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Some people get very sick when infected with SARS-CoV-2, while others have only mild symptoms or no symptoms at all. In addition to risk factors such as older age and chronic diseases, such as diabetes, our genetic heritage it also contributes to our individual risk of Covid-19 severity.
In the fall of 2020, the team at
Hugo Zeberg of the Karolinska Institute (Denmark) and of
Max Planck Institute for Evolutionary Anthropology– MPI-EVA (Germany), and Svante Pääbofrom
MPI-EVA, advertised in
«Nature» that the greatest genetic risk factor identified to date for suffering from Covid-19 in its most severe forms was a trait inherited directly from Neanderthals.
This same group, in the spring of 2021, studied this variant in ancient human DNA and observed that its frequency has increased significantly since the last ice age and in an article published in
«Proceedings of the National Academy of Science»
(PNAS)
They showed that Neanderthals also added to our DNA another variant of the same gene that is capable of just the opposite: protecting us from disease.
In fact, up to half of people born outside of Africa are carriers of a variant. del gen neanderthal that reduces by up to 22% the risk of needing intensive care once the disease is contracted.
Now, they write in an article published today in
«PNAS»has become unexpectedly common for a genetic variant inherited from Neanderthals.
“This major genetic risk factor for Covid-19 is so common that we wonder if it might actually be good for something, like providing protection against another infectious disease,” he says. Hugo Zebergwho is the sole author of the new study in
PNAS.
The work explains that the genetic risk factor is located in a region of chromosome 3 that consists of many genes. Many surrounding genes encode receptors in the immune system, and one of these receptors, CCR5, is the one used by HIV, the virus that causes AIDS, to infect white blood cells.
Now Zeberg’s team has found that people who carried the risk factor for Covid-19 had fewer CCR5 receptors.
So these people have a lower risk of becoming infected with HIV?
When analyzing patient data from three biobanks important (
FinnGen,
UK Biobank and
Michigan Genomic Initiative), the researchers found that carriers of the risk variant of Covid-19 had a higher risk 27% lower risk of becoming infected with HIV.
“These results show how a genetic variant can be both good news and bad news: bad news if a person becomes infected with Covid-19, and good news because offers protection against HIV infection», Zeberg points out.