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Y-Chromosome based evidence for pre-neolithic origin of the genetically homogeneous but diverse sardinian population: inference for association scans

Contu, Daniela and Morelli, Laura Cornelia Clotilde and Santoni, Federico and Foster, Jamie W. and Francalacci, Paolo and Cucca, Francesco (2008) Y-Chromosome based evidence for pre-neolithic origin of the genetically homogeneous but diverse sardinian population: inference for association scans. PLoS One, Vol. 3 (1), e1430. ISSN 1932-6203. Article.

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DOI: 10.1371/journal.pone.0001430

Abstract

The island of Sardinia shows a unique high incidence of several autoimmune diseases with multifactorial inheritance, particularly type 1 diabetes and multiple sclerosis. The prior knowledge of the genetic structure of this population is fundamental to establish the optimal design for association studies in these diseases. Previous work suggested that the Sardinians are a relatively homogenous population, but some reports were contradictory and data were largely based on variants subject to selection. For an unbiased assessment of genetic structure, we studied a combination of neutral Y-chromosome variants, 21 biallelic and 8 short tandem repeats (STRs) in 930 Sardinian males. We found a high degree of interindividual variation but a homogenous distribution of the detected variability in samples from three separate regions of the island. One haplogroup, I-M26, is rare or absent outside Sardinia and is very common (0.37 frequency) throughout the island, consistent with a founder effect. A Bayesian full likelihood analysis (BATWING) indicated that the time from the most recent common ancestor (TMRCA) of I-M26, was 21.0 (16.0–25.5) thousand years ago (KYA) and that the population began to expand 14.0 (7.8–22.0) KYA. These results suggest a largely pre-Neolithic settlement of the island with little subsequent gene flow from outside populations. Consequently, Sardinia is an especially attractive venue for case-control genome wide association scans in common multifactorial diseases. Concomitantly, the high degree of interindividual variation in the current population facilitates fine mapping efforts to pinpoint the aetiologic polymorphisms.

Item Type:Article
ID Code:141
Status:Published
Refereed:Yes
Uncontrolled Keywords:Y-Chromosome, origin of genetic diseases, thalassemia, diabetes, multiple sclerosis, Sardinia
Subjects:Area 06 - Scienze mediche > MED/03 Genetica medica
Area 05 - Scienze biologiche > BIO/18 Genetica
Divisions:002 Altri enti e centri di ricerca del Nord Sardegna > CRS4 Center for Advanced Studies, Research and Development in Sardinia, Pula
001 Università di Sassari > 01 Dipartimenti > Zoologia e genetica evoluzionistica
Publisher:Public Library of Science
ISSN:1932-6203
Copyright Holders:© 2008 Contu et al.
Deposited On:18 Aug 2009 10:01

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