A genomic insight into diversity among tribal and nontribal population groups of Manipur, India.

Twenty autosomal markers, including linked markers at two gene markers, are used to understand the genomic similarity and diversity among three tribal (Paite, Thadou, and Kom) and one nontribal communities of Manipur (Northeast India). Two of the markers (CD4 and HB9) are monomorphic in Paite and one (the CD4 marker) in Kom. Data suggest the Meitei (nontribal groups) stand apart from the three tribal groups with respect to higher heterozygosity (0.366) and presence of the highest ancestor haplotypes of DRD2 markers (0.228); this is also supported by principal co-ordinate analysis. These populations are found to be genomically closer to the Chinese population than to other Indian populations.

Folic acid, dietary habits, and homocysteine levels in relation to neural tube defects: A case-control study in North India.

PURPOSE: The present study attempts to understand the complex contribution of biochemical (plasma homocysteine) and nutritional parameters (dietary pattern and folate supplementation) to the neural tube defects (NTDs) affected pregnancies and controls in North Indian population. METHODS: Case-control study design was adopted to assess the role of folic acid, dietary habits, and homocysteine in relation to NTD births. The subjects comprised of 130 mothers of affected children (cases) and 233 mothers of healthy children (controls), who were either carrying NTD fetus or gave birth to NTD child. RESULTS: The mean homocysteine levels were elevated in cases (15.71 ± 8.35 µmol/L) as compared to controls (12.87 ± 5.95 µmol/L) but were lower among the non-vergetarians (13.55 ± 6.64 µmol/L) than the vegetarians (14.78 ± 7.93 µmol/L). Vegetarian dietary habit increased the NTD risk by 1.6 fold (95% CI = 1.0-2.7) while folic acid supplementation demonstrated a protective effect for conceptions (OR = 0.59; 95% CI = 0.3-0.9). Consumption of folic acid with non-vegetarian diet witnessed lowering of homocysteine in cases (12.88 ± 6.81 µmol/L) and in controls (11.85 ± 5.54 µmol/L), with an odds ratio depicting a 3.1 fold risk for consuming vegetarian diet without folic acid supplementation during the peri-conceptional period. CONCLUSION: It is suggested that plasma hyperhomocysteinemia bears negative impact on child-bearing women group, of north Indian ancestry, in modulating the risk of NTDs. Efforts should be made to enhance awareness regarding folic acid and vitamin B12 (non-vegetarian diet) supplementations alongwith proper nutritional intake among women, especially those consuming vegetarian diet to control homocysteine levels in order to reduce the risk of NTDs.

Dopamine D2 receptor and ankyrin repeat and kinase domain containing 1 genes among the two linguistically distinct tribal populations of Ranchi district, Jharkhand, India.

In the recent years, haplotype studies have emerged as a critical tool for studying the human migratory patterns. Dopamine D2 receptor (DRD2) and Ankyrin Repeat and Kinase Domain Containing 1 (ANKK1) genes, which also bear specific clinical implications in various neuropsychiatric and behavioural/addictive disorders, are significant nuclear DNA markers for studying human genome diversity. The present study was conducted in order to understand the distribution pattern of the three DRD2 and ANKK1 TaqI sites and also the frequencies of their haplotypes among Oraons (n = 48) and Mundas (n = 50)--the two linguistically distinct tribal population groups of Jharkhand. The phylogenetic inference was drawn through the statistical comparisons of the present DRD2 and ANKK1 TaqI site data with the available data from population groups belonging to other parts of India and also rest of the world (ALFRED Database). All the three TaqI sites were found to be polymorphic among Oraons and Mundas with relatively high average heterozygosities. Oraons exhibited a comparatively higher frequency of the ancestral B2D2A1 haplotype (0.356) than the Mundas (0.193). Significant and higher linkage disequilibrium (LD) values between all three sites were observed among Mundas which is indicative of admixture, whereas Oraons exhibited non significant and low LD values. The presence of ancestral haplotype B2D2A1 in higher frequency and lower and non-significant LD among Oraons suggest that they might be the older inhabitants in the region though the major limitation of the study is small sample size which might have introduced bias in the accuracy of the calculated pairwise LD for the three polymorphic sites.

