von Willebrand Disease
What is von Willebrand disease?
The most common inherited bleeding disorder is von Willebrand disease (vWD). As many as 1 in every 100 people have some form of the disease. vWD is inherited from one or both parents, depending on the type of the disease. vWD affects men and women equally. Although uncommon, vWD can also develop as a person gets older (acquired vWD).
vWD affects a protein in the blood called von Willebrand factor (vWF). vWF does two important things that allow normal blood clotting. At the beginning of making a clot, platelets stick to the area in and around the hole of the damaged blood vessel. vWF helps platelets stick to each other and/or to injured blood vessels (see The Basics for more information). After the platelets plug the hole, the complex set of clotting factor proteins help to make a mesh like fibrin clot. One of the factors involved is factor VIII (8), the factor that’s missing in hemophilia A. vWF helps protect factor VIII from being broken down and removed from the bloodstream.
A person with inherited vWD can have any of the 3 types of the disease. These types are:
- Type 1 (classic): Describes vWD in a person with low levels of vWF and/or factor 8. This is the most common type (around 70% to 75% of cases) and the mildest form of the disease
- Type 2 (variant): Describes vWD in a person with low or normal levels of vWF, but the factor does not work as it should. This type affects around 20% to 25% of people with VWD. There are also 4 subtypes of type 2 vWD: 2A, 2B, 2M, 2N
- Type 3 (severe): Describes vWD in a person with very low or almost no levels of vWF and low levels of factor VIII. This is the most serious and rarest type of the disease. Type 3 vWD affects 1 in every 1 million people
|Type 1 (classic)||Low vWF and/or factor VIII||Mildest||70-75% of vWD|
|Type 2 (variant)||Low/normal vWF but doesn’t work like it should||Intermediate||20-25% of vWD|
|Type 3 (severe)||Low/no vWF, low factor VIII||Severest||1 in 1 million|
It is important to know the type of vWD because that will affect the type of treatment your health care professional and treatment center team would recommend.
What causes it?
Von Willebrand disease can have different inheritance patterns depending on the type of vWD. Most cases of type 1 and type 2 von Willebrand disease are inherited in an autosomal dominant fashion, meaning that you only need one copy of the affected gene coding for vWF from either your mother or father to have the disease. Type 3, some cases of type 2, and a small number of type 1 cases of von Willebrand disease are inherited in an autosomal recessive pattern, which means you need to inherit one affected copy from each of your parents. In these cases if you only inherit one copy of the gene you are a carrier and can still pass it to your children even though you don’t show bleeding symptoms.
It is also possible for people to “acquire” vWD later in life. This can happen suddenly. It may also happen because of an underlying condition, such as an immune system problem or because of certain medicines.
What are the symptoms?
Because people with vWD can have severe or mild forms of the disease, there is a wide range of signs and symptoms. The following signs and symptoms are common among all people with vWD:
- Easy bruising
- Bleeding from the nose, gums, or mouth
- Bleeding from the stomach or intestines
- Vomit that is black and syrupy or bright red or coffee ground in appearance
- Red- or black-colored stool
- Bleeding after surgery, including dental work
- In women, heavy menstrual bleeding
People with moderate or severe forms of the disease often show signs in early childhood or adolescence, often associated with a surgical procedure.
How is it diagnosed?
VWD is diagnosed by performing various tests that evaluate clotting capability and platelet function including platelet count, complete blood count (CBC), prothrombin time (PT) and activated partial thromboplastin time (aPTT). These tests do not give a definitive diagnosis of vWD, but rather suggest underlying coagulation factor deficiency or low platelet count. After these tests are found to have an abnormality, the amount of von Willebrand protein can be measured to determine vWD diagnosis. All of these tests will be performed at a hemophilia treatment center (HTC) by a specialist.
How is it treated?
The treatment of vWD is based on the type and severity of the disease. DDAVP (desmopressin acetate), which stimulates the release of vWF from cells, is given to patients with vWD. In addition, clotting factor concentrates that are rich in vWF could be given instead as well.
Also, agents that help prevent the breakdown of blood clots; and, for women, hormone therapy, such as birth control pills could be used to control and prevent bleeding.