VWF and thrombotic thrombocytopenic purpura: TTP is caused by congenital (cTTP) or by immune-mediated (iTTP) deficiency/absence of von Willebrand factor (VWF)-cleaving protease ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif member 13), leading to platelet consumption in VWF-platelet aggregates and ultimately microvascular thrombosis [2].