In conclusion, we have described the European genetic structure by three different measures: the inflation factor λ, Fst and PC. As a result, according to the first two PCs, individuals from the same geographic origin cluster together and form a genetic map where four areas could be identified: 1) Central and Western Europe, 2) the Baltic countries, Poland and Western Russia, 3) Finland, and 4) Italy. If not corrected for the inter-population differences would affect the significance of disease-gene associations. A detailed description of the European population structure has consequences and implications for the design of future GWAS, particularly regarding sample size and choice of controls. As a matter of fact, the knowledge of genetic distances between different populations is helpful in defining which biobanks could sensibly contribute samples and data to GWAS.
