Population structure in Argentina
May
Population structure in Argentina
Marina Muzzio 0 1 2
Josefina M. B. Motti 0 2
Paula B. Paz Sepulveda 0 1 2
Muh-ching Yee 0 2
Thomas Cooke 0 2
MarÂõa R. Santos 0 1 2
Virginia Ramallo 0 2
Emma L. Alfaro 0 2
Jose E. Dipierri 0 2
Graciela Bailliet 0 1 2
Claudio M. Bravi 0 1 2
Carlos D. Bustamante 0 2
Eimear E. Kenny 0 2
0 sphere came from Mozambique , Loango and Angola
1 Instituto Multidisciplinario de BiologÂõa Celular (IMBICE) CCT-La Plata CONICET-CICPBA, La Plata , Buenos Aires , Argentina , 2 Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata , Buenos Aires , Argentina , 3 Universidad Nacional del Centro de la Provincia de Buenos Aires , FACSO, NEIPHPA, Quequ eÂn, Buenos Aires , Argentina , 4 Stanford University, Stanford, California, United States of America , 5 CENPAT CONICET, Puerto Madryn, Chubut, Argentina, 6 INECOA ( Instituto de Ecorregiones Andinas) UNJu-CONICET, Instituto de BiologÂõa de la Altura, Universidad Nacional de Jujuy, San Salvador de Jujuy, Jujuy, Argentina, 7 Charles Bronfman Institute for Personalized Medicine, Icahn School of Medicine at Mount Sinai , New York, New York , United States
2 Editor: Taras K Oleksyk, Recinto Universitario de Mayaguez Universidad de Puerto Rico , UNITED STATES
We analyzed 391 samples from 12 Argentinian populations from the Center-West, East and North-West regions with the Illumina Human Exome Beadchip v1.0 (HumanExome-12v1A). We did Principal Components analysis to infer patterns of populational divergence and migrations. We identified proportions and patterns of European, African and Native American ancestry and found a correlation between distance to Buenos Aires and proportion of Native American ancestry, where the highest proportion corresponds to the Northernmost populations, which is also the furthest from the Argentinian capital. Most of the European sources are from a South European origin, matching historical records, and we see two different Native American components, one that spreads all over Argentina and another specifically Andean. The highest percentages of African ancestry were in the Center West of Argentina, where the old trade routes took the slaves from Buenos Aires to Chile and Peru. Subcontinentaly, sources of this African component are represented by both West Africa and groups influenced by the Bantu expansion, the second slightly higher than the first, unlike North America and the Caribbean, where the main source is West Africa. This is reasonable, considering that a large proportion of the ships arriving at the Southern Hemi-
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Funding: MM, JMBM, GB and CMB are funded by
the Consejo Nacional de InvestigacioÂn CientÂõfica y
TecnoloÂgica (CONICET; http://www.conicet.gov.ar/
?lan=en) and the Agencia Nacional de PromocioÂn
CientÂõfica y TecnoloÂgica (http://www.agencia.
mincyt.gob.ar/), Argentina; MM also received
Introduction
One of the most important applications of admixture research is to reduce bias of association
studies, since it has long been known that the underlying genetic structure can produce a high
percentage of false positive results due to differences in the genetic composition of cases and
controls [1±6]. This bias occurs when the frequency of the case disease varies between
populations, so that the probability of selecting affected individuals from specific subpopulations
grows; thus, any allele with a higher frequency in the over represented population will show an
association with the phenotype [7±9].
funding from the Pew Charitable Trusts (http://
www.pewtrusts.org/en).
DNA studies allow researchers to analyze population differences as well as the ancestry of a
given individual, whether following a single line of ancestry (uniparental markers) or focusing
on the autosomal regions and the X chromosome, which reveal different ancestral
components. There is great interest in identifying admixture to show continental ancestry in
genetically divergent populations [10±14]. These methods have been applied to African-American
populations [15±20](Zhu et al. 2005, Smith et al. 2004, Tian et al. 2008, Reich et al. 2005, Deo
et al. 2007, Reich et al. 2007), and have been powerful in identifying ancestry in Latin
American populations [21±24].
Populations in the Americas are the result of admixture between Native Americans, West
Eurasians and Africans; however, we are just beginning to understand the finer details of this
process and its genetic correlates [25±27]. Thanks to large consortia, new studies analyzing full
genomes are being published [
28
]. It is of biomedical and anthropological interest to survey
admixture in these populations, which would help to elucidate the unique Latin American
genetic landscape.
Early evidence of people in South America is seen at sites such as Monte Verde in Chile
[
29
], with people arriving before 12,000 years ago (ya) [
30
], and a rapid settlement of the
continent is supported by DNA studies [
31
](Bodner et al. 2012), mostly (...truncated)