Issue |
Med Sci (Paris)
Volume 23, Number 11, Novembre 2007
|
|
---|---|---|
Page(s) | 1008 - 1013 | |
Section | M/S revues | |
DOI | https://doi.org/10.1051/medsci/200723111008 | |
Published online | 15 November 2007 |
Effets fondateurs et variabilité génétique au Québec
Founder effects and genetic variability in Quebec
1
Centre de recherche, CHU Sainte-Justine, 3175, chemin de la Côte Sainte-Catherine, Montréal, Québec, H3T 1C5, Canada
2
Département de pédiatrie, Université de Montréal, Montréal (Québec) Canada
3
Groupe de recherche interdisciplinaire en démographie et épidémiologie génétique (GRIG), Département des sciences humaines, Université du Québec à Chicoutimi, 555, boulevard de l’Université, Chicoutimi (Québec) G7H 2B1, Canada
Au Québec, l’effet fondateur et ses conséquences sont souvent évoqués dans les études génétiques. La caractérisation de cet effet fondateur s’est beaucoup appuyée sur la distribution observée des maladies monogéniques : une grande partie des travaux portant sur la région du Saguenay. Pour obtenir une image plus globale de la diversité génétique, nous avons entrepris un programme de recherche sur l’ensemble des populations régionales du Québec visant l’examen de marqueurs neutres de plusieurs systèmes génétiques. Les résultats présentés ici indiquent que la population du Québec ne semble ni plus homogène ni très différente des populations européennes. On y observe cependant une série d’effets fondateurs régionaux surtout visibles au sein des systèmes génétiques qui contiennent des variants peu fréquents et plus ou moins marqués selon les caractéristiques des histoires démographiques régionales.
Abstract
Knowledge of the genetic population structure lies at the heart of mapping studies aiming genes responsible for Mendelian and complex traits. The Quebec population, which is of mostly French descent, is considered an excellent model for such genetic epidemiological endeavours because it is a young founder population. Yet, the assessment of the founder effect has relied mostly on the observed distribution of monogenic diseases and on the analysis of the underlying mutations with investigations focusing on the Saguenay region. To eliminate this clinical bias and to obtain a more complete image of the genetic diversity, different regional populations of Quebec were investigated by analysing neutral markers that represent maternal, paternal and X chromosome lineages. Results indicate that Quebec does not appear more homogeneous nor significantly different from European populations. However, a series of regional founder effects, particularly visible at the level of rare variants, are observed. These effects can be explained by the successive migrations of descendants of the first immigrants from the initial sites of settlement towards the outer regions. Depending on the number of founders and their diversity, as well as on the degree of isolation and the magnitude of the interbreeding with the neighbouring or local populations, such as Amerindians or later migrants, the consequences of these regional founder effects are more or less detectable in the contemporary population.
© 2007 médecine/sciences - Inserm / SRMS
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