Ethnic heterogeneity in body composition patterning and CVD risk factors: a multi-ethnic study of Asian Indian Tribes.

BACKGROUND: Indian subcontinent exhibits considerable degree of ethnic heterogeneity in cardiovascular disease (CVD) risks. Given the importance of ethnicity, the present multi-ethnic study was conducted to find out the differences in body composition patterning and its influence on CVD risk variables. OBJECTIVE: Owing to considerable ethnic heterogeneity among Asian Indians the study was performed to determine the association of variability between body composition and CVD risk factors at the micro-level among different tribes by sex, province, and generation. METHODS: Nine tribes from three different states (provinces) were considered. Anthropometric measurements, body composition, adiposity, blood pressure, and fasting blood glucose was measured using standard technique. Body composition was measured using BIA method by means of body fat monitor. Mean differences of the body composition measures were analysed by ANOVA. Stepwise multiple regressions were done with CVD risk variables as dependent and body composition profiles as independent variables to find out the significant predictors. Those were then loaded for principal component factor analyses (PCFA). RESULTS: Tribal subjects of both sexes and from both younger and older generations in Gujarat had significantly higher percentage body fat, subcutaneous fat-whole body, and subcutaneous fat-trunk as compared to tribal subjects of Odisha, and West Bengal, as well as significantly lower skeletal mass-whole body and skeletal mass-trunk. PCFA showed two components: (i) percentage body fat with muscle mass; and (ii) visceral fat with resting metabolism. These two components cumulatively explained 80-90% of the total variance associated with CVD risk variables, across the nine tribes. CONCLUSION: Tribal subjects of Gujarat had higher CVD risks with significantly higher fat mass and lower muscle mass followed by the tribal subjects of Odisha, and West Bengal respectively. The younger generation are equally at risk as their older counterparts. The CVD risks are developing at a much faster rate resulting in a serious public health threat, even in traditional societies. Body composition measures could be considered as a better non-invasive technique for early intervention and proper risk management among the Asian Indians in general and tribal populations in particular.

Prevalence and risks of hypertension among Indian tribes and its status among the lean and underweight individuals.

OBJECTIVE: With the increased worldwide prevalence of hypertension among the underprivileged populations, fewerstudies have reported such risks among Indian tribes. In the context of high prevalence of undernutrition, no such study has examined hypertension among lean and underweight Indian tribal individuals separately. METHODS: We selected total samples of 1066 adult males and 1090 adult females in 20-60 years age-group cross-sectionally to examine the status of hypertension and its risks among nine major tribes in three Indian states; separate analyses for lean and underweight tribal individuals were done. RESULTS: Increased prevalence of hypertension (females, 14.2%; males, 9.3%) was observed among the tribes with the overall percentage of individuals at adversity (hypertensive + isolated hypertensive) at more than 20% (males 20.1%; females 26.5%). Age-group-wise prevalence showed a sharp rise in the prevalence of hypertension in the 40 + year individuals; additionally, this rise was alarming among females. Undernutrition was observed to be a potential risk factor as a remarkable prevalence of hypertension was observed among the undernourished (approximately 9%) and lean tribal participants (12%). Underweight females were observed to be at higher risk. Tribal statuses were observed to be alarming than the national trends due to their very low average BMI along with high average SBP. A curvilinear prevalence of hypertension was observed while comparing through both the nutritional extremes. CONCLUSION: The increased prevalence and risks of hypertension in the background of lean and underweight status of Indian tribes indicates their epidemiological transition burdened with alarming cardio-metabolic health risks that warrant an early and consistent surveillance.

Comparing the ability of anthropometric indicators in determining the prevalence of hypertension among Indian tribes.

