A group of genes inherited from Neanderthals significantly reduce the risk of developing severe COVID-19.
The genomic region, located on chromosome 12, is associated with a 22 percent lower risk of requiring intensive care when infected with SARS-CoV-2, the virus which causes COVID-19. The genetic variants are also expressed in up to half of the populations outside of Africa.
'It is striking that this Neanderthal gene variant has become so common in many parts of the world. This suggests that it has been favourable in the past,' said Professor Svante Pääbo, joint author of the study.
Two researchers at the Karolinska Institutet in Sweden and the Max Planck Institute for Evolutionary Anthropology in Germany conducted the study. They analysed the DNA of those who had been infected with SARS-CoV-2 and had developed COVID-19. They then compared these sequences to Neanderthal DNA. Those whose sequence matched that of Neanderthals in this genomic region had a reduced risk of requiring COVID-19 hospitalisation.
Although Neanderthals became extinct about 40,000 years ago, these variants have increased in frequency over the last 20,000 years, likely due to their protective nature. The protective Neanderthal variants are located in the OAS genes. These encode enzymes that degrade viral RNA and could be crucial in the immune defence against SARS-CoV-2.
These findings are in stark contrast with the duo's previous report of Neanderthal variants that triple the risk of developing severe COVID-19 (see BioNews 1066).
Professor Pääbo said 'It is also striking that two genetic variants inherited from Neanderthals influence COVID-19 outcomes in opposite directions. Their immune system obviously influences us in both positive and negative ways today.'
Dr Hugo Zeberg, the other study author, concluded 'This shows that our heritage from Neanderthals is a double-edged sword when it comes to our response to SARS-CoV-2. They have given us variants that we can both curse and thank them for.'
The research was published in the journal PNAS.