- Rebecca Morelle
- Science Correspondent, BBC News
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2 hours
Image source, Science Photo Library
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The new coronavirus causes some people to have severe symptoms while others have none.
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One of the biggest enigmas of the pandemic is why some people with Covid-19 have no symptoms and others do get seriously ill.
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But a study recently published in Nature analyzed more than 2,200 intensive care patients and identified specific genes that may offer answers.
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These genes make that some people are more susceptible to severe symptoms of covid-19.
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The findings shed light on where the immune system is failing, which could help identify new treatments.
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And these will continue to be needed even though vaccines are being developed, said Dr Kenneth Baillie, consultant for medicine at the Royal Infirmary in Edinburgh and director of the GenOMICC project, the results of which are collected in the study published in Nature.
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“Vaccines should drastically reduce the number of COVID-19 cases, but doctors are likely to continue treating the disease in intensive care for several years around the world, so there is an urgent need to find new treatments,” he noted Baillie, also a co-author of the study.
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“Nuisance” cells
The scientists analyzed the DNA of patients in more than 200 intensive care units in UK hospitals.
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Image source, Getty Images
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The study suggests that there are genes that make some people more susceptible to severe symptoms of COVID-19.
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They scanned each person’s genes, which contain the instructions for every biological process, including how to fight a virus.
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Their genomes were then compared to the DNA of healthy people to identify any genetic differences, and several were found. The first, in a gene called TYK2.
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“It is part of the system that makes immune cells more ‘angry’ and more inflammatory,” explained Dr. Baillie.
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But if the gene is defective, this immune response it can be accelerated, putting patients at risk for damaging lung inflammation.
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One class of anti-inflammatory drugs already used for conditions like rheumatoid arthritis targets this biological mechanism, including a drug called Baricitinib.
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“He may be a very plausible candidate for a new treatment,” said Dr. Baillie. “But of course we need to realize clinical trials on a large scale to find out if that’s true or not. “
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Very little interferon
The study found other genetic differences in a gene called DPP9, which plays a role in inflammation, and in a gene called OAS, which helps prevent the virus from making copies of itself.
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Interferons are produced naturally by the human body, but they are also applied as drugs.
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Variations were also identified in a gene called IFNAR2 in intensive care patients.
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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.
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It is believed that producing too little interferon can give the virus an advantage early, allowing it to rapidly replicate and lead to more serious disease.
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Two other recent studies published in the journal Science They have also implicated interferon in cases of Covid-19, through genetic mutations and an autoimmune disorder that affects its production.
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Professor Jean-Laurent Casanova, who carried out the research, from Rockefeller University in New York, said: “[El interferón] represented almost 15% of critical cases of covid-19 registered internationally in our group “.
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Interferon can be given as a treatment, but a World Health Organization clinical trial concluded that it does not help very sick patients. However, Professor Casanova said the timing of administration was important.
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“I hope that if it is administered in the first two, three or four days infection, interferon works, because it would essentially provide the molecule that the [paciente] it does not produce by itself or by itself, “he explained.
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“When things go wrong”
Dr Vanessa Sancho-Shimizu, a geneticist at Imperial College London, said the genetic discoveries were providing insight without precedents of the biology of disease.
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Image source, Getty Images
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“Clinicians will likely continue to treat COVID-19 in intensive care for several years around the world,” says Dr. Kenneth Baillie.
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“It really is an example of precision medicine, where we can identify the moment when things go wrong in an individual, “he told BBC News.
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“The findings from these genetic studies will help us identify particular molecular pathways that could be targets for therapeutic intervention,” he said.
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But the genome still holds some mysteries.
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The GenOMICC study and other research have revealed a group of genes in the chromosome 3 strongly linked to severe symptoms of covid-19. However, the biology behind this is not yet understood.
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Now more patients will be asked to participate in this research.
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Dr Baillie said, “We need all of you, but we are particularly interested in recruiting people from minority ethnic groups that are overrepresented in the critically ill population. “
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“There is still a very urgent need to find new treatments for this disease and we have to make the right decisions about which treatments to try next, because we don’t have time to make mistakes,” he added.
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