Obesity has a strong genetic component, and people with a high genetic and environmental risk are particularly susceptible, according to findings presented at the 52nd European Association for the Study of Diabetes Annual Meeting.
“We know that genes and environmental factors influence our BMI — we know less about if and how they interact,” Timothy Frayling, PhD, professor at the University of Exeter Medical School, United Kingdom, told Endocrine Today. “We wanted to answer the question of whether or not aspects of the environment and our lifestyles accentuate any genetic predisposition to obesity. The question is important, as it may highlight aspects of the environment that cause some people to be particularly susceptible to gaining weight.”
Frayling and colleagues analyzed data from 120,000 adults from the UK Biobank study, using BMI as the outcome, and genetics (69-variant genetic risk score for obesity) and self-reported estimates of nine measures, including TV watching, Western diet and physical activity, as exposures. Researchers tested the association of the genetic risk score with BMI in high- and low-obesogenic environment groups and tested for interactions.
Researchers found gene–environment interaction with self-reported TV watching (P for interaction = .00007) and self-reported physical activity (P for interaction = .000005).
For example, among adults who reported watching at least 4 hours of television daily, carrying 10 additional BMI-raising alleles was associated with approximately 4-kg extra weight in someone 1.73 m tall. Among those who self-reported watching less than 4 hours of television daily, carrying 10 additional BMI-raising alleles was associated with approximately 3.1-kg extra weight.
Evidence of interaction persisted when using a composite measure of the obesogenic environment (P for interaction = .0002) and permutations of the data based on randomly selecting groups of individuals of different BMI.
“It is unlikely that one specific aspect of the environment accentuates the genetic risk of obesity,” Frayling said. “Instead, a general measure of the obesogenic environment, socioeconomic position (a measure of relative wealth), best captured the environmental factors that interact with genetic risk for obesity. These findings contrast with those from most previous studies.” – by Regina Schaffer
Tyrrell J, et al. Abstract #97. Presented at: 52nd EASD Annual Meeting; Sept. 12-16, 2016; Munich.
Disclosure: Frayling reports no relevant financial disclosures.