Which statement best differentiates von Willebrand disease Type 1, Type 2, and Type 3?

Which statement best differentiates von Willebrand disease Type 1, Type 2, and Type 3?

• A. Type 1 (MC) = 20-50% normal vWF levels; Type 2 = abnormal or dysfunctional vWF; Type 3 = complete vWF deficiency
• B. Type 1: Abnormal or dysfunctional vWF; Type 2: 20-50% normal vWF; Type 3: complete deficiency
• C. Type 1: Complete vWF deficiency; Type 2: 20-50% normal vWF; Type 3: abnormal vWF
• D. Type 1: 20-50% normal vWF; Type 2: complete deficiency; Type 3: abnormal vWF

Answer: (A)

Understanding von Willebrand disease types requires focusing on whether the problem is how much vWF is present (quantity) or how well it works (quality). Type 1 is a partial quantitative deficiency, with vWF levels typically reduced to about 20–50% of normal. That means there is less vWF to support platelet adhesion and to stabilize factor VIII, but some functional protein remains. Type 2 is a qualitative defect: the vWF that is present is abnormal or dysfunctional, so its ability to mediate platelet adhesion and aggregation is impaired even if the amount isn’t severely low. Type 3 is the severe form with near-complete absence of vWF, resulting in very low or undetectable vWF activity and markedly reduced factor VIII, leading to a high bleeding risk. The option that describes Type 1 as roughly 20–50% of normal vWF, Type 2 as abnormal/dysfunctional vWF, and Type 3 as complete deficiency aligns with these distinctions. Other choices mix up quantity and quality across the types, which doesn’t fit how the diseases are categorized.

Understanding von Willebrand disease types requires focusing on whether the problem is how much vWF is present (quantity) or how well it works (quality). Type 1 is a partial quantitative deficiency, with vWF levels typically reduced to about 20–50% of normal. That means there is less vWF to support platelet adhesion and to stabilize factor VIII, but some functional protein remains. Type 2 is a qualitative defect: the vWF that is present is abnormal or dysfunctional, so its ability to mediate platelet adhesion and aggregation is impaired even if the amount isn’t severely low. Type 3 is the severe form with near-complete absence of vWF, resulting in very low or undetectable vWF activity and markedly reduced factor VIII, leading to a high bleeding risk. The option that describes Type 1 as roughly 20–50% of normal vWF, Type 2 as abnormal/dysfunctional vWF, and Type 3 as complete deficiency aligns with these distinctions. Other choices mix up quantity and quality across the types, which doesn’t fit how the diseases are categorized.