Medicine & USMLE

Bernard-Soulier Syndrome

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Platelet Disorders
  1. Platelet Plug Formation
  2. Von Willebrand Disease
  3. Bernard-Soulier Syndrome
  4. Glanzmann Thrombasthenia
  5. Immune Thrombocytopenic Purpura (ITP)
  6. Thrombotic Thrombocytopenic Purpura (TTP)
  7. Hemolytic Uremic Syndrome (HUS)
  8. Disseminated Intravascular Coagulation (DIC)

Summary

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Key Points

  • Bernard-Soulier Syndrome
    • Cause
      • Defect in GpIb receptors
        • Defective glycoprotein receptor on platelet surface prevents platelet adhesion to vWF
        • This eventually blocks formation of platelet plug (see: Platelet Plug Formation)
    • Genetics
      • Autosomal recessive inheritance
    • Presentation
      • Bleeding
        • Mucosal bleeding, e.g. gingival bleeding, menorrhagia
        • Microhemorrhages, e.g. petechiae, epistaxis, easy bruising
    • Diagnosis
      • Abnormal ristocetin test
        • Ristocetin antibodies promote binding of GpIb with vWF, which causes platelet aggregation in normal patients
        • No aggregation of platelets occurs in Bernard-Soulier disease
        • Does not correct with addition of normal plasma
          • Since plasma contains vWF, but does not contain GpIb
          • Contrast vs. von Willebrand disease, where replacement of deficient vWF causes correction
      • Increased bleeding time (BT)
        • Due to defective primary hemostasis from inability to bind vWF
      • PT, PTT are generally unaffected
      • Giant platelets seen on peripheral smear
        • Normal or decreased platelet count
    • Treatment
      • Supportive
        • Avoid drugs that increase risk of bleeding
        • May require platelet transfusions during surgery