How can your DNA be affected if you contract COVID-19 or become seriously ill?

One of the biggest questions of the pandemic is why do some people with covid-19 have no symptoms and others get seriously ill? A study conducted in the middle of the pandemic looked at more than 2,200 intensive care patients and identified specific genes that may offer answers. These genes make some people more susceptible to severe symptoms of covid-19.

The findings shed light on where the immune system fails, which could help identify new treatments. Vaccines should dramatically reduce the number of Covid-19 cases, but doctors are likely to continue to treat the disease in intensive care for several years around the world, so there is an urgent need to find new treatments.

The scientists analyzed the DNA of patients in more than 200 intensive care units, scanning each person’s genes, which contain the instructions for every biological process, including how to fight a virus. Their genomes were then compared to the DNA of healthy people to identify any genetic differences, and several were found.

The first is a gene called TYK2, which is part of the system that makes immune cells more aggressive and more inflammatory, but if the gene is defective, this immune response can be accelerated, putting patients at risk for harmful lung inflammation. It is the practically identical gene shared by severe covid-19 patients and healthy people.

The study found other genetic differences in a gene called DPP9, which plays a role in inflammation, and a gene called OAS, which helps prevent the virus from making copies of itself. Variations in a gene called IFNAR2 were also identified in intensive care patients.

The IFNAR2 gene is linked to a powerful antiviral molecule called interferon, which helps activate the immune system as soon as an infection is detected. It is thought that producing too little interferon may give the virus an early advantage, allowing it to replicate rapidly and cause more serious illness.

Findings from these genetic studies will help identify particular molecular pathways that could be targets for therapeutic intervention. It really is an example of precision medicine, where you can identify when things go wrong in an individual.