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.

Brief communication: Allelic and haplotypic structure at the DRD2 locus among five North Indian caste populations.

The dopamine D2 receptor (DRD2) gene, with its known human-specific derived alleles that can facilitate haplotype reconstruction, presents an important locus for anthropological studies. The three sites (TaqIA, TaqIB, and TaqID) of the DRD2 gene are widely studied in various world populations. However, no work has been previously published on DRD2 gene polymorphisms among North Indian populations. Thus, the present study attempts to understand the genetic structure of North Indian upper caste populations using the allele and haplotype frequencies and distribution patterns of the three TaqI sites of the DRD2 gene. Two hundred forty-six blood samples were collected from five upper caste populations of Himachal Pradesh (Brahmin, Rajput and Jat) and Delhi (Aggarwal and Sindhi), and analysis was performed using standard protocols. All three sites were found to be polymorphic in all five of the studied populations. Uniform allele frequency distribution patterns, low heterozygosity values, the sharing of five common haplotypes, and the absence of two of the eight possible haplotypes observed in this study suggest a genetic proximity among the selected populations. The results also indicate a major genetic contribution from Eurasia to North Indian upper castes, apart from the common genetic unity of Indian populations. The study also demonstrates a greater genetic inflow among North Indian caste populations than is observed among South Indian caste and tribal populations.

MTHFR C677T and factor V Leiden in recurrent pregnancy loss: a study among an endogamous group in North India.

AIM: In our study an attempt has been made to find the prevalence of genetic thrombophilia in recurrent pregnancy loss (RPL). METHODS: Methylene tetrahydrofolate reductase C677 (MTHFR C677T) and factor V Leiden (FVL) were investigated in 84 Rajput women with two or more pregnancy losses and in 80 age- and ethnicity-matched healthy controls. Restriction digestions of polymerase chain reaction product with HinfI and Mnl I were used for MTHFR C677T and FVL polymorphism detection, respectively. RESULTS: MTHFR C677T mutation was found in 9/84 patients (10.71%) and 2/80 controls (2.5%), yielding an odds ratio (OR) for RPL related to MTHFR C677T of 4.68 (95% confidence interval [CI] = 0.98-22.37; p = 0.03). FVL was found in 4/84 patients (4.76%) and none among the controls, yielding a modified OR for RPL related to FVL of 9.00 (95% CI = 0.48-169.9; p = 0.05). Both, MTHFR C677T and FVL were not found to be significantly more prevalent in patients than controls as a whole. However, MTHFR C677T showed significant association with early pregnancy loss (OR = 6.3; 95% CI = 1.22-32.85; p-value = 0.03; Bonferroni-corrected p-value = 0.04). CONCLUSIONS: Our study supports the association between MTHFR C677T and patients with early RPL among north Indian Rajputs and strengthens the notion that thrombophilia plays a role in this clinical entity.