VWF and thrombotic thrombocytopenic purpura: Thrombotic thrombocytopenic purpura (TTP) is a rare but critical clinical disease; its pathogenesis is mainly due to the lack of the von Willebrand factor-cleaving enzyme (ADAMTS13), and thus the von Willebrand factor (vWF) molecule is not cleaved in the plasma, and a large number of platelets aggregate and conducts widespread microvascular thrombosis.