Association of fat mass and obesity-associated (FTO) gene rs9939609 with obesity-related traits and glucose intolerance in an indigenous population, the Xavante.

BACKGROUND AND AIMS: Common variants in fat mass and obesity-associated (FTO) gene have been implicated as a susceptibility locus for obesity and type 2 diabetes in different populations. Here, in an indigenous population-based study, we examined whether FTO rs9939609 has a role in susceptibility to glucose intolerance and obesity. METHODS: The study population comprised 949 full Xavante indigenous people (465 men) aged 18-99 years. The participants were submitted to clinical examination, anthropometrical measures and basal and 2-h post 75g oral glucose load capillary glucose measurements. FTO rs9939609 was genotyped and logistic regression was carried out to test the additive effect of the risk allele. RESULTS: The frequency of the minor allele of the FTO rs9939609 (0.06) was lower in Xavante than observed in some populations. A significant association between the variant and overweight was observed (OR = 1.56 (95% CI:1.06-2.29, p = 0.02), using an additive model of inheritance, adjusted by age and gender and considering the family structure. We found no associations with obesity or glucose intolerance. CONCLUSIONS: The FTO rs9939609 is associated with overweight, but not with obesity or glucose intolerance. The low frequency of the A allele suggests that it is not an important risk determinant for these conditions in Xavante indigenous people.

Serum 25-hydroxyvitamin D concentration and its association with glucose intolerance in an indigenous population.

BACKGROUND AND AIMS: Type 2 diabetes is a multifactorial disease resulting from diverse genetic and environmental factors as well as the interaction between them. Low levels of 25-hydroxyvitamin D [25(OH)D], an indicator of vitamin D status, have been associated with an increased risk of type 2 diabetes, but not consistently. Also, it remains to be determined if this association differs among ethnic groups. Therefore, we aimed to evaluate vitamin D status and its association with glucose intolerance in a Brazilian indigenous population, the Xavante Indians. METHODS: The study population consisted of 819 full Xavante Indians (410 women), aged ≥18 years and living in two indigenous reserves located in Mato Grosso State, central region of Brazil. Clinical examination and anthropometrical measurements were made, blood samples were obtained for total cholesterol, HDL-cholesterol, triglycerides and 25(OH)D measurement. Fasting and 2-h post 75 g oral glucose load capillary glucose was measured. Vitamin D status was defined by serum 25(OH)D levels: vitamin D sufficiency (25(OH)D: 30-100 ng/mL), vitamin D insufficiency (25(OH)D: 20- <30 ng/mL) and vitamin D deficiency (25(OH)D: < 20 ng/mL). Multiple logistic regression was performed to identify independent associations between 25(OH)D levels and impaired glucose tolerance or diabetes mellitus. RESULTS: Analyses stratified by 25(OH)D levels shows that 65.5% of the population had vitamin D deficiency/insufficiency (25(OH)D < 30 ng/mL). 25(OH)D concentrations were lower in individuals with impaired glucose tolerance or diabetes mellitus than in normal glucose tolerant individuals. Multiple logistic regression analysis showed an inverse association between increments of 25(OH)D and presence of diabetes mellitus (OR per 1 ng/mL increase in 25(OH)D: 0.97; 95% confidence interval: 0.95-0.99), or impaired glucose tolerance (OR per 1 ng/mL increase in 25(OH)D: 0.87; 95% confidence interval: 0.85-0.89), in an age, sex, BMI and season of sampling-adjusted model. CONCLUSIONS: The present population-based study found a high prevalence of hypovitaminosis D among Xavante Indians. In this at-risk population of type 2 diabetes, a significant association of higher serum 25(OH)D with a decreased prevalence of diabetes mellitus and impaired glucose tolerance was observed.

High prevalence of type 2 diabetes mellitus in Xavante Indians from Mato Grosso, Brazil.

OBJECTIVE: To estimate the prevalence of diabetes, hypertension, obesity, and describe demographic, anthropometric and medical characteristics, in a genetically distinct population: the Brazilian Xavante Indians. DESIGN: Population-based survey carried out among 948 Xavante from Mato Grosso, Brazil. Fasting and 2-hour after 75 g glucose capillary glycemia were measured by a portable glucometer (HemoCue Glucose201+). Diabetes was defined according to WHO criteria. Anthropometric data and medical characteristics were measured, and fat mass (%) was evaluated using bioelectrical impedance. Blood pressure was measured by an automated device (OMRON 742INTC), and hypertension was defined according to WHO criteria. RESULTS: Age-adjusted prevalence rates with 95% confidence intervals were diabetes: 28.2% (25.3-31.1) in general, 18.4% (14.9-22.2) in men and 40.6% (36.2-45.1) in women (P<.001); impaired glucose tolerance: 32.3% (20.5-26.0) in general, 29.7% (25.4-33.9) in men and 34.4% (30.2-38.8) in women (P>.05); hypertension: 17.5% (15.1-19.9) in general. Obesity was found in 50.8% of the individuals. Fat mass (%) was associated with diabetes in men (P<.05) and women (P<.05). Thigh circumference and waist/ thigh ratio were lower in those with diabetes, in men and women (P<.001). CONCLUSIONS: The high prevalence of diabetes and obesity in Xavante is likely related to their recent change in food habits and physical activities. Our results should raise awareness about the magnitude of this health problem and also indicate that it could increase dramatically in the future if no preventive actions are adopted.

