Structure and function of von Willebrand factor
VWF is a multimeric glycoprotein made up primarily of identical subunits having a molecular weight of around 250 kDa and synthesised by endothelial cells and megakaryocytes.
The size of multimers ranges from 500 kDa to over 10,000 kDa for multimers comprising more than 40 subunits and measuring more than 2 µm.
High molecular weight multimers play an important role in platelet adhesion. Multimers of all sizes bind to factor VIII molecule which makes the FVIII molecule more stable, thus protecting against rapid proteolysis in the circulation.
Von Willebrand disease can thus lead to haemorrhaging with a clinical presentation typical of platelet diseases or mild to moderate haemophilia A, or a combination of both.
The gene for von Willebrand factor is located on chromosome 12.
Numerous mutations have been described.
The current classification of von Willebrand disease is based on genetic and laboratory criteria.