| 1. |
- Humphreys, Keith, et al.
(författare)
-
The Genetic Structure of the Swedish Population
- 2011
-
Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 6:8, s. e22547-
-
Tidskriftsartikel (refereegranskat)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.
|
|
| 2. |
- Leu, Monica, et al.
(författare)
-
NordicDB : a Nordic pool and portal for genome-wide control data
- 2010
-
Ingår i: European Journal of Human Genetics. - : Springer Science and Business Media LLC. - 1018-4813 .- 1476-5438. ; 18:12, s. 1322-1326
-
Tidskriftsartikel (refereegranskat)abstract
- A cost-efficient way to increase power in a genetic association study is to pool controls from different sources. The genotyping effort can then be directed to large case series. The Nordic Control database, NordicDB, has been set up as a unique resource in the Nordic area and the data are available for authorized users through the web portal (http://www.nordicdb.org). The current version of NordicDB pools together high-density genome-wide SNP information from similar to 5000 controls originating from Finnish, Swedish and Danish studies and shows country-specific allele frequencies for SNP markers. The genetic homogeneity of the samples was investigated using multidimensional scaling (MDS) analysis and pairwise allele frequency differences between the studies. The plot of the first two MDS components showed excellent resemblance to the geographical placement of the samples, with a clear NW-SE gradient. We advise researchers to assess the impact of population structure when incorporating NordicDB controls in association studies. This harmonized Nordic database presents a unique genome-wide resource for future genetic association studies in the Nordic countries. European Journal of Human Genetics (2010) 18, 1322-1326; doi: 10.1038/ejhg.2010.112; published online 28 July 2010
|
|
| 3. |
- Wilson, Kathryn M., et al.
(författare)
-
Acrylamide exposure measured by food frequency questionnaire and hemoglobin adduct levels and prostate cancer risk in the Cancer of the Prostate in Sweden Study
- 2009
-
Ingår i: International Journal of Cancer. - : WILEY-LISS. - 0020-7136 .- 1097-0215. ; 124:10, s. 2384-2390
-
Tidskriftsartikel (refereegranskat)abstract
- Acrylamide, a probable human carcinogen, is formed during the cooking of many commonly consumed foods. Data are scant on whether dietary acrylamide represents an important cancer risk in humans. We studied the association between acrylamide and prostate cancer risk using 2 measures of acrylamide exposure: intake from a food frequency questionnaire (FFQ) and acrylamide adducts to hemoglobin. We also studied the correlation between these 2 exposure measures. We used data from the population-based case-control study Cancer of the Prostate in Sweden (CAPS). Dietary data was available for 1,499 cases and 1, 118 controls. Hemoglobin adducts of acrylamide were measured in blood samples from a subset of 170 cases and 161 controls. We calculated odds ratios (ORs) for the risk of prostate cancer in high versus low quantiles of acrylamide exposure using logistic regression. The correlation between FFQ acrylamide intake and acrylamide adducts in non-smokers was 0.25 (95% confidence interval: 0.14-0.35), adjusted for age, region, energy intake, and laboratory batch. Among controls the correlation was 0.35 (95% CI: 0.21-0.48); among cases it was 0.15 (95% CI: 0.00-0.30). The OR of prostate cancer for the highest versus lowest quartile of acrylamide adducts was 0.93 (95% CI: 0.47-1.85, p-value for trend = 0.98). For FFQ acrylamide, the OR of prostate cancer for the highest versus lowest quintile was 0.97 (95% CI: 0.75-1.27,p trend = 0.67). No significant associations were found between acrylamide exposure and risk of prostate cancer by stage, grade, or PSA level. Acrylamide adducts to hemoglobin and FFQ-measured acrylamide intake were moderately correlated. Neither measure of acrylamide exposure-hemoglobin adducts or FFQ-was associated with risk of prostate cancer. (C) 2008 Wiley-Liss. Inc.
|
|
