A new study has revealed that three genes inherited from Neanderthals reduce the risk of severe Covid-19 by 22 percent.
The genes sit side by side on chromosome 12, and this large amount of genetic material contains 75,000 individual pieces of DNA.
Researchers have compared the DNA of 2,200 Covid-19 patients from around the world with the genes of three Neanderthals who lived 50,000, 70,000 and 120,000 years ago.
They found that people with Neanderthal versions of the genes OAS1, OAS2 and OAS3 were less likely to develop severe symptoms after infection with the coronavirus.
These genes produce enzymes that specifically target invasive RNA viruses, and the Neanderthal version is considered more potent.
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Previous research has found that eight genetic sites are spread across five chromosomes (3, 6, 12, 19 and 21) that are ‘associated with the risk of requiring intensive care in SARS-CoV-2 infection’. However, the new analysis only shows that those found on chromosomes 3 and 12 come from Neanderthals (photo). Chromosome 12 contains three genes that help fight Covi and reduce the risk of serious infection by 22%
Professor Hugo Zeberg and Dr Svante Pääbo of the Karolinska Institutet in Stockholm and the Max Planck Institute for Evolutionary Anthropology in Leipzig conducted the study.
Previous research has found that eight genetic sites are spread across five chromosomes (3, 6, 12, 19 and 21) that are ‘associated with the risk of requiring intensive care in SARS-CoV-2 infection’.
However, the new analysis shows only those found on chromosomes 3 and 12 are derived from cross-species trials between Homo sapiens and Neanderthals.
Researchers have compared the DNA of 2,200 Covid-19 patients from around the world with the genomes of three Neanderthals who lived 50,000, 70,000 and 120,000 years ago. They found that people with Neanderthal versions of the genes OAS1, OAS2 and OAS3 were less likely to develop severe symptoms after coronavirus infection.
The chromosome 3 gene was the subject of previous research by the same team of experts.
It revealed that the Neanderthal version, which occurs in about one in eight people today, doubles the risk of needing intensive care if someone catches Covid.
But the piece of Neanderthal DNA on chromosome 12 is more common.
It was present in about one in ten people who lived more than 20,000 years ago and then increased to about 15 percent to 10,000 years ago.
According to the researchers, it has become increasingly dominant, and about a third of the people who lived between 3000 and 1000 years ago.
Pictured is the percentage of people in Eurasia with the Covid vegs on chromosome 12 over time. It is now more than 30 percent, but experts believe that in some populations it often reaches and exceeds 50 percent
In the photo a world map showing the percentage of people who have the Neanderthal versions of the OAS1, OAS2 and OAS3 genes (red sections of pie charts). Due to the ancient migration patterns of Neanderthals and the fact that they lived sparsely in Africa before they became extinct, very little Neanderthal DNA is seen in people living in sub-Saharan Africa today.
‘Strikingly, the current allele frequency in Eurasia is about 30 percent, indicating that the Neanderthal haplotype has increased in frequency relatively recently,’ the researchers write in their paper.
They add: “It is present in populations in Eurasia and the Americas at frequencies that often reach and exceed 50 percent.”
Dr Pääbo says it is ‘striking’ that two Neanderthal variants could have such a drastic effect on the human immune response to SARS-CoV-2 infection.
“It shows that our legacy of Neanderthals is a double-edged sword when it comes to our response to SARS-CoV-2,” adds Professor Zeberg.
According to the researchers, the location of the Neanderthal DNA on chromosome 12 is key because it contains three genes (OAS1, OAS2 and OAS3) that play a critical role in fighting infection.
They specifically help to produce enzymes that target and destroy invasive RNA, such as SARS-CoV-2 which causes Covid-19.
The new research, published in the journal PNAS, also found that the Neanderthal variant produces more viral enzymes than the ancestral Homo sapine alternative.
“It can be speculated that, when modern humans encountered new RNA viruses outside Africa, the higher enzymatic activity of the ancestral variants they acquired through genetic interactions with Neanderthals could have been beneficial,” the researchers write.
‘Remarkably, there is evidence that the Neanderthal-like OAS haplotype has recently increased in frequency in Eurasia, suggesting that selection may have positively impacted the Neanderthal-derived OAS locus over the past millennium.
Due to the ancient migration patterns of Neanderthals and the fact that they inhabited Africa sparsely before they became extinct, very little Neanderthal DNA is seen in people living in sub-Saharan Africa today.
The researchers say that the Neanderthal Covid walls are ‘almost completely absent’ from these populations.
“In the Americas, it occurs in some populations of African descent in lower frequencies, presumably due to no flow from populations of European or Native American descent,” they add in the newspaper.
The latest study supports previous findings from a separate team of researchers from Canada, who also concluded that the OAS1 gene reduces the risk of serious illness, hospitalization and death due to Covid-19.
Although they did not look at the origin of the gene, they did find five genes that increase the chance of serious infection.
Four of these genes – TYK2 and DPP9 on chromosome 19; IFNAR on chromosome 21 and OAS on chromosome 12 – were also studied by the latest study.