The underlying pathophysiology of TTP is inhibition/inactivation of A Disintegrin And Metalloprotease with ThromboSpondin type 1 repeats, 13 (ADAMTS13), a metalloprotease responsible for cleaving large multimers of von Willebrand factor (vWF) into smaller units. The gene discussed is ADAMTS13; the disease is thrombotic thrombocytopenic purpura.