Population genetics of Finns

The Finnish population is one of the most genetically studied in the world. A relatively small number of founder individuals and strong genetic isolation over centuries have shaped the unique genetic makeup across the country that we are now utilizing heavily in genetic studies of diseases and traits.

Here, we present a fine-scale genetic structure of Finland before 1950s, thus focusing on the time before large-scale migrations and urbanization that have occurred since 1950s. The work was led by Academy Research Felllow Matti Pirinen. These results were published in 2017 in G3: Genes, Genomes, Genetics.

Data and Methods: Data are from the FINRISK Study of the National Institute for Health and Welfare and contain 1,042 individuals whose both parents were born under 80 km from each other. No pairs of close relatives were included. Additionally, genetic data from 230,000 positions of the genome was utilized. Computational methods used were ChromoPainter and FineSTRUCTURE.

Maps: Each point represents one individual and is located at the mean coordinates of the parents’ birthplaces. We show 17 maps that divide the individuals into groups based on genome information and shown by separate colors. The first map presents only one group and at each subsequent step one of the groups splits into two subgroups. The interpretation is that, on each map, the individuals in one group are on average more genetically similar with each other than with the individuals from the other groups. We expect that the order of splits has an approximate correspondence to the amount of genetic differentiation between the groups and the tree on the right hand side of the map shows the relationships of the groups measured by a genetic distance.

Below the maps you can study the structure at a specific level. If you want to compare the groups to the dialectal regions of the Finnish language visit Matti Pirinen's homepage.

Reuse: Figures can be reused under the license CC-BY 4.0.

Contact: Matti Pirinen (supervision) and Sini Kerminen (analyses).

Organizations: Institute for Molecular Medicine Finland (FIMM), University of Helsinki and the National Institute for Health and Welfare

Funding: University of Helsinki and the Academy of Finland.

 

1,042 Finns located at the mean of their parents' birthplaces. Samples cover Finland evenly except for Lapland in the North, with only a few individuals, and the islands of Åland with no individuals.The main genetic division splits Finland into an eastern (blue) and a western (red) part separated by a border line drawn from the southeastern corner of Finland to the western coast near Oulu.East population is split into a northern subgroup (cyan), that includes Kainuu and Northern Ostrobothnia, and a southern subgroup (blue), that includes Central Finland, Savonia and Karelia.Now also the western population is split into northern (black) and southern (red) subgroups.We observe a population (yellow) that is more scattered across the country than any other population we have identified. This population includes individuals near the cities of Helsinki and Vyborg.A geographically clustered population (green) in South Ostrobothnia splits from the southwestern Finland (red).This split separates Kainuu (pink) and North Ostrobothnia (cyan).North Ostrobothnia is further divided into the light green population covering Kuusamo, an internal genetic isolate in Finland, and the cyan population closer to the west coast.Population in South Ostrobothnia divides into a northern (rose) and southern (green) part. Comparison with the dialectal regions shows that the northern population overlaps with the Savonian dialect.Lapland in the north separates from the individuals on the coast of Ostrobothnia.More structure is revealed in the Kainuu region.A population (dark purple) that extends from Kymenlaakso on the south coast to Central Finland splits from the scattered eastern group (yellow). A north-south split within Savonia-Karelia region.Western Savonia (orange) emerges.North Savonia (white) and North Karelia (blue) emerge.Southwest corner of Finland splits into eastern (skyblue) and western (red) parts.The last split happens in the southwest part of Finland where historical Southwest Finland (red) separates from Pirkanmaa (golden).