Bernard soluier syndrome is due to defective
**Question:** Bernard-Soulier syndrome is due to defective
A. von Willebrand factor
B. glycoprotein IIb/IIIa complex
C. von Willebrand factor and von Willebrand factor receptor
D. von Willebrand factor and von Willebrand factor receptor
**Correct Answer:** B. glycoprotein IIb/IIIa complex
**Core Concept:** Bernard-Soulier syndrome is a rare bleeding disorder characterized by platelet dysfunction and abnormally large platelets. It is caused by defects in platelet membrane glycoproteins, specifically the glycoprotein IIb/IIIa complex, which plays a crucial role in platelet adhesion, aggregation, and fibrin clot formation.
**Why the Correct Answer is Right:**
Bernard-Soulier syndrome is classified into three types: type 1, type 2, and type 3. In type 1, there is a decrease in von Willebrand factor and von Willebrand factor receptor; in type 2, there is a decrease in glycoprotein IIb/IIIa complex and an increase in von Willebrand factor; and in type 3, there is a deficiency of both glycoprotein IIb/IIIa complex and von Willebrand factor. In this question, we are considering the type 2 variant, where the defect lies in the glycoprotein IIb/IIIa complex.
**Why Each Wrong Option is Incorrect:**
A. Defective von Willebrand factor: In type 1 variant, there is a decrease in both von Willebrand factor and receptor, not the glycoprotein IIb/IIIa complex.
C. Defective von Willebrand factor and von Willebrand factor receptor: This option is a combination of options A and B, but the correct answer is solely the glycoprotein IIb/IIIa complex, not both it and the receptor.
D. Defective von Willebrand factor and von Willebrand factor receptor: Similar to option C, this option combines both relevant and irrelevant factors, making it incorrect.
**Clinical Pearl:** Understanding Bernard-Soulier syndrome is essential for clinicians dealing with patients with bleeding disorders, as it helps in diagnosing and treating these patients appropriately. Adequate knowledge about the different types and defects associated with them can lead to accurate diagnosis and management of bleeding disorders.