A new study has found that three genes inherited from Neanderthals reduce the risk of severe Covid-19 by 22%.
Genes are located next to each other on chromosome 12 and this large chunk of genetic material includes 75,000 individual pieces of DNA.
The researchers compared the DNA of 2,200 Covid-19 patients 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 OAS1, OAS2, and OAS3 genes were less likely to develop severe symptoms after coronavirus infection.
These genes produce enzymes specifically targeted at invasive RNA viruses and the Neanderthal version is believed to be more potent.
Scroll down to see the video
Previous research has found eight genetic localizations spread across five chromosomes (3, 6, 12, 19, and 21) that are “associated with the risk of requiring intensive care after SARS-CoV-2 infection.” However, the new analysis shows that only the finds on chromosome 3 and 12 come from Neanderthals (pictured). 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 Institute in Stockholm and the Max Planck Institute for Evolutionary Anthropology in Leipzig, respectively, conducted the study.
Previous research has found eight genetic localizations spread across five chromosomes (3, 6, 12, 19, and 21) that are “associated with the risk of requiring intensive care after SARS-CoV-2 infection.”
However, the new analysis shows only those found on chromosomes 3 and 12 that come from cross-species tests between Homo sapiens and Neanderthals.
The researchers compared the DNA of 2,200 Covid-19 patients around the world with the genomes of three Neanderthals who lived 50,000, 70,000 and 120,000 years ago. They found people with Neanderthal versions of the OAS1, OAS2, and OAS3 genes 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.
He revealed that the Neanderthal version, which is present in about one in eight people today, actually doubles the risk of needing intensive care if a person catches Covid.
But stretching of Neanderthal DNA on chromosome 12 is more common.
It was present in about one in ten humans who lived more than 20,000 years ago, and then increased to about 15% until 10,000 years ago.
Researchers estimate that it continued to be more dominant, with about a third of the people living between 3,000 and 1,000 years ago.
In the image, the percentage of people in Eurasia with genes against Covid on chromosome 12 over time. It now exceeds 30%, but experts say it often reaches and exceeds 50% in some populations
In the image, a world map showing the percentage of people who have Neanderthal versions of the OAS1, OAS2, and OAS3 genes (red portions of pie charts). Due to the ancient migratory patterns of Neanderthals and the fact that they lived little in Africa before extinction, very little Neanderthal DNA is seen today in people living in sub-Saharan Africa.
“Interestingly, the current frequency of alleles in Eurasia is around 30 percent, suggesting that the Neanderthal haplotype may have increased in frequency relatively recently,” the researchers write in their article.
They add: “It is present in populations of Eurasia and America at carrier frequencies that often reach and exceed 50%.”
Dr. Pääbo says it is “surprising” that two Neanderthal variants can have such drastically different impacts on the human immune response to SARS-CoV-2 infection.
“This demonstrates that our Neanderthal heritage is a double-edged sword when it comes to our response to SARS-CoV-2,” adds Professor Zeberg.
Researchers believe that the location of Neanderthal DNA on chromosome 12 is key, as it includes three genes (OAS1, OAS2, and OAS3) that play a critical role in fighting infection.
Specifically, they help produce enzymes that target and destroy invasive RNA, such as the SARS-CoV-2 that Covid-19 causes.
The new research, published in the journal PNAS, also found that the Neanderthal variant produces more enzymes that fight viruses than the old Homo sapien alternative.
“It can be speculated that when modern humans found new RNA viruses outside Africa, the higher enzymatic activity of the ancestral variants they acquired through genetic interactions with Neanderthals may have been advantageous,” the researchers.
“Interestingly, there is evidence that the Neanderthal-like OAS haplotype may have recently increased in frequency in Eurasia, suggesting that the selection may have positively affected the Neanderthal-derived OAS locus in last millennium.
Due to the ancient migratory patterns of Neanderthals and the fact that they lived little in Africa before extinction, very little Neanderthal DNA is observed in people living in sub-Saharan Africa.
In fact, researchers say the genes that fight Neanderthal covides 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,” the document adds.
The latest study supports previous findings from a team of researchers separate from Canada, who also concluded that the OAS1 gene reduces the risk of serious illness, hospitalization, and death from Covid-19.
Although they did not look at the origin of the gene, they found five genes that increase the chances of severe infection.
Four of these genes: TYK2 and DPP9 on chromosome 19; The latest study also studied IFNAR on chromosome 21 and OAS on chromosome 12.