Von Willebrand Disease (VWD) – an inherited blood clotting disorder caused by either a deficiency or a dysfunction of the von Willebrand factor (vWf) protein which resides in the blood plasma, platelets and subendothelial matrix, is the most common inherited bleeding disorder affecting nearly 1% of the U.K. population, or one in 100 people. Unlike hemophilia, which mainly affects males, VWD affects both sexes.
There are three major types of VWD:
Type 1 VWD is the most common, representing about 80% of cases. Type 1 is due to a decreased quantity of normal functioning vWf Type 1 is the mildest in terms of bleeding symptoms and may also have low levels of factor VIII.
Type 2 VWD is due to a VWf functional defect and is subdivided further into type IIA, IIB, IIM, and IIN:
•Type IIA VWD - most common type II variant and causes a reduction in platelet binding because of a deficiency of specific von Willebrand factor subunits.
•Type IIB VWD - causes an increase in binding of vWf to platelets which results in the platelets and vWf subunits being removed from the bloodstream too quickly.
•Type IIM - rare type of VWD characterized by a decreased affinity of the Willebrand factor for platelets.
•Type IIN - causes a large decrease in binding of vWf to factor VIII.
Type 3 VWD is very rare and the most severe form, with a marked decrease or absence of detectable vWf including severe bleeding, as well as significantly decreased factor VIII function.
There are also two less common types – Pseudo VWD, caused by defects in a person’s platelets rather than problems with their von Willebrand factor, and Acquired VWD which is not inherited developing later in life.
Because of the nature of the disease and the many different subtypes, individualised treatment based upon specific diagnosis and bleeding phenotype are crucial in the successful treatment of patients. People with mild cases may not require any treatment, but should avoid certain medications that could aggravate bleeding, such as aspirin and ibuprofen. For the more serious cases, the available therapies include desmopressin (DDAV), the recommended treatment option for Type 1 and some Type 2 WVD cases and plasma-derived or recombinant-derived VWf concentrates.
To learn more about von Willebrand disease and current treatments, click here.