Researchers at Sant Joan de Déu have contributed to the discovery of a genetic disorder responsible for multisystem inflammatory syndrome in children associated with COVID

During the pandemic, children were less affected by SARS-CoV-2 than adults and most of them were either asymptomatic or got through the infection with very slight symptoms. However, in April 2020 paediatricians started to see some cases of children who had to be admitted to ICU because after the infection they presented severe multisystem inflammatory syndrome, very similar to a disease known as Kawasaki syndrome.

A world study in which researchers from SJD Barcelona Children's Hospital’s Kids Corona platform took part – led by Iolanda Jordan and Laia Alsina with the support of Jordi Anton, Victòria Fumadó, Rosa Maria Pino and the Biobanc – has made it possible to discover one of the genetic causes of this inflammatory syndrome for the first time, which is also known as MIS-C. This study was led by the renown researcher from The Rockefeller University, Dr Jean-Laurent Casanova that has been published in the prestigious journal Science, one of the publications with the greatest impact in the field of biomedicine.

The researchers have identified a genetic disorder due to autosomal recessive inheritance in five children, two of whom are patients at SJD Barcelona Children's Hospital, that increases the chances of this multisystem inflammatory complaint occurring.

This genetic mutation, which affects the OAS1, OAS2, genes or RNase L, induces type-1 interferons. When a cell is infected by a virus, it secretes interferons, which are crucial proteins in the immune system because they are essential in activating antiviral defences in the cells close to the infected one in order to restrict the spread of the virus.

The study showed that children who have deficiencies in the OAS1, OAS 2 o RNase L genes produce excessive amounts of cytokines and a hyperinflammatory state in response to infection due to SARS-CoV-2, which explains the clinical profile observed in MIS-C. This genetic defect is a primary immunodeficiency, or congenital immunity error. SJD Barcelona Children's Hospital is a leader in Catalonia, Spain and Europe in the study of primary immunodeficiencies, led by Laia Alsina , and of autoinflammatory diseases, led by Jordi Anton.

The authors of the study consider that this discovery will make it possible to make advances in the understanding of other diseases such as Kawasaki syndrome.