Having Neanderthal genes may triple the risk of developing severe Covid-19, says study
A stretch of DNA in modern humans that increases Covid-19 severity risk can be traced back to Neanderthals, say researchers
Neanderthals interbred with humans ages ago, leaving a part of them in us. This union was one advantageous once, shielding their descendants from some infectious diseases. Now, a new study suggests that people carrying Neanderthal genes are more likely to suffer from severe Covid-19.
According to the researchers involved in the study, a stretch of DNA in modern humans can be traced back to Neanderthals. Having this strand triples the risk of needing a ventilator to support breathing, they said. "It is striking that the genetic heritage from Neanderthals has such tragic consequences during the current pandemic," said Professor Svante Pääbo, who leads the Human Evolutionary Genomics Unit at the Okinawa Institute of Science and Technology Graduate University (OIST).
The strand in question is found on chromosome 3, which is one of the 23 pairs present in human cells. Chromosome 3 carries 1,000 to 1,100 genes that provide instructions for making proteins. The team has linked variants in these genes with a larger risk of developing severe Covid-19. They are present in about 50% of people in South Asia and about 16% of people in Europe today, the researches wrote in their study.
The study enrolled over 3,000 people, including both hospitalized and non-hospitalized Covid-19 patients. Their analysis showed that gene variants on chromosome 3 were linked to a severe infection. The researches found a close match or similar variations in the DNA from a 50,000-year-old Neanderthal skeleton in Croatia.
"It turns out that this gene variant was inherited by modern humans from the Neanderthals when they interbred some 60,000 years ago," Hugo Zeberg, an assistant professor at the Karolinska Institute in Stockholm, said. “Today, the people who inherited this gene variant are three times more likely to need artificial ventilation if they are infected by the novel coronavirus Sars-CoV-2.”
The team also looked at whether this gene variant was widespread across the world. It is particularly common in South Asians, where about half of the population carries the Neandertal risk variant. In Europe, one in six people possesses the variant and is almost non-existent in Africa and East Asia.
The researchers are yet to understand how genes could increase the risk of severe Covid-19. "We are trying to pinpoint which gene is the key player, or if there are several key players, but the honest answer is that we don’t know which are critical in Covid-19,” Zeberg told The Guardian. "This is something that we and others are now investigating as quickly as possible," Professor Pääbo explained in a statement.
"There really isn't anything medically or biologically special about the fact that this variant arose in Neanderthals," Dr. Jeffrey Barret, a geneticist at Britain's Sanger Institute who was not involved in the study, told CNN. "Humans have a great deal of genetic diversity, some of which arose in our pre-human ancestors, some in Neanderthals, some during the time when all ancient humans lived in Africa, and some more recently."
The study is published in Nature.