Von Willebrand factor is released from endothelial cells as ultra-large multimers of VWF (UL-VWF) which can bind the glycoprotein (GP) Ibα components of platelet GPIb-IX-V receptor and induce platelet adhesion and aggregation by shear stress in the arterioles and capillaries (Figure 1B).20,21 These microvascular thrombi of platelets with UL-VWF result in platelet consumption and hemolysis and cause thrombotic microangiopathy of several TMAs.22 This evidence concerns the gene VWF and thrombotic microangiopathy.