A gene associated with obesity which is specific to the Indian population has been isolated for the first time by Indian researchers. Identification of genetic determinant of Body Mass Index (BMI) will help in better understanding the biological basis of overweight and obesity.
The study was undertaken by research team led by Dr. Kumarasamy Thangaraj of the Hyderabad-based Centre for Cellular and Molecular Biology (CCMB). The aim of the study was to find a novel locus in Indian population. For this they excluded the genes that have already been associated with obesity in other populations.
For the study a total of 204 non-smoking participants free of chronic diseases and belonging to different BMI categories (underweight, normal and overweight and obese) were chosen for the study. The subjects were 20-30 years old.
Close to 1 million SNP (single nucleotide polymorphism) markers distributed throughout the genome were analyzed. "We found one SNP marker (which is within a gene) of THSD7A was significantly associated with obesity. This gene has not been associated with obesity in the Indian population," said Dr. Thangaraj.
A replication study was undertaken to reconfirm its role. It involved 655 people belonging to different BMI categories — underweight, normal, overweight and obese — was undertaken. "We found highly significant association between the marker and obesity in the replication study," he said.
Angiogenesis is promoted by THSD7A, a neural N-glycoprotein. Angiogenesis modulates obesity, adipose metabolism and insulin sensitivity. Now the authors have been able to find a correlation and this information can be used for drug target, early diagnosis of obesity and treatment. Explaining how the gene is linked to obesity, Dr. Thangaraj said: "The gene is present in everyone. But when there is a mutation to the gene, there is a likelihood that the person carrying the mutated gene will end up being obese."
However the gene mutation is not found in all obese people. And the gene mutation was also found in very small number of underweight people. "That is because obesity is a multigenic condition," he explained. "Despite being a multigenic condition, people carrying the mutation can always take measures to keep obesity at bay," he said. There is a possibility that the SNP marker of THSD7A may be associated with obesity in other South Asian population.
The results were published recently in the International Journal of Obesity