Association of Native American ancestry and common variants in ACE, ADIPOR2, MTNR1B, GCK, TCF7L2 and FTO genes with glycemic traits in Colombian population.

Insulin resistance and defects in other related glycemic traits are common findings in the context of Metabolic Syndrome. Although genetic factors are clearly implied in susceptibility, and some gene variants have been identified mainly in populations of European ancestry, little is known about this aspect in admixed populations. The association of insulin resistance, ß-cell function, fasting insulin and glucose levels with 48 gene variants, previously related to metabolic syndrome components, and with the ancestral genetic composition, estimated on 50 ancestry informative markers, was evaluated in 417 individuals from the Colombian admixed population. The Native American genetic ancestry was associated with a low ß-cell function (odds ratio (OR) of 1.73 and 95% confidence interval (95% CI) of 1.07-2.81, p = 0.026). Significant genotypic associations were obtained (q-value < 0.05) for gene variants in ACE (rs4340; OR (95% CI): 2.79 (1.58-4.91), insulin resistance; mean difference (95% CI): 0.273 (0.141; 0.406), fasting insulin), ADIPOR2 (rs11061971; OR (95% CI): 0.14 (0.04-0.48), low ß-cell function), MTNR1B (rs10830963; mean difference (95% CI): 0.032 (0.013; 0.051), fasting glucose) and GCK (rs4607517; mean difference (95% CI): 0.038 (0.020;0.056) and rs1799884; mean difference (95% CI): 0.027 (0.013-0.041), fasting glucose). Also the well-known gene variants rs7903146 in TCF7L2, and rs17817449 in FTO, were nominally associated with hyperglycemia (rs7903146), as well as with higher fasting insulin levels (rs17817449). Our findings indicate that gene variants in ACE, ADIPOR2, MTNR1B, GCK, TCF7L2 and FTO, are associated with glycemic traits in the admixed Colombian population, while a higher Native American genetic component is related to lower ß-cell function.

Insulin resistance and ß-cell function in Colombian mestizo and Embera-Chamí populations and their relation with adiposity degree.

BACKGROUND AND OBJECTIVE: Insulin resistance (IR) is a condition favored by metabolic and endocrine changes experienced by adipose tissue in the context of obesity. The prevalence and the presentation of both IR and obesity vary among the populations, and may be affected by ancestral genetic composition among other factors. The aim of this study was to compare the presence of IR and obesity in Amerindians of the Embera-Chamí ethnicity and Colombian mestizo population. PATIENTS AND METHODS: A sample of 630 individuals, 471 mestizos and 159 Amerindians of the Embera-Chamí ethnicity, from the general population of Colombia were studied. For each participant, anthropometric and biochemical measurements, as well as blood pressure and the Homeostatic Model Assessment (HOMA) of IR and ß-cell function (%B) were recorded. These values were compared between the two populations. RESULTS: While prevalence of central obesity was similar in both populations (48.7% and 42.6% in the mestizo and Embera groups respectively; p=0.148), body mass index (BMI) values suggested a higher prevalence of overweight in the Embera than in mestizo population (43.4% Embera, 31.8% mestizo; p=0.027). Despite the similarities in the prevalence of HOMA-IR and HOMA-%B status between both populations, the Embera population had a significantly greater pancreatic ß-cell function, higher insulin levels, and better glucose control, across BMI and central obesity categories, than the mestizo population. CONCLUSION: There are differences in aspects related to energy metabolism between the samples of the mestizo and Amerindian populations analyzed.