ADAMTS13 (A Disintegrin and Metalloprotease with Thrombospondin type 1 repeats, member 13) is also known as von Willebrand factor-cleaving protease (VWFCP). It is a 195 kDa plasma glycoprotein that cleaves the Tyr1605-Met1606 bond in the A2 domain of von Willebrand factor. IgG autoantibodies against ADAMTS13 is a primary cause of the potentially fatal syndrome thrombotic thrombocytopenic purpura (TTP).