Both developed MAS and proceeded to allogeneic-HSCT after 2 years (failed sDMARD, anti-TNF, and IL-1 blockade) and after 5 years (failed sDMARD, IL-1 blockade, IL-6 blockade, and required etoposide as a bridge to HSCT), respectively, post their sJIA diagnosis. This evidence concerns the gene IL1B and macrophage activation syndrome.