Characterization of the genetic structure of Turkey reveals a high level of admixture
We investigated the genetic structure of Turkey from 3,599 unrelated subjects who have been whole-exome (n = 2,826) and wholegenome (n = 773) sequenced. We observed a high level of admixture consistent with ancient DNA studies. Present-day Turkey has three distinct Anatolian ancestries and six 1000 Genome population contributions from Africa, Europe, South Asia and East Asia. Almost all Turkish individuals have the contribution of all ancestries in their genomes. Treemix analysis revealed that Turkey serves as a crossroad between Middle Eastern and European populations. Wright’s fixation index and principal component analysis was consistent with a close relationship of the Turkish population with European populations. Since the Turkish population, as well as other populations with high consanguinity contribute substantially to the identification of Mendelian phenotypes, we characterized inbreeding status and length of runs of homozygosity. We uncovered a significant number of individuals with very high inbreeding coefficients and increased burden of long runs of homozygosity. Derived allele frequency calculations showed that approximately 30% of exome and 50% of genome variants in the very rare range are unique to the Turkish Variome. In conclusion, our results indicate a high level of admixture in the Anatolian peninsula, and the variation specific to the Turkish population is a valuable resource for disease gene identification studies.