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Pediatrics · Systemic paediatrics: Bernard-Soulier syndrome
Sample itemA boy has mucosal bleeding with a platelet count of 60,000 per microlitre and giant platelets on the smear. Ristocetin does not induce aggregation, and the defect is not corrected by adding normal plasma. Which platelet defect is present?
Original practice item, not a recalled exam question. Nothing here is recorded.
The answer and the reasoning
B. Deficient glycoprotein Ib-IX-V receptor
Bernard-Soulier syndrome is due to deficient platelet GPIb-IX-V, the receptor for von Willebrand factor, so adhesion fails. Giant platelets with mild thrombocytopenia and absent ristocetin aggregation not corrected by normal plasma distinguish it from von Willebrand disease. Platelet transfusion treats serious bleeding.
Option by option
A. Deficient alpha granules
Alpha granule deficiency causes grey platelet syndrome, with pale agranular platelets.
B. Deficient glycoprotein Ib-IX-V receptor (correct)
Correct. Loss of the vWF receptor GPIb-IX-V explains giant platelets and absent ristocetin response.
C. Deficient dense granule contents
Dense granule deficiency affects secondary aggregation and not platelet size.
D. Deficient glycoprotein IIb/IIIa
GPIIb/IIIa deficiency causes Glanzmann disease, with normal platelet size and ristocetin response.
Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.
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