April’s Topic is Genetic Testing

Who should have genetic testing, why, and when?

Suppose you have been clinically (through an EKG, echocardiogram, and a visit with a cardiologist) diagnosed with HCM. In that case, most experts recommend that you have genetic testing to determine the underlying reason your heart is too thick.

Why does it matter?  

Some hearts look like HCM but have a specific genetic mutation for one of the HCM spectrum disorders – Amyloidosis, Fabrys, Danon, Sarcoidosis, etc. These disorders are often managed differently from HCM alone, so you need to know if you have one.

HCM is mainly caused by gene mutations (sometimes called variants or markers). Not all HCM is linked to a specific variant, and we believe more mutations will be identified in the future. 

In recent studies at large HCM Centers, about 40% of those tested had a gene mutation known to cause HCM. As of 2023, 60% will not have a mutation currently identified as causing HCM. It is still believed that HCM is a genetic disorder that families can pass down – even if the mutation is currently unknown. 

Your genetic test can show one of three results:

• Positive / Mutation identified (you have a known variant). 
• Negative / No mutation identified (you do not have a known variant).
• VUS (a variant of uncertain significance whose meaning is still evolving). It’s a bit confusing, but as researchers learn more, a VUS can be reclassified as a positive or negative.

If your genetic test is positive, this information can be used to screen family members to see if they have the same variant. Your children, parents, and siblings can be tested for your variant, and if they don’t have it, they can skip clinical tests (echocardiogram, etc.) unless they develop heart symptoms. 

A negative genetic test DOES NOT take away your HCM diagnosis, and it DOES NOT mean that your family can safely avoid clinical screening for HCM (echocardiogram, EKG, and an exam by a cardiologist). Researchers are still discovering variants that may cause HCM and are starting to look into combinations of two or more genetic variants (polygenetic) that could cause HCM. If you do not have a known variant, your close relatives must be screened regularly using clinical tests to see if they develop HCM. 

Once you’ve gone through our free Intake process, we will invite you to join our new Nest education program.  For a great explanation of genetic testing in HCM, sign up for the Nest portal when you’re invited.

Knowing your mutation may allow gene therapy to treat your HCM in the future. Clinical gene therapy trials for those with a mutation on MYBPC3 have started! We expect other common HCM variants (such as MYH7, etc.) to be included in future clinical trials.

A last thought: many people who test positive for one of the known variants say, “I have the gene for HCM,” but this is misleading. They have a mutation on one of many genes that may contribute to HCM.For more information about genetics and genetic testing, please visit the HCMA website at https://4hcm.org/genetic-testing-an-overview/ and https://4hcm.org/genetic-testing-other-considerations/.