The diagnostic criteria for HLH in adults includes five of the following nine findings: fever, splenomegaly, bi‐cytopenia, hypertriglyceridemia, hemophagocytosis in bone marrow studies, low or absent natural killer cell activity, elevated ferritin, soluble CD25 or CXCL9 levels.3 The gene discussed is CXCL9; the disease is Hemophagocytosis.