In contrast to HMB-CAEBV episodes (the range of onset-age, 4 months-21 years; median, 12 years 3 months), acute EBV-HLH episodes (range, 1–11 years; median, 3 years 4 months) had cytopenia (Hb <9.0 mg/dl and thrombocytopenia <100,000/mm3 in all; neutropenia <1,000/mm3 in 5 patients), coagulopathy (abnormal PT, aPTT, D-dimmer, or fibrogen in 7 patinets), and atypical lymphocytes (over 10% in 3 patients). This evidence concerns the gene GSTM1 and neutropenia.