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Objectives: To investigate genetic homogeneity in a set of hypertensive families and in subsets chosen for high and low prevalence of obesity; and to compare fasting insulin and lipids, ion transport, and water homeostasis in the obese and lean families. Research Methods and Procedures: The study was carried out in a relative population isolate of the Saguenay/Lac St. Jean region in Canada. Genetic homogeneity was evaluated with the mean coeffigcients of kinship (φ) and inbreeding (F) computed with ascending genealogies. Serum insulin and lipids were measured after overnight fasting. Total body water was estimated with bioelectrical impedance. Sodium-lithium countertransport and sodium-potassium co-transport were determined in freshly isolated erythrocytes. Results: F and φ were increased in hypertensive families compared with families selected at random. F and φ were further increased within the subsets of obese and lean families. In addition, fasting insulin, total body water, sodium-lithium countertransport, and sodium-potassium co-transport were higher in the obese than in the lean families. The two subsets of families did not differ by fasting lipids. Discussion: In the Saguenay/Lac St. Jean population, the degree of genetic homogeneity was increased in families selected for hypertension, and it was further increased in subsets of hypertensive families with high and low prevalence of obesity. This suggests that hypertension in lean and obese individuals may represent, at least in part, separate genetic entities. Some of the extra genes shared in common within the subsets may contribute to their differences in body weight, insulin sensitivity, ion transport, and water homeostasis.

Summary Data from uniparentally inherited genetic systems were used to trace evolution of human populations. Reconstruction of the past primarily relies on variation in present-day populations, limiting historical inference to lineages that are found among living subjects. Our analysis of four population groups in the Gaspe Peninsula, demonstrates how this may occasionally lead to erroneous interpretations. Mitochondrial DNA analysis of Gaspesians revealed an important admixture with Native Americans. The most likely scenario links this admixture to French-Canadians from the St. Lawrence Valley who moved to Gaspesia in the 19th century. However, in contrast to genetic data, analysis of genealogical record shows that Native American maternal lineages were brought to Gaspesia in the 18th century by Acadians who settled on the south-western coast of the peninsula. Intriguingly, within three generations, virtually all Metis Acadian families separated from their nonadmixed relatives and moved eastward mixing in with other Gaspesian groups, in which Native American maternal lines are present in relatively high frequencies. Over time, the carriers of these lines eventually lost memory of their mixed Amerindian-Acadian origin. Our results show that a reliable reconstruction of population history requires cross-verification of different data sources for consistency, thus favouring multidisciplinary approaches.