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HCM Genetics Testing & Counseling

Hypertrophic cardiomyopathy (HCM) is the most common genetic heart (cardiac) condition. It affects more than one in 500 people in the US. 

Genetic counseling and genetic testing can be helpful so you can learn more about your family’s risk (chances) of inheriting this condition.

DNA is the genetic material that provides instructions for what our bodies look like and how they work. Within our DNA we have over 20,000 genes. Each of these genes contain hundreds to thousands of DNA bases (A, T, C, and G), which spell out the code for a unique protein and have a unique role in your body.

Causes of Hypertrophic Cardiomyopathy: Genetic Mutations

Currently, there are 26 genes that have been associated with HCM. Two of the most common are called: 

  • MYH7and 
  • MYPBC3

We have two copies of each of these genes (one inherited from mom and the other from dad). HCM is caused when there is a disease-causing genetic change (mutation) in one copy of any one of these genes.

HCM is most commonly an autosomal dominant condition. This means that a person only needs one non-working copy of the gene in question to have HCM.

People with HCM have an underlying genetic change in these DNA bases (called a mutation). These mutations cause their heart muscles to develop abnormally.

For people with HCM, there is a 50 percent chance that each first-degree relative (parents, siblings, and children) also inherited the genetic mutation that causes HCM.

Can Genetic Testing Detect HCM?

Genetic testing can’t always detect the mutations that cause HCM. Doctors are learning more about the genes involved, but we know we haven’t identified every single gene that can cause HCM. 

For this reason, the percentage of time we are able to find a genetic change in an individual with HCM (also called the detection rate) is not 100 percent. We detect about 60 percent of the mutations (genetic changes) responsible for HCM.

Simply having a mutation that’s known to cause HCM doesn’t automatically mean you’ll develop the disease. Often times, people who have the same mutation known to cause HCM can have different presentations of the disease, even among family members. This means that not everyone with the HCM mutation will develop HCM.

Should I Get Screened for HCM?

If your family member has HCM and if your family member has a mutation that causes HCM, your family member’s children and siblings can get genetic testing. Genetic testing can help find these children’s and siblings’ chances of developing HCM.

Genetic testing can also help children and siblings know how often they should get a heart screening.

If children and siblings test negative for the HCM mutation, this means they do not have higher chances (increased risk) of developing hypertrophic cardiomyopathy or for passing it onto their children They also don’t need regular HCM screening. 

Sometimes people with HCM don’t seem to have any of the genetic mutations that cause HCM. In these cases, all first-degree relatives of the person with HCM should have non-invasive heart (cardiac) screening, starting in childhood. 

  • First-degree relatives should continue getting cardiac screening every year during their teen years, and then every three to five years after that.
  • Your cardiologist will also make recommendations for how often you should be screened.
Multigenerational family of women

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