The effects of genes, environment and ethnicity on insulin resistance and obesity in aboriginal and non-aboriginal South American populations
Year: 2011
Type: dissertation
Study design: Observational Study
Abstract: The worldwide prevalence of type 2 diabetes (T2D) has increased dramatically over the past half-century and is continuing to rise at a rapid rate, along with increasing levels of obesity.These changes are having a profound effect on healthcare planning and provision in many countries.Strong environmental effects in T2D risk are clear from longitudinal studies.In addition, groups with traditional lifestyles who migrate to a more 'Westernised' environment and lifestyle suffer increased diabetes prevalence.Environmental factors, however, do not seem to explain all of the variance in type 2 diabetes prevalence, nor all the variance in response to intervention studies.Offspring of patients with type 2 diabetes have about a three-fold higher risk of developing the disease than those with no diabetes family history.Diabetes prevalence also differs between ethnic groups within countries.South Asian populations living in the UK and US have approximately 4-6 times the risk of developing diabetes compared to those of European descent.This effect may also be evident in other Native American populations such as the Mapuche in Chile.Mapuche populations living a traditional rural lifestyle appear to be relatively protected, on limited data, against diabetes risk (prevalence of ~1% to ~4%; but this risk increases markedly in the urban environment (6.2 to 8.2%).These observations suggest that genetic predisposition is also a factor in determining diabetes risk, but this is complicated by gene-environment interactions, where individuals with different genotypes respond differently in different environments.© CA Celis Morales (2011) finding appropriate treatments and effective preventative programmes, with concomitant improvements in public health in Chile.In order to explore how environment and genes interact in the development of obesity and cardiometabolic disease, this study focuses on indigenous populations that show increased risk of obesity, diabetes and related cardio-metabolic phenotypes when exposed to a 'Westernised' environment.For this study four groups of participants were recruited: Mapuches (M) living in Rural (MR) and Urban environments (MU), and Chileans of European descent (E) living in Rural (ER) and Urban environments (EU).Detailed characterisation of body composition, fitness, physical activity patterns, nutritional factors, socio-economic, genetics and metabolic factors in these four groups was performed.The main findings from this thesis were: (a) urbanisation, adiposity, physical activity and sedentary behaviours influence insulin resistance to a greater extent in Chilean Mapuches than in Chileans of European descent.These associations persist after adjustment for a comprehensive range of potential confounding factors; (b) FTO genotype influences insulin resistance in the Mapuche but no European Chilean population.These associations persist after adjustment for a comprehensive range of potential confounding factors; (c) FTO influences obesity-related traits in the Chilean population.However, these relationships were not all independent of lifestyle factors and these factors should therefore be taken into account in future research studies, which try to address the real genetic effect of FTO and its contribution to obesity; (d) that physical activity plays a key role in modulating the genetic predisposition to obesity and insulin resistance.This observation has important public health implications, because the present data indicate that being physically active can overcome, at least in part, the genetic predisposition to obesity induced by variation in the FTO gene.However, further studies into the mechanisms underpinning this effect are needed.This has potential implications both on the design as well as on the implementation of lifestyle strategies to reduce metabolic risk in different ethnic groups, and for advancing the basic understanding of the mechanisms behind human obesity and insulin resistance.
Authors: Celis Morales, Carlos Alberto
Language: English
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W1601010558