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inherited bleeding disorders

Tuesday 14 June 2005

Platelet aggregation at sites of vascular injury is essential for the formation of the primary haemostatic plug.

The mechanism of platelet aggregation under conditions of physiological flow is a complex multistep process, which requires the synergistic action of several different platelet receptors.

Platelet interaction with collagen at sites of damage to the vascular endothelium involves adhesion, activation, secretion of platelet granular contents and finally aggregation.

Other agonists other than collagen, such as fibrinogen, vWF and soluble agonists released from activated platelets (thromboxane A2 (TXA2) and ADP) are involved in platelet aggregation.

Platelets express a variety of receptors including GP Ib-IX-V, GP VI, GP Ia-IIa and GP IIb-IIIa. One aspect of this complexity of function is the variety of inherited defects of platelet function.

Types

- hereditary disorders of platelet adhesion

  • Bernard-Soulier syndrome
  • von Willebrand disease

- inherited disorder of platelet aggregation

  • Glanzmann thrombasthenia

- defects in collagen receptors
- defects in ADP receptors
- defects in TXA2 receptors
- defects in TXA2 production
-  generation of procoagulant activity
- secretion from dense bodies and alpha-granules

- defects in platelet storage granules

  • Chediak-Higashi disease
  • Hermansky-Pudlak disease
  • Wiskott-Aldrich disease

References

- Ramasamy I. Inherited bleeding disorders: disorders of platelet adhesion and aggregation. Crit Rev Oncol Hematol. 2004 Jan;49(1):1-35. PMID: 14734152