Evaluation of body adiposity index (BAI) to estimate percent body fat in an indigenous population.

BACKGROUND & AIMS: The aim of this study was to evaluate the usefulness of Body Adiposity Index (BAI) as a predictor of body fat in Xavante Indians and to investigate which anthropometric measures of adiposity best correlate with body fat in this population. METHODS: We evaluated 974 individuals (476 male), aged 42.3 ± 19.5 years. Percentage of body fat (%BF) determined by bioimpedance analysis (BIA) was used as the reference measure of adiposity. Bland-Altman analysis was used to assess the agreement between the two methods: BAI and BIA. Associations between anthropometric measures of adiposity were investigated by Pearson correlation analysis. RESULTS: BAI overestimates %BF (mean difference: 4.10%), mainly at lower levels of adiposity. Significant correlations were found between %BF and all measurements, being the strongest correlation with BAI. However, stratified analyses according to gender showed that among men waist circumference has the strongest correlation (r = 0.73, p < 0.001) and among women BAI (r = 0.71, p < 0.001), BMI (r = 0.69, p < 0.001) and waist circumference (r = 0.70, p < 0.001) performed similarly. CONCLUSION: BAI can be a useful tool to predict %BF in Xavante Indians, although it has some limitations. However, it is not a better predictor of adiposity than waist circumference in men or BMI and waist circumference in women.

Genome-wide analysis in Brazilian Xavante Indians reveals low degree of admixture.

Characterization of population genetic variation and structure can be used as tools for research in human genetics and population isolates are of great interest. The aim of the present study was to characterize the genetic structure of Xavante Indians and compare it with other populations. The Xavante, an indigenous population living in Brazilian Central Plateau, is one of the largest native groups in Brazil. A subset of 53 unrelated subjects was selected from the initial sample of 300 Xavante Indians. Using 86,197 markers, Xavante were compared with all populations of HapMap Phase III and HGDP-CEPH projects and with a Southeast Brazilian population sample to establish its population structure. Principal Components Analysis showed that the Xavante Indians are concentrated in the Amerindian axis near other populations of known Amerindian ancestry such as Karitiana, Pima, Surui and Maya and a low degree of genetic admixture was observed. This is consistent with the historical records of bottlenecks experience and cultural isolation. By calculating pair-wise F(st) statistics we characterized the genetic differentiation between Xavante Indians and representative populations of the HapMap and from HGDP-CEPH project. We found that the genetic differentiation between Xavante Indians and populations of Ameridian, Asian, European, and African ancestry increased progressively. Our results indicate that the Xavante is a population that remained genetically isolated over the past decades and can offer advantages for genome-wide mapping studies of inherited disorders.

Cirurgia cardíaca em índios brasileiros / Heart Surgery in Brazilian Indians

PURPOSE: Our experience with surgical treatment of heart diseases in Indians living in the Amazon rain forest in primitive stages was reviewed. METHODS: From 1988 to 1995, 18 patients underwent cardiovascular surgical procedures at the São Paulo Hospital of the Escola Paulista de Medicina. Seven patients had valvar disease, nine congenital heart defects, one submitral aneurysm and one arrhythmia. Thirteen Indians came from tribes of the Amazon rain forest area: three from the Xavante, two from Waiapi, two from Tucano, two from Macuxi, two from Mayoruna, and one of each tribe of Xikrin, Guajajara, Terena, Surui, Galibi, Cinta-Larga and Pataxó. RESULTS: We performed 22 operations, with two hospital deaths. Follow-up was possible in 87.5 of cases, with one late death. The majority of cases were due to congenital heart defects and in this series it was noted the absence of operations to treat coronary artery disease. The incidence of valve disease was higher in accultured or semi-accultured Indians. CONCLUSION: The surgical treatment of cardiovascular disease has made possible to the surviving indians to return to and be accepted by their fellow tribesmen.

Aneurisma submitral do ventrículo esquerdo em um índio brasileiro / Submitral left ventricular aneurysm in a Brazilian Indian

O aneurisma subvalvar do ventrículo esquerdo é doença rara, de etiologia desconhecida e descrita principalmente em negros africanos. Neste artigo relata-se o caso de um índio brasileiro com sintomas de insuficiência cardíaca e sopro de insuficiência mitral. A radiografia de tórax observou-se abaulamento discreto do contorno cardíaco esquerdo em ao ecocardiograma bidimensional, aneurisma submitral do ventrículo esquerdo, confirmado por ventriculografia esquerda.O tratamento cirúrigico consistiu de ressecçöes do aneurisma e valvoplastia mitral. Durante a cirurgia encontrou-se uma perfuraçäo do aneurisma para a cavidade atrial esquerda que näo foi detectada por ecocardiografia nem por ventriculografia

Subralvar left ventricular aneurysm is a rare disease of unknown etiology, that has been described most often in black Africans. A case of Brazilian indian with heart failure and a murmur of mitral regurgitation is reported. The chest x-ray showed a mild bulge in the left cardiac border and two-dimensional echocardiography demonstrated submitral left ventricular aneurysm, confirmed by left ventricular angiography. Surgical treatment consisted of ressection of the aneurysm and mitral valvuloplasty. A perforation of the aneurysm, undetected neither by two-dimensional echocardiography nor by angiography was found at surgery.