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

Abstract

Mitochondrial DNA (mtDNA) HVS-I region sequences were obtained from 47 unrelated individuals represent- ing 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 Eura- sian (53.2%) and Asian (46.8%) mtDNA lineages, which is reflected by their intermediate position relative to other Eura- sian groups in MDS plots based on genetic distance matrices. The Uzbeks also exhibit high sequence diversity, a frag- mented median-joining network, and a low regionalST 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 ad- dition, a star-like cluster within haplogroup H was identified in the Uzbek network, potentially representing a west Eura- sian genetic substratum of an earlier occupation by Caucasoid peoples.