IFNG and hemophagocytic syndrome: Consistent with our previous published results, all groups developed certain characteristics of FHL independent of IFN-γ-R response in either the host or BM, including weight loss (Fig 1A), splenomegaly (Fig 1B), elevated serum IFN-γ, sIL-2r (Fig 1C and 1D), lower end of normal range of leukocytes (WBC), red blood cells (RBC) and thrombocytopenia (Fig 1E–1G) [19, 26].