Nationwide Genomic Study in Denmark Reveals Remarkable Population Homogeneity

Abstract

and computational methods has also boosted the emergence of many single-country genomic projects in Europe (Jakkula et al. 2008; Price et al. 2009; Genome of the Netherlands Consortium 2014; Karakachoff et al. 2015; Leslie et al. 2015) and the release of useful data to the public (Welter et al. 2014). In this work, we extend the collection of single-country genetic studies by introducing a new project from Denmark. Unlike previous genomic projects involving Denmark (Bae et al. 2013; Larsen et al. 2013), ours was conceived from the beginning as a scientific outreach initiative with benefits for both the general public and our research objectives. We invited high school students from across Denmark to participate in activities whose primary goal was to promote genomic literacy in secondary education (Athanasiadis et al. 2016). Most participants donated a DNA sample, which we used to explore the extent to which recent and more distant historical events left their mark on the genetic makeup of the Danish population. Apart from the population structure and demographic history in Denmark, an additional focus of this work has been the quantitative study of basic anthropometrical traits. With this work, we ultimately report back to our DNA donors the biological and historical insights we gained from analyzing their genetic data. Our results showed remarkable homogeneity across different geographic regions in Denmark, although we were still able to detect weak signals of genetic structure. Denmark received substantial admixture contributions primarily from neighboring countries in the past 10 centuries with overall influence of decreasing weight from Britain, Sweden, and Norway. We also observed considerably diverse demographic histories among the Scandinavian countries, as reflected in their historical effective population size. Finally, we found that human height can be predicted with remarkable accuracy in Danish adolescents. Overall, this work showcases how far we can go with the analysis of genetic data from small, fairly homogeneous populations.