Could the Covid be genetic?
We know that it is an infectious disease of viral origin, linked to SARS-Cov-2, but the response of our organism varies according to our genes.
This idea of a "genetic trail" had already been put forward by various research teams since this new enemy appeared, but the work carried out by the Imagine Research Institute (Necker Hospital, Inserm, Rockefeller University and Howard Hughes Medical Institute in New York) provide new information on this topic which has just been published in Science magazine.
A Franco-American team, led by Jean-Laurent Casanova and Laurent Abel, shows that 15% of severe forms of Covid have genetic and immunological causes.
Why do genetics play a crucial role?
“For several years now, we have realized that infectious diseases can also be explained by genetic causes.
We see it now with the Covid.
Since the start of the pandemic, we have set up an international consortium, Covid Human Genetic Effort, with the aim of identifying the genetic factors that may explain the severe forms, explains Laurent Abel.
If some of our genes fail, our body's immune response will be less effective.
The production of certain proteins essential to our defense will no longer be possible.
"
In detail, the researchers found that “3 to 4% of patients with severe form of Covid have mutations in their genes.
This has the direct consequence of reducing their production of type 1 interferons. These molecules of the immune system normally have powerful antiviral activity.
Faced with this situation, the patient's illness worsens, ”adds Laurent Abel.
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Research is underway to develop screening techniques for these at-risk patients, but some are quite advanced.
There is also real hope for a treatment, using drugs made from type 1 interferons which will compensate for their deficiency in the body.
They have been available for over thirty years and without noticeable side effects if taken for a short time.
The trail of an X chromosome mutation
Researchers at the Imagine Institute have made another discovery, which highlights the fragility of some patients.
“We have noticed that 10 to 11% of patients who develop severe forms of Covid have the particularity of producing autoantibodies.
These neutralize type 1 interferons and prevent them from fighting the disease, ”continues the specialist.
Asked about the common points from the point of view of the genetic heritage between these patients, the researcher points out that they are "in the great majority of men".
Indeed, of the 101 people in the group presenting this clinical profile, 95 were men.
In addition, one of the six women who had autoantibodies also had incontinence pigmenti, a genetic disease caused by a mutation in a gene carried by the X chromosome, which distinguishes the female and male sex.
"Our hypothesis is that the origin of these autoantibodies is linked to a mutation in some of the X chromosome", specifies Laurent Abel.
Other publications have already shown a certain fragility of men in the face of Covid, with proportions of severe forms greater than what was expected from a statistical point of view.
The genetic track (s) that may explain these facts are not yet all known.