GAD2: Is The Cause For Obesity Discovered?

According to the study, GAD2, a specific gene, was responsible for both encouraging and protecting against obesity!
The Public Library of Science recently posted a pre-publication synopsis of research that is driving the media wild. A team of researchers (Phillip Frougel et al) examined nearly 1,200 French. 575 of the subjects were obese, and 646 were "controls". Their focus was on a specific set of alleles that had speculative relationships to obesity. According to the study, GAD2, a specific gene, was responsible for both encouraging and protecting against obesity!

Can This Mean An End To Obesity?

This study could be groundbreaking, due to the simple fact that health practitioners may be able to identify a propensity for obesity at early stages in life, and take preventative measures early enough to prevent obesity from occurring. The researchers themselves admit that genetics are not the only factor that leads to obesity - it is the result of a complex interaction between genetics and the environment. By understanding genetics, however, the environment can be appropriately influenced when necessary to help avoid the negative result of becoming extremely overweight.

The Human Genome Project began in 1990 as an attempt to identify all of the approximately 30,000 genes present in human DNA. The goal was to determine the sequences of 3 billion chemical base pairs that make up human DNA then store this information in a database to be used by researches. The project was originally planned to last fifteen (15) years, but technological advances accelerated the progress so that the project concluded this year (2003).

An Augustinian monk named Gregor Mendel first discovered genes in 1865. He learned that certain "factors" helped determine certain traits in human beings. This launched the science of genetics, or the study of genes. While genes determine traits, there are various versions of genes that are known as alleles.

Various alleles can produce different outcomes. Genes are strung together into structures known as chromosomes - humans have 46 chromosomes, each a collection of specific genes. Chromosomes hold an incredibly long molecule called DNA, or deoxyribonucleic acid.

Certain genes can produce very obvious traits, such as eye color or hair color. Other genes may be related to biological functions and can even cause genetic diseases or increase the risk that someone will develop a disease. It has long been assumed that certain genes may cause certain people to become obese, as studies of families have shown trends of obesity that run from generation to generation. The cause of much debate, however, was whether this was due to genetics, due to environmental factors (i.e. a family tradition of overeating) or a combination of the two.

The term genome refers to the complete structure of DNA, so the Human Genome Project refers to the mapping of humans' entire DNA. Once this was mapped, a serious of studies began (and are still being conducted) to compare certain health trends with known genetic traits. It is the result of this research that led to the recent study, which examined a specific gene known as GAD2.

What Is GAD2?

GAD2 was previously identified, but the current study correlated the presence of variations of this gene, known as alleles, with the actual condition of 1200 subjects. GAD2 stands for Glutamate decarboxylase 2. This particular gene impacts the production of GABA, an amino acid that acts as a neurotransmitter. Therefore, variations in the GAD2 gene can result in differences between humans with how GABA is produced.

GABA stands for Gamma-aminobutyric Acid. GABA was first discovered in 1863 about the same time that Mendel was beginning to understand genes. GABA, as a neurotransmitter, affects the central nervous system. It has been shown to stimulate production of growth hormone, affect appetite, and even impact sleeping patterns (known as the diurnal cycle). Due to the popularity of supplemental GABA as a fat loss aid, it stands to reason that a gene related to the production of GABA could be implicated in obesity.

Interestingly, the study identified two specific alleles, or variations, of the GAD2 gene, that affected obesity. Subjects with two or more of a particular allele present were more likely to be obese. The researches hypothesize that this triggered an increase in the amount of GABA present in a gland known as the hypothalamus, which would trigger hunger and cause the subject to overeat. On the other hand, another allele of GAD2 actually seemed to be protective against obesity, presumably by failing to adequately stimulate appetite and therefore making the subjects less likely to overeat.

While there is still work and research remaining before any final conclusions can be drawn (the paper is not even at its final publication stage), this is a very exciting discovery. Not only can it possibly help identify individuals who are at risk from obesity early on, it may also provide clues for how to effectively treat the condition. If an individual suffering from obesity is determined to have the culprit GAD2 gene, they may be able to combat the effects by knowing exactly how this genetic condition is affecting their nervous system and appetite. Who knows? There may even be certain supplements that would be able to address the excess production of GABA and thus make it easier for those suffering from obesity to combat their overaggressive appetite and take more control over their life.

There is no doubt that environment also contributes to the problem of overweight and obesity. Understanding genetic factors does not provide an excuse for living unhealthy or becoming obese, nor does it automatically provide the solution or a cure. If anything, however, it continues to educate us about the complexity of issues such as obesity and help us understand the factors so that we can better equip ourselves to combat the epidemic that is taking over the world.

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