Epigenetic differences between obese and lean people

In most industrialized nations today, obesity is highly prevalent and represents a significant cost to society, both in terms of economy and health. Individuals are classified obese when they have a Body Mass Index (BMI) of 30 or over. In the UK, 1 in 4 people are classified as obese and the direct costs to the NHS of this disease are estimated to be £4.2 billion per year. Obesity related mortality by far exceeds that of other common diseases, indicating that, in addition to the commonly unheeded advice of ‘eat less, move more’, there is an urgent need for novel therapeutic strategies. Understanding the underlying genetics of obesity will aid this research effort. New research in BMC Medicine adds to the body of data characterizing the genetic differences between obese and lean individuals.

Wang and colleagues attempt to elucidate the mechanisms behind impaired immune function in the obese by looking at changes in immune-specific genes in blood cells. They look at immune function because a common factor in the pathogenesis of obesity related diseases is the presence of a low level inflammatory process, which involves the activation of immune-specific genes. These genes can be differentially regulated with chemical modification to the DNA that cause the gene structure to physically change, either activating or suppressing its activity. This process is called epigenesis and interestingly, these modifications can change depending on lifestyle factors during the course of normal life.Wang and colleagues found that some immune-specific genes have differential DNA modifications in obese individuals when compared to lean controls. This may impact on some of the immune dysfunctions seen in obese individuals.

This study is part of a growing research movement, reviewed in a commentary by Paul Franks and Charlotte Ling for BMC Medicine, that takes into account epigenetic differences between the obese and non-obese. At present, we do not know if these differences are caused by, or rather cause obesity. Further studies are warranted in this exciting field, which may then bring about novel approaches to the treatment of obesity, perhaps tailored to individuals’ epigenesis profiles.

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