OBJECTIVE: We compared the ability of the selected anthropometric indicators to best predict the prevalence of hypertension among the Indian tribes. METHODS: A cross-sectional study was undertaken among 1431 adult participants (705 males and 726 females) between the ages of 20 and 60 years from six major tribes in India. Selected anthropometric indicators such as body mass index (BMI), waist-hip-ratio (WHR), waist-height-ratio (WHtR), percentage body fat (PBF), visceral fat (VF), minimum-waist-circumference (MWC) and sum-of-the-four skinfold thickness (SF4), along with the physiological parameters such as blood pressure were recorded. Discriminant analysis (DA) was performed to examine and compare the ability of the selected anthropometric indicators towards classifying hypertension among males, females and the total population. RESULTS: Significant independent association was observed for hypertension and similar conditions within gender and selected age-group categories. The overall hypertension prevalence among the studied tribes was observed at 12.6%. Standardized function coefficients (SFCs) in discriminant analysis revealed PBF(0.89, 0.36, and 0.76 for overall, males, and females respectively) as the most powerful discriminator of hypertension. In addition, visceral fat (0.74, 1.46, and 0.58 for overall, males and females respectively) was observed to be the other significant indicator of hypertensive blood pressure. These exploratory findings for the first time indicate fat deposition, rather than body density alone, as an emerging physiological and metabolic risk among Indian tribes. CONCLUSION: In the context of the highly prevalent chronic undernutrition, internal fat deposition is a major classifying factor of physiological and metabolic intolerance. It also indicates the increasing trend in lifestyle changes and the associated adversities among the Indian tribes.

Determinants of demographic characteristics of the Lamkang tribe, Manipur.

The present study provides the demographic account of the Lamkang tribe of Manipur who suffered the bottleneck effect in 1840s and 1992. The objectives are: (i) to determine the age-sex composition of the Lamkang, (ii) to see the sex disparity among the Lamkang (iii) to examine the various biological and social factors that govern the fertility pattern among the Lamkang tribe of Manipur. The present study reveals that the Lamkang population is showing tendency towards fertility transition as evident from the population pyramid. This has shown the beginning of positive effects of education and employment on the reduction of fertility. Overall, males have a higher literacy and better occupation than their female counterparts. One-way analysis of variance reveals that the mean number of conceptions and mean number of live births show statistically significant differences with respect to women's education and family type, which is also reaffirmed by correlation analysis indicating that factors such as family type and women's education along with the other factors such as age at marriage, age at first conception, age at menarche show significant association with fertility.

Gender Disparities in the Prevalence of Undernutrition and the Higher Risk among the Young Women of Indian Tribes.

BACKGROUND: High undernutrition is a grave concern in India. Marginalized populations like Indian tribes have been under the serious stress of such nutritional extreme. Women, in particular, are the worst sufferers. Gender-related comprehensive studies regarding the prevalence and risks of undernutrition among the tribes have not been properly pursued in India; the vulnerability of the young females has least been examined. METHODS AND FINDINGS: We conducted a cross-sectional study during January 2011 to December 2013 among 1066 males and 1090 females (n = 2156) in the 20-60 years age group belonging to the nine major tribes; Santals, Oraons and Koras (West Bengal): Santals, Bhumijs and Bathudis (Odisha): Dhodias, Kuknas and Chaudharis (Gujarat). The undernutrition burden was estimated and such risks were analyzed for the women in comparison to the men. The overall undernutrition among the females was found to be 47.4% (95% CI 44.4-50.4) against 32.1% (95% CI 29.3-34.9) among males, indicating about a half of the female population undernourished. The odds of risks for underweight status among females were observed to be high in comparison to males with an odds of 1.9 (95% CI, 1.6-2.2; p≤0.001) for the overall undernutrition category, 1.7 (95% CI, 1.3-2.3; p≤0.001) for the mild undernutrition category, 1.3 (95% CI, 1.1-1.6; p≤0.01) for combined moderate and mild undernutrition category and 3.3 (95% CI at 2.3-4.6; p≤0.001) for severe undernutrition category. The young females were observed with a high prevalence of undernutrition along with increased risk. The 30-year mean BMI trend of the Indian population in comparison to the males, females, and overall tribal population places the tribal females at the highest risk. CONCLUSION: Indian tribes are suffering from the higher prevalence of undernutrition by further highlighting a high gender bias. The health and empowerment of adolescent and young tribal girls needs additional focus. Overall, no remarkable control on undernutrition has been achieved among Indian tribes despite various efforts.

