Although the result of ADAMTS13 activity detected by a fluorescence energy transfer assay was 16%, experts with experience in management of TTP still believed that the patient should be diagnosed with TTP because of typical clinical manifestations and ADAMTS13 inhibitor positivity.[6] He was treated with daily plasma exchange (9 times) at 1.0× patient plasma volume until the platelet count recovered to normal and was maintained for at least 2 days, and his clinical symptoms were relieved. The gene discussed is ADAMTS13; the disease is thrombotic thrombocytopenic purpura.