ADAMTS13 and thrombotic thrombocytopenic purpura: For example, thrombotic thrombocytopenic purpura is caused by a severe deficiency of von Willebrand cleaving protease (also known as a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13 (ADAMTS13)) [3], and thus treatment should restore ADAMTS13’s function.