Plasma exchange is effective in acute TTP through replacing deficient ADAMTS-13, removing associated antibody, and reducing circulating ULVWF multimers; however, in many patients, prolonged PEX is required to achieve remission, and between 30% and 60% of patients relapse over a variable period of months to years.73 Therefore, the information about the ADAMTS-13 activity and antibodies can guide the decision regarding the appropriate therapy regimen for each patient.77 The gene discussed is ADAMTS13; the disease is thrombotic thrombocytopenic purpura.