Considered a prothrombotic condition secondary to an underlying disturbance of coagulation and complement systems, etiologies include: thrombotic thrombocytopenic purpura (TTP), a systemic disorder of microvascular thrombosis of ADAMTS13 deficiency, hemolytic uremic syndrome (HUS), with and without complement mutations, characterized by nonimmune hemolytic anemia, thrombocytopenia, and renal failure, and drug induced TMA (DI-TMA), through either a direct toxic effect or duration dependent toxicity. The gene discussed is ADAMTS13; the disease is hemolytic-uremic syndrome.