The researchers found a genetic mutation that reduces the risk of serious Covid-19 infection by about 22%. It was found in all Neanderthal DNA samples and in about 30% of samples from people of European and Asian origin.
“This region encodes proteins that activate enzymes that are important during infections by RNA viruses,” they wrote.
It may be one of those mutations that has been transmitted over the millennia because it helped people survive, reported Svante Paabo and Hugo Zeberg, from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.
“We have shown that a haplotype on chromosome 12, which is associated with a reduction of about 22% in the relative risk of becoming seriously ill with COVID-19 when infected with SARS-CoV-2, is inherited from Neanderthals,” they wrote. “The relative risk of needing intensive care is reduced by about 22% per copy of the Neanderthal haplotype,” they added.
“This haplotype is present in substantial frequencies in all regions of the world outside Africa,” they added. “It is present in the populations of Eurasia and the Americas in carrier frequencies that frequently reach and exceed 50%.”
The finding may help explain why black patients are much more likely to suffer from severe coronavirus. Neanderthals, which went extinct some 40,000 years ago, lived side by side and sometimes crossed with modern humans in Europe and Asia, but not in Africa, and people of purely African descent do not carry DNA from Neanderthals. Studies estimate that about 2% of DNA in people of European and Asian descent can be traced back to Neanderthals.
The team used samples taken from more than 2,200 people alive with severe cases of coronavirus or compatible controls. They discovered a genetic region that affected susceptibility to serious illnesses. Next, they checked the DNA taken from the skeletons of four ancient humans – a 70,000-year-old Siberian Neanderthal, a 50,000-year-old Croatian Neanderthal, a 120,000-year-old Neanderthal from the Denisova Cave in Siberia and a 80,000-year-old Neanderthal old from the same location as a Denisovan – another subspecies of ancient humans. All four samples carried the same versions of this genetic sequence.
Last year, Paabo and Zeberg identified a genetic mutation inherited from Neanderthals that increased the risk of serious diseases. As with most traits, disease susceptibility and serious consequences are affected by a variety of genetic differences.