NBC News
Genetic test could predict the risk of a child of suffering from obesity when he is an adult, clearing the way for early interventions.
Some genetic variants can affect the way in which the body of a person stores fat or make it more prone to eating in excess. You can also predict how someone will respond to different drugs to lose weight.
More than 600 researchers from all over the world collaborated in a study published Monday in Nature Medicine magazine to collect genetic data of more than 5 million people, the largest and most diverse set to date. They also used the genetic information of 23Andme.
From the database, the researchers created what is known as a polygenic risk score, which takes into account the genetic variants of a person linked to a higher body mass index (BMI) in adulthood.
According to researchers, this score could be used to predict the risk of obesity of someone in adulthood, even before he turns five years
“Childhood is the best time to intervene,” said Ruth Loos, co -author of the study and professor at the Basic Metabolic Research Center of the Novo Nordisk Foundation of the University of Copenhagen. (The research carried out in this center is not influenced by the Pharmaceutical Novo Nordisk, although some of the study authors had links with pharmaceutical companies that produce medicines to lose weight).
The findings come at a time when obesity is increasing worldwide. According to the World Health Organization, obesity rates in adults have doubled since 1990, and those of adolescents have quadrupled. About 16% of adults around the world have obesity and the situation is worse in the United States, where more than 40% of adults are obese, according to statistics from the centers for disease control and prevention.
Doubly effective
The new test is not the first that predicts the risk of obesity of a person, but Loos and his team showed that it was approximately double effective that the method that doctors currently use to evaluate their patients. This polygenic score can represent about 8.5% of the risk that a person has a raised BMI in adulthood. The new measurement increases that percentage to 17.6%, at least in people with European ancestry.
“This is a fairly powerful risk indicator, but still leaves many unknowns,” said Dr. Roy Kim, a pediatric endocrinologist at Cleveland Clinic Children’s that did not participate in the investigation.
Based on this score, more than 80% of the risk of obesity of a person can be explained by other factors, such as where he lives, what type of food has access and how much exercise does.
The test was not so effective in predicting the risk of obesity in the non -European population. In the Americans of Oriental Asia, he explained about 16% of the risk of having an elevated BMI, but only 2.2% in Ugandes of rural areas.
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About 70% of people whose data were included in the study were European descent. About 14% were Hispanics and had a mixture of ascendencies. 8% were of Asian ancestry and somewhat less than 5% of predominantly African ancestry. These samples came mostly from Americans of African origin, which had mixed ancestry. Only 1.5% were mainly southeasian ancestry.
According to Loos, the new score is a great advance, but it is still a prototype. The next step is to collect more data – and more diverse – about people of African descent in particular, to improve the efficacy of the score for all, not only for whites.
The doctor pointed out that the score could offer an indicator – what is bloodthirsty hypertension for heart disease, for example – to help predict the risk of a person developing obesity.
“Obesity does not depend only on genetics, so genetics alone can never predict obesity exactly,” Loos said. “For the general obesity we see throughout the world, we need other factors, such as lifestyle, which must be included in predictions.” Genetics plays a more important role in severe obesity, that is, with an BMI greater than 40, he added.
However, identifying the genetic risk of a person in childhood and intervening early with advice on lifestyle could mean a big difference, he said. Investigations have shown that about 55% of obese children will be in adolescence, and that approximately 80% of them will be in adulthood.
“The behavior is very important,” Kim explained. “Your environment, your access to healthy foods, opportunities to exercise, even your knowledge about healthy foods, all affects the risk of obesity of a person.”
How important is genetics?
Although studies in identical twins have discovered that genetics can explain up to 80% of the factors for which a person suffers from obesity, those related to lifestyle continue to play a very important role, according to Kim.
“Even with the same genetic composition, people can have different body types,” he said. “In my consultation, from very young we educate patients about the importance of eating foods rich in protein, a lot of fruit and vegetables and not too many refined carbohydrates.”
Dr. Juliana Simonetti, co -director of the Integral Weight Control Program of the University of Utah, has been using genetic tests in her adult patients for about five years. According to her, knowing a person’s genes can help doctors better to treat weight gain.
“Obesity is not homogeneous. We have different types and different presentations,” Simonetti explained, which did not participate in the new study.
With a person’s genes, Simonetti determines whether the patient has problems shaking.
“They eat but do not feel satiated,” Simonetti said, adding that it is a disorder caused by genetic mutations that affect certain organism. People who present these mutations “tend to have a higher weight,” he said.
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But such mutations do not tell all the genetic history of obesity, Simonetti said. The genes that a person inherits from any of their parents, even if they are not mutations, also determine how someone’s body stores weight or uses energy. Both issues can play an important role in the risk of obesity.
According to Simonetti, genetic tests are also beginning to be able to determine the effectiveness of certain drugs to lose weight, but this is only the beginning.
“We talk about three of the 80 mutations we can treat,” he said. “We are improving, and the more data we have, I hope we do a better job when it comes to being more precise in understanding the responses to treatment.”
