Hypertrophic cardiomyopathy (HCM) is a genetic heart condition that makes it hard for the heart to pump blood. Genetic testing is often recommended for family members of people with HCM.
In this article, Uzochukwu Ibe, MD, MPH, answers questions about genetic testing for hypertrophic cardiomyopathy, a genetic heart condition that can lead to sudden cardiac death.
Genetic testing for HCM requires a blood sample that is sent to a lab where DNA analysis is performed. The goal of this test is to identify errors in the protein made by that gene.
Genetic testing often involves a genetic counselor before and after testing.
Ideally, genetic testing should be performed in an HCM center. It’s done using different modalities looking for the eight most commonly identified sarcomere genes with the goal of identifying a disease-causing variant.
Family members should get post-mortem testing for HCM.
Sometimes, families are alerted to the presence of a genetic abnormality leading to HCM when there has been a sudden death in the family.
In this scenario, post-mortem testing is recommended to confirm the diagnosis of HCM and to facilitate genetic testing and clinical screening in first-degree relatives.
Genetic testing for HCM is very important for family planning.
HCM is passed through an autosomal dominant inheritance pattern, which means that if one parent has the gene, that disease-causing gene can be passed to the next generation.
Prenatal genetic counseling helps in explaining the risk of transmission and reproductive options like in vitro fertilization (IVF) and targeted genetic testing to ensure that all information is available to the family.
Having a positive genetic mutation for HCM doesn’t mean you have the condition, but it does make you at higher risk to develop HCM. Having said that, the presence of the mutation can let doctors know that they should keep track of your long-term health in regard to HCM.
If the disease-causing gene is inherited by a first-degree relative, they require lifelong surveillance. Those who do not carry the variant do not need lifelong surveillance.
Multiple faulty genes have been implicated in patients with HCM. The common genes are the beta myosin heavy chain 7 (MYH7) and myosin binding protein C3 (MYBPC3).
These two genes account for the majority of HCM while the other identified genes (TNNI3, TNNT2, TPM1, MYL2, MYL3, and ACTC1) are less commonly implicated.
Each offspring of a family member with HCM has a 50% chance of inheriting the variant. In some cases where the mutation is inherited, the disease process might not present itself.
Some genetic conditions may appear to skip a generation if no symptoms exist or the disease does not present itself.
In patients with suspected HCM, a transthoracic echocardiogram should be performed. All first-degree relatives of patients with HCM should have genetic testing coupled with an echocardiogram.
If there’s a positive genetic screening, echocardiograms may be done as frequently as every year or every 1 to 2 years.
Yes, you can get HCM without a family history. A subgroup of patients with HCM has no family history or any evidence of a genetic cause. We group this into a “non-familial” hypertrophic cardiomyopathy.
Uzochukwu Ibe, MD, MPH is a board certified Internal medicine physician and a board certified general Cardiologist. He is completing his fellowship in Interventional Cardiology in Akron, Ohio.