Chennai-based researchers who are part of an international study on the gene-environment interplay in diabetes have exciting data that suggests that lifestyle modifications can override the effect of genes in an Indian population.
Chennai is one of the centres of InterAct, which aims at investigating how genes and lifestyle factors interact to lead to type 2 diabetes. Project coordinator Nick Wareham, who is also Director of the MRC Epidemiology Unit and co-Director of the Institute of Metabolic Science, was in the city recently to review the progress in the Chennai leg of the study.
“We have some exciting developments, preliminary data that suggests that the effect of some genes in an Indian population may be altered by lifestyle interventions,” he says.
Dr. A.Ramachandran’s Hospital, the Indian partner, has followed up 1,000 persons who started out non-diabetic for over three years, to see how many of them go on to develop diabetes. Dr. Ramachandran, who is leading the study here says, “If we need to dig into genetics, we are going to need a very large sample of persons, sometimes across countries. This is what the InterAct study is trying to do.”
Dr. Wareham explains, “The whole premise is that we know that certain people are more susceptible to the adverse effects of living a westernised lifestyle. That hypothesis has been around for 50 years. Nobody has been able to unravel it, find out what specifically underlies that observation.”
He goes on to say, in a chat with The Hindu , “To do that, you need to study a very large number people over a long period – find out the important factors that drive diabetes, before the condition sets in. There are nine countries in Europe apart from Chennai that are part of this study.
Genetic analysis
“Not only is the study very large; we’ve done genetic analysis on nearly 30,000 people. In each individual, we don’t just type one gene. We type variants across the whole of the genome, and we get about 10 million bits of info on every individual. This is a massive undertaking,” Dr. Wareham says.
The InterAct consortium has set up a very large study of diabetes incidence nested within the pre-existing large multi-centre EPIC (European Prospective Investigation into Cancer & Nutrition) study. It includes 350,000 participants from 10 European countries. EPIC was designed to investigate the relationships between diet, nutritional status, lifestyle and environmental factors and the incidence of cancer and other chronic diseases.
“All the participants thought themselves to be reasonably healthy – we measured their diet, physical activity and collected blood samples that were frozen and stored over many years. Over four million were followed up, as part of the InterAct diabetes study, and in that time, 12,500 people had become diabetic.”
“The reason that we have come to build on our collaboration is that Dr. Ramachandran’s team has some very good study subjects - a 1,000 people, and interventions to change lifestyles have been delivered. The other reason why we want to do it here, obviously, is because people from India are more at risk of diabetes,” Dr. Wareham says.
He suspects it might be in part genetic, but it could also be because the interplay between genes and lifestyles is probably greater in the Indian context.
“It’s true to say,” he reveals, “that the genes we’ve looked at so far seem to have a strong interaction with the lifestyle in this part of the world.
We need to verify and develop that observation, but we also need to think about what that means, and how we should study that further.”
Also, uniquely, this study is utilising tools to study physical activity scientifically, going beyond mere interviews with subject about their activities.
“It is tough to measure physical activity, and even tougher to measure sedentary behaviour.”
