The coronavirus triggers an over-reaction of the immune system in some people, leading to massive inflammation and lung damage – the so-called cytokine storm. It is theoretically possible that genetic variations influence this response.
A second locus, on chromosome 3, shows an even stronger link with Covid-19, discovered Dr. Franke and his colleagues. But this place is home to six genes, and it is not yet possible to say which of them influences the course of Covid-19.
One of these candidate genes codes for a protein known to interact with ACE2, the cellular receptor that the coronavirus needs to enter host cells. But another nearby gene codes for a powerful immune signaling molecule. It is possible that this immune gene also triggers an overreaction that results in respiratory failure.
Dr. Franke and his colleagues are part of an international effort called the Covid-19 Host Genetics Initiative.
A thousand researchers in 46 countries collect DNA samples from people with the disease. They are now starting to post data on the initiative’s website.
Andrea Ganna, genetic epidemiologist at the University of Helsinki, said that the data collected by the initiative was starting to point to one place on chromosome 3 as a potentially important player.
It is not common for genetic variants to emerge from the studies of so few people, said Jonathan Sebat, a geneticist at the University of California at San Diego, who was not involved in the new study.