giant platelet syndrome

Bernard-Soulier syndrome

An autosomal recessive MIM 231200 or codominant condition, with mucocutaneous and visceral haemorrhage due to deficiency of glycoprotein Ib, the receptor for von Willebrand factor (vWF), and GP1s (glycocalicin); both are involved in the interaction between vWF and platelet membrane, which is critical for normal platelet adhesion in the early phases of primary hemostasis.
 
Clinical findings
Major mucocutaneous haemorrhage of early onset, including epistaxis, ecchymoses/purpura, nosebleeds, gingival, GI and menorrhagia, and bleeding after minor trauma.
 
DiffDx
ITP, giant-platelet syndrome, May-Hegglin anomaly, Epstein syndrome, Montreal syndrome, platelet-type von Willebrand syndrome (pseudo-von Willebrand’s disease with macrothrombocytopenia).
 
Lab
Variable thrombocytopenia, morphologically abnormal giant platelets on peripheral blood smears, defective prothrombin consumption, increased bleeding time due to poor platelet adhesion to subendothelium, no platelet aggregation with ristocetin Platelet defects, increased size of basophilia of membrane, aggregation (or absence) of cytoplasmic granules, pseudopod formation, and cytoplasmic vacuolisation.
 
Molecular pathology
Caused by a mutation of GP9 on chromosome 3q21.3.

Management
Avoid aspirin, anti-inflammatories or other prohemorrhagic agents.

giant platelet syndrome

Bernard-Soulier syndrome, see there.