[Classification of von Willebrand disease]

Von Willebrand disease (VWD) is known for its marked heterogeneity which was already recognized by von Willebrand in 1926. The basis of phenotypic differentiation are quantitative and qualitative or functional differences between the different types and subtypes of VWD. One of the most important tools in the classification of VWD is multimer analysis that visualizes many of the structural abnormalities of mutant VWF. The introduction of multimer analysis was followed by the identification of an increasing number of different VWD phenotypes that were first reviewed in 1987 by Ruggeri and Zimmerman, thus forming a first classification of the disease. However, the detection of additional phenotypes required a revision of the nomenclature at a time point when only a few types of VWD had already been analyzed on the molecular level. Consequently, the molecular data only played a minor role in the revised classification published by Sadler in 1994. The advent of molecular techniques provided the opportunity for genotype/phenotype studies which recently helped not only to elucidate or confirm important functions of VWF and its steps of post-translational processing but also many disease causing defects. The reproducible correlation between certain phenotypes and particular mutations can now be used for a molecular approach towards a soundly based classification of VWD, equally useful for the clinician and for research requirements.