Hereditary platelet disorders

All rare. Acquired platelet dysfunction is much more likely to be a cause of bleeding or easy bruising. Two main hereditary qualitative defects are found

1. Defective platelet membrane glycoproteins (GPs). GPIIb/IIIa is a receptor for fibrinogen and other adhesive GPs; also affected is GPIb (specific platelet receptor for vWF). Disorders include Glanzmann's thrombasthenia (abnormal GPIIb/IIIa) and Bernard-Soulier syndrome (BSS)—abnormal GPIb, a specific receptor for vWF with defective adhesion to blood vessels.

2. Abnormalities of platelet granules ie storage pool deficiency (SPD). Either the alpha (a) granules (grey platelet syndrome), the dense granules (May-Hegglin anomaly, Hermansky-Pudlak syndrome, Chediak-Higashi syndrome and the thrombocytopenia-absent radius (TAR) syndrome), or both.

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