A new genetic test has been developed to predict which children face the highest genetic risk of a high body mass index (BMI) later in life. This advancement offers parents the opportunity to implement healthy lifestyle choices early, potentially mitigating the risk of obesity. The test, known as a polygenic score (PGS), was created by a large team of international researchers and is designed to assess genetic variations linked to BMI.
According to Roelof Smit, a genetic epidemiologist at the University of Copenhagen, “What makes the score so powerful is its ability to predict, before the age of five, whether a child is likely to develop obesity in adulthood, well before other risk factors start to shape their weight later in childhood.” The ability to intervene at this early stage could significantly influence a child’s health trajectory.
While the potential of this test is promising, it is important to recognize its limitations. Genetics account for only a portion of the risk associated with high BMI, and there is increasing discussion among researchers about the effectiveness of BMI as a measure of obesity and overall health. Nevertheless, the researchers assert that the new PGS is up to twice as accurate as previous models. It was developed using a comprehensive database that includes genetic information from over 5.1 million individuals.
The team tested the PGS across several health databases, which contained longitudinal records of genetic data and BMI for hundreds of thousands of individuals. When the PGS was incorporated alongside other BMI predictors, higher scores correlated with greater adult weight gain. The predictive power of the PGS varied based on age and ancestry. For instance, PGS scores calculated at age 5 explained 35 percent of the BMI variation by age 18, while for middle-aged Europeans, it accounted for 17.6 percent. In contrast, the score explained only 2.2 percent of BMI variation among rural Ugandans, likely due to underrepresentation in the training data and the greater genetic diversity within African populations.
Another noteworthy finding indicated that individuals with a strong genetic predisposition to higher BMI experienced greater initial weight loss during their first year in weight loss programs, although they were also more susceptible to regaining weight later. “Our findings emphasize that individuals with a high genetic predisposition to obesity may respond more to lifestyle changes and, thus, contrast with the determinist view that genetic predisposition is unmodifiable,” the researchers stated in their published paper.
The implications of accurately predicting BMI at an early age could provide families with a longer timeframe to establish healthier dietary and activity patterns, potentially influencing future BMI outcomes. As Ruth Loos, a geneticist at the University of Copenhagen, remarked, “This new polygenic score is a dramatic improvement in predictive power and a leap forward in the genetic prediction of obesity risk, which brings us much closer to clinically useful genetic testing.”
This research, published in Nature Medicine, marks a significant step toward utilizing genetic insights in proactive health management for children, aiming to combat the rising rates of obesity globally.
