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Genes influence every part of the human body, whether it is the development of the body, the adaptation to the environment, or the actual physiological make-up of the human form. Although much research has been done in recent years to identify obesity-related genes, to date the full scale of the interaction between genes and lifestyle has not been fully understood.
It is true that some genes do predispose people to gain weight, but these cases are very rare, and the obesity is usually a component of another genetic disorder, such as Prader-Willi syndrome. With all the research conducted to date, it has been discovered that the genetic factors that have been identified related to obesityare only a very small component in someone's risk of becoming obese.
Rare Forms of Obesity – Monogenic Obesity
There are several forms of obesity that results form mutations in single genes but these are very rare. These monogenic mutations are associated with food intake, appetite control and energy use. This rare form of obesity is seen in disorders such as the above-mentioned Prader-Willi Syndrome and Bardet-Biedl Syndrome, and the obesity is accompanied by other abnormalities, particularly with mental retardation and reproductive issues.
Multiple Gene Mutations
The common obesity that has reached pandemic proportions throughout the world has led scientists to try and identify whether genetic obesity is due to a single gene mutation or multiple gene mutations. Research studies have been undertaken that looked predominantly at twins, to see if a set of twins is more predisposed to obesity if they carry certain gene mutations.
Genome-Wide Association Studies
Undertaking a genome-wide association study involves scanning hundreds of thousands of genetic markers using complete sets of DNA from individuals. The process is used to identify variations in genes that may relate a particular disease. What they are looking for are gene variants, which are very small variations of DNA that can indicate risk of certain diseases.
The first obesity-related gene variant using this method was discovered in 2007, and this is called the fat mass and obesity associated gene on chromosome 16. It has been discovered that those who carry this gene variant have up to a 30 percent higher risk of becoming obese. There is a second gene variant related to obesity that is found on chromosome 18.