ADAMTS13 and thrombotic thrombocytopenic purpura: Thrombotic thrombocytopenic purpura (TTP) is a rare thrombotic microangiopathy caused by decreased activity of ADAMTS-13 (A Disintegrin And Metalloproteinase with a ThromboSpondin type 1 motif, member 13), which leads to disseminated thrombus formation [1].