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The work of each of our genes consists in making proteins that facilitate the work of cells. The protein produced by the CCR5 gene plays an important role in the immune system. So, when the gene is mutated, the protein produced is disrupted and "a side effect is that you can not be infected with HIV," said Nielsen, explaining that "HIV uses this particular protein to get into the cell" . . "
Nielsen is asked about the overall effects: "Is it good for you, on average, to have this mutation?" he asked himself.
To answer this question, Nielsen and his co-author, Xinzhu Wei, a researcher at the University of Berkeley, analyzed the genetic and mortality data of over 400,000 people in the British Biobank database. They found that people carrying two copies of the mutation had less than a 20% chance of reaching the age of 76 years compared to people with a copy or no copy of the mutation.
The new study "shows nothing about the effects of mutation as such, but what it shows is an overall effect on mortality," said Nielsen. Previous studies have, however, shown that the mutation increases the risk of infection with West Nile virus in a carrier as well as its risk of death from influenza. "We do not have enough data to know for sure what is the mechanism for increasing mortality, but this effect on infectious diseases, particularly influenza, is a good candidate," Nielsen said.
& # 39; Unexpected consequences & # 39;
Dr. Hans-Peter Kiem, professor of medicine and pathology at the University of Washington, told CNN in an email that the study pointed out that any gene editing passed on to an offspring "is irresponsible and should not be done considering the many unknowns Potential consequences. "
Kiem, who did not participate in the study, explained that seeing how the effect of increased mortality risk is limited to people carrying a double mutation CCR5 implies that people wearing a defective gene and a normal gene have the most beneficial "fitness" effects – – a higher than usual protection against HIV (if not as much HIV resistance as those with a double CCR5 mutation) and a risk of normal mortality otherwise.
In the end, the new study "underscores the importance of thorough and well thought-out population studies and preclinical studies on gene editing" to understand the effect of genetic mutations, he said. And further research is needed to see if the same results would be achieved in different parts of the world with different populations.
"The relationships between a gene and a disease are rare, and we must keep in mind that many of the diseases that affect humans result from a gene / environment interaction," Knowles said. "This means that gene editing will not be the solution for most diseases."
"We need to be careful not to lose sight of both the possibility of unintended consequences and the relative cost of health care benefits," she said, noting that "all the time spent on research and money "in this technology may not be to our advantage.
She also pointed out "the wealth of genetic information that is now available (in this case, from the British biobank)". These genetic data resources "revolutionize not only what we can look for, but also how quickly we can get answers" to questions such as those posed in the new study.
Nielsen finally warned against any misinterpretation of his work. Currently, scientists are experimenting with the treatment of HIV infections using artificial mutations.
Even though a mutation may not be beneficial for healthy people, in people infected with HIV, "there is clearly a positive effect" when a mutation is introduced, Nielsen said. "I would not want to see our results as a call to stop these experiences or therapies for HIV."
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