More carriers of 12 rare genetic diseases in Quebec’s Saguenay–Lac-St-Jean than ‘anywhere in the world’: study
Posted March 2, 2023 8:35 pm.
Last Updated March 2, 2023 11:25 pm.
A high frequency of carriers for 12 rare genetic diseases is found in Saguenay–Lac-St-Jean than other parts of the world, according to a research conducted by a group of genetic counsellors at the region’s Centre intégré universitaire de santé et de services sociaux (CIUSSS).
The high-carrier frequency for these genetic disorders in the Saguenay population is unlike “anywhere in the world,” said Dr. Tania Cruz-Mariño, a medical geneticist at the McGill University Health Centre (MUHC).
“And then for us, it’s so frequent as to one in 32.”
Doctors at the CIUSSS, along with genetic counsellors at the University of Sherbrooke’s Biochemistry and Functional Genomics department, began studying the case after seeing an increasing number of French-Canadian families carrying rare diseases compared to the rest of the world. By Feb. 14, they published ‘Portrait of autosomal recessive diseases in the French-Canadian founder population of Saguenay-Lac-Saint-Jean’ in the American Journal of Medical Genetics.
“Five of these conditions are potentially lethal and there are three that will have some degree of developmental disorder,” said Dr. Cruz-Mariño.
Researchers attributed the founder effect to the phenomenon seeing as the carriers shared one thing in common: ancestors who carried the recessive genes to the same diseases and migrated to the region. This does not mean that the carriers are blood related or share close family ties as no consanguinity was found from the 1,000 DNA samples studied in this research.
“When the region is isolated, there is less contribution from other population to the genetic background which would dilute this first founder effect related to this disease,” explained Dr. Luigi Bouchard, a professor in the Department of Biochemistry and Functional Genomics professor at the University of Sherbrooke,
Dr. Bouchard adds that Saguenay–Lac-St-Jean tends to have bigger families in the region. Adding, “when you have more children, the risk to spread these mutations are increased.”
Dr. Cruz-Mariño and Dr. Bouchard are calling for more people of the founder population in the Quebec regions of Saguenay–Lac-St-Jean, Charlevoix and Haute-Côte-Nord to get screened for eight other genetic disorders, five of which are potentially lethal even during the prenatal stage.
