Almost everyone has a personal or family history of some sort of heart condition. Individuals can be born with a heart defect or develop a heart condition at a later point in their lives. We have continued to research the causes of heart conditions and have come a long way from even ten years ago. While a lot of heart conditions like heart failure, arrythmias, and coronary artery disease can be a combination of genetics and environment, there are some heart conditions like hypertrophic cardiomyopathy that have been found to have a hereditary genetic cause and can be passed from generation to generation in a family.
What is Hypertrophic Cardiomyopathy?
Hypertrophic cardiomyopathy is a heart condition that involves a thickening of the heart muscle. The portion of the heart muscle that separates the lower left chamber from the lower right chamber is extra thick and can block the flow of oxygen-rich blood. This can lead to an abnormal heartbeat and the heart is not as efficient at pumping blood. Typically, someone with hypertrophic cardiomyopathy can be diagnosed in young adulthood, but it can happen at any point of life. Sometimes people with hypertrophic cardiomyopathy have no symptoms and don’t know until they are diagnosed. Other people can have chest pain, shortness of breath, heart palpitations, lightheadedness, dizziness, and fainting. While many people only have mild symptoms or are symptom-free, hypertrophic cardiomyopathy increases the risk of sudden death or sudden heart failure.
What to do With a Hypertrophic Cardopmyopathy Diagnosis
When an individual is diagnosed with hypertrophic cardiomyopathy, it is important to ask about their family history. If someone has family members also diagnosed with hypertrophic cardiomyopathy, symptoms of heart conditions, suddenly passed away of unknown cause (or in an accident or drowning and how it happened is unclear), or has any history of heart conditions, genetic testing should be considered. There are several genes, or packages of genetic instructions in every cell of our bodies, that are known to cause hypertrophic cardiomyopathy and can be passed down from generation to generation. The most common genes known to cause familial hypertrophic cardiomyopathy are MYH7, MYBPC3, TNNT2, and TNNI3. These genes provide genetic instructions that produce proteins that play important roles in forming muscle cell structures called sarcomeres. Sarcomeres are the basic component of muscle that cause a muscle to contract. If the genes are not working properly, the protein does not work, and the muscle can’t contract in the way our body needs.
It is also important to remember that even if you don’t have a family history of hypertrophic cardiomyopathy and are diagnosed with the condition, about 20%-30% of individuals found to have a change in one of the genes we discussed actually do not have a family history. It can be found to be a new change in the gene of the person diagnosed with hypertrophic cardiomyopathy.
An individual diagnosed with hypertrophic cardiomyopathy can be referred to a genetic counselor or someone who specializes in genetic testing to discuss the option of pursuing genetic testing. A genetic counselor will discuss your family history and diagnosis and talk about genetic testing options. It is common to have a genetic test for cardiomyopathy that tests for multiple genes that could be the cause of your condition, because it is important to cover all the genes that seem appropriate to your situation and family history. The genetic counselor will send you to a lab to have your blood drawn, and then your blood will be used by the lab to analyze your genes to look for any changes.
Genetic Testing for Heart Conditions
While the most common types of results from a genetic test are either positive (meaning a change was found in one of your genes that causes disease) or negative (no change was found in any of the genes tested), there is another type of result that can occur. A change can be found in one of your genes that we are not sure causes your heart condition or what is seen in your family history. These types of changes are called variants of uncertain significance. A variant of uncertain significance can be seen because we do not have enough data or research on those changes to determine if it causes disease or if it is benign. In those situations, the lab continues to gather data over the next several years and hopefully changes your result to either positive or negative once they have enough data on that change.
If you are found to have a positive genetic testing result, this means that a change in one of your genes was found and is known to cause hypertrophic cardiomyopathy. It is recommended to discuss your results with your doctor as well as your family, and to potentially have your family members tested if they have a desire to do so. For most genes associated with hypertrophic cardiomyopathy, there is a 50% chance for each family member to inherit the gene change as well.
Please contact AT-GC to meet with a genetic counselor if you would like to pursue genetic testing, have a personal or family history of hypertrophic cardiomyopathy, or are interested in learning more.