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What genetics can – and can’t – discover about an individual’s risk is COVID

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What genetics can - and can’t - discover about an individual’s risk is COVID

Imagine going through a genetic test that can determine your personal risk of complications and death from a specific disease, such as cancer, heart attack or even COVID. A version of such a test exists – albeit imperfect.

Genomic Associations (GWAS) are becoming an increasingly common way to assess COVID risk. The approach has the potential to control disease by identifying locations, or loci, in the human genome that expose an individual to a higher or lower risk of serious disease. Scientists hope this could eventually open the door to new treatments.

“Sequencing the entire genome allows us to test every pair of bases in the genome,” said Athanasios Kusatanas, chief genome scientist at London-based Genomics England. “And it allows you to find specific genes that can be used with greater accuracy.”

However, some experts warn that GWAS alone is not enough to accurately assess COVID risk. They say genomic analysis can be difficult to separate from social risk factors and can leave health systems open to discrimination.

Manuel Ferreira, a researcher at the genetic company Regeneron, is part of a team that uses GWAS to search for COVID-related loci by sifting thousands of genomes from four aggregate databases. In his latest study, published in March Genetics of natureFerreira and his co-authors analyzed the figures and found that people with a a rare variant of c ACE2 gen the risk of developing severe COVID-19 seemed to be almost 40 percent lower than in the general population. “This is what we call the‘ strong effect, ’” Ferreira says.

The ACE2 the gene encodes a specialized ACE2 protein located on the cell surface. Usually protein helps regulate things like blood pressure and inflammation by skipping certain pieces of protein in or out of the cell. But it also provides SARS-CoV-2, the virus that causes COVID, the cellular entry point for infection. When the virus comes in contact with the ACE2 protein, it clings to its outer thorn protein like a burr, hooked on a sock. From there, the virus enters the target cell.

But Ferreira found that people wearing a certain option ACE2 genes have about 39 percent fewer receptors for a protein that sits on their cell surfaces. Researchers believe that as a result, fewer SARS-CoV-2 viruses can enter these people, greatly reducing the risk of severe COVID. “In a sense, it’s not entirely surprising, since we know what the virus requires [these] the receptors get into the cell, ”Ferreira says.

Kenneth Bailey, a research physician at the University of Edinburgh, recently collaborated with Kusatanas of Genomics England in a study that identified 16 new loci associated with serious COVID risk. Some of them, Bailey believes, are potential targets for new drug treatments. “I’m sure there are still targets for therapy that we haven’t understood in biology [of] still good enough, ”he says.

But other researchers warn that when it comes to predicting severe COVID, it is virtually impossible to separate genetic risks from social risk factors such as access to health care and working conditions, even through genome-wide analysis.

Elsie Taveras is a pediatrician at Massachusetts General Hospital. But when the pandemic began, she, like many others in her field, was dragged to the floor of the intensive care unit to help treat the influx of patients. Immediately she noticed a pattern among those suffering from severe COVID: most of them were colored people from low-income communities. Many did not speak English.

“I would never have thought that the most important thing I can bring to the care team is not so much my medical experience,” Taveras says. “I could be there because I could help this team with my Spanish.”

Between language barriers and limited financial resources, many Taveras patients shied away from treatment until their illness worsened. Others lived in houses of several generations or worked on front-line jobs in which isolation was virtually impossible. This social pressure exposes them to a higher risk of severe COVID – not because of genetics, but simply because of circumstances.

Geneticists are doing their best to take such differences into account in their analyzes. “Epidemiologically, how can you better understand the extent of genetics [versus social risk factors] Taveras argues that the severity of the disease depends on “adjusting some of these variables”. By comparing individuals of similar background, socioeconomic status, gender, or medical history, researchers can establish a baseline estimate of a patient’s chances of developing severe COVID. But even with such controls, “it’s imperfect,” Taveras says.

An previous genetic analysisfor example, high risk of COVID was associated with the presence of blood A and low risk with blood group O. But subsequent studies found that the association between type O and risk of COVID was negligible, whereas the association with type A blood did not exist.

Ferreira’s study relied on a database containing hundreds of thousands of genomes. These data gave the researchers a clear picture of the subjects ’origins and medical records, but had little context for their income level, housing status, or primary language.

Ferreira and his colleagues found that people of European descent had about 1 in 200 chances of transferring the risk of COVID-19. ACE2 option. The odds of people of African descent were about 1 in 100, while those of South Asian descent were about one in 25 (although this last sample was very small and the result was not statistically significant). But even these estimates can be rich.

“We have such a long and complex history of the biological race as a controversial category,” said Azita Chelapu, a medical philosopher at the Open University in England. “Not surprisingly, geneticists took this for what they took in the context of COVID-19,” she says, although ancestral categories often paint an incomplete picture of diversity in a population. For example, Ferreira’s study looked at the genomes of nearly 45,000 people of European descent, but only about 2,500 people of African descent and 760 people of South Asian descent.

In addition, Chelapu argues, focusing on individual loci lacks a way for genes to interact with their environment and with each other in context. “My genes by themselves don’t do anything,” she says.

But other researchers still see tremendous value in finding specific loci associated with COVID. “We kind of throw tires at the analysis,” says Bailey of Edinburgh, “and we keep getting the same results. So we are very confident that these [effects] real. “

GWAS was also used for accurate determination loci associated with loss of taste and smell in patients with COVID as well as markers associated with development of pneumonia after COVID infection. Future GWAS studies may shed light on the mysteries of lingering symptoms, which together are known as long COVID.

Ultimately, Chelapu, Bailey, and others agree that genomic analysis has the potential to develop the next generation of COVID treatments. The Ferreira study of ACE2 protein, for example, could provide a new way to prevent SARS-CoV-2 infection: by blocking receptors rather than attacking the virus itself. Current ACE blockers, which are commonly prescribed to control blood pressure, have so far been ineffective against COVID. But Ferreira believes a blocker specifically designed with COVID in mind could be more viable. “Our genetics suggest blocking [ACE2] it would be useful, ”Ferreira says. And due to the shortage of vaccines, antivirals and monoclonal antibodies around the world, new treatments are much needed.

When it comes to assessing the serious risk of COVID, balancing internal and external factors is key. “There is certainly value in understanding genetic contribution,” says Taveras, “as long as we remember that there is also a relative contribution to disease severity from these social risk factors that we cannot measure as accurately as a genetic mutation.”

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