As novel as COVID-19 is, there are certain elements of the disease we have known about from the beginning, including the fact that those infected present in a myriad of ways. For some, COVID-19 wrecks such havoc on their bodies that they require hospitalization, while others have mild symptoms similar to the flu, while still others have no symptoms at all.
Several factors influence a person’s susceptibility to disease, including age, preexisting conditions and genetics. Now, researchers from Max Planck Institute for Evolutionary Anthropology have shown genetics are to blame for severe COVID-19. Not just any genetics, though—specifically, 60,0000-year-old genes inherited from our Neanderthal ancestors in Southern Europe.
"It is striking that the genetic heritage from Neanderthals has such tragic consequences during the current pandemic," said Svante Pääbo, who currently leads the Human Evolutionary Genomics Unit at the Okinawa Institute of Science and Technology Graduate University, and is affiliated with Max Planck in Germany.
Research performed over the last several months by the COVID-19 Host Genetics Initiative identified a region on chromosome 3 that influences whether a person will become severely ill. In fact, the gene variant carries up to a 3x higher risk of mechanical ventilation. According to the researchers, the genetic region is extremely long, spanning almost 50,000 base pairs. In addition, the variants are strongly linked, meaning if a person has one of the variants, they are very likely to have all 13 that pose a higher risk of severe COVID-19. Previously, these variants had been linked to Neanderthals or Denisovans, which is why Pääbo told Forensic it was “natural” for he and colleague Hugo Zeberg to become involved.
Together, the anthropologists discovered that not only did the variants come from Neanderthals, but specific Neanderthals. Two Neanderthals from Southern Siberia and a Denisovan did not present with the variants, while a Neanderthal from Southern Europe carried an almost identical genetic region.
Next, the researchers questioned whether the variants came directly from Neanderthals or had been inherited by both Neanderthals and present-day people through a common ancestor. According to their paper, published in Nature, the lack of random genetic mutations and recombination between chromosomes told Pääbo and Zeberg that the variants were closer to 50,000 years old (interbreeding) as opposed to 550,000 years old (last common ancestor). The fact that the variants between the Southern Europe Neanderthal and present-day people were strikingly similar over such a long stretch of DNA added additional evidence that the genetic region most likely came about through interbreeding when the two groups met around 60,000 years ago.
Lastly, the anthropologists discovered that, in modern times, the genetic variants are localized. In South Asia, for example, 50 percent of the population carries the gene, while almost none of the population of East Asia has the variants.
Pääbo said his team—in addition to other research groups—is extremely interested in understanding exactly why the ancient Neanderthal gene region is associated with increased risk of modern-day severe COVID-19.
"This is something that we are now investigating as quickly as possible," said Pääbo. “It may open up new possibilities to treat severe COVID-19.”
With no current treatments for COVID-19, the “as quickly as possible” should not be understated.
Photo credit: OIST