Classification of vonWillebrand diseases

Von Willebrand disease is a heterogeneous
group of disorders divided into several subtypes.
In types I and III, the defect is quantitative;
in type II, qualitative. Dominant and recessive
phenotypes with vWF deficiency often cannot
be readily distinguished because heterozygosity
may not be manifest and can only be determined
by laboratory tests. Type I with subtypes
A and B is the most frequent group (70% of
all patients). vWF deficiency may simulate
platelet dysfunction or hemophilia.