A gentleman came to see me recently. He’d just turned 50, and he said his family had been “bugging” him to get his heart checked. His mother had experienced complications with hypertrophic cardiomyopathy (HCM) – a serious condition that causes thickening of the walls of the heart. He’d heard the condition could be genetic.
“Here’s my mom’s genetic info,” he said, slipping a sheet of lab results into my hand.
I reviewed the results and, sure enough, his mother had a genetic marker for HCM. We had a discussion about the condition and potential implications for him, and I recommended he undergo genetic testing for HCM.
How does genetic testing work?
Genetic testing may sound scary, but for patients the test is actually really simple. We usually draw just one vial of blood or get a saliva sample. That’s it. This can be done in the clinic or later at a local laboratory.
After the patient and I talked, I contacted one of the commercial organizations we work with that performs the testing. The representative contacted the patient, they discussed insurance coverage (his out-of-pocket cost was about $50), and the representative requested a saliva sample. We then proceeded with testing.
Because his mother had HCM, the man had a 50 percent chance of inheriting the mutation. That means his brother did, too. The patient contacted his brother, who also decided to submit a saliva sample.
Genetic testing involves extracting DNA from blood and analyzing the approximately 10 to 20 genes where mutations are linked to HCM. Gene sequences from patients are compared with databases from normal and HCM-affected populations to determine patients’ level of risk.
It turns out that the man’s family was right to “bug” him – both he and his brother tested positive for a genetic mutation associated with HCM.
Who should get genetic testing for HCM?
We usually screen two groups of people for HCM: those who have the condition and those who have a family history of it with a known genetic marker.
Following current guidelines, if you have HCM we recommend all of your first-line relatives (your parents, kids, and siblings) receive genetic testing. If a genetic marker can be found in a patient with HCM, interested family members can be screened with a definitive genetic test rather than lifelong screenings that include heart scans and clinic visits.
As a regional referral center, we often see people in the other group – those who don’t have a known personal history of HCM but who do have a family member with the condition. Often, genetic testing has been done on that family member, and we can use his or her information to definitively screen other family members.
If your genetic screening comes back clear, you don’t need to worry, and you don’t need regular additional testing. If your test shows that you have a genetic marker for HCM, we move on to the next steps to prevent issues such as chest pain, fatigue, shortness of breath, and other serious symptoms before they develop.
We typically don’t recommend genetic testing for people who aren’t in one of these groups. The chance of anyone without a personal or family history of HCM to randomly test positive for HCM through genetic testing is about 1 in 1,000. In other words, there’s a fairly low likelihood that you would test positive for an HCM-related gene mutation if you have no family history of HCM and you don’t have HCM yourself.
What happens if I have a gene mutation?
If you have a gene mutation linked to HCM but don’t know whether you have the condition, our next step is to recommend heart testing to determine whether you have it. We usually recommend an echocardiogram and an electrocardiogram (EKG) to start. Depending on these results, we also may recommend performing an MRI or a stress echocardiogram or ask that you wear a Holter monitor (heart monitor) for a day or two.
Regardless of whether you have HCM, we will likely recommend that all your first-line relatives get a genetic screening for the HCM-related mutation. As I mentioned, there’s a 50 percent chance the marker could be passed on within your family, so we want to be able to determine who is potentially at risk.
Both the man who visited my office and his brother did not have any symptoms of HCM, but both carried the genetic mutation. Some people never manifest hypertrophy. The man has children in high school, though, and we strongly recommended that he have his kids screened. Puberty is a key time when we start seeing the heart’s septum enlarge – a telltale sign of HCM.
Regular screening intervals vary by age of the children and young adults who carry the HCM-related gene mutation. We work closely with collaborators at Children’s Health to get the tests they may need. Kids who test negative for carrying the gene marker may need no further testing.
Cost is becoming less of a barrier for genetic testing. Several years ago, genetic testing could cost thousands of dollars, often entirely out-of-pocket, but insurance companies are now starting to offer co-pays for genetic testing. Today, your out-of-pocket likely will be much less, usually between zero and $100.
Genetic testing allows us to focus on your individual cardiovascular care. Doctors don’t fully understand the mystery of what causes HCM, but genetic testing is helping us learn more about the condition.
When we know what gene markers to look for, we can help you avoid complications of HCM in the future. On top of that, we can help you avoid unnecessary testing, which can save you significant time and money.