What is Hypertrophic Cardiomyopathy?
Hypertrophic cardiomyopathy (HCM) is a disease where the heart muscle becomes abnormally thick. This reduces the heart’s ability to pump blood efficiently, which, in severe cases, can lead to heart failure or cardiac arrest.
The clinical presentation of HCM is varied. It often goes undiagnosed because many people with the disease can be asymptomatic, or have very few symptoms, and can lead normal lives without significant problems. However it can also cause sudden death, and is the most common cause of sudden cardiac death among young people and trained athletes.
HCM is a common condition that affects people of any age, sex and all ethnicities. It is found in about one in every 500 people.
What causes Hypertrophic Cardiomyopathy?
HCM is most often caused by genetic abnormality – to date, there have been several hundred mutations affecting more than 15 genes associated with HCM. It is an autosomal dominant condition, meaning that individuals have a 50 percent chance of inheriting the predisposition for this condition from parents, and passing it on to their children as well. The disease does not skip generations.
However, the manifestation of the condition varies greatly, even within the same family. If one family member carries the HCM gene and develop severe symptoms, it does not mean that other family members will have similar symptoms – some may only have mild symptoms, or even be asymptomatic throughout their lives.
Why test for Hypertrophic Cardiopathy?
Genetic testing can confirm a diagnosis of HCM by identifying any gene mutation that is known to cause HCM in you. If the gene mutation is identified in you, your relatives who are at risk for HCM (parents, siblings, children) can be tested for the same gene change. This allows for early identification of relatives that are predisposed to developing HCM, and any individual with the identified gene mutation should consult regularly with a cardiologist. But if your relatives are shown not to carry the gene mutation causing HCM in your family, they will not need any further checks for HCM.
Genetic testing could also tell if a patient is likely to develop electrical abnormalities (also called arrhythmias), which could mean that the patient is at risk of sudden cardiac death. There is a five percent risk of sudden cardiac death at adolescence, and the probability tapers off with age. Only one percent of all patients with HCM are at risk for sudden cardiac death.
Finally, genetic testing can help in family planning. If any parent tests positive for a HCM-causing gene mutation, the mutation can be passed on to the next generation.
How does the test work?
The genetic test for HCM is a blood test ordered by your physician. Your DNA is extracted from the blood and analyzed by searching specifically for mutations in any genes that are associated with HCM. The test takes approximately four weeks to complete, and the results will be sent to your physician, who will explain the test results to you.
We will need two tubes of blood (about 7 to 10ml) and a signed consent form from you to send to the laboratory. We recommend genetic counseling before genetic tests are ordered to discuss the implications of the testing and potential results.