Von Willebrand disease is caused by a change (mutation) in a gene that makes von Willebrand factor. Von Willebrand factor is a protein that helps platelets stick to damaged areas of blood vessels.
The abnormal gene is passed down from a mother or father or both parents.
Usually, children who get the gene from just 1 parent will have type 1 or type 2 disease. They may have no symptoms or mild symptoms. But sometimes their symptoms are very serious. Even within a family, some people may have more problems with their disease than others.
Children who get the gene from both parents will likely have type 3 disease. Their symptoms are usually serious.