A type of coronavirus, known as SARS-CoV-2, causes the disease called COVID-19. This disease has caused a global pandemic and has had a historic impact on people’s lives. Of the millions of people infected by the virus, the severity of the disease ranged from asymptomatic to death. Scientists are working to better understand how a person’s genes influence the severity of their COVID-19 symptoms. By understanding this relationship, scientists can predict who is at higher risk for a serious outcome.
There are thousands of genes within the body of a human being. Genes code for different traits, such as hair or eye color. Individuals have different versions of the same gene. These are known as a alleles. Alleles are located in a compact form of genetic material, called place of a chromosome. The locus of a chromosome is like the postal address of an allele in that it indicates a location.
A global group of scientists known as the COVID-19 Host Genetics Initiative, or COVID-19 HGI for short, has been working to understand the link between the severity of COVID-19 and genetics. They collected data from 46 studies involving 19 countries with a total of 49,562 patients. The scientists divided the patients into three categories: if they were severely ill or died from COVID-19, if they had a moderate to severe case of COVID-19 in which they were hospitalized, or if they had a mild case that did not turned out. in hospitalization.
Analyzing a large number of studies, the scientists found that thirteen significant loci were linked to COVID-19 infection. Six of the thirteen loci were related to critical symptoms. Nine of the loci were associated with moderate to severe symptoms that resulted in hospitalization. Of these nine loci, five of these were also found in critical cases of COVID-19. For every other case of COVID-19, there were seven loci that were linked to viral infection.
The scientists sought to better understand the relationship between the thirteen loci and the severity of COVID-19. Using a meta-analysis of the data, they looked at the structure of more than 40 alleles from patients with mild and moderate cases. This strategy allowed them to determine which loci were most likely to increase disease severity.
Four of the loci were present in both moderate-severe and mild cases. Because these loci were not related to the severity of COVID-19, the scientists determined that the link was more likely to be between exposure and infection. In other words, these loci were related to the probability between exposure to COVID-19 and whether or not a person became infected with COVID-19. Therefore, the scientists concluded that these loci are unlikely to be responsible for the severity of the symptoms.
The scientists found that one locus in particular had the most significant link between exposure to COVID-19 and infection. They suggested that there were unexplored structures within the locus that made exposure more likely to result in mild infection rather than hospitalization or death, since the causes of exposure versus disease severity are unknown. However, they also stated that more research was needed to understand why these structures were linked to mild infection.
The scientists then determined that nine loci from patients with moderate to severe disease had a link between exposure and critical symptom severity, including hospitalization. Four of the thirteen loci, not including these nine loci, were found to be associated with immunocompromise. Therefore, the severity of COVID-19 was found to be higher due to a weaker immune system.
The scientists concluded that genetics is not only related to the severity of an individual’s COVID-19 symptoms, but is also responsible for who is more likely to become infected after exposure. Although several studies have been conducted on COVID-19, there are not enough to fully understand the infection process and how it affects people in the long term. By collecting more samples from patients who have had COVID-19, the scientists plan to use their collected data to understand upcoming variants of SARS-CoV-2.