von Willebrand factor: the complex molecular genetics of a multidomain and multifunctional protein.

von Willebrand disease (VWD), the most common inherited bleeding disorder in humans, is characterised by a prolonged bleeding time due to quantitative and/or functional deficits of von Willebrand factor (VWF), a huge multimeric protein. Given the large size and complexity of the protein, the many functions of VWF, for example, binding to collagen, to platelet GPIb, and to FVIII, the localisation of these binding sites in different VWF domains, as well as the dependence on a high molecular weight multimer structure for proper function, VWF is prone to quantitative and very heterogeneous structural and functional defects. Comprehensive clinical and laboratory phenotypic description of patients with VWD in correlation to the genotype has considerably increased our knowledge on this disorder and the physiology and pathophysiology of VWF. This article focuses on the phenotype/genotype relationship in VWD and the context of VWD types and subtypes with particular VWF domains.