Hostname: page-component-586b7cd67f-rdxmf Total loading time: 0 Render date: 2024-12-02T18:19:26.244Z Has data issue: false hasContentIssue false
  • English
  • Français

Myotonic Dystrophy in Quebec: Geographical Distribution and Concept of Genetic Homogeneity

Published online by Cambridge University Press:  18 September 2015

Claude Laberge
Claude Laberge*
Affiliation:
Service de Médecine Génétique, Centre Hospitalier de l'Université Laval, Québec
*
CHUL, Room 9355, 2705 Boul. Laurier, Ste-Foy, Québec, Canada G1V 4G2
Rights & Permissions [Opens in a new window]

Abstract:

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

The geographical distribution relative to place of residence of patients with myotonic dystrophy (MD) and admitted to a Quebec hospital during a five year period (1980-1984) is presented and discussed. The sample consists of 72 males and 68 females of varying ages over 10 years. Analysis of the data shows a North Shore distribution of patients in a cline from Saguenay-Lac-St-Jean, through Quebec City and to Montreal. However, a low prevalence is apparent on the South Shore, east of Québec City, for which an historical and genealogical explanation are discussed. This geographic distribution favours the hypothesis of genetic homogeneity for the MD gene in the Quebec population. A stronger second argument comes from genealogical studies of 10 families sampled from the Chicoutimi Muscular Dystrophy Clinic. Genealogical paths traced to ancestors who founded Charlevoix for these 10 families go back to a cluster of 25 founders, one of whom must have been the carrier of the MD gene. The probative third argument for genetic homogeneity comes from the allellic distribution of the apolipoprotein E (ApoE) gene in the Québec City, Saguenay and in families with MD. The ApoE locus is on chromosome 19 and closely linked to MD. In MD-affected individuals there is a linkage disequilibrium for the e4 allelle while non-MD members of these families show allellic frequencies not differing significantly from the control population. This suggests that the gene that is carried by all MD patients (at least in Northeast Québec) came through a “founder effect” and was carried in -cis on the chromosome 19 of the first carrier. Consequences of this genie homogeneity in relation to studies of penetrance and phenotypic variation in clinical expressivity are discussed.

Type
SPECIAL SUPPLEMENT Dystrophie myotonique au Québec
Information
Canadian Journal of Neurological Sciences , Volume 16 , Issue 1 , February 1989 , pp. 123 - 128
Copyright
Copyright © Canadian Neurological Sciences Federation 1989

References

REFERENCES

1.Organisation Mondiale de la Santé. Classification Internationale des Maladies. Revision 9, 1975. Genève, 1977.Google Scholar
2.Thibault, MC, Mathieu, J, Moorjani, S, et al. Myotonic dystrophy: linkage with apolipoprotein E and estimation of the gene carrier status with genetic markers. Can J Neur Sci 1989, this issue.CrossRefGoogle ScholarPubMed
3. Girard Fr Éloi. Receuil de Généalogies des Comtés de Charlevoix et Saguenay. La Malbaie 1941; 575.Google Scholar
4.Jetté, R. Dictionnaire généalogique des familles canadiennes franÇaises. Des origines à 1730. Presses de l’Université de Montréal 1983; 1325.Google Scholar
5.Moorjani, S, Morissette, J, Laberge, C, et al. ApoE polymorphism in Québec population. Clin and Invest Med 1987; 10: 4, B51.Google Scholar
6.Bouchard, G, Morissette, J, Kouladjian, K. La statistique agrégée des patronymes du Saguenay et de Charlevoix comme indicateurs de la structure de la population aux XIXe et XXe siècles. Cahiers québécois de démographie 1987; 61: 67–98.Google Scholar
7.Sing, CE, Davignon, J. Role of apolipoprotein E polymorphism in determining normal plasma lipid and lipoprotein variation. Am J Hum Genet 1985; 37: 268–285.Google ScholarPubMed