Introduction to Genetic Testing for Obesity
A genetic test may one day predict a child’s risk of obesity in adulthood, paving the way for early interventions. Certain genetic variants can affect how a person’s body stores fat or make them more prone to overeating. Genetic variation can also predict how well a person will respond to different weight loss drugs.
The Study and Its Findings
In a study published Monday in the journal Nature Medicine, more than 600 researchers from around the world worked together to compile genetic data from more than 5 million people — the largest and most diverse genetic dataset to date. They also used genetic data from 23andMe. From the dataset, the researchers were able to create what’s known as a polygenic risk score, which takes into account which genetic variants a person has that have been linked to a higher BMI in adulthood. The score, the researchers said, could be used to predict a person’s risk of obesity as an adult — before they even turn 5.
“Childhood is the best time to intervene,” said study co-author Ruth Loos, a professor at the University of Copenhagen’s Novo Nordisk Foundation Center for Basic Metabolic Research. The findings come as obesity is rising around the world. Rates of obesity in adults have more than doubled globally since 1990, and adolescent rates have quadrupled, according to the World Health Organization. About 16% of adults worldwide have obesity and the situation is worse in the United States, where more than 40% of adults have obesity, Centers for Disease Control and Prevention statistics show.
Effectiveness of the New Test
Comparison with Existing Methods
The new test is not the first that predicts a person’s risk of obesity, but Loos and her team showed it was about twice as effective as the method doctors currently use to assess their patients. That polygenetic score can account for about 8.5% of a person’s risk for having a high BMI as an adult. The new score increased that to about 17.6%, at least in people with European ancestry.
Limitations and Future Improvements
Based on this score, more than 80% of a person’s risk for obesity can be explained by other factors, such as where they live, what kinds of foods they have access to, and how much they exercise. The test was not nearly as effective in predicting obesity risk in non-Europeans. It explained about 16% of the risk for having a high BMI in East Asian Americans, but just 2.2% in rural Ugandans. Loos said the new score is a big step forward, but that it’s still a prototype. The next step is to collect more — and more diverse — data on people with African ancestry in particular to improve how well the score works for everyone, not just white people.
Understanding the Role of Genetics in Obesity
Genetic Risk and Lifestyle Factors
“Obesity is not only about genetics, so genetics alone can never accurately predict obesity,” Loos said. “For the general obesity that we see all over the world, we need other factors such as lifestyle that need to be part of the predictions.” Genetics play a bigger role in severe obesity, meaning a BMI of more than 40, she added. Still, identifying a person’s genetic risk early on in childhood and intervening early with lifestyle coaching could make a big difference, she said. Research has shown that about 55% of children with obesity go on to have obesity in adolescence, and that about 80% of those individuals will have obesity in adulthood.
Importance of Genetics and Lifestyle
Although studies in identical twins have found that genetics can account for as much as 80% of the reason a person has obesity, lifestyle factors still play a huge role. “Even with the same genetic makeup, people can have different body types,” said Dr. Roy Kim, a pediatric endocrinologist at Cleveland Clinic Children’s who was not involved with the research. “From a very young age in my practice, we educate patients about the importance of eating protein-rich foods, a lot of fruits and vegetables and not too many refined carbs.”
How Important are Genetics, Really?
Genetic Testing in Practice
Dr. Juliana Simonetti, co-director of the Comprehensive Weight Management Program at the University of Utah, has been using genetic testing in her adult patients for about five years. She said understanding a person’s genes can help doctors better treat weight gain. “Obesity is not homogeneous. We have different kinds and different presentations,” said Simonetti, who wasn’t involved with the new study. Simonetti uses a person’s genes to determine if a patient struggles with satiety, or feeling full. “They eat but do not feel full,” Simonetti said, adding that this is a disorder caused by genetic mutations affecting certain pathways in the body.
Conclusion
The development of a genetic test that can predict the odds of obesity is a significant step forward in the fight against this global health issue. While genetics play a crucial role in obesity, lifestyle factors are equally important. Early intervention, including lifestyle coaching, can make a significant difference in preventing obesity in adulthood. Further research is needed to improve the diversity and effectiveness of the genetic score, but the potential for personalized treatment and prevention strategies is promising.
FAQs
What is a polygenic risk score?
- A polygenic risk score is a calculation that takes into account multiple genetic variants associated with a higher risk of a particular condition, in this case, obesity.
How effective is the new genetic test in predicting obesity risk?
- The new test is about twice as effective as existing methods for people of European ancestry, explaining about 17.6% of the risk for having a high BMI as an adult.
Can genetic testing determine how well a person will respond to weight loss drugs?
- Yes, genetic testing is starting to be able to determine how well certain weight loss drugs will work for a person, although this is still in the early stages.
Is obesity solely caused by genetics?
- No, obesity is not only about genetics. Lifestyle factors, such as diet and exercise, play a significant role in obesity risk.
- At what age can the genetic risk of obesity be predicted?
- The genetic risk of obesity can be predicted before a child turns 5, according to the study.
