03:58am Wednesday 15 July 2020

Cutting-edge genetic testing identifies inherited risk for enlarged heart

Montreal  – A study presented today at the Canadian Cardiovascular Congress has identified the genetic mutations that account for a significant proportion of cases of familial dilated cardiomyopathy (DCM), a disease affecting thousands of Canadians.

For many people with DCM – an enlarged heart and weakened heart muscle – the first sign of trouble might be sudden death. About 30 per cent of cases are thought to be genetic (also known as ‘familial’).

If someone has that family form of the disease, there’s a 50 per cent chance of passing on the risk to their offspring. Researchers at the Montreal Heart Institute have now used cutting edge genetic testing to detect that risk.

“It’s important to diagnose DCM before it presents symptoms. If we do it early, we can sometimes prevent progressive heart failure, heart transplantation or sudden death,” says Dr. Rafik Tadros, electrophysiology and genetics fellow at the Montreal Heart Institute.  

An additional benefit of identifying these individuals is that family members can be tested to determine if they are carriers of these mutations and take measures to reduce their risk.

The team, led by Drs. Guillaume Lettre and Mario Talajic, identified, among other findings, mutations in the TTN and BAG3 genes carried by a significant number of family members of people with inherited DCM.

To get a more accurate picture of the risks, the Montreal Heart Institute performed whole exome DNA sequencing in 27 families who are followed at their cardiovascular genetics clinic.

“By analyzing the coding part of the whole genome we were able to identify some of the genetic mutations linked to DCM, giving us a greater understanding of how to deal with this important condition,” says Dr. Tadros. “It has opened the door to understanding the role these genes play and can help us prevent sudden cardiac death in relatives.”

Traditionally, two methods have been used for early detection of hereditary DCM: echocardiography, a type of imaging, and genetic testing which only looked at five genes for mutations. Both methods have their limitations.

 “What’s amazing is that we used to look at one sentence in your genetic blueprint, and now we can read the entire book,” says Dr. Beth Abramson, Heart and Stroke Foundation spokesperson.  “We have found more pages that can identify family members at risk earlier and more thoroughly than ever  for better understanding, diagnosis and treatment.”

She also notes, “This is exciting information for physicians working with these rare cases but is also important to remember that the most common causes of heart disease relate to lifestyle. It is important that all of us, regardless of family history, take care of our hearts: small but important changes like smoking cessation, following a healthy diet, and physical activity go a long way in protecting our health.”

As Dr. Tadros explains, mutations in TTN and BAG3 account for a significant proportion of familial DCM – and neither gene is screened in typical genetic testing. “For families that may be at risk, the results of this study will lead to earlier diagnosis and targeted prevention.”

The Canadian Cardiovascular Congress is co-hosted by the Heart and Stroke Foundation and the Canadian Cardiovascular Society.

 
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About the Montreal Heart Institute: www.icm-mhi.org

Information: Julie Chevrette, Communications Officer
Montreal Heart Institute
514 376-3330, ext. 2641 | [email protected]


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