Genetic Studies reveal the Role of Genes in Reducing Obesity

Obesity is a disease of modern society whose prevalence has increased drastically in the past few decades. Even though its occurrence is found to be higher in western societies, it is slowly spreading to other parts of the world and hence becoming a global health concern. It leads to many chronic diseases like type 2 diabetes, hypertension, cardiovascular problems etc. and is also the cause of many deaths in the US.

There have been significant changes in the lifestyle habits since the past three decades. Availability of food has comparatively increased. Ready-to-eat and processed foods are being produced on a large scale and marketed heavily. Subsequently, consumption of these processed foods has increased significantly. A large variety of fast foods are available at affordable prices. Large scale development in technology has reduced the necessity of physical labor. Hence, man leads a more sedentary life. A combination of high-calorie intake along with the lack of physical activity is considered to be the primary reason behind obesity.

Even though obesity is primarily considered to be due to detrimental environmental factors, the role of genetic factors is equally important.

After the breakthrough advancement in the human genome project, it is possible to study the entire genome and identify the genes specifically related to obesity. To analyze the genetic factors behind childhood obesity, obese children with a BMI in the upper 5th percentile were chosen from European American and African American societies. A thorough scan of the whole genome was done to locate the copy number variations (CNV). CNV is a kind of mutation which brings alterations in the genome. Large fragments of DNA, either duplicated or deleted, are known as CNVs. Results showed that the presence of CNVs was related to the susceptibility of the subjects of both the societies to childhood obesity. A fragment from chromosome 16 was found to be deleted in children suffering from obesity since childhood. The deletion of SH2B1 from the chromosome16 makes the person crave for food. This increases the tendency to eat, hence leading to obesity (Glessner JT, Bradfield JP, et al. 2010).

Another study led by Bradfield JP, 2012, from “The Children's Hospital of Philadelphia”, identified two other gene loci to be responsible for obesity. One of them was found near OLFM4 (olfactomedin 4) gene, located on chromosome 13 and another gene loci was within HOXB5 gene, located on chromosome number 17. Identification of such regions within the genome will help us to take certain preventive measures in order to control obesity. This can also streamline our gene therapy approaches.

Definitely No. In order to reduce the burden of obesity, it is required to work in multiple angles. Making people aware of health benefits of physical activity, explaining about healthy diet, distribution of meal plans, finding opportunities for physical exercise within our day-to-day activities (like cycling to the school or office instead of boarding a vehicle, climbing stairs and avoiding the lift, etc) are few ways in which obesity can be fought with. The role of a doctor in identifying the root cause of obesity is also equally important. Inventing drugs targeting obesity related genes can prove to be a boon to the society.

1. Glessner JT, Bradfield JP, et al. 2010. A genome-wide study reveals copy number variants exclusive to childhood obesity cases. Am J Hum Genet. 87(5): 661-6.

2. Bradfield JP, Taal HR, et al. 2012. A genome-wide association meta-analysis identifies new childhood obesity loci. Nat Genet. 44(5): 526-31.