Shimizu et al. studied cytokines during MAS in serum of sJIA patients and compared them to cytokine patterns in EBV-induced HLH (EBV-HLH), Kawasaki disease (KD) and healthy age matched controls [8] IL-18 concentrations during MAS were significantly higher compared to EBV-HLH and KD and were found to correlate to measures of disease activity (CRP, ferritin, LDH and other cytokines). The gene discussed is IL18; the disease is macrophage activation syndrome.