Types of Von Willebrand Disease and How They Are Inherited
Everyone has two sets of chromosomes: one set inherited from their mother, and a second set inherited from their father. Von Willebrand disease types 1 and 2 occur when a child inherits a fully working von Willebrand factor gene from one parent, but an altered one from their other parent. Type 3 von Willebrand disease occurs when a child inherits an altered gene from both parents; in this case, both parents will also have a milder form of von Willebrand disease.
Von Willebrand disease is transmitted on an autosomal (also known as a non-sex linked) chromosome, meaning that males and females are equally likely to inherit the gene (unlike hemophilia, which mostly affects men). There are subtle differences in inheritance patterns depending on the type of von Willebrand disease.
TYPE 1 VON WILLEBRAND DISEASE
If either parent has an altered gene that results in type 1 von Willebrand disease, there is a 50% chance that each child of that parent will inherit the von Willebrand disease gene. However, for reasons not yet understood, in some cases the von Willebrand disease gene is present but “non-penetrant,” meaning that it does not cause bleeding symptoms.
TYPE 2 VON WILLEBRAND DISEASE
As with type 1, if either parent has an altered gene resulting in type 2 von Willebrand disease, there is a 50% chance that the children of that parent will inherit the von Willebrand disease gene. However, unlike type 1, when the gene for type 2 is present, it always causes the disorder. Therefore, anyone with the altered gene will have type 2 von Willebrand disease.
TYPE 3 VON WILLEBRAND DISEASE
Type 3 occurs when a child receives an altered gene from both parents. When both parents have an altered gene causing von Willebrand disease type 1, there is a:
- 25% chance that each child will have type 3 von Willebrand disease
- 50% chance that each child will inherit a gene resulting in type 1 von Willebrand disease (in other words, they will only inherit the faulty gene from one parent)
- 25% chance that each child will not inherit any altered von Willebrand disease gene
For more information about inheritance patterns of von Willebrand disease, visit the Genetics Home Reference, a service of the US National Library of Medicine.
Learn more about different types of von Willebrand Disease