Genetic variation at Q192R and L55M polymorphisms in PON1.

Earlier we have reported Q192R allele frequencies among four Indian populations as a part of an investigation of the distribution of Paraoxonase 1 polymorphisms. Here we present the results obtained after screening eleven populations representing different regions of India for Q192R and L55M. Population genetic analysis examining the effect of micro-evolutionary forces at these loci confirmed genetic differentiation at Q192R earlier suggested. The study groups showed high frequencies of L55 and differential distribution of Q192 and R192. Tests for deviation from neutrality indicated heterozygote excess at rs662 which has Q192R polymorphism. Higher levels of heterozygosity at Q192R than L55M might be because of its role in wide substrate specificity of the enzyme. A small but highly significant correlation between genetic and geographic distances was observed in a spatial autocorrelation analysis indicating non-random distribution of Q192 allele. Our findings are pertinent to toxicogenetic studies evaluating risk assessment towards organophosphate compounds among different continental groups.

Triple Burden of Obesity, Undernutrition, and Cardiovascular Disease Risk among Indian Tribes.

BACKGROUND: Socio-cultural transitions among individuals from vulnerable groups introduce epidemiological transition, with a concomitant increase in the prevalence of undernutrition, obesity, and cardiovascular disease risks. An accepted conventional wisdom exists for Indian tribes that they are undernourished and away from lifestyle-related diseases. However, the extent of this triple burden affecting them is unknown. In this study, we assessed this triple burden among the 9 major tribes of India. METHODS AND FINDINGS: During January 2011 to December 2013, we conducted a cross-sectional study among 1066 men and 1090 women constituting a total of 2156 adults belonging to the 9 major tribal groups: Santals, Oraons, and Koras (West Bengal); Santals, Bhumijs, and Bathudis (Odisha); and Dhodias, Kuknas, and Chaudharis (Gujarat) to estimate the prevalence of the triple burden (undernutrition, overweight or obesity, and hypertension). A high prevalence of undernutrition and hypertension was observed among the Koras (51.9%and 10.6%, respectively), Bathudis (51.3% and 12.1%, respectively), and Oraons (49.6% and 16.5%, respectively). However, the prevalence of overweight and hypertension among the Bhumijs (17.7% and 14.7%, respectively), Dhodias (23.8% and 12.9%, respectively), Kuknas (15.8% and 11.3%, respectively), and Santals of West Bengal (12.2% and 11.8%, respectively) and Odisha (15% and 9.6%, respectively) was most alarming. The prevalence of overweight or obesity among the women was 10.9% and 1.5%, respectively, with 14.0% hypertensive women. The prevalence of overweight and obesity among the men was 14.8% and 1.7%, respectively, with 9.2% hypertensive men. Undernutrition was highly prevalent among men and women. However, data from the past 30 years on systolic blood pressure (SBP) and body mass index (BMI) revealed that the studied tribes were at a higher risk than the general Indian population. In addition, a vast gender disparity with relation to the disease and risk prevalence was observed. CONCLUSION: The alarming trend of an increasing prevalence of overweight/obesity, undernutrition, and hypertension is observed among indigenous populations of India, emphasizing the incorporation of a specific health management policy.

Allele frequencies of PON1 Q192R polymorphism in four populations of India.

The allelic distribution at Paraoxonase 1 (PON1) Q192R polymorphism determines differential sensitivity towards certain organophosphate pesticides. The alleles Q (Glutamine) and R (Arginine) at amino acid position 192 are responsible for the lower and higher activity of the enzyme towards paraoxon respectively, making knowledge of this distribution in different populations vital. This study reports the genotype and allele frequencies of the Gln192Arg polymorphism of PON1 in four populations of India, comprising two caste and two tribal groups hitherto unexamined for this polymorphism. The R allele frequencies in Jat, Meo, Santhal and Zeliangrong populations were found to be 0.47, 0.45, 0.54 and 0.51 respectively. The gene diversity analyses show a high genetic differentiation at this locus indicative of the role of populations' history and other evolutionary forces. A comparison with allele frequencies among 106 populations from different continents showed a concordance with their geographic distribution which will have repercussions in policies targeting pesticide usage.

