Which statement describes Type 1 von Willebrand disease?

Which statement describes Type 1 von Willebrand disease?

• A. Type 1: 20-50% of normal vWF
• B. Type 1: Abnormal or dysfunctional vWF
• C. Type 1: Complete vWF deficiency
• D. Type 1: Normal vWF levels with platelet defect

Answer: (A)

Type 1 von Willebrand disease is a quantitative deficiency of von Willebrand factor, meaning there is less vWF present rather than a defect in the protein’s function. In this type, levels are typically about 20–50% of normal. Because there’s less vWF, platelet adhesion to damaged vessels is impaired and factor VIII is often reduced as well, leading to mucocutaneous bleeding that’s usually mild to moderate. Laboratory testing often shows reduced vWF antigen and reduced ristocetin cofactor activity, with these reductions tracking together because the problem is fewer molecules rather than dysfunctional ones. Describing vWF as abnormal or dysfunctional points to Type 2, where the protein is present but works poorly or with abnormal multimer distribution. Complete absence of vWF describes Type 3, which is a severe deficiency. Normal vWF levels with a platelet defect would point away from vWD and toward a primary platelet function disorder.

Type 1 von Willebrand disease is a quantitative deficiency of von Willebrand factor, meaning there is less vWF present rather than a defect in the protein’s function. In this type, levels are typically about 20–50% of normal. Because there’s less vWF, platelet adhesion to damaged vessels is impaired and factor VIII is often reduced as well, leading to mucocutaneous bleeding that’s usually mild to moderate. Laboratory testing often shows reduced vWF antigen and reduced ristocetin cofactor activity, with these reductions tracking together because the problem is fewer molecules rather than dysfunctional ones.

Describing vWF as abnormal or dysfunctional points to Type 2, where the protein is present but works poorly or with abnormal multimer distribution. Complete absence of vWF describes Type 3, which is a severe deficiency. Normal vWF levels with a platelet defect would point away from vWD and toward a primary platelet function disorder.