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The Genetic Structure of the Swedish Population

Humphreys, Keith; Grankvist, Alexander; Leu, Monica; Hall, Per; Liu, Jianjun; Ripatti, Samuli; Rehnstroem, Karola; Groop, Leif LU ; Klareskog, Lars and Ding, Bo, et al. (2011) In PLoS ONE 6(8).
Abstract
Patterns of genetic diversity have previously been shown to mirror geography on a global scale and within continents and individual countries. Using genome-wide SNP data on 5174 Swedes with extensive geographical coverage, we analyzed the genetic structure of the Swedish population. We observed strong differences between the far northern counties and the remaining counties. The population of Dalarna county, in north middle Sweden, which borders southern Norway, also appears to differ markedly from other counties, possibly due to this county having more individuals with remote Finnish or Norwegian ancestry than other counties. An analysis of genetic differentiation (based on pairwise F-st) indicated that the population of Sweden's... (More)
Patterns of genetic diversity have previously been shown to mirror geography on a global scale and within continents and individual countries. Using genome-wide SNP data on 5174 Swedes with extensive geographical coverage, we analyzed the genetic structure of the Swedish population. We observed strong differences between the far northern counties and the remaining counties. The population of Dalarna county, in north middle Sweden, which borders southern Norway, also appears to differ markedly from other counties, possibly due to this county having more individuals with remote Finnish or Norwegian ancestry than other counties. An analysis of genetic differentiation (based on pairwise F-st) indicated that the population of Sweden's southernmost counties are genetically closer to the HapMap CEU samples of Northern European ancestry than to the populations of Sweden's northernmost counties. In a comparison of extended homozygous segments, we detected a clear divide between southern and northern Sweden with small differences between the southern counties and considerably more segments in northern Sweden. Both the increased degree of homozygosity in the north and the large genetic differences between the south and the north may have arisen due to a small population in the north and the vast geographical distances between towns and villages in the north, in contrast to the more densely settled southern parts of Sweden. Our findings have implications for future genome-wide association studies (GWAS) with respect to the matching of cases and controls and the need for within-county matching. We have shown that genetic differences within a single country may be substantial, even when viewed on a European scale. Thus, population stratification needs to be accounted for, even within a country like Sweden, which is often perceived to be relatively homogenous and a favourable resource for genetic mapping, otherwise inferences based on genetic data may lead to false conclusions. (Less)
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PLoS ONE
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6
issue
8
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Public Library of Science
external identifiers
  • wos:000293561200022
  • scopus:79961163100
ISSN
1932-6203
DOI
10.1371/journal.pone.0022547
language
English
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yes
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f85a9697-ec41-402a-b350-ed248d95b009 (old id 2162318)
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2011-10-03 08:41:17
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2017-11-12 03:41:04
@article{f85a9697-ec41-402a-b350-ed248d95b009,
  abstract     = {Patterns of genetic diversity have previously been shown to mirror geography on a global scale and within continents and individual countries. Using genome-wide SNP data on 5174 Swedes with extensive geographical coverage, we analyzed the genetic structure of the Swedish population. We observed strong differences between the far northern counties and the remaining counties. The population of Dalarna county, in north middle Sweden, which borders southern Norway, also appears to differ markedly from other counties, possibly due to this county having more individuals with remote Finnish or Norwegian ancestry than other counties. An analysis of genetic differentiation (based on pairwise F-st) indicated that the population of Sweden's southernmost counties are genetically closer to the HapMap CEU samples of Northern European ancestry than to the populations of Sweden's northernmost counties. In a comparison of extended homozygous segments, we detected a clear divide between southern and northern Sweden with small differences between the southern counties and considerably more segments in northern Sweden. Both the increased degree of homozygosity in the north and the large genetic differences between the south and the north may have arisen due to a small population in the north and the vast geographical distances between towns and villages in the north, in contrast to the more densely settled southern parts of Sweden. Our findings have implications for future genome-wide association studies (GWAS) with respect to the matching of cases and controls and the need for within-county matching. We have shown that genetic differences within a single country may be substantial, even when viewed on a European scale. Thus, population stratification needs to be accounted for, even within a country like Sweden, which is often perceived to be relatively homogenous and a favourable resource for genetic mapping, otherwise inferences based on genetic data may lead to false conclusions.},
  author       = {Humphreys, Keith and Grankvist, Alexander and Leu, Monica and Hall, Per and Liu, Jianjun and Ripatti, Samuli and Rehnstroem, Karola and Groop, Leif and Klareskog, Lars and Ding, Bo and Gronberg, Henrik and Xu, Jianfeng and Pedersen, Nancy L. and Lichtenstein, Paul and Mattingsdal, Morten and Andreassen, Ole A. and O'Dushlaine, Colm and Purcell, Shaun M. and Sklar, Pamela and Sullivan, Patrick F. and Hultman, Christina M. and Palmgren, Juni and Magnusson, Patrik K. E.},
  issn         = {1932-6203},
  language     = {eng},
  number       = {8},
  publisher    = {Public Library of Science},
  series       = {PLoS ONE},
  title        = {The Genetic Structure of the Swedish Population},
  url          = {http://dx.doi.org/10.1371/journal.pone.0022547},
  volume       = {6},
  year         = {2011},
}