23andMe is launching a study to look into the genetics of symptom severity

Why do some people infected with the new coronavirus get seriously ill and die while others experience only mild symptoms? It’s a question that’s puzzling scientists. Age, underlying health, and the amount of exposure likely determine how severe a person’s disease is. But genetics could play a role, too.

23andMe, the popular DNA testing company, launched a study this week to understand how genetics may affect these differences. Previous research has found that mutations in certain genes can influence a person’s susceptibility to infectious diseases like hepatitis B and C, HIV, malaria, and tuberculosis.

Beginning this week, the company is asking customers to participate in the study. 23andMe has sold more than 10 million of its DNA testing kits, and about 80% of those customers have consented to letting 23andMe and its scientific collaborators use their personal data for research. That represents a huge pool of people to draw from. The company says it hopes to enroll hundreds of thousands of U.S. customers in the study, which will include people who have tested positive for the virus and people who haven’t.

Customers will be asked to fill out an initial survey and will then be invited to take additional surveys every month. “This will enable us to collect data regarding new infections in the population should the outbreak continue to spread,” says an April 6 blog post by the company.

At the same time, 23andMe scientists will conduct what’s called a genome-wide association study using participants’ genetic information. The approach involves scanning certain regions of DNA across the genomes of many people to find genetic variations associated with a particular disease or health condition. In this case, researchers are looking for variants associated with severe Covid-19 symptoms.

“If we can identify genetic variants associated with severe symptoms, scientists may be able to better understand who is more at risk due to genetic predispositions,” the 23andMe blog post says. “These genetic insights could also give scientists a better understanding of how the novel coronavirus infects our cells and impacts our bodies.”

Meanwhile, an international research project called the Covid Human Genetic Effort will investigate why some younger people who get Covid-19 have more severe illness. Researchers will sequence the genomes of people with severe Covid-19 under age 50 who were previously healthy, as well as those with mild and no symptoms, to look for genetic differences.