The wide variation in the severity of COVID-19 cases is probably due to a range of factors, including how much virus a person is exposed to, any preexisting conditions they may have, and their genetics. Tiny variations in gene sequences can cause small and large changes in biology. Researchers have now identified a genetic variant that seems to protect those who carry it against serious cases of COVID-19. This finding was made possible because the researchers assessed a diverse set of human genetic data, and did not limit their research to a few groups. The work has been reported in Nature Genetics.
Other studies have looked for genetic differences among those who suffer cases of COVID-19 of varying severity. But those studies have primarily relied on DNA from people of European ancestry. For example, a DNA segment inherited from Neanderthals that is still found in many people outside of Africa is thought to protect against severe COVID-19. But the region that this DNA sits in contains other variants as well, so the exact sequence that's providing the protection is still elusive.
Identifying the genomic regions that can protect people from serious COVID-19 cases may help scientists create effective treatments.
In this study, the researchers focused on people who would not carry Neanderthal DNA, and would not carry the large region that was already identified. There was a tiny piece of that region, however, found in people with African or European ancestry. People with mostly African ancestry had the same protection from COVID-19 as those of European ancestry, so the gene variant could then be pinpointed.
"The fact that individuals of African descent had the same protection allowed us to identify the unique variant in the DNA that actually protects from COVID-19 infection," explained first study author Jennifer Huffman, a researcher at the VA Boston Healthcare System.
The researchers analyzed data from 2,787 COVID-19 patients with African ancestry who had been hospitalized and 130,997 individuals from other studies that served as controls. The protective variant is called (rs10774671-G), and it influences the size of a protein encoded for by OAS1. Previous studies have indicated that variants that lead to longer versions of the OAS1 protein are better at breaking down the virus that causes COVID-19, SARS-CoV-2.
"This study shows how important it is to include individuals of different ancestries. If we had only studied one group, we would not have been successful in identifying the gene variant in this case," said corresponding study author Hugo Zeberg, an assistant professor at the Department of Neuroscience at Karolinska Institutet.
Sources: Karolinska Institutet, Nature Genetics
