What is the basic defect in von Willebrand disease?

What is the basic defect in von Willebrand disease?

• A. Factor IX deficiency
• B. Deficiency or dysfunction of von Willebrand factor
• C. Platelet receptor GP IIb/IIIa deficiency
• D. Decreased fibrinogen

Answer: (B)

The basic defect is deficiency or dysfunction of von Willebrand factor. Von Willebrand factor is the glue that lets platelets stick to exposed damaged vessels by binding to the platelet receptor GPIb, and it also protects and carries factor VIII in the circulation. When vWF is reduced or not functioning properly, platelet adhesion is impaired, leading to defective formation of the initial platelet plug and mucocutaneous bleeding. Because factor VIII is also reduced in many types, the coagulation pathway can be affected as well, which can prolong the bleeding time and sometimes the PTT. This combination explains why the hallmark is a problem with von Willebrand factor itself, rather than a deficiency in a clotting factor like IX, a platelet receptor, or fibrinogen.

The basic defect is deficiency or dysfunction of von Willebrand factor. Von Willebrand factor is the glue that lets platelets stick to exposed damaged vessels by binding to the platelet receptor GPIb, and it also protects and carries factor VIII in the circulation. When vWF is reduced or not functioning properly, platelet adhesion is impaired, leading to defective formation of the initial platelet plug and mucocutaneous bleeding. Because factor VIII is also reduced in many types, the coagulation pathway can be affected as well, which can prolong the bleeding time and sometimes the PTT. This combination explains why the hallmark is a problem with von Willebrand factor itself, rather than a deficiency in a clotting factor like IX, a platelet receptor, or fibrinogen.