The Genetic Roots of HCM: A Family Affair

Hypertrophic cardiomyopathy (HCM) is a condition where the heart muscle, particularly in the left ventricle, becomes abnormally thick. This thickening can stiffen the heart, making it harder to pump blood efficiently. Crucially, HCM is often inherited, meaning it’s passed down through families via a genetic mutation.

“It’s an autosomal dominant disease, meaning there’s a 50 percent chance a child will inherit the gene from a parent with HCM,” explains Matthew Martinez, MD, Director of Atlantic Health System Sports Cardiology at Morristown Medical Center. “This places all first-degree relatives – parents, siblings, and children – at significant risk.” However, the expression of the gene, and therefore the severity of HCM, can vary dramatically even within the same family.

Dr. Martinez notes, “You might see one family member requiring surgery, another remaining entirely asymptomatic, and yet another needing a heart transplant. The spectrum is wide.” This variability underscores the importance of proactive screening, even in the absence of noticeable symptoms.

Why HCM Often Remains Hidden

One of the most dangerous aspects of HCM is its often silent nature. Many individuals live with the condition for years, even decades, without experiencing any symptoms. Mild symptoms, such as shortness of breath during exertion or unexplained fatigue, are frequently dismissed as signs of aging or simply being out of shape.

“People rationalize their symptoms,” says Dr. Martinez. “They think, ‘I’m just getting older,’ or ‘I need to exercise more.’ They find reasons not to be concerned.” This leads to a startling statistic: up to 85 percent of people with HCM remain undiagnosed.

Diala Steitieh, MD, Director of the hypertrophic cardiomyopathy program at Weill Cornell Medicine, emphasizes the potential dangers of this lack of awareness. “Even without symptoms, the condition can progress, leading to complications like irregular heart rhythms or changes in heart function. In rare cases, undiagnosed HCM can tragically result in sudden cardiac death.”

Proactive Screening: A Lifeline for Families

Regular screenings are paramount for identifying HCM in at-risk individuals. These non-invasive tests, ideally conducted by a cardiologist specializing in HCM, typically include:

• Echocardiogram: An ultrasound that visualizes the heart’s structure and function, assessing how well it pumps blood.
• Electrocardiogram (ECG/EKG): Measures the heart’s electrical activity, detecting irregular rhythms and potential thickening of the heart muscle.
• Physical Exam and Family History: A thorough assessment of the patient’s health and a detailed review of their family’s cardiac history.
• Additional Tests: Depending on initial findings, a cardiologist may recommend a Holter monitor (for continuous rhythm tracking), an exercise stress test, or advanced imaging like cardiac MRI or CT scans.

Even a negative screening result doesn’t guarantee lifelong immunity. Repeat screenings are crucial to monitor for any changes over time. Fortunately, screening tests are generally covered by insurance for those with a first-degree relative diagnosed with HCM, though it’s always best to verify coverage details with your insurance provider.

Did You Know? Early detection of HCM through regular screenings can significantly improve treatment outcomes and reduce the risk of life-threatening complications.

Who Should Be Screened?

The recommendation is clear: anyone with a first-degree relative diagnosed with HCM should undergo screening. For children and adolescents, screenings should be repeated every 1-3 years. Adults should be screened every 3-5 years.

“Screening demonstrably leads to more diagnoses,” states Dr. Martinez. “And a diagnosis, even without symptoms, allows for informed treatment decisions and risk reduction.” While the necessity of screening second-degree relatives (aunts, uncles, cousins) is still debated, Dr. Steitieh advises, “Screening may be appropriate in certain situations, particularly with a strong family history, a known genetic mutation, or concerning symptoms.”

Protecting Young Hearts: HCM in Children

Children with a parent diagnosed with HCM face a 50 percent chance of inheriting the condition. Moreover, HCM tends to worsen more rapidly in children, increasing their risk of severe complications, including sudden cardiac death, even in the absence of symptoms.

Early screening is therefore vital for children and teens. They should be screened as soon as a first-degree relative receives a diagnosis, with follow-up screenings every 1-3 years. “A diagnosis allows for treatment, and treatment leads to better outcomes,” emphasizes Dr. Martinez.

Unlocking the Genetic Code: The Role of Genetic Testing

Genetic testing differs from screening but can be a valuable tool, particularly in families with a high prevalence of HCM. It identifies the specific gene mutation responsible for the condition in an individual. This information allows other family members to be tested to determine if they carry the same mutation.

“Unlike imaging tests, genetic testing can pinpoint which relatives are truly at risk and require ongoing cardiac evaluations, and which are less likely to develop the condition,” explains Dr. Steitieh. However, it’s important to remember that carrying a gene mutation doesn’t automatically mean someone will develop HCM. Furthermore, genetic testing has limitations. “We haven’t yet identified all the genes that can cause HCM,” Dr. Steitieh cautions.

If you choose to pursue genetic testing, you’ll first meet with a genetic counselor to discuss the benefits, drawbacks, and what to expect. A blood or saliva sample will be analyzed for HCM variants, and the results will be discussed with your counselor.

What questions do you have about the role of genetics in heart health? And how can we better support families navigating the complexities of HCM?

Frequently Asked Questions About Hypertrophic Cardiomyopathy

• What is the primary cause of hypertrophic cardiomyopathy?

  Hypertrophic cardiomyopathy is caused by genetic mutations that lead to the thickening of the heart muscle, particularly in the left ventricle.

• How often should first-degree relatives of someone with HCM be screened?

  First-degree relatives should be screened initially and then repeat screenings every 1-3 years for children and adolescents, and every 3-5 years for adults.

• Can genetic testing definitively tell me if I will develop HCM?

  Genetic testing can identify if you carry a known HCM-causing gene, but it doesn’t guarantee you will develop the condition, as not all carriers become symptomatic.

• What are the common symptoms of hypertrophic cardiomyopathy?

  HCM often has no symptoms, but when present, they can include shortness of breath, fatigue, chest pain, and palpitations.

• Is hypertrophic cardiomyopathy a life-threatening condition?

  While many people with HCM live normal lives, it can lead to serious complications, including sudden cardiac death, if left undiagnosed and unmanaged.