However, few studies have compared serum IL-18 levels between AOSD, HLH, and MAS in adults (unlike sJIA, HLH and MAS in pediatric patients), because adult HLH and MAS have a lower incidence compared to those in pediatric patients, and few studies of adult HLH or MAS have been performed (14). The gene discussed is IL18; the disease is hemophagocytic syndrome.