If we set the HLH cytokine criteria as IL-10 higher than 60 pg/ml and IFN-γ higher than 75 pg/ml based on our previous study, 193 (75.4%) patients fulfilled the criteria, including 14 of 18 (77.7%) with FHL, 2 of 9 (22.2%) with XLP, 152 of 179 (84.9%) with EBV-HLH, and 13 of 28 (46.4%) with sHLH caused by other triggers (p < 0.001). This evidence concerns the gene IFNG and hemophagocytic syndrome.