Covid 19 can cause both mild symptoms and life-threatening breathing difficulties. This variability in clinical signs is not yet apparent. Scientists are wondering about the genetic factors that promote or hinder the transmission of coronaviruses.
Covid-19 is a disease that can go completely unnoticed – almost a third of cases are thought to be asymptomatic – but can also cause life-threatening breathing distress; many patients admitted to the ICU are elderly or have underlying conditions such as diabetes or hypertension, but some are also young without any preexisting health conditions.
Scientists cannot yet explain this “selectivity” of the coronavirus, but the role of genetic factors in the onset and progression of the symptoms of covide-19 is still an unexplored path.
“We see a big difference in clinical presentation, but we also see a big difference across countries, To what extent of this can be explained by genetic predisposition is a very open question,” Andrea Ganna, a geneticist at the Institute of Molecular Medicine in Helsinki, told Science magazine.
Possible mutations in the ACE2 gene
To unravel this mystery, scientists want to compare the DNA of people who contracted a mild form of Covid-19 with those who contracted a severe form, who had no co-morbidity factors. These analyses may enable us to identify those most susceptible to the effects of the epidemic.
One gene that researchers are particularly interested in is the gene that encodes the cellular receptor ACE2. The virus uses it as a gateway to infect the host cells. Genetic variation in this gene may prevent or promote coronavirus infection. Such a phenomenon is already known, especially in the case of HIV. Some people are naturally resistant to infection due to a mutation in the gene encoding CCR5, a receptor on the surface of white blood cells that acts as an entry point for the virus.
Projects to collect data
Projects are proliferating in order to collect sufficient genetic data. For example, two scientists have set up the “COVID-19 Host Genetics Institute” project, which wants to centralize data collected in studies that study the link between DNA and health. Several biobanks, mainly in Europe, have shown interest.
Another initiative collects data directly from patients who are admitted to hospitals for Covid-19. In Italy, 11 hospitals have agreed to take DNA samples from patients with their permission. With the number of infected patients unfortunately increasing, the amount of collected data should skyrocket which should make it possible to identify potential causative genes in a matter of months. The outcome of this gene hunt is difficult to predict, but scientists hope to identify the genes that promote or protect against the disease, allowing the identification of those that are most at risk.