We identified unusually large von Willebrand factor (vWF) multimers caused by deficient activity of vWF-cleaving protease in 2 patients with Upshaw-Schulman syndrome. The autoantibodies that inhibited the protease activity were not detected in the plasma of either patient. Periodic fresh-frozen plasma transfusion was effective for management of the hemolysis and thrombocytopenia. We detected enriched enzyme activity in a particular plasma fraction, although molecular cloning of this specific protease is needed to determine a more detailed pathogenesis and to develop new therapeutic approaches.
- Chronic relapsing thrombotic thrombocytopenic purpura; von Willebrand factor multimer
- Upshaw-Schulman syndrome
- Von Willebrand factor-cleaving protease
ASJC Scopus subject areas