work-up by a cardiologist or electrophysiologist) may be an important part of interpreting certain genetic results, and how your results might impact other family members.

In some cases, your genetic counselor may suggest initiating testing with a different family member, as this can sometimes make targeted and informative testing more possible for you and other relatives.