PPIB and COVID-19: 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.<h4>Conclusions</h4>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.