Gene Flow at the Crossroads of Humanity: mtDNA Sequence Diversity and Alu Insertion Polymorphism Frequencies in Uzbekistan

Mitochondrial DNA (mtDNA) HVS-I region sequences were obtained from 47 unrelated individuals representing 10 of 12 viloyats of Uzbekistan. In addition, frequencies for five Alu insertion polymorphisms were determined for the same 47 individuals. These data were used to assess the genetic position of Uzbekistan relative to other Central Asians and, more generally, to Eurasian groups. Results show that the Uzbek sample has an approximate balance of west Eurasian (53.2%) and Asian (46.8%) mtDNA lineages, which is reflected by their intermediate position relative to other Eurasian groups in MDS plots based on genetic distance matrices. The Uzbeks also exhibit high sequence diversity, a fragmented median-joining network, and a low regional ST score, all of which suggests a high degree of gene flow from neighboring gene pools. This is consistent with Central Asia’s history of repeated incursions by various nomadic peoples from the Asian steppe and the location of the well-traveled Silk Road within the present-day borders of Uzbekistan. In addition, a star-like cluster within haplogroup H was identified in the Uzbek network, potentially representing a west Eurasian genetic substratum of an earlier occupation by Caucasoid peoples.