A Major Risk Factor for COVID-19 Is Inherited from Neanderthals

A new study published today in Nature has revealed that a genetic region in chromosome 3—whose variants impose a larger risk that COVID-19 carriers will develop a severe form of the disease—is almost identical to that of a 50,000-year old Neanderthal from southern Europe. Further analysis has shown that, through interbreeding, the variants came over to the ancestors of modern humans about 60,000 years ago.

"It is striking that the genetic heritage from Neanderthals has such tragic consequences during the current pandemic," said study leader Svante Pääbo, from Okinawa Institute of Science and Technology Graduate University. 

Previous research by the COVID-19 Host Genetics Initiative looked at over 3,000 people including both people who were hospitalized with severe COVID-19 and people who were infected by the virus but weren't hospitalized. It identified a region on chromosome 3 that influences whether a person infected with the virus will become severely ill and needs to be hospitalized. Since variants like these have previously been found to come from Neanderthals or Denisovans, Pääbo and their team decided to investigate whether this was the case.

They found that a Neanderthal from southern Europe carried an almost identical genetic region whereas two Neanderthals from southern Siberia and a Denisovan did not. Then, they questioned whether the variants had come over from Neanderthals or had been inherited by both Neanderthals and present-day people through a common ancestor.

The team concluded that Neanderthals related to the one from southern Europe contributed this DNA region to present-day people around 60,000 years ago when the two groups met.They also found that there are major differences in how common these variants are in different parts of the world. In South Asia about 50% of the population carry them. However, in East Asia they're almost absent. The team explains that those who carry these Neanderthal variants have up to three times the risk of requiring mechanical ventilation. "Obviously, factors such as your age and other diseases you may have also affect how severely you are affected by the virus. But among genetic factors, this is the strongest one."