Y chromosome haplogroup distribution in Indo-European speaking tribes of Gujarat, western India.

The present study was carried out in the Indo-European speaking tribal population groups of Southern Gujarat, India to investigate and reconstruct their paternal population structure and population histories. The role of language, ethnicity and geography in determining the observed pattern of Y haplogroup clustering in the study populations was also examined. A set of 48 bi-allelic markers on the non-recombining region of Y chromosome (NRY) were analysed in 284 males; representing nine Indo-European speaking tribal populations. The genetic structure of the populations revealed that none of these groups was overtly admixed or completely isolated. However, elevated haplogroup diversity and FST value point towards greater diversity and differentiation which suggests the possibility of early demographic expansion of the study groups. The phylogenetic analysis revealed 13 paternal lineages, of which six haplogroups: C5, H1a*, H2, J2, R1a1* and R2 accounted for a major portion of the Y chromosome diversity. The higher frequency of the six haplogroups and the pattern of clustering in the populations indicated overlapping of haplogroups with West and Central Asian populations. Other analyses undertaken on the population affiliations revealed that the Indo-European speaking populations along with the Dravidian speaking groups of southern India have an influence on the tribal groups of Gujarat. The vital role of geography in determining the distribution of Y lineages was also noticed. This implies that although language plays a vital role in determining the distribution of Y lineages, the present day linguistic affiliation of any population in India for reconstructing the demographic history of the country should be considered with caution.

Distribution of beta-globin haplotypes among the tribes of southern Gujarat, India.

The present study was carried out in Indo-European speaking tribal population groups of southern Gujarat (India) to elucidate the allelic and haplotypic content of ß-globin system in individuals with HbAA genotypes. 6 neutral restriction sites of the ß-globin system were analysed and various statistical parameters were estimated to draw meaningful interpretations. All the 6 sites were found to be polymorphic and most were in Hardy-Weinberg Equilibrium in the studied group. Haplotypes were constructed using two different combinations of the 6 restriction sites analysed. Analysis of the 5 sites revealed a set of three predominant haplotypes, '+----', '-++-+' and '-+-++'; and haplotypes '+--', '++-' and '+++' were found to be the most frequent when the 3 sites were used to construct the haplotypes. Haplotypic heterozygosity levels (>83%) observed in the present study group were comparable to those observed in African and Afro-American populations and greater than other world populations. All the ancestral haplotypes, +-----, -++-+, -+-++ and ----+ were found in the study group. The distribution pattern of various haplotypes was consistent with the global pattern. The paucity of comparable data from other Indian populations restricted one from making interpretations about the study group's relationships with other Indian populations but the results were indicative of older population histories or experience of gene flow by the study group and their affinities with populations of southern India.

Genomic congruence of Indo-European speaking tribes of western India with Dravidian-speaking populations of southern India: A study of 20 autosomal DNA markers.

BACKGROUND: Due to its geographic location, Gujarat has played a major role in assimilation of different cultures with those of the subcontinent of India and is home to a number of Indo-European speaking tribes. AIM: This study examined the genetic structure and extent of gene differentiation in eight Indo-European speaking tribal populations of southern Gujarat in western India. It also determined if there was any residual effect of linguistic and cultural assimilation of Indo-European speaking groups on the genomic profile of the tribes under study. METHODS: Twenty autosomal DNA markers (Alu InDels and Restriction Fragment Length Polymorphisms) were analysed. RESULTS AND CONCLUSIONS: Average heterozygosity levels were high and degree of gene differentiation (G(ST) = 2%) was small, indicating that genetic drift may not have played a major role in bringing out a characteristic genetic differentiation in these groups. The genetic structure of the populations revealed that neither of these groups was overtly admixed nor completely isolated. Other analyses undertaken on the population affiliations revealed only a slight influence of Indo-European speaking populations on the tribal groups of Gujarat, but there was an overwhelming influence of Dravidian speaking groups of southern India, suggesting that genetic affinities may not necessarily be dependent on linguistic similarities.

