Three genes inherited from Neanderthals lower the risk of severe Covid-19 by 22 percent, a new study finds.
The genes sit side by side on chromosome 12, and this large chunk of genetic material contains 75,000 individual pieces of DNA.
Researchers 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 invading RNA viruses, and the Neanderthal version is believed to be more powerful.
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Previous research has found eight genetic locations across five chromosomes (3, 6, 12, 19 and 21) that are “associated with the risk of needing intensive care after SARS-CoV-2 infection.” However, the new analysis shows that only those found on chromosome 3 and 12 are 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 from the Karolinska Institutet in Stockholm and the Max Planck Institute for Evolutionary Anthropology in Leipzig respectively conducted the research.
Previous research has found eight genetic locations spread across five chromosomes (3, 6, 12, 19, and 21) that are “associated with intensive care risk following SARS-CoV-2 infection.”
However, the new analysis shows that only those found on chromosomes 3 and 12 come from cross-species cross between Homo sapiens and Neanderthals.
Researchers 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 have severe symptoms after infection with the coronavirus
The chromosome 3 gene was the subject of previous research by the same team of experts.
It revealed that the Neanderthal version, which is present in about one in eight people today, doubles the risk of someone needing intensive care if someone contracts 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, then increased to about 15 percent up to 10,000 years ago.
The researchers estimate that it was becoming increasingly dominant: About a third of people who lived between 3,000 and 1,000 years ago had it.
Pictured, the percentage of people in Eurasia with the Covid-fighting genes on chromosome 12 over time. It’s now over 30 percent, but experts say it often reaches and exceeds 50 percent in some populations
Pictured, a world map showing the percentage of people with the Neanderthal versions of the OAS1, OAS2 and OAS3 genes (red parts of pie charts). Due to the ancient migration patterns of Neanderthals and the fact that they lived sparsely in Africa before their extinction, very little Neanderthal DNA is seen today in people living in Sub-Saharan Africa
Intriguingly, the current allele frequency in Eurasia is about 30 percent, suggesting that the Neanderthal haplotype has increased in frequency relatively recently, the researchers write in their paper.
They add, “It is present in populations of Eurasia and North and South America with carrier frequencies often reaching or exceeding 50 percent.”
Dr. Pääbo says it is “striking” that two Neanderthal variants can have such drastically different effects on the human immune response to SARS-CoV-2 infection.
“This shows that our Neanderthal heritage is a double-edged sword when it comes to our response to SARS-CoV-2,” adds Professor Zeberg.
The researchers believe that the location of the Neanderthal DNA on chromosome 12 is key, as it contains three genes (OAS1, OAS2 and OAS3) that play a critical role in fighting infection.
In particular, they help produce enzymes that attack and destroy invasive RNA, such as SARS-CoV-2 that causes Covid-19.
The new research, published in the journal PNAS, also found that the Neanderthal variant makes more virus-fighting enzymes than the ancestral Homo sapien alternative.
“It could be speculated that, when modern humans outside Africa encountered new RNA viruses, the higher enzymatic activity of the ancestral variants obtained through genetic interactions with Neanderthals may have been beneficial,” the researchers write.
“Intriguingly, there is evidence that the Neanderthal-like OAS haplotype has increased in frequency in Eurasia recently, 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 lived sparsely in Africa before their extinction, very little Neanderthal DNA is seen today in people living in Sub-Saharan Africa.
In fact, the researchers say the Neanderthal Covid-fighting genes are “almost completely absent” in these populations.
“In the Americas, it occurs at lower frequencies in some populations of African descent, presumably due to gene flow from populations of European or Native American descent,” they add in the paper.
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 from Covid-19.
Although they didn’t look at the gene’s origin, they found five genes that increase the risk 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.