Variability of the genetic contribution of Quebec population founders associated to some deleterious genes.

Relatively high frequencies of some rare inherited disorders can be found in the Saguenay Region (Quebec). To understand this phenomenon, a research project on the 17th-century founder effect that led to the formation of French Canadians' gene pool is being carried out. The focus of this study is on founders who contributed to the Saguenay gene pool and who are related to contemporary probands suffering from any one of five hereditary diseases: cystic fibrosis, tyrosinemia, hemochromatosis, Charlevoix-Saguenay spastic ataxia, and sensorimotor polyneuropathia with or without agenesis of the corpus callosum. A control group has been added for comparison purposes. Altogether, 545 ascending genealogies have been reconstructed, using the Interuniversity Institute for Population Research's RETRO database, leading to > 2,500 founders. The genetic contribution of each founder to each group has been measured. Results show that (1) nearly 80% of the individuals' gene pool come from founders who settled in Nouvelle-France in the 17th century, whatever the group; (2) 15% of the founders explain 90% of the total genetic contribution of the founders, but this pattern varies from one group to another; (3) there is no subgroup of founders more related to any given group of individuals.