Von Willebrand disease (VWD) is an inherited bleeding disorder with an estimated prevalence between 23 and 110 per 1 million people. These numbers vary because the criteria for diagnosis are not always the same.

Causes of VWD

VWD is caused by mutations in the VWF gene. This gene provides instructions to build the von Willebrand factor (VWF), which plays a crucial role in blood clotting. VWF has two primary functions: It stabilizes clotting factor VIII and also helps platelets bind to the inside of injured blood vessels. Both features help with the formation of blood clots to stop bleeding.

VWD affects men and women equally, but the condition may have a more significant impact on women due to bleeding challenges related to menstruation and childbirth.

VWD types

Mutations in the VWD gene either lead to low levels of VWF in the blood, dysfunctional VWF, or absent VWF. While some types tend to be more severe than others, the severity of symptoms varies greatly among individuals with the same VWD type.

VWD type 1 is the mildest form and accounts for 70% to 80% of cases. Patients with this type have low levels of VWF. Children frequently experience nosebleeds, easy bruising, and bleeding from the gums. Women commonly have heavy menstrual bleeding.

In VWD type 2, VWF factor is not functional. This type is usually more severe than VWD type 1. Depending on the specific defect of VWD, type 2 is further subdivided into type 2a, 2b, 2m, and 2n.

VWD type 3 is the most severe form and accounts for about 5% of cases. VWF is almost entirely absent in affected individuals who experience severe bleeding, bleeding into joints and muscles, and frequent hematomas (effusion of blood).

Acquired VWD is the only form that is not inherited and that develops later in life.

Diagnosis of VWD

Characteristic symptoms, such as mucocutaneous bleeding, is usually a sign that prompts the physician to do further testing.

Complete blood counts and a coagulation test that measures how long it takes for the blood to clot help to confirm whether the patient has a bleeding disorder.

There are specific tests to rule out or confirm VWD. The VWF antigen test determines the amount of VWF in the blood. Another test, the ristocetin cofactor activity assay, measures how well VWF stops bleeding. The clotting factor VIII activity assay measures how well factor VIII works.

If these tests are positive, a specialized VWD test that determines the structure of VWD can then help to identify the VWD type.

A genetic test that identifies mutations in the VWF gene can serve as final confirmation of a VWD diagnosis. However, failure to detect a mutation does not necessarily rule out VWD.

Treatment of VWD

There is currently no cure for VWD, but there are effective treatments for all three types.

Standard treatment is desmopressin, a derivative of the hormone vasopressin, that helps the release of VWF and clotting factor VIII, which are stored in the wall of blood vessels.

Patients with severe symptoms or those who do not respond to desmopressin treatment are usually treated with VWF and factor VIII concentrates. This is known as replacement therapy, as it replaces the missing factors.

Other treatments include hormonal contraceptives, antifibrinolytics (that reduce the breakdown of blood clots), and fibrin glue that is directly applied to the wound to stop bleeding.

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