IL-18 is upregulated in many diseases including inflammatory bowel diseases (IBD), macrophage activation syndrome (MAS), and COVID-19 (1, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30). The gene discussed is IL18; the disease is macrophage activation syndrome.