The IL-6 and IL-10 levels were comparable between primary and secondary HLH (median of IL-6, 48.0 vs. 45.8 pg/ml, p = 0.902; median of IL-10, 396.2 vs. 459.2 pg/ml, p = 0.659), while the IFN-γ level was much lower in pHLH (median, 85.5 vs. 694.9 pg/ml, p < 0.001). This evidence concerns the gene IFNG and hemophagocytic syndrome.