Genomic and linguistic affinities: a study of allelic and haplotype diversity at DRD2 locus among the tribes of Gujarat, western India.

Do genetic and linguistic affinities necessarily go hand in hand? An attempt has been made in the present work to explore this dimension of population structure using three evolutionarily important TaqI sites (TaqI A, TaqI B, and TaqI D) on the dopamine receptor D2 (DRD2) locus. For the first time, DNA samples from 612 unrelated individuals belonging to 11 Indo-European-speaking tribal population groups of Gujarat, western India, have been analyzed for these three sites. All the three sites are found to be polymorphic with greater interpopulation variation seen at the TaqI B site. The average heterozygosity for the haplotype system has been found to be high in the populations under study. Most of the populations share six of the eight haplotypes pointing toward underlying genetic uniformity, which is further reaffirmed by regression analysis of heterozygosity on genetic distance. The frequency of ancestral haplotype B2D2A1 is found to range between 1.9% and 15.9%. Linkage disequilibrium between TaqI B and TaqI D sites and between TaqI B and TaqI A sites is statistically significant in all but one population. Our findings reveal strong affinities between Indo-European-speaking tribal groups of Gujarat and Dravidian-speaking tribal groups of South India, suggesting that genetic affinities may not necessarily be dependent on linguistic similarities.