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FRANCE – Covid-19 patients with a Neanderthal DNA fragment that crossed into the human genome about 60,000 years ago are at increased risk of serious complications from the disease, the researchers reported.
People infected with the new coronavirus, for example, who carry the genetic coding bequeathed by our early human cousins, are three times more likely to need mechanical ventilation, according to a study published Wednesday in Nature.
There are many reasons why some people with Covid-19 end up in intensive care and others have only mild symptoms, or none at all.
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Older age, being a man, and pre-existing medical problems can increase the chances of a serious outcome.
But genetic factors may play a role, too, as the new findings make clear.
“It is surprising that the genetic inheritance of Neanderthals has such tragic consequences during the current pandemic,” said co-author Svante Paabo, director of the department of genetics at the Max Planck Institute for Evolutionary Anthropology.
Recent research by the Covid-19 Host Genetics Initiative revealed that a genetic variant in a particular region of chromosome 3, one of the 23 chromosomes in the human genome, is associated with more severe forms of the disease.
That same region was known to harbor a genetic code of Neanderthal origin, so Paabo and co-author Hugo Zeberg, also from Max Planck, decided to look for a link to Covid-19.
– Unevenly distributed –
They found that a Neanderthal individual from southern Europe carried a nearly identical genetic segment, comprising about 50,000 of the so-called base pairs, the main components of DNA.
Tellingly, two Neanderthals found in southern Siberia, along with a specimen of another early human species that also roamed Eurasia, the Denisovans, were not carrying the telltale fragment.
Modern humans and Neanderthals could have inherited the gene fragment from a common ancestor half a million years ago, but they are much more likely to have entered the homo sapiens gene pool through more recent interbreeding, the researchers concluded.
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The potentially dangerous strand of Neanderthal DNA is currently not evenly distributed throughout the world, the study showed.
About 16 percent of Europeans carry it, and about half of the population in South Asia, and the highest proportion, 63 percent, is in Bangladesh.
This could help explain why people of Bangladeshi descent living in Britain are twice as likely to die from Covid-19 as the general population, the authors speculate.
In East Asia and Africa, the genetic variant is practically absent.
About two percent of the DNA of non-Africans around the world originates from Neanderthals, previous studies have shown.
Denisovan remains are also widespread but more sporadic, comprising less than one percent of the DNA among Asians and Native Americans, and about five percent of Aboriginal Australians and the people of Papua New Guinea.
