Types of von Willebrand Disorder
There are three main types, which are each treated differently. Type 1, type 2 and type 3. The severity of symptoms depends partly on the type of VWD a person has. Even within each type of VWD, symptoms can be quite variable.
Type 1 – is the common form of VWD and is generally less severe. About 3 in 4 people who have VWD have type 1. People with this type have low levels of VWF and may have low levels of factor VIII. Bleeding is mostly only a problem if people have particularly low VWF levels, have surgery, injure themselves or have a tooth removed.
Type 2 – in people with this type of VWD, the von Willebrand factor does not work properly. Bleeding tends to be more frequent and heavier than type 1. About 1 in 4 people who have VWD have type 2.
There may be a low level of VWF and sometimes factor VIII is low too. The important difference is that the quality of VWF is affected. This means it is less effective in helping the blood to clot.
There are four main subtypes of type 2 VWD. These are 2A, 2B, 2M and 2N.
Type 2A – The VWF multimers are not the right size
Type 2B – The VWF multimers are not the right size and the VWF becomes too active. It attaches to the platelets in the blood when it is not supposed to. The body quickly gets rid of the platelets with the attached VWF. This causes a shortage of both platelets and VWF in the blood.
Type 2M – Low or absent binding to the receptor on platelets. VWF is not able to stick to the platelets. Factor VIII binds as normal.
Type 2N (Normandy) – Autosomal recessive. Factor VIII levels reduced to 5-25%, as VWF has a reduced affinity for factor VIII.
Type 3 – This is the most severe and rarest type, affecting about 1 in 500,000 people.
People who have type 3 VWD have virtually no VWF. If you have this type, your body will not produce any VWF. As a result, your platelets will not be able to form a clot and your FVIII level will be low as well. This will put you at risk of severe bleeding that is difficult to stop. Bleeding from the mouth, nose and gut is common, and joint and muscle bleeds can occur after an injury.
More information is available in our Understanding von Willebrand Disorder booklet.