Von Willebrand disease.

Von Willebrand disease (vWD) is a genetic disorder affecting the normal clotting function of platelets in the blood. There are three types of vWD that run in families, all due to inheriting a gene mutation. The pattern of inheritance may be autosomal dominant or autosomal recessive, although with either, both males and females are affected equally; some persons could be carriers of the defective gene without exhibiting any symptoms. There is another form of vWD called acquired von Willebrand syndrome. This disease is not caused by inheriting a gene mutation, and thus does not run in families. This disease is characterized by the qualitative or quantitative deficiency of von Willebrand factor (vWF). This glycoprotein, present in platelets and the endothelium of blood vessels, facilitates the adhesion of platelets to one another to form a stable clot when there has been injury to a blood vessel. Therefore, patients with vWD exhibit the signs and symptoms of blood clotting abnormality.