Common genetic heritage and admixture among Indian population groups as revealed by mtDNA markers

Abstract

The present study determines the inter- and intra-population affinities or variations among the diverse population groups of India. The major goal of the present study was to understand the peopling of India and its role in the peopling of Southeast Asia using 11 restriction fragment length polymorphism (RFLP) mitochondrial DNA (mtDNA) markers. A total of 950 unrelated individuals be- longing to 19 population groups having varied ethnic, linguistic, and geographic backgrounds were chosen for the present study. All the studied sites, except HpaI 3592, are found to be polymorphic in the data set. High frequencies of M haplogroup are found among the South Indian populations, where- as N haplogroup is found to be high among the North Indian populations. Sub-haplogroups C and D of M are found only in the Tibeto-Burman-speaking Northeast population groups, suggesting their probable migration from Central Asia. Sub-haplogroups A and B of N are shared by both Northeast and North Indian population groups. The sub-haplogroups of M and N are absent among the South Indian and East Indian populations except the Thoti of the South India Dravidian tribe. The Northeast Indian populations exhibit the highest haplotypic diversity, whereas the South and East Indian popu- lations have the lowest haplotypic diversity. The study provides evidence for a common maternal ge- netic substratum of Indian populations with probable differential admixture from Eurasia, i.e Europe and Asia, with a decreasing trend from North to South India. Sub-haplogroups of M and N and 9 bp deletion frequency patterns suggest gene flow from East Asia to India was restricted only to Northeast India and not suggest significant movement of people from India to East Asia through Northeast India.