Von Willebrand Disease (VWD)
VWD, the most common of the heritable bleeding disorders,
results from qualitative or quantitative deficiencies of von
Willebrand factor (VWF). VWF has essential roles in
platelet-dependent primary haemostasis, and as a carrier for
coagulation factor VIII in the blood circulation. Inheritance of
VWD is autosomal. The molecular biology of VWD is complex.
There are three main types of VWD. Type 1 VWD is the most common
form of the disorder, resulting from a partial quantitative
deficiency of VWF. Type 2 VWD results from VWF qualitative
deficiencies, including type 2A, 2B, 2M and 2N VWD variants. Type 3
VWD is a rare, recessive, often severe bleeding disorder, the
result of essentially complete quantitative deficiency of VWF.
Genetic diagnosis has an important role in type 3 VWD in carrier
diagnosis, where this may not be achievable by phenotypic means,
and in PND in affected families (as above for haemophilia A and
haemophilia B). Genetic diagnosis also has a role in selected cases
of type 2 VWD. Generally speaking there is little application of
genetic diagnosis in type 1 VWD.