Researchers at the Sainte-Justine University Hospital Center and University of Montreal have discovered that the genomic signature inherited by today's 6 million French Canadians from the first 8,500 French settlers who colonized New France some 400 years ago has gone through an unparalleled change in human history, in a remarkably short timescale. This unique signature could serve as an ideal model to study the effect of demographic processes on human genetic diversity, including the identification of possibly damaging mutations associated with population-specific diseases.
Until now, changes in the relative proportion of rare mutations, that could be both detrimental and adaptive, had only been shown over relatively long timescales, by comparing African and European populations. According to Dr. Alan Hodgkinson, the co-first author of an article published online in PLOS Genetics recently and a postdoctoral fellow, “through this first in-depth genomic analysis of more than a hundred French Canadians, we have been surprised to find that in less than 20 generations, the distribution and relative proportion of rare, potentially damaging variants have changed more than we anticipated.”
Such an increase in rare variation is presumably due to a high birth rate of the settlers and the genetic isolation from France, with limited exchange with other non-French communities in the same geographical area, since emigration virtually stopped after 1759, just before the English conquest. Indeed, the founding population is estimated to have contributed 90% of the current French Canadian genetic pool.
According to Dr. Philip Awadalla, senior author and principal investigator, “the fact that two very close populations (French versus French Canadians) accumulate such an excess of differences in rare variants has important consequences in the design of genetic studies, including the identification of possibly damaging mutations associated with diseases specific to this population.” The model unveiled by the researchers could also serve conservation genetics, namely in determining the impact of genetic diversity on the minimal number of individuals required for the survival of specific species or captive populations.
About the study
This first whole-exome sequencing study of the French Canadian population was performed at the Child Health Genomics Platform of the Sainte-Justine University Hospital Research Center and Genome Quebec - McGill University Innovation Center. The results were published on line in PLOS Genetics on September 26, 2013, under the title “Whole-Exome Sequencing Reveals a Rapid Change in the Frequency of Rare Functional Variants in a Founding Population of Humans” The study benefited from the financial support of Genome Québec, Canadian Foundation for Innovation, and the Canadian Institute of Health Research.
About the researchers
Dr. Philip Awadalla
· Principal investigator, at Sainte-Justine University Hospital Research Centre
· Professor, Department of Pediatrics, University of Montreal
· Principal Investigator and Scientific Director, CARTaGENE
Dr. Alan Hodgkinson
· Fonds de recherche du Québec – Santé Postdoctoral Fellow, Sainte-Justine University Hospital Research Center
About the Sainte-Justine University Hospital Center's Research Center
The Sainte-Justine University Hospital Research Center is a leading mother-child research institution affiliated with the University of Montreal, officially known as Université de Montréal. It brings together more than 1200 people, including over 215 researchers and 415 graduate and post-graduate students who carry out fundamental, clinical, translational, and evaluative research on mother and child health. Research work falls under six research axes, namely Health Outcomes; Brain Diseases; Musculoskeletal Diseases and Movement Sciences; Viral and Immune Disorders and Cancers; Fetomaternal and Neonatal Pathologies; and Metabolic Health. It is focused on finding innovative prevention means, faster and less invasive treatments, as well as personalized approaches to medicine. The Center is part of the Sainte-Justine University Hospital Centre, which is the largest mother-child centre in Canada and second most important in North America. More on www.chu-Sainte-Justine.org/research/
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Dr. Hodgkinson and Professor Awadalla are available for interviews by appointment.
Mélanie Dallaire, senior consultant, media relations, Sainte-Justine University Hospital Center
Office : 514 345-7707 or 514 345- 4663 Pager : 514 415-5727
William Raillant-Clark, Université de Montréal
Marise Daigle, communication consultant, Sainte-Justine University Hospital Center's Research Center