A new study has found that a genetic variant responsible for increased risks of severe COVID-19 is almost identical to those found in a Neanderthal ancestor from southern Europe.
The SARS-CoV-2 virus causes the novel coronavirus disease in 2019 (COVID-19). As the infection spread worldwide, some people were becoming only mild or even asymptomatic, while others are requiring hospitalization and even leading to death.
Several studies on the highly contagious disease have revealed factors that influence a person's susceptibility and response to the coronavirus. These factors, which previously included age and pre-existing conditions, now include genetics, according to a new study led by researchers from Max Planck Institute for Evolutionary Anthropology. Their findings are published in the journal Nature.
COVID Susceptibility Clues in Genetic Records
Chromosomes are microscopic structures found in the nucleus of both plant and animal cells, containing protein and strands of DNA - or the genetic instructions of the host organism. For humans, we have 23 pairs or 46 chromosomes that determine our unique genetic makeup. Researchers noted that although most of these instructions are similar - like eye or hair color or allergy - some mutations exist and persist down to the DNA level.
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The study conducted by the COVID-19 Host Genetics Initiative has analyzed information from 3,000 people who contracted the coronavirus disease. This included people who needed hospitalization from a severe case and those who became ill but without the need for intensive medical attention.
Researchers were able to identify a specific region on their chromosome 3 that was different among those who had severe cases and those that did not. This distinct genetic region is relatively long, covering about 49,400 base pairs. Additionally, its variants suggest a higher risk of contracting a severe case of COVID-19. The presence of one variant also indicates the presence of all thirteen of these mutations.
Svante Pääbo, from the MPI for Evolutionary Anthropology and Okinawa Institute of Science and Technology, worked with Hugo Zeberg, also from MPI for Evolutionary Anthropology, the Karolinska Institutet. Together, they investigated whether these variants actually came from Neanderthals or Denisovans - ancestors to the modern man.
A Genetic Similarity to Neanderthals
The genetic region that contained these variants were found by the researchers to be almost similar to those seen from a 50,000-year-old Neanderthal from southern Europe. Conversely, two other Neanderthals, both from southern Siberia and a Denisovan, did not carry any similar genes.
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Researchers explained that if this genetic region resulted from interbreeding between two peoples, it could be dated as recently as 50,000 years ago, from the southern Europe Neanderthal. However, if this region was from a common ancestor shared by the prehistoric humans, researchers estimated that this region has been in existence among humans for at least 550,000 years.
The MPI for Evolutionary Anthropology team suggested that interbreeding was the more likely scenario, citing random mutations and recombinations that maintained the similarities between the southern Europe Neanderthal and modern-day humans. Additionally, they explained that those with similar genetic makeup with the 50,000-year-old Neanderthal carry up to three times the risk of severe COVID-19, in addition to other factors such as age and medical history.
