The year you were born appears to have an impact on your risk of obesity. Scientists from the Massachusetts General Hospital tried to solve the riddle of genetics versus environment on obesity. They found that the influence of the FTO gene, which previous research has linked to obesity, depends on the year of your birth.
"Looking at participants in the Framingham Heart Study, we found that the correlation between the best known obesity-associated gene variant and body mass index increased significantly as the year of birth of participants increased," says James Niels Rosenquist, M.D., Ph.D., of the Massachusetts General Hospital (MGH) Department of Psychiatry and lead author of the report. "These results — to our knowledge the first of their kind — suggest that this and perhaps other correlations between gene variants and physical traits may vary significantly depending on when individuals were born, even for those born into the same families."
The researchers examined records of participants in the Framingham Offspring Study, which followed the children of participants in the original study from 1971, when they ranged in age from 27 to 63, to 2008. They investigated whether or not conditions experienced by different age groups might alter the impact of a gene.
The body mass index (BMI) of participants was measured eight times during the study period. When scientists examined the relationship between the FTO variants the participants had inherited and compared them to their BMI, they found that the impact of the "obesity" gene was twice as strong in those born after 1942 as it was in people born before 1942.
Although the researchers couldn't pinpoint exactly what caused the difference, they speculated that post-World War II factors, such as less physical activity and eating more processed, high-calorie foods, were likely contributors.
"We know that environment plays a huge role in the expression of genes, and the fact that our effect can be seen even among siblings born during different years implies that global environmental factors such as trends in food products and workplace activity, not just those found within families, may impact genetic traits," says Rosenquist, an instructor in Psychiatry at Harvard Medical School. "Our results underscore the importance of interpreting any genetic studies with a grain of salt and leave open the possibility that new genetic risk factors may be seen in the future due to different genetically-driven responses to our ever-changing environment."
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