The international research group, led by University of Helsinki researchers, has produced more detailed information about the genetic variation within Finland than has been previously available. The results were published 5.10.2017 in the G3: Genes, Genomes, Genetics journal. The researchers have also opened a website for the project, where anyone can access the results using interactive maps.
The study used modern methods from genome research and statistics, grouping more than 1,000 DNA samples from all over Finland into genetically similar groups, gradually increasing the specificity. This grouping employed existing information on more than 230,000 genetic markers.
While this is not the first study on genetic variation in Finland, the rapid development of genetic and statistical methods has now enabled significantly more precise analyses.
The objective of the study was to understand Finland’s genetic structure before the migrations of the second half of the 20th century. For this reason, subjects selected for the study were Finns born before the 1970s whose parents had been born no more than 80 kilometres from each other.
“Previous studies had specifically examined people who lived as far apart from each other geographically as possible. Instead, we wanted to study all of the Finnish population as widely and evenly as possible,” says Sini Kerminen, who is currently preparing her doctoral thesis at the Institute for Molecular Medicine Finland (FIMM), part of the Helsinki Institute of Life Sciences (HiLIFE) of the University of Helsinki.
Dozens of Finnish genetic subgroups
After being genetically categorised, the individuals were placed on a map of Finland at the midway point between the places where their parents had been born. Independent of the level of detail of the categorisation, genetically similar individuals formed surprisingly coherent groups on the map.
On the most general level, Finns were divided into eastern and western groups along the medieval border of the Treaty of Nöteborg that split Finland between Sweden and the Novgorod Republic in 1323. It was possible to identify most research subjects as eastern or western Finns with higher than 80% probability.
Next populations to appear as distinct groups were Kainuu and Pohjanmaa. The researchers kept dividing the subjects into smaller subgroups as long as it was statistically appropriate. At the most granular level, the Finns in the study were divided into 52 subgroups.
“What made our results particularly interesting is that our groupings followed Finland’s old dialect areas with surprising precision. We could also see signs of significant events in recent Finnish history in the genes, such as the migration from the areas of Karelia that Finland ceded to Russia, which may be linked to the paths taken by Karelian refugees during World War II,” says Academy Research Fellow Matti Pirinen from the University of Helsinki, who led the study.
“Our ancestors live on in our genes. In some respects, we can even expect our genes to depict our history more accurately than the history books. Detailed understanding of the fine-scale genetic population structure is also important for medical research so that individuals with an illness can be compared to healthy individuals with the exact same genetic background.”
The study is based on samples from the national FINRISK study compiled by the National Institute for Health and Welfare (THL). The chosen sample of 1,042 individuals represents the Finnish genome from the early 20th century.
All results and associated maps can be found on the FIMM website. The images can be used freely. The study was funded by the University of Helsinki Funds and the Academy of Finland.
Sini Kerminen, Aki S. Havulinna, Garrett Hellenthal, Alicia R. Martin, Antti-Pekka Sarin, Markus Perola, Aarno Palotie, Veikko Salomaa, Mark J. Daly, Samuli Ripatti and Matti Pirinen. Fine-Scale Genetic Structure in Finland. G3: GENES, GENOMES, GENETICS October 1, 2017 vol. 7 no. 10 3459-3468; https://doi.org/10.1534/g3.117.300217.
Further information:
Academy Research Fellow Matti Pirinen
University of Helsinki
Helsinki Institute for Life Sciences (HiLIFE), Institute for Molecular Medicine Finland (FIMM),
Department of Mathematics and Statistics,
Faculty of Medicine
email: matti.pirinen@helsinki.fi