The initial platelet adhesion to subendothelial matrix proteins is abnormal in which conditions?

The initial platelet adhesion to subendothelial matrix proteins is abnormal in which conditions?

• A. von Willebrand disease and Bernard-Soulier syndrome
• B. GPIIb/IIIa inhibitors
• C. hemophilia A or B
• D. factor XIII deficiency

Answer: (A)

Initial platelet adhesion to the subendothelial matrix relies on von Willebrand factor acting as a bridge between exposed collagen and the platelet GPIb-IX-V receptor. When this adhesion step is faulty, platelets can’t properly cling to damaged vessel walls. In von Willebrand disease, there is a deficiency or dysfunction of von Willebrand factor, so the bridge to platelets is weak and adhesion is impaired. In Bernard-Soulier syndrome, the GPIb-IX-V receptor on platelets is defective, so even normal von Willebrand factor cannot effectively mediate attachment. These two conditions specifically disrupt the very first step of plug formation. The other options affect other parts of hemostasis: GPIIb/IIIa inhibitors block platelet aggregation (the later clumping step), while hemophilia A/B and factor XIII deficiency disrupt the coagulation cascade and fibrin stability rather than the initial platelet adhesion. Therefore, the combination of von Willebrand disease and Bernard-Soulier syndrome best explains abnormal initial platelet adhesion.

Initial platelet adhesion to the subendothelial matrix relies on von Willebrand factor acting as a bridge between exposed collagen and the platelet GPIb-IX-V receptor. When this adhesion step is faulty, platelets can’t properly cling to damaged vessel walls.

In von Willebrand disease, there is a deficiency or dysfunction of von Willebrand factor, so the bridge to platelets is weak and adhesion is impaired. In Bernard-Soulier syndrome, the GPIb-IX-V receptor on platelets is defective, so even normal von Willebrand factor cannot effectively mediate attachment. These two conditions specifically disrupt the very first step of plug formation.

The other options affect other parts of hemostasis: GPIIb/IIIa inhibitors block platelet aggregation (the later clumping step), while hemophilia A/B and factor XIII deficiency disrupt the coagulation cascade and fibrin stability rather than the initial platelet adhesion. Therefore, the combination of von Willebrand disease and Bernard-Soulier syndrome best explains abnormal initial platelet adhesion.