ADAMTS13 (a Distntegrin and Metalloproteinase with a Thrombospondin Type 1 motif, member 13), also known as von Willebrand's Factor-cleaving proteinase (VWFCP), is an enzyme that cleaves the large, multimeric formsĀ of von Willebrand's Factor (vWF). ADAMTS13 deficiency causes an acute haemolytic condition called Thrombotic Thrombocytopenic Purpura (TTP).