Hypertrophic cardiomyopathy: Who has an inherited risk?

The detective work

The genetic risk for HCM is passed from one generation to the next by way of dominant-acting mutations in genes governing the structure of the heart muscle. That means that first-degree relatives (parents, siblings, and children) of an affected person have a 50% chance of having inherited the same mutation. Before genetic testing became widely available, doctors had only this information to help guide families. Now, it's possible to determine if a family member is at risk for developing HCM even before the disease can be clinically diagnosed.

"When you decide do genetic testing, the implications go beyond just the individual being tested," says Dr. Ho. The most efficient approach is first to do comprehensive gene sequencing on the person with the most serious manifestation of disease. This gives the best chance of uncovering the most important disease-causing mutations. If an HCM mutation is found, other family members can undergo more limited—and less costly—screening to look for that specific mutation.