Abstract
The genetic structure of populations is a potential source of population history information and an important factor in gene mapping studies. The main aim of this thesis was to study the population structure in Finland and Sweden using, for the first time, genome-wide data from thousands of single nucleotide polymorphism (SNP) markers. Furthermore, this thesis introduced a novel gene mapping approach, subpopulation difference scanning (SDS), and tested its theoretical applicability in the Finnish population.
The study subjects included 280 Finnish and 1525 Swedish individuals, and genotypes from Russian, German, British and other populations served as reference data. The results revealed that the Finns differed clearly from central Europeans. Within Finland, the genetic difference between eastern and western Finns was striking. The Finns, particularly eastern Finns, also showed reduced genetic diversity as well as an increased genetic affinity to East Asian reference populations. In Sweden, the overall population structure seemed clinal and lacked strong borders. The population in southern Sweden was relatively homogeneous and genetically close to the Germans and British, while the northern subpopulations differed from the south and also from each other. Overall, these results are congruent with earlier observations from smaller numbers of markers and with population history, particularly the small population sizes that have led to genetic drift.
The genetic substructure within Finland could prove useful in mapping genes for diseases that show regional incidence differences. Because a gene underlying an incidence difference must itself harbor a frequency difference, the SDS approach proposes that such genes could be mapped by focusing further analyses on genome areas that show a (sufficient) difference between the high- and low-incidence subpopulations. Population simulations demonstrated that the SDS approach may work for cardiovascular diseases, which have an east-west difference within Finland.
In summary, the results of this thesis emphasize the capacity of genome-wide SNP data to detect patterns of population structure, also in populations that have often been assumed homogeneous, such as the Finns and Swedes. Obviously, knowledge of genome-wide population structure has immediate relevance also to studies focusing on diseases and other important phenotypes.
The study subjects included 280 Finnish and 1525 Swedish individuals, and genotypes from Russian, German, British and other populations served as reference data. The results revealed that the Finns differed clearly from central Europeans. Within Finland, the genetic difference between eastern and western Finns was striking. The Finns, particularly eastern Finns, also showed reduced genetic diversity as well as an increased genetic affinity to East Asian reference populations. In Sweden, the overall population structure seemed clinal and lacked strong borders. The population in southern Sweden was relatively homogeneous and genetically close to the Germans and British, while the northern subpopulations differed from the south and also from each other. Overall, these results are congruent with earlier observations from smaller numbers of markers and with population history, particularly the small population sizes that have led to genetic drift.
The genetic substructure within Finland could prove useful in mapping genes for diseases that show regional incidence differences. Because a gene underlying an incidence difference must itself harbor a frequency difference, the SDS approach proposes that such genes could be mapped by focusing further analyses on genome areas that show a (sufficient) difference between the high- and low-incidence subpopulations. Population simulations demonstrated that the SDS approach may work for cardiovascular diseases, which have an east-west difference within Finland.
In summary, the results of this thesis emphasize the capacity of genome-wide SNP data to detect patterns of population structure, also in populations that have often been assumed homogeneous, such as the Finns and Swedes. Obviously, knowledge of genome-wide population structure has immediate relevance also to studies focusing on diseases and other important phenotypes.
| Original language | English |
|---|---|
| Place of Publication | Helsinki |
| Publisher | |
| Print ISBNs | 978-952-10-8190-3 |
| Electronic ISBNs | 978-952-10-8191-0 |
| Publication status | Published - 2012 |
| MoE publication type | G5 Doctoral dissertation (article) |
Fields of Science
- 1184 Genetics, developmental biology, physiology
- population genetics
- population structure
- genetic structure
- genome-wide analysis
- gene mapping
- Population history
- SUBPOPULATION
- population genomics
- Finland
- Sweden
- Northern Europe