Genomic structure of the immigrant Siddis of East Africa to southern India: a study of 20 autosomal DNA markers.

The Siddis are a tribal group of African origin living in Karnataka, India. They have undergone considerable cultural change due to their proximity to neighboring population groups. To understand the biological consequences of these changes, we describe the genomic structure of the Siddis and the contribution from putative ancestral populations using 20 autosomal DNA markers. The distribution of Alu indel markers and a genetic distance analysis reveals their closer affinities with Africans. The levels of genomic diversity and heterozygosity are high in all the populations of southern India. Genetic admixture analysis reveals a predominant contribution from Africans, a lesser contribution from south Indians, and a slight one from Europeans. There is no evidence of gametic disequilibrium in the Siddis. The genetic homogeneity of the Siddis, in spite of its admixed origin, suggests the utility of this population for genetic epidemiological studies.

Haptoglobin polymorphism among the tribal groups of southern Gujarat.

BACKGROUND: Gujarat is located at the western most point of the Indian subcontinent. Valsad and Surat districts are part of the 'tribal belt'of Gujarat and constitute 29.1% of total tribal population of Gujarat. These tribal populations are a rich source of gaining insights in the patterns of genetic diversity and genetico-environmental disorders against the back drop of their ecological, historical and ethnographic aspects. AIM: The objectives were to find out a) the genetic diversity among the tribes of Gujarat with reference to haptoglobin (Hp) locus b) the relationship between Hp polymorphism and sickle cell anemia/trait. MATERIALS AND METHODS: 431 individuals belonging to eight tribal groups were studied for Hp polymorphism using polyacrylamide disc gel electrophoresis (PAGE). Hb*S was screened by dithionate tube turbididy (DTT) test and confirmed using cellulose acetate membrane electrophoresis (CAME). STATISTICAL ANALYSIS: Allele frequency was calculated by direct gene counting method. Average heterozygosity and gene diversity were computed using software DISPAN. Analysis of molecular variance (AMOVA) was estimated using software ARLEQUIN version 3.1. RESULTS AND CONCLUSIONS: Pattern of allele frequency distribution showed preponderance of Hp(2) allele in all the eight tribal groups, which is in accordance with its frequency in different populations of Indian subcontinent. Total average heterozygosity (H(T)) was found to be low (0.160) but the level of genetic differentiation (G(ST)) was found to be moderately high (5.6%). AMOVA analysis indicated least among group variance between west and south Indian populations (-0.04%) indicating the affinities of the tribes of Gujarat with that of Dravidian speaking groups. Analysis of Hp phenotypes among sickle cell anemia/ trait individuals revealed a high frequency of Hp 0-0 phenotype (92.7%) among SS individuals as opposed to only 9.7% among AS individuals, reaffirming the selective advantage of HbAS state in relation to hemolytic disorders.

Haplotype diversity and linkage disequilibrium at the DRD2 locus among the tribes of western and southern regions of India.

