Serum: MPO-ANCA positive 414 U/ml, ESR 116 mg/dl, CRP 1.1 mg/dl, thrombocytopenia; after 4 weeks, CRP elevated to 16 mg/dl, anemia, thrombocytopenia, elevated LDH 503 IU/l, elevated sIL-2R 4818 U/ml and normalized MPO-ANCA; peripheral blood smear: hemophagocytosis. This evidence concerns the gene MPO and Thrombocytopenia.