Question

Bernard-Soulier syndrome is due to a deficiency of which platelet glycoprotein?

• A. Gp IIb/IIIa
• B. Gp Ib
• C. von Willebrand factor (vWF)
• D. TNF

Hint:

Think of the platelet receptor that grabs von Willebrand factor for adhesion.

Answer 1

The Correct Option is B

Step 1: Bernard-Soulier syndrome (BSS) is a rare autosomal recessive bleeding disorder of platelet adhesion. Step 2: The defect is a deficiency or dysfunction of the platelet membrane glycoprotein Ib-IX-V complex (Gp Ib), which is the receptor for von Willebrand factor. Step 3: Because platelets cannot bind vWF on the damaged subendothelium, platelet adhesion fails, producing giant platelets, thrombocytopenia and prolonged bleeding time. Step 4: Gp IIb/IIIa deficiency is Glanzmann thrombasthenia (an aggregation defect), vWF deficiency itself is von Willebrand disease, and TNF is a cytokine unrelated to this platelet defect. Hence the answer is Gp Ib.