Obesity and its genes
Is it possible to predict obesity by genes
Kirill Stasevich, Science and Life (nkj.ru ) based on materials ScienceNews.
Being overweight depends on genes. One of the most famous and most studied here is the FTO (fat mass and obesity-associated protein) gene – some variants of FTO add an average of three extra kilograms to its carriers. But this is just one of the "obesity genes" – according to some estimates, there are several hundred of them involved here. Nothing surprising: overweight is caused by a multitude of molecular and cellular processes that obey a multitude of genes.
Therefore, if we want to predict the probability of obesity, then we can, of course, choose one or two genes, but the prediction will be inaccurate. It is better to analyze the entire genome by comparing certain genetic variants with overweight. This is exactly the work done by Harvard researchers who analyzed more than 2.1 million genetic variants in the genomes of one hundred thousand people. (Genetic variants here should not be understood as specific genes encoding proteins, but as sites-loci in DNA, where substitutions, insertions and drops of genetic letters accompany the appearance of extra pounds; moreover, it is not even necessary to know what exactly in the sense of metabolism this or that site is responsible for.)
As a result, it was possible to create a predictive scale, which at the bottom had the sum of genetic variants that help to stay slim, and at the top – the sum of genetic variants that help to gain excess weight. In an article in Cell (Khera et al., Polygenic Prediction of Weight and Obesity Trajectories from Birth to Adulthood) states that the most unsuccessful combinations of genes can be found in 10% of people, just as the most successful combinations can be found in 10% of people; the remaining 80% occupy an intermediate position on this scale. The difference between "top" and "bottom" on the genetic scale of obesity is on average about 13 kg. Someone who has a particularly unsuccessful combination of genes is 25 times more likely to get severely obese than someone who has particularly successful genes.
This is not the first attempt to predict obesity by genes, but, as the authors write, the most accurate. At the same time, many experts doubt that it is possible to talk about predictions here at all – according to Ruth Loos from Mount Sinai Medical Center, genes are responsible for 50% of obesity, and the remaining 50% is due to lifestyle. So in order to predict, in addition to information about genes, you also need to know how a person lives. For example, among those people whose genomes were analyzed, there was a group of 3,722 people, among whom 371, judging by their genes, should have been severely obese. But only 58 of them were obese. The rest, obviously, managed to live in such a way that the weight did not get out of control, even if they had to put a lot of effort into it.
That is, perhaps the new polygenic analysis works better than previous similar methods, but in real life, we repeat, genetic predictions need to be evaluated in combination with other factors. And if someone has the genes to be fat, it does not mean that you need to submit to fate - it means that you need to be more attentive to yourself.
By the way, the situation is similar with genes related to intelligence: most recently we wrote that in adolescents aged 12-16, the difference in cognitive skills by genes can be predicted by a maximum of 11%. However, it is possible that in the case of obesity and in the case of intelligence, the predictive power of genetic methods will increase when we better understand the mechanisms of regulation of genetic activity.
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