Findings could lead to low-cost genetic screening for people in Quebec at risk for certain inherited cancers
Source: McGill University
August 25, 2025
Researchers have shed new light on the most common genetic variant linked to hereditary cancer in Quebec's French-Canadian population. Their findings could result in cheaper and more effective screening methods.
The variant is associated with Lynch syndrome, a condition that greatly increases the risk of colorectal and other cancers.
Using genetic data from the CARTaGENE population cohort and genealogical records from the BALSAC database, the researchers traced the variant back roughly 11 generations to a single ancestor. The team, co-led by William Foulkes, MBBS, PhD, senior scientist in the Cancer Research Program at the Research Institute of the McGill University Health Centre (The Institute), estimates that about one in 800 French-Canadians carries the mutation, with higher rates in regions such as Charlevoix, Côte-de-Beaupré, Saguenay–Lac-Saint-Jean, Beauce and Côte-du-Sud.
The variant, PMS2 c.2117del, was originally discovered in 2008 in several members of a single Quebec family who had Lynch syndrome. What wasn't known until now was how widespread the variant is across the population, or where it originated.
"This study shows how clinical data can deepen our understanding of Quebec's genetic history, and how historical records can clarify current genetic risks," said co-leader Simon Gravel, Professor in the Department of Human Genetics at McGill.
Dr. Foulkes said the findings could help make genetic screening to identify Quebecers at elevated risk of hereditary cancer cheaper and more effective. "The fact that this pathogenic variant is so common suggests we could design a low-cost test targeting just a dozen variants that could catch those at high risk for up to 50 per cent of inherited cancers."
Early detection of colorectal cancer is key, as the disease is often highly treatable when caught early, added Dr. Foulkes. This discovery could thus pave the way for more effective and personalized prevention strategies for at-risk families in Quebec.
About the study
PMS2 c.2117del (p.Lys706Serfs*19) is the Most Frequent Cancer-Associated Founder Pathogenic Variant in the French-Canadian Population of Quebec, Canada by Anne-Laure Chong, Alejandro Mejia-Garcia, Supriya Behl, Zaki El Haffaf, Sébastien Chénier, Bruno Maranda, Valérie Désilets, Sébastien Lévesque, Lysanne Castonguay, Anne-Marie Mes-Masson, Sylvie Giroux, François Rousseau, Nancy Hamel, George Chong, Simon Gravel, and William D. Foulkes was published in Clinical Genetics.
The study was supported by Génome Québec, the Ministère de l'Économie, de l'Innovation et de l'Énergie, CanPath and CARTaGENE.
Media Contact:
Keila DePape, Media Relations, McGill University
keila.depape@mcgill.ca