Association of blood group B and of rare variants affecting immune system with multisystem inflammatory syndrome in children in an Italian cohort

Background: Multisystem inflammatory syndrome in children (MIS-C) is an uncommon delayed complication of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children, whose cause remains unknown. The aim of this study was to investigate the role of genetic predisposition to COVID-19 and dysregulated inflammatory response in the development of MIS-C in Italian children. Methods: = 266). Results: = 0.007). A total of 49 rare damaging variants, 4 classified as pathogenic, were prioritized in 39 immune-related genes; all patients harbored at least one variant. Conclusions: These results not only support a role of blood group B as a risk factor for MIS-C development in children with COVID-19, possibly through modulation of the coagulability and microvascular dysfunction, but also support an immune-genetic basis for this condition.