Tenneessee: A single gene mutation may be all it takes to determine if a person is prone to becoming obese, scientists have discovered. A rare version of the BDNF gene could predispose people to gaining weight, by producing lower levels of BDNF protein - a regulator of appetite - in the brain. Researchers at the National Institutes of Health suggest that by boosting levels of the protein, they may be able to develop a therapeutic treatment to help combat obesity. Obesity is one of the most serious public health concerns faced by many nations, including the UK and US, contributing to conditions such as heart disease, stroke and type 2 diabetes. Genetic factors are known to predispose a person to gaining weight, as well as influence the effectiveness of weight-loss strategies.–MOL
The body relies on cells to process and store energy. Therefore, changes to the genes that regulate these functions can cause an imbalance that leads to excessive energy storage and weight gain.
Dr Jack Yanovski, one of the study's authors and an investigator at NIH, said: 'The BDNF gene has previously been linked to obesity, and scientists have been working for several years to understand how changes in this particular gene may predispose people to obesity. 'This study explains how a single genetic change in BDNF influences obesity and may affect BDNF protein levels.
'Finding people with specific causes of obesity may allow us to evaluate effective, more personalised treatments.'  The BDNF protein plays a variety of roles in the brain and nervous system. And, at high levels the protein can stimulate the feeling of being full. 
Dr Joan Han, formerly a NIH investigator and now at the University of Tennessee and her team first analysed the BDNF gene. They were looking for naturally occurring genetic changes that alter levels of BDNF production. To do so they examined brain tissue samples.
Researchers identified an area of the gene where a single change reduced BDNF levels in the hypothalamus, a key area of the brain that controls eating and body weight. The genetic change identified was not a rare mutation, but rather a variation that occurs in the general population.
Every person has two copies, or alleles, of each gene, inheriting one copy from each parent. Alleles can vary at any location across the gene. During their experiments, researchers referred to the common allele as 'T', and the less common allele - that which produces less BDNF protein - as 'C'.
Using this information, they studied the BDNF gene in four groups of people, encompassing more than 31,000 males and females enrolled in clinical research studies. They compared a person's BDNF gene combination - CC, CT or TT - to factors that define obesity, including body mass index (BMI) and percentage body fat. In African American adults, the team found the C allele was linked to higher BMI and body fat percentage in those with CT or CC types.
In a group of healthy children of many races, the researchers found that CC types had higher BMI scores and percentage of body fat, when compared to CT or TT types, who were similar to each other. Finally, in a group of Hispanic children, the researchers found that the C allele (CT and CC types) was associated with a higher BMI score.