Pathogenesis and classification of von Willebrand disease.

Von Willebrand disease, the most common congenital bleeding disorder in humans, is the consequence of quantitative and/or qualitative defects of von Willebrand factor, a protein necessary for platelet adhesion and thrombus formation at sites of vascular injury. Distinct molecular defects of von Willebrand factor are responsible for the heterogeneity of von Willebrand disease subtypes. A classification in four main groups, each characterized by distinctive pathogenetic features, represents the basis for a correct therapeutic approach to bleeding episodes in these patients.