Failure to remove endothelium-bound VWF in case of thrombotic thrombocytopenic purpura (TTP) secondary to congenital or acquired ADAMTS13 deficiency allows individual VWF multimers to self-associate to form long strands (up to several hundred μm long) that promote platelet adhesion and thrombus formation leading to microvascular occlusion (13). This evidence concerns the gene ADAMTS13 and thrombotic thrombocytopenic purpura.