This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Pathology
Bernard-Soulier syndrome is caused by the deficiency of 
Select and explain. 
A. Glycoprotein complex Ib-IX, B. Glycoprotein complex IIb-IIIa, C. Glycoprotein complex Ib-IIIa, D. Glycoprotein complex IIb-IX
A: Glycoprotein complex Ib-IX
Answer: A: Glycoprotein complex Ib-IX 
Explanation: Bernard-Soulier syndrome is caused by an inherited deficiency of the platelet membrane glycoprotein complex Ib-IX. This glycoprotein is a receptor for vWF and is essential for normal platelet adhesion to the subendothelial extracellular matrix. Affected patients have a variable, often severe, bleeding tendency.Ref: Robbins and Cotran Pathologic Basis of Disease; 9th edition; Chapter 14; Red Blood Cell and Bleeding Disorders; Page no: 660