Fat mice provide genetic clues to obesity puzzle

A new study published in Nature Medicine provides clues as to how a gene mutation may lead to obesity. Mutations in the brain-derived neurotrophic factor gene (BDNF) have previously been shown to cause obesity in mice and have been identified in severely obese children. Genome-wide association studies have also confirmed BDNF as a susceptibility gene for common obesity in humans. The study investigated the mechanism by which BDNF mutations lead to obesity. Obesity is caused by an excess of energy, which can result from high energy intake, low energy expenditure, or both. Obesity was caused solely by overeating in mice with BDNF mutations, which consumed up to 80% more food than those without the mutation (‘wild type’ mice). When the mice with the mutation were restricted to the amount of food that that the wild type mice chose to eat, they did not become obese...