Scientists are calling for the creation of genetic sequencing catalogs for all populations after discovering “substantial” differences in genetic variation in the relatively short 400-year period of the French Canadian population.

Researchers at the University of Montreal and the Sainte-Justine University Hospital Center have discovered that the genomic signature of today’s 6 million French Canadians has “gone through an unparalleled change in human history, in a remarkably short timescale.”

The population has inherited its gene pool from the first 8,500 French settlers that colonized New France some 400 years ago.

The study, published online in PLOS Genetics, found rare genetic variants have changed more than expected in the population.

Dr. Alan Hodgkinson, co-first author and postdoctoral fellow at Sainte-Justine, says:

Through this first in-depth genomic analysis of more than 100 French Canadians, we have been surprised to find that, [in fewer than] 20 generations, the distribution and relative proportion of rare, potentially damaging variants have changed more than we anticipated.”

The unique signature of the French Canadian population could serve as an “ideal model” to study demographic effects on human genetic diversity, the researchers say. This could help to identify mutations associated with population-specific diseases.

Until now, they add, changes in the relative proportion of rare mutations had been shown only over relatively long timescales.

The authors propose that their findings are explained by the specific population effects of French colonization in Canada – they “demonstrate that the recent founding event and subsequent colonization events may have had a substantial deleterious impact across genomes.”

The rapid genetic variation could also have been influenced by founders coming from different regions in France or other European countries, and, the authors explain, by the unequal sex ratio of the Quebec settlers, of over 10 times more men than women.

“Although we understand from population genetics that most variants will be rare,” the researchers’ findings speak to the need for “continued sequencing of isolated or semi-isolated populations,” the authors say, concluding:

Beyond the particular case of the French Canadian population, this study highlights the importance of local demographic events in shaping genetic variation, and the need for creating population-based catalogs of human genetic variation.”

The surprising increase in rare variation among French Canadians is attributed by the researchers to the original settlers’ high birth rate.

The colony was also genetically isolated from France, and there was limited exchange with other non-French communities in the same geographical area, “since emigration virtually stopped after 1759, just before the English conquest.”

In fact, the scientists say, an estimated 90% of the current French Canadian genetic pool is traced to the founding population.

Dr. Philip Awadalla, senior author and principal investigator in the study, says there are medical implications to the research:

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.”