BACKGROUND: Dopamine receptor D2 (DRD2) is an important gene having functional significance in the fields of neuropsychiatry and pharmacology and also has importance in evolutionary studies. MATERIALS AND METHODS: This study was undertaken to find out the haplotype distribution and linkage disequilibrium (LD) pattern for the three TaqI sites (TaqI 'A', TaqI 'B' and TaqI 'D') in the DRD2 gene in 232 unrelated individuals from five ethno-linguistically distinct endogamous tribal populations; Siddis and Gonds of Uttara Kannada district, Karnataka; Varli and Kolgha of Valsad district, Gujarat; and Dangi Konkana of Dang district, Gujarat. The genotype data obtained after molecular analysis of the three DRD2 sites was subjected to statistical analysis such as calculation of allele frequencies, haplotype frequencies among others. Subsequently, a neighbor-joining tree was also constructed from the data obtained. RESULTS: The three DRD2 sites were found to be polymorphic in all the populations. All the populations showed high levels of heterozygosities. Out of the eight possible haplotypes, most populations shared seven haplotypes. Of all the populations, Siddis showed the highest frequency of the ancestral haplotype B2D2A1 (11.4%). Significant LD was found to exist for TaqI 'A' and TaqI 'B' sites in both the populations. CONCLUSION: The findings are in concurrence with those from other Indian studies, especially from Dravidian-speaking South Indian populations. Similar pattern of diversity observed for ethnically and linguistically diverse populations in the present study is indicative of complex structure of Indian populations.

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.

Genetic affinities of the Siddis of South India: an emigrant population of East Africa.

Historical records indicate that the Portuguese brought the African Siddis to Goa, India, as slaves about 500 years ago. Subsequently, the Siddis moved into the interior regions of the state of Karnataka, India, and have remained there ever since. Over time the Siddis have experienced considerable cultural changes because of their proximity to neighboring population groups. To understand the biological consequences of these changes, we studied the Siddis to determine the extent of genetic variation and the contributions from the African, European, and Indian ancestral populations. In the present study we typed the Siddis for 20 polymorphic serological, red cell, and Alu insertion-deletion loci. The overall pattern of phenotype (and genotype) distribution is in accordance with Hardy-Weinberg expectations. Considering the ethnohistorical records and the availability of secondary-source genetic data, we used two data sets in the analysis: one comprising eight serological and red cell enzyme markers with eight population groups and another comprising six Alu insertion-deletion markers with seven tribal groups of South India. The dendrograms generated from these two data sets on the basis of genetic distance analysis between the selected populations of African, European, and Indian descent reveals that the Siddis are closer to the Africans than they are to the South Indian populations. Genetic admixture analysis using a dihybrid model (19 loci) and a trihybrid model (10 loci and 8 loci) shows that the predominant influence comes from the Africans, a lesser contribution from the South Indians, and a slight contribution from the Portuguese. Thus the original composition of the African genes among the Siddis has been diluted to some extent by the contribution from southern Indian population groups. There is no nonrandom association of alleles among a set of 10 genetic marker systems considered in the present study. The demonstration of genetic homogeneity of the Siddis, despite their admixed origin, suggests the utility of this population for genetic and epidemiological studies.

Fertility and mortality differentials among the population groups of the Himalayas.

Selection potential based on differential fertility and mortality has been computed for 24 Himalayan populations classified into four groups: Himalayan populations with Asian affinities (HPA), Brahmans, Rajputs, and Scheduled Castes (Shilpkars). Irrespective of the methodology followed, the total index of selection was found to be highest (0.794) in Barbatiyas (HPA) and lowest (0.428) in Rajputs. The relative contribution of fertility component (If) to the index of total selection (It) is higher than the corresponding mortality component (Im) in all 24 groups. An analysis of correlation and regression on different components of the indices of selection performed among these 24 Himalayan populations revealed that the contributions of If in determining It are stronger than Im. Further, both If and Im are strongly associated with It and account for 76% and 67% of total variability in It, respectively. Examination of the relationship of the selection potential with the differential altitude and social categories showed a decrease in the index from high altitude to low altitude. Similarly, an inverse relationship was found between various indices and social categories. Himalayan populations with Asian affinities (HPA) in the present study reveal higher values of selection potential. Interestingly, these populations invariably reside in high altitude areas where health and communication infrastructures are poorly developed. Thus, the differential pattern of fertility and mortality among the Himalayan populations indicates that they are passing through a stage of transition, as is evident from the decrease in various selection indices. It is also apparent that groups that are less developed socioeconomically, as well as those inhabiting high altitude regions, are lagging behind in this process.