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Admixed ancestry and stratification of Quebec regional populations

Authors

  • Claude Bherer,

    1. Centre de Recherche du CHU Sainte-Justine, Université de Montréal, Montréal, Québec, Canada
    2. Groupe de recherche interdisciplinaire en démographie et épidémiologie génétique, Université du Québec à Chicoutimi, Chicoutimi, Québec, Canada
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  • Damian Labuda,

    1. Centre de Recherche du CHU Sainte-Justine, Université de Montréal, Montréal, Québec, Canada
    2. Département de pédiatrie, Université de Montréal, Montréal, Québec, Canada
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  • Marie-Hélène Roy-Gagnon,

    1. Centre de Recherche du CHU Sainte-Justine, Université de Montréal, Montréal, Québec, Canada
    2. Département de médecine sociale et préventive, Université de Montréal, Montréal, Québec, Canada
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  • Louis Houde,

    1. Groupe de recherche interdisciplinaire en démographie et épidémiologie génétique, Université du Québec à Chicoutimi, Chicoutimi, Québec, Canada
    2. Département de mathématiques et d'informatique, Université du Québec à Trois-Rivières, Trois-Rivières, Québec, Canada
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  • Marc Tremblay,

    1. Groupe de recherche interdisciplinaire en démographie et épidémiologie génétique, Université du Québec à Chicoutimi, Chicoutimi, Québec, Canada
    2. Département des sciences humaines, Université du Québec à Chicoutimi, Chicoutimi, Québec, Canada
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  • Hélène Vézina

    Corresponding author
    1. Groupe de recherche interdisciplinaire en démographie et épidémiologie génétique, Université du Québec à Chicoutimi, Chicoutimi, Québec, Canada
    2. Département des sciences humaines, Université du Québec à Chicoutimi, Chicoutimi, Québec, Canada
    • Groupe de recherche interdisciplinaire en démographie et épidémiologie génétique (GRIG), Université du Québec à Chicoutimi, 555 boul. de l'Université, Chicoutimi, Québec, G7H 2B1
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Abstract

Population stratification results from unequal, nonrandom genetic contribution of ancestors and should be reflected in the underlying genealogies. In Quebec, the distribution of Mendelian diseases points to local founder effects suggesting stratification of the contemporary French Canadian gene pool. Here we characterize the population structure through the analysis of the genetic contribution of 7,798 immigrant founders identified in the genealogies of 2,221 subjects partitioned in eight regions. In all but one region, about 90% of gene pools were contributed by early French founders. In the eastern region where this contribution was 76%, we observed higher contributions of Acadians, British and American Loyalists. To detect population stratification from genealogical data, we propose an approach based on principal component analysis (PCA) of immigrant founders' genetic contributions. This analysis was compared with a multidimensional scaling of pairwise kinship coefficients. Both methods showed evidence of a distinct identity of the northeastern and eastern regions and stratification of the regional populations correlated with geographical location along the St-Lawrence River. In addition, we observed a West-East decreasing gradient of diversity. Analysis of PC-correlated founders illustrates the differential impact of early versus latter founders consistent with specific regional genetic patterns. These results highlight the importance of considering the geographic origin of samples in the design of genetic epidemiology studies conducted in Quebec. Moreover, our results demonstrate that the study of deep ascending genealogies can accurately reveal population structure. Am J Phys Anthropol, 2011. © 2010 Wiley-Liss, Inc.

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