Scientists claim that a DNA strand that triples the risk of developing severe COVID-19 was transmitted from Neanderthals to modern humans.
Since it first appeared in late 2019, the new virus, SARS-CoV-2, has had a number of impacts on the people it infects. Some become seriously ill with COVID-19, and require hospitalization, while others have mild or even asymptomatic symptoms.
There are several factors that influence a person’s susceptibility to a serious reaction, such as their age and the existence of other medical conditions. But genetics also play a role, according to a new study, published in Nature.
The origins of the risk genes came to light when scientists from Sweden and Germany compared the DNA of severely ill COVID-19 patients with the Neanderthals and Denisovans.
The stretch of DNA that makes patients more likely to become seriously ill was closely matched with a 50,000-year-old Neanderthal from Croatia.
“It is surprising that the genetic inheritance of Neanderthals has such tragic consequences during the current pandemic,” explained the study co-author Svante Paabo, director of the Max Planck Institute for Evolutionary Anthropology in Leipzig.
The researchers observed more than 3,000 people, including both who were hospitalized with severe COVID-19 and those who were infected with the virus but were not hospitalized. A region was identified on chromosome three that influences the possibility of a person infected with the virus becomes seriously ill and needs to be hospitalized. Likewise, it was proven that the variants had come from Neanderthals because of miscegenation and not from a common ancestor.
As a result, around 16% of Europeans and half of South Asians today are carriers of these genes inherited more than 50,000 years ago.
According to the study, the gene group of chromosome three is most commonly found in Bangladesh, where 63% of the population carries at least one copy of the DNA sequence.
“Genes in this region may well have protected Neanderthals from some other infectious diseases that do not exist today. And now, when faced with the new coronavirus, these Neanderthal genes have these tragic consequences,” Paabo said.
Those who carry these Neanderthal gene variants have up to three times the risk of requiring mechanical ventilation, explained Hugo Zeberg, an assistant professor at the Karolinska Institute in Stockholm.
Beyond COVID-19 risk genes, Neanderthals have bequeathed other genes to modern humans. Some increase sensitivity to pain, while others reduce the risk of abortions. “Some are beneficial and some are harmful,” Zeberg said. “This has been a double-edged sword, ” he added.