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After the outbreak of the new crown epidemic, people noticed that some people are more susceptible to the virus than others, and some infected people are more likely to develop symptoms than others, and there are significant differences in the severity of symptoms among different patients. However, so far, scientists still know it but do not know why, and are still looking for the root cause behind the phenomenon.
Gene is an entry point for research in this area. Which fragments of deoxyribonucleic acid (DNA) are related to COVID-19? If this association can be found, does it mean that everyone’s resistance to new coronary pneumonia is actually determined by genetic genes?
By comparing all the genomes in the DNA sequence one by one, scientists hope to determine whether there is an association between a specific genetic change and a specific disease.
So far, two clues worthy of continued follow-up have been found: changes in the two pieces of DNA located on chromosome 9 and chromosome 3.
Witch Lander, Professor of Biology, Teesside University, UKVikki Rand) And biologicalprofessionDoctoral student Maria O’Hanlon (Maria O’Hanlon）inAcademic website (The Conversation)The author introduces these two interesting research directions.
1. Genetic risk
The clues on chromosome 3 are relatively simple. A study of patients in Spain and Italy found that the severe disease caused by the virus is associated with changes in a small region on chromosome 3; this small chromosome number is 3p21.31.
There is a gene in this region, SLC6A20, which carries genetic information that is an instruction to make a protein that can interact with a molecule called ACE2 that the virus uses to enter the cell.
The genetic information carried by other genes on this chromosome targets chemokine receptors, which are related to inflammation.
Since ACE2 and inflammation are the core factors of severe COVID-19, it may provide clues to explain why the variation of this region on chromosome 3 is associated with severe COVID-19.
The chromosomal variation that led to the increased susceptibility to the new coronavirus may have been inherited from the ancient ancestor Neanderthal caveman.
So far, 3p21.31 is the only genetic region that is significantly associated with severe COVID-19. Therefore, genetic variation in this region can be regarded as a risk factor.
2. Blood type and Covid-19
The segment on chromosome 9 is the ABO blood type system, which determines the blood type of each person.
This clue points to the relationship between blood type and susceptibility to the new crown, that is, are people of a certain blood type relatively less likely to be infected with the virus, and have a lower chance of causing serious illness or death after infection? If the answer is yes, is it possible to further verify that the key to this association is that antibodies in the blood can prevent the virus from invading cells?
Some studies in the early stages of the European epidemic found that blood types O and AB may be associated with the new crown, and some studies believe that blood types have no effect on the consequences of viral infections.
With the spread of the epidemic, the increase in infection cases, and the expansion of the scale of research, a rule gradually emerged: people with blood type A are more likely to develop the disease than people with blood type O, and the latter are less likely to cause serious illness after being infected with the virus than people with other blood types.
However, these studies are not enough to win the trust because of the small number of samples, and at most provide a possible direction.
Later, a study of new coronavirus-related respiratory failure cases found that patients with blood type O are less likely to have respiratory failure than patients with other blood types, and patients with type A blood are 1.5 times more likely to have respiratory failure than patients with other blood types. The sample for this study included 1,600 patients from Spain and Italy.
Then there was a published paper that provided support for this research.
This paper analyzes and evaluates 7 unrelated studies, with a sample of nearly 3 million people, including 7,500 new crown patients. The results of the evaluation found that the majority of people who tested positive for the new coronavirus were type A blood, while people with type O blood were less likely to be infected with the new coronavirus.
This result was subsequently supported by a larger study in Canada; the latter study found that people with blood type O are about 12% less likely to be infected than people with other blood types, and have a higher risk of serious illness or death than people with other blood types. 13% lower.
So, the question is, is there any relationship between blood type and susceptibility to the new coronavirus?
According to the results of the study after the SARS outbreak in 2002-2004, people with blood type O are less likely to be infected with the coronavirus, which is a proposed possibility. One explanation at the time was the antibodies in blood type O It may be able to prevent SARS virus from invading cells.
However, this hypothesis has not been verified.
What is certain now is that Covid-19, like SARS, is also a coronavirus.
Scientists hope that more samples, more data, and more research can bring more clues and find a clearer context.