Covid: according to AP-HP, a quarter of severe disease caused by immune abnormality

Published by Laurent P. · Published on 26 August 2021 at 11h59
According to two new studies carried out by AP-HP and published in the Science Immunology magazine, severe Covid is caused by – according to the first study – a genetic abnormality attacking type 1 interferons, namely the protein preventing the virus from replicating, and according to the second study, by the presence of self-antibodies targeting the same protein in 15 to 20% of cases.

What if there was an explanation about some of severe Covid cases? Two studies – carried out by AP-HP – have been published this August 20 in Science Immunology and results are similar. Scientists have discovered several things: in the first study, searchers have noticed some patients had a genetic abnormality targeting a protein in particular, the one able to prevent coronavirus from replicating in the body, namely type 1 interferon.

Based on the fact severe diseases mostly impact men, the latter have worked on what the difference between men and women was, namely men’s only X chromosome. Then, they sequenced the genetic code of the chromosome in patients who developed severe infection and compared to the same chromosome in asymptomatic people. The outcome: a “functional loss in a gene” in some clinical cases, as our peers from Franceinfo explain. According to statistics, the anomaly exists in 1.3% of people who developed severe infection.

As for the second study, it tends to show that in 15 to 20% of hospitalized people – namely a good third of them – self-antibodies were found in the blood, targeting type-1 interferon and leaving free rein to the virus to multiply in an uncontrolled fashion. Scientists and authors of the same study have also discovered self-antibodies were especially random in the body before turning 65, assessing the self-antibody rate between 0.2 and 0.5% at this age. The self-antibody toll increases over time, reaching 4% between 70 and 79, and 7% between 80 and 85 years of age.

Causes and mechanisms of this increase in the genera population are still to clarify, but it mostly explains why age is a major risk factor in developing severe Covid-19”, AP-HP adds. Both studies enable to more easily aim at people likely to develop severe infection and act accordingly.

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