Haptoglobin polymorphism among fourteen populations of India.

Haptoglobin (HP) is a serum protein that has the capability of binding the extracorpuscular haemoglobin released during haemolysis. It plays an important role in protection of haemolytic disease by reducing the oxidative and peroxidative potential at free haemoglobin. The present study was aimed to determine the prevalence of HP polymorphism among different Indian populations, anthropologically belonging to diverse ethnicity. The polymorphism was screened among 642 unrelated individuals belonging to 14 population groups of India including both tribal and non-tribal caste groups from different geographical regions of India with distinct linguistic affiliations. An attempt is also made to understand the distribution of HP polymorphism among the studied populations. The result reveals the HP gene to be polymorphic in all the studied populations. Except the two tribal populations (Thotis of Andhra Pradesh and Patelias of Rajasthan) and one caste population (Rajput of Himachal Pradesh), all the studied populations are found to obey the Hardy-Weinberg equilibrium. The significance of the present study is elucidated with the prevalence of high mutant HP*2 allele frequency in India. Selection could be one of the most plausible explanations for this high HP frequency because of its uniformly high occurrence among all the studied populations.

The genomic similarities with linguistic difference: a study among the Oraon and Munda tribes of the Ranchi district, Jharkhand, India.

AIMS: The present study was conducted on two tribal communities, the Oraon and Munda, inhabiting the Ranchi district of Jharkhand state, India. The study was designed to elucidate genetic similarity, if any, shared between these tribes as they belong to the common Proto-Australoid stock but bear different linguistic affiliations. For this, a total of 98 intravenous blood samples (48 Oraon and 50 Munda) were collected from unrelated individuals of either sex up to first cousins, with their prior informed written consent. The DNA was extracted and studied for a total of 20 autosomal markers, including 7 Alu Indels, 3 DRD2 TaqI sites, 3 ß-globin sites, and 7 restriction site polymorphisms. RESULTS: All the 20 studied molecular markers were found to be polymorphic in both the tribal population groups and showed similarities with respect to allele frequencies, with a low coefficient of gene differentiation (G(ST)) value. Moreover, sharing and distribution patterns of haplotypes of the ß-globin gene cluster suggest that the Oraon and Munda share a common ancestry. However, small differences between them with reference to the linkage disequilibrium (LD) pattern indicate that the Munda might have emerged as a result of admixture between Proto-Australoids and Austro-Asiatic-speaking Mongoloids as supported by the principal co-ordinate analysis, wherein the Munda are closely placed with the Dravidian-speaking Proto-Australoid tribes of India. CONCLUSION: A common genetic substratum (Proto-Australoid stock) of the Oraon and Munda was evident in the present study, although these tribes are distinct linguistically.

Haplotype diversity and linkage disequilibrium at DRD2 locus--a study on four population groups of Andhra Pradesh, India.

Dopamine receptor D2 (DRD2) is expressed in the central nervous system and has a high affinity for many antipsychotic drugs. Besides several epidemiological investigations on association of DRD2 locus polymorphism(s) with neuropsychiatric problems and addictive behavior, a few polymorphisms in this locus have also been used to understand genomic diversity and population migratory histories globally. The present study attempts to understand the genomic diversity/affinity among four endogamous groups of Andhra Pradesh (India) against the backdrop of diversity studies from other parts of India and the rest of the world, with special reference to DRD2 locus. The four population groups from Adilabad District of Andhra Pradesh, namely, Brahmin (n=50), Nayakpod (n=49), Thoti (n=52), and Kolam (n=53), were included in the study. The DRD2 markers typed for the present study are three biallelic restriction fragments, that is, TaqI A (rs1800497), TaqI B (rs1079597), and TaqI D (rs1800498). Scoring of DRD2 haplotypes with respect to the three TaqI sites shows that five out of eight possible haplotypes are shared by the four populations. Ancestral haplotype B2D2A1 is most frequent among Thotis (0.359). The results of the present study indicate a differential gene flow into South India followed by certain important demographic events resulting in diversified peopling of India.