Covid: A genetic mutation would be associated with the absence of symptoms

At least 20% of people who become infected with the SARS-CoV-2 coronavirus never feel sick. Now scientists have identified a genetic mutation that is associated with a greater chance of not experiencing symptoms during an infection.

This mutation could confer an advantage immune cells people who have previously been exposed to “seasonal” coronaviruses, which cause the common cold.

That extra help means the immune system can quickly find and destroy SARS-CoV-2 before it goes haywire trying to fend off the pathogen, says Jill Hollenbach, an immunogeneticist at the University of California, San Francisco, who co-authored a report published July 19 in the journal Nature.

The study deserves a big round of applause, says Jean-Laurent Casanova, a pediatric immunologist at Rockefeller University in New York.

Researchers show a “modest” link but “stronger than any other”. another common gene association published” in COVID-19he says.

Many studies investigating the link between genetics and the risk of covid-19 have focused on how it causes severe illness or death.

These are important studies, Hollenbach says, but most people infected with SARS-CoV-2 have a mild attack of the disease.

To detect people with asymptomatic infections, the authors used a database of bone marrow donors and included nearly 30,000 people.

Participants reported all positive tests for SARS-CoV-2 and all symptoms. Of more than 1,400 participants who tested positive during the 15-month study, which was conducted before vaccines became widely available, 136 remained asymptomatic.

The researchers then looked for a link between people who had silent infections and variations in the HLA genes, which code for proteins found on the surfaces of nearly every cell in the body.

The proteins display fragments of potential invaders to the immune system, triggering immune defenders called T cells to spring into action against the invaders.

The authors found a link between asymptomatic infection and mutation HLA carried by approximately 10% of the examined population.

People with the mutated gene were twice as likely to remain asymptomatic than people without it; people with two copies of the gene were eight times more likely. “We were quite surprised by the magnitude of the effect,” says Hollenbach.

The results could help developing professionals the next generation of vaccines against covid-19 which not only control the severity of the disease, but also prevent the symptoms.