Obesity And Genomics

May 19th, 2011 |

Author: Editor

Overweight occurs when body fat accumulates over time as a result of a chronic energy imbalance (calories consumed exceed calories consumed). Obesity is a major health hazard worldwide and is equipped with several relatively common diseases such as diabetes, high blood pressure, heart disease and some cancers.
The “obesity epidemic” – where genes are really involved?
In recent decades, obesity has reached epidemic proportions in populations whose environments provide a wealth of energy-dense foods and few opportunities for physical activity achieved. Although changes in the genome of the population to slowly happen to be responsible for this rapid rise in obesity, these genes play a role in the development of obesity. Probably regulate genes, such as our body to store the catch, and give energy from food. The origin of these genes, however, may not be new.
How could genes contribute to obesity? A “thrifty genotype” hypothesis
Moreover, any explanation of the obesity epidemic, include both the role of genetics and the environment. A widely quoted genetic explanation for the rapid increase in obesity is the mismatch between today’s environment and “energy-thrifty genes” that multiplied in the past under different environmental conditions, when food sources were quite unpredictable. In other words, according to the “thrifty genotype” hypothesis to survive the same genes that helped our ancestors occasional famines today from environments that provided plenty of food throughout the year in question.
What other options might genes affect obesity?
It has been argued that the thrifty genotype, only part of a wider range of options which genes fat accumulation in a given environment preferred. These possibilities include eating the drive too much (poor regulation of appetite and satiety), the tendency to sedentary (physically inactive), a reduced ability to dietary fat to use as fuel, and a larger, slightly irritated capacity to store body fat. Not all people in industrialized countries with abundant food and physical activity are reduced or become obese, nor are all overweight people have the same body fat distribution, or suffer the same health issues. This diversity comes from the groups of the same race or ethnic origin, and even live in families in the same environment. The variation in how people react to the same environmental conditions, is another indication that the genes play a role in the development of obesity. This is consistent with the theory that obesity results from genetic variations interact with environmental conditions.

What is known about specific genes associated with obesity?
The indirect scientific evidence for a genetic basis for obesity comes from a variety of studies. Usually this evidence are studies of the similarities and differences between family members, twins and adopted children. Another source of evidence includes studies showing that some genes found in higher frequencies among the obese (association studies). These studies suggest that a significant amount of weight variation in adults is due to genetic factors. However, the identification of these factors was difficult.
Regarding direct evidence for obesity genes, the best results of several cases of extreme obesity caused by mutations (changes in the genetic material) of single genes (monogenic cases) can occur. But these cases represents only a small fraction of cases worldwide. Recently, however, have mutations in a gene has been (melanocortin 4 receptor gene, based on the control of feeding behavior) is observed, be strong, with a minority (perhaps 5%) of cases associated with obesity in several populations.
Progress in the identification of several genes with the most common form of obesity has accelerated slowly, but surely. As of October 2005 (the latest update of the human obesity gene map), single mutations in 11 genes were highly involved in 176 cases of obesity worldwide. In addition, 50 chromosomal locations relevant to obesity has been assigned to identify possible causative genes in most of these regions. (Chromosomes are threadlike structures that contain genes are densely packed in the nucleus of every cell.) Also, studies with genome-wide scan on 253 groups of genes associated with obesity, with about a fifth of them concentrated reported two or more studies. (Genome, the total number of genes contained in the chromosomes.) Finally, do 426 versions of 127 genes related to obesity. At least five independent studies have replicated each association in 22 of these genes.
Reported recently several independent population-based studies that a gene of unknown function could (FTO, fat mass and obesity associated gene) for up to 22% of all cases of common obesity in the population responsible. Interestingly, this gene also shows a strong association with diabetes. The mechanism by which this gene is currently under intense scientific research.
How can Public Health Genomics contribute to the effects of obesity in the population?
Scientists have made great progress in understanding important environmental causes of obesity and the identification of many more genes that could be involved. Greater efforts are now directed to assess the interaction of genes and environment in the obesity epidemic. The translation of these efforts in public health practice from a genomic perspective will take some time.
… And how can family history help?
Fortunately, there is an easy way for Public Health Genomics start reducing the impact of obesity in the population. It is through the use of family history. Family history reflects genetic susceptibility and environmental factors shared by close relatives. Health care physicians routinely collect family health history to identify people at high risk for obesity disorders such as diabetes, cardiovascular disease and certain cancers. Weight loss or prevention of excess weight gain is particularly important in this high risk group. Each health promotion efforts can reduce the negative effects of obesity in the population will be more effective if it leads intensive lifestyle interventions to high risk groups (high-risk prevention strategy). However, should not such strategies from the population prevention strategy in which independent of genetic predisposition and environmental influences, all people should follow a healthy diet and to take to help regular physical activity into their daily lives, the risk of obesity and associated recommended distractions .
How can you tell if you or your family are overweight?
The majority of health personnel practitioners use the Body Mass Index (BMI) to determine whether a person is overweight. Check your body mass index with a BMI calculator.