Abstract
Population isolates are a valuable resource for medical genetics because of their reduced genetic, phenotypic and environmental heterogeneity. Further, extended linkage disequilibrium (LD) allows accurate haplotyping and imputation. In this study, we use nuclear and mitochondrial DNA data to determine to what extent the geographically isolated population of the Val Borbera valley also presents features of genetic isolation. We performed a comparative analysis of population structure and estimated effective population size exploiting LD data. We also evaluated haplotype sharing through the analysis of segments of autozygosity. Our findings reveal that the valley has features characteristic of a genetic isolate, including reduced genetic heterogeneity and reduced effective population size. We show that this population has been subject to prolonged genetic drift and thus we expect many variants that are rare in the general population to reach significant frequency values in the valley, making this population suitable for the identification of rare variants underlying complex traits.
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Acknowledgements
This research received support from Fondazione Alma Mater Ticinensis (to AT), the Italian Ministry of the University FIRB-Futuro in Ricerca 2008 (to AA) and Progetti Ricerca Interesse Nazionale 2009 (to AA and AT), Compagnia di San Paolo, Torino, Fondazione Cariplo, Milano and Health Ministry Progetto Finalizzato (to DT). We would like to thank the inhabitants and the administrators of the Val Borbera for their kind participation in the study. A special thanks to Professor Clara Camaschella, Dr Silvia Bione, Dr Laura Crocco, Ms Maria Rosa Biglieri, Dr Diego Sabbi for help with the data collection, to Dr Gabriella Parodi, Dr Laura Gaggiano and the Cooperatova ARCA (Al) for help with the church archives. We acknowledge Professor Guido Barbujani, Professor Alberto Piazza, Professor Chris Tyler-Smith and Dr Kimmo Palin and two anonymous reviewers for valuable suggestions and comments on the manuscript.
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Colonna, V., Pistis, G., Bomba, L. et al. Small effective population size and genetic homogeneity in the Val Borbera isolate. Eur J Hum Genet 21, 89–94 (2013). https://doi.org/10.1038/ejhg.2012.113
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DOI: https://doi.org/10.1038/ejhg.2012.113
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