VWF and congenital thrombotic thrombocytopenic purpura: TTP is a disorder resulting from genetic or acquired severe deficiency of plasma ADAMTS13, a metalloprotease that cleaves endothelium‐derived ultralarge von Willebrand factor (vWF), leading to unrestrained adhesion of the vWF multimers to platelets and microthrombi formation, resulting in thrombocytopenia and microangiopathic hemolytic anemia.158, 159, 160, 161