“GAD2 Identified as Candidate Gene for Obesity” Summary
Obesity is a very hard condition to link to one specific gene because it often runs in families, but their lifestyle habits, as well as genes, contribute to obesity. Also, many genes contribute a small effect to obesity and may differ in different populations. Nuclear families in France were studied to link a candidate gene for obesity by Philippe Froguel and his colleagues. There are many variations in genes from person to person that affect from appearances to diseases, and in most cases of obesity, it is influenced by many genes. Froguel previously linked a region of chromosome 10 and obesity. The GAD2 gene also turned up frequently. GAD2 codes for an enzyme that catalyzes a neurotransmitter to be made that interacts with a neuropeptide that helps stimulate appetite. When screening the subjects and the controls for the GAD2 alleles in the study, Froguel identified one group of alleles as “protective” against obesity. Another group of alleles were identified as “at-risk.” It was supported by the genetic screenings of the nuclear families in the study. Obese individuals with two copies of an “at-risk” allele had more difficulty controlling food intake when compared to the control subjects. It was then hypothesized that an over expression of the GAD2 gene may increase the amount of GABA, a neurotransmitter, in the hypothalamus. This then leads to increasing effects and overeating. Studies have been done on turkeys and mice that were injected with the GABA activator. Both the turkeys and the mice ate more and gained more weight when given more of the activator. This experiment supports the notion that not regulating GABA localization will cause overeating and more weight gained. Genetic factors cannot explain why obesity rates have risen rapidly, but they can help doctors give people preventive approaches to help the condition of obesity. The results do conclude that GAD2 is a candidate gene for obesity, and with further research, how the gene actually influences weight will be found.