Pathogenesis of thrombotic thrombocytopenic purpura

The recent discovery of important molecular and genetic mechanisms of thrombotic thrombocytopenic purpura and hemolytic uremic syndrome provide an opportunity to reconstruct scientific and clinical paradigms. Acquired and congenital defects of the metalloprotease ADAMTS13 are a central feature in the pathogenesis of a major type of thrombotic microangiopathy. This and other pathogenic mechanisms can redefine the terminology of thrombotic microangiopathy. Deficient activity of ADAMTS13 suggests several possible models of microvascular thrombosis. The sporadic relationship between thrombotic microangiopathy and ADAMTS13 deficiency draws attention to other critical pathologic factors that are still poorly understood. Investigation of vascular injury and mechanisms of microvascular thrombosis remain the frontiers of investigation in thrombotic microangiopathy.