Genetics determines the severity of Covid-19

• Health: One in five inhabitants of the planet has a health problem that increases the risk of suffering the most serious Covid-19

The Covid-19 is, for now, a disease of uncertainties. Some people develop severe forms while others have no symptoms, or they are very mild, without researchers knowing exactly why.

Those unknowns have less to do with the nature of the virus than with how our bodies respond to it. For example, it is known that age is a factor, as well as the presence of chronic diseases such as diabetes or hypertension. But other elements also seem to play an important role, including subtle differences in the body of each patient or in the viral load to which they have been exposed.

A European study, with the participation of the Network Biomedical Research Center (CIBER), points out that genetic characteristics may explain the greater vulnerability of certain people to developing serious forms of the infection. The work, published this Thursday in the New England Journal of Medicine , links two genetic variants located in specific regions of the genome with an increased risk of respiratory failure. "We have looked for the answer in the genes and have found a strong association between certain variants on chromosomes 3 and 9 and the severity of the disease caused by SARS-CoV-2," the authors explain.

During the peak of the pandemic in Spain and Italy (between March and April), CIBER researchers from different hospitals started a collaborative project, coordinated by geneticists from Norway and Germany, to try to find out why some people are asymptomatic or present mild symptoms. , while others develop gravity charts. The authors began to explore the possibility of an innate predisposition that increases the risk of developing a severe form with lung failure.

"As in other diseases, genetics is only one of the many factors that condition severity and mortality, " explains Dr. Jesús Bañales, a researcher at the University Hospital of Donostia and one of the study participants. "Genetic variants can change by population, something that would explain, at least partially, the differences in infection severity in different groups."

Two genetic regions

In just three weeks they collected 1,610 blood samples from patients with a severe form of Covid-19, all of whom required respiratory assistance, either oxygen or mechanical ventilation. Subsequently, DNA was extracted for study in a laboratory in Kiel, Germany, in which nearly nine million genetic variants were tracked with the assistance of expert geneticists and bioinformatics.

"In less than 2 months, all the necessary information was available to evaluate the results and compare them with a control group of 2,205 healthy patients," the authors report. Thus, a higher frequency of 26 variants was observed in patients affected by respiratory failure in relation to the control group. "In particular two of them, located on chromosomes 3 (rs11385942) and 9 (rs657152), showed a powerful association with gravity," they point out.

Chromosome 3 seems to affect the expression of certain genes that favor the entry of the virus, as well as the subsequent appearance of the so-called cytokine storm . In most patients with the most severe variant of the disease, there is a secondary worsening phase, which doctors are observing about ten days after its onset. In some people this second phase produces an excessive and abnormal reaction of the immune and inflammatory systems -the cytokine storm- that involves the massive release of molecules involved in the control of immunity, to the point that it can lead to exhaustion and collapse of the organism.

This genetic variant of chromosome 3 affects a region that regulates six genes , which may also influence the severity of symptoms, although the researchers estimate that it is still premature to definitively establish the role of each one in the course of infection. One of them seems to be involved in the interaction with the ACE2 protein ; Previous work has established that the coronavirus binds to the ACE2 protein on the surface of cells. Furthermore, another one of these six genes is related to the inflammatory response in the lungs in response to pathogens.

Blood groups

The second region associated with severe respiratory problems has been located on chromosome 9, specifically in the gene that determines the blood group within the AB0 system, which is used to classify human blood into different types, depending on the presence or absence of certain markers in the red blood cells. In this sense, the results reflect that people who have blood group A have a 50% higher risk of needing respiratory assistance in case of infection. At the opposite pole, blood group 0 appears to have protective effects , specifically a 35% lower risk.

Although, again, the researchers are cautious about the implications. "It is true that one of the two identified genetic variants is located in the gene that determines the blood group," says Bañales, "however, the interrelation between blood group and the evolution of patients with Covid-19 is unknown and is currently unknown. is studying".

Identifying the groups most vulnerable to a serious variant of the disease -which includes pulmonary insufficiency- opens the door to reinforce the protection of people at higher risk, as well as the design of personalized treatments . The authors explain that the genetic variant on chromosome 3 is more frequent in relatively young people (59 years on average), which could explain, at least in part, the severity of the cases observed in this age group.

Furthermore, the frequency of both genetic variants on chromosomes 3 and 9 is significantly higher in patients who required mechanical ventilation, compared to those who only had to be administered oxygen, so the authors conclude that these genetic variants weigh in the development of the most severe forms of respiratory failure.

In accordance with the criteria of The Trust Project

• Science and health
• Covid 19
• Coronavirus

HealthOne in five patients hospitalized for Covid-19 dies

Character Adele's Sirtfood diet: like the Mediterranean but with more marketing

Salud'Supercontagiadores' and with a different strain than the rest of Europe, this is the Spanish epidemic

See links of interest

• News
• Translator
• Programming
• Calendar
• Horoscope
• Classification
• League calendar
• Films
• Cut notes
• Themes

• RB Leipzig - Fortuna Düsseldorf
• Borussia Dortmund - 1. FSV Mainz 05
• Bayer 04 Leverkusen - 1. FC Köln
• FC Augsburg - TSG 1899 Hoffenheim
• Osasuna - Atlético de Madrid