Children with Covid-19 can, in very rare cases, develop a severe form triggering myocarditis. Researchers have managed to highlight a potential cause: genetic abnormalities.
"Genes associated with the occurrence of severe forms"
Severe inflammation was triggered between 4 to 6 weeks after Sars-Cov-2 infection. In its statement, the National Institute of Health and Medical Research, Inserm, says that for two-thirds of children who have contracted a severe form, "this inflammatory syndrome reaches the heart, leading to cases of myocarditis." Several professionals in the medical and scientific sectors were then interested in these rare forms reaching children first "in England, in March 2020 [...] in France, then all over the world." On August 22, Public Health France recorded 640 cases. To find explanations, the experts analyzed the blood taken from 56 children, including 30 who developed multisystem inflammatory syndrome and 21 myocarditis, from April 6 to May 30, 2020.
As Mickaël Ménager of the Imagine Institute of Genetic Diseases explains, the researchers used several cutting-edge techniques, including:
- An ultra-sensitive assay of cytokines (hormones of the immune system);
- Characterization of blood cells;
- A cell-by-cell genetic analysis.
According to the results published in the journal MED, they "were able to identify the abnormal expression of several genes associated with the occurrence of severe forms of myocarditis"
Identify children at risk through testing
Three molecular abnormalities could be highlighted in the different groups: a "decrease in the number of monocytes and dendritic cells (white blood cells), as well as an increase in the level of inflammatory cytokines and an overactivation of what is called the "NF-kB pathway" within these cells." However, this pathway has the role of putting genes into action so that they trigger an immune response. However, the system is overactivated, resulting in hyperinflammation. They discovered that these different phenomena are the cause of an abnormal expression of a hundred genes present in white blood cells. This scientific discovery is important because it could "allow the development of tests to identify patients at risk of developing these severe cardiac inflammations."
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