Haplotype and Allelic Variations at Dopamine Receptor Gene (DRD2) among six Austro-Asiatic Speaking Tribal Groups of Central India

Abstract

Central India is mainly constituted by two states, namely; Madhya Pradesh and Chhattisgarh that are homeland of several caste and tribal groups speaking diverse language belongs to Indo-European, Dravidian and Austro-Asiatic thus makes it an important place for testing several language-gene interaction models. Various archaeological evidences indicated that the Narmada region has played a significant role in initial peopling of the Asian subcontinent. There is a necessity to fill the big lacuna by inclusion of this region to reveal a continuous picture of the origin and genetic affinity of the Indian population. It is hypothesized that Austro-Asiatic speaking tribes are autochthonous to India. The present study was conducted to examine the haplotype variations at Dopamine Receptor Gene (DRD2) in the Austro-Asiatic Speaking Tribal Groups of Central India. Haplotypes provide information on evolutionary histories, beyond what can be learned from individual marker. A total of 327 unrelated samples belonging to Birhor, Gadaba, Kol, Hill korwa, Saora and Baiga were analyzed for three selected TaqI sites of DRD2 gene using Polymerase chain reaction (PCR). All the loci were found to be polymorphic among the studied populations. The frequency of ancestral allele B2 is less than 50% in all six populations (41.4-49.2%) while D2 allele exhibit frequency of 15.3-44.8%. A1 allele observed with a frequency ranging from 36.2-48.2%. The average heterozygosity ranged from 0.417 in Baiga to 0.501 in Kol. The ancestral haplotype (B2D2A1) in all six populations exhibit 0% frequency. LD values calculated for the three bi-allelic sites, TaqIB, TaqID, and TaqIA are low, i.e., below 0.8 with respect to all populations in each pair. Overall, allele frequency distribution patterns and high average heterozygosity values, suggest a genetic proximity among the studied populations. Low recurrence of genealogical alleles and nonattendance of familial haplotype in the examined populace bunches, demonstrating towards indigenous inception of Central Indian Austro-Asiatic talking tribes.