Using principal component PC analysis, we studied the genetic constitution of 3,112 individuals from Europe as portrayed by more than 270,000 single nucleotide polymorphisms SNPs….resulting in a total of 1,564 samples.

…analysis revealed that the genetic structure of the European population correlates closely with geography. The first two PCs highlight the genetic diversity corresponding to the northwest to southeast gradient and position the populations according to their approximate geographic origin.

The resulting genetic map forms a triangular structure with

a Finland,

b the Baltic region, Poland and Western Russia, and

c Italy

as its vertexes, and with

d Central- and Western Europe in its centre.

When the PC analysis was confined to the 1,019 Estonian individuals (0.1% of the Estonian population), a fine structure emerged that correlated with the geography of individual counties.

With at least two cohorts available from several countries, genetic substructures were investigated in Czech, Finnish, German, Estonian and Italian populations.

Together with previously published data, our results allow the creation of a comprehensive European genetic map that will greatly facilitate inter-population genetic studies including genome wide association studies GWAS.

via PLOS ONE: Genetic Structure of Europeans: A View from the North–East.