We examined the etiologies of TMA; there was no coexistence of infection, hypocomplementemia, decline of ADAMTS13 activity, the appearance of ADAMTS13 inhibitor, or decline of haptoglobin as mentioned above, suggesting that this case was unlikely to have hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura. The gene discussed is ADAMTS13; the disease is thrombotic thrombocytopenic purpura.