Thinking About Genetic Testing for Dilated Cardiomyopathy (DCM)?
We help you understand genetic testing for a heart condition called Dilated Cardiomyopathy (DCM).
What is Dilated Cardiomyopathy (DCM)?
DCM is a heart problem where the heart muscle in one or both of the main pumping chambers (ventricles) becomes stretched out (dilated) and weak (systolic dysfunction). This happens even when there are no other major heart problems like blocked arteries or leaky valves. DCM can be passed down in families, and scientists have found over 60 genes linked to it.
Why Should You Think About Genetic Testing for DCM?
Genetic testing for DCM is suggested and can be very helpful for you and your family.
Helping With Your Care and Treatment: Knowing about a specific gene change can guide your doctors in choosing the best treatments for you.
For example, if you have changes in genes like LMNA, FLNC, DES, RBM20, or PLN, you might have a higher risk of sudden cardiac death or heart failure. This information can help doctors decide if you need a special device, like an ICD (Implantable Cardioverter Defibrillator), or a pacemaker.
Helping Your Family (Cascade Testing): This is a very important reason to consider genetic testing.
If a gene change is found in you, your family members who might also have the gene (like your parents, brothers, sisters, or children) can get "cascade genetic testing". This means they get a specific test just for that gene change.
This can help find family members who have the gene change but don't have any symptoms yet. Finding it early can allow doctors to give them early treatment or advice that could prevent serious problems or even save their lives.
Family Planning: If you are planning to have children, genetic testing can help you understand the risk of passing DCM on to them. You can then talk to a genetic counsellor about options for family planning, such as preimplantation genetic testing (PGT) before pregnancy.
Understanding Your Genetic Test Results
Genetic test results are like clues; they tell you about the chances of something, not always a definite "yes" or "no".
How Gene Changes Are Classified: Gene changes are put into groups based on how likely they are to cause disease.
Pathogenic (P) or Likely Pathogenic (LP): These are gene changes that are considered to cause the disease or are very likely to cause the disease.
Variant of Uncertain Significance (VUS): This means there isn't enough information yet to say if the gene change causes disease or not. VUS results are usually not used to test other family members. More genes tested can lead to more VUS results.
Likely Benign or Benign: These gene changes are generally thought to be harmless.
Results Can Change Over Time: What a gene change means can sometimes change as scientists learn more. Because of this, it's a good idea to recheck the meaning of your gene changes every 2-3 years. Labs should inform patients if interpretations change.
Negative Results: If your test doesn't find a pathogenic or likely pathogenic gene change, it doesn't mean you don't have a genetic condition. It just means the test couldn't find the specific cause in your family. In these cases, family members should still have regular heart check-ups.
What This Means for Your Family (Cascade Testing)
Most inherited heart diseases, including many types of DCM, are usually passed down in an autosomal dominant way. This means that each child of a person with the gene change has a 50% chance of getting the same gene change. If a gene change that causes DCM is found in you, the next step is often to test and screen your family members.
Family Members with the Gene Change But No Symptoms: If a family member has the gene change but doesn't show signs of DCM, they should learn about the symptoms of DCM and know that they might carry the gene but never get sick, or get sick later in life (this is called "reduced penetrance" or "variable expressivity"). They should have regular heart check-ups to monitor for the disease.
Family Members Without the Gene Change: If a family member tests negative for the specific gene change found in your family, neither them nor their children are at risk of getting DCM from that gene.
Family Screening When No Gene Change is Found: If no disease-causing gene change is found in you, your family members will still need regular heart check-ups because heart problems can show up differently or at different ages in families.
Genetic Testing in Canada is Protected:
The Genetic Non-Discrimination Act (GNDA) protects people in Canada from discrimination based on genetic test results.
You cannot be forced to take a genetic test or share your results to access services, such as insurance, employment, housing, or financial products.
It is illegal for any company or organization to deny you service or charge you more because of your genetic information.
You must give written consent before your genetic test results can be collected, used, or shared.
These protections apply across many areas, including workplaces, insurance companies, banks, schools, and landlords.
The law includes strong penalties: up to $1 million in fines or up to 5 years in prison for violations.
The only exception is for health-care providers or researchers who use genetic testing for your medical care or approved studies.
Bottom line: Your genetic information is legally protected in Canada. You can pursue testing without fear of being treated unfairly.
