Les probabilités de transmission des gènes fondateurs dans cinq populations régionales du Québec

Certain rare hereditary diseases have an unusually high incidence in the population of Quebec. The deleterious genes associated with these disorders were probably introduced in the seventeenth century by immigrants whose descendants are the ancestors of a large part of the modern population of Quebec. The goal of this study is to measure the differential transmission of the genes of founders at the origin of five regional populations of Quebec (Beauce, Charlevoix, Rimouski, Saguenay and Terrebonne). Using gene dropping, 50,000 simulations were performed with an initial sample of 756 ascending genealogies. The results show certain founders to have a non-negligible probability of having transmitted their genes to at least 5% of the population in the Charlevoix and Saguenay regions. The probabilities of reaching carrier frequencies between 1% and 5% (this is the frequency level at which several recessive genes in the population are found) are much higher, and for a larger number of founders in the five regions. Nevertheless, the observed differences between the probabilities obtained for the founders of each region suggest distinct trajectories in the transmission of founder genes, attributable to differential migratory and reproductive behaviour among the descendants of the founders.