[Variant of Paris-I Lariboisière thrombasthenia, a molecular anomaly of the IIb-IIIa platelet glycoprotein complex].

Platelet GP IIb-IIIa complex is missing or strongly reduced in thrombasthenia type I or II; in parallel the binding of fibrinogen is either nil or strongly reduced after platelet activation and these platelets do not aggregate. In the platelets of the described variant, GP IIb-IIIa level and PLA1 antigen are around 50% of the normal but the fibrinogen sites are either missing or unavailable. The hypothesis is that the patient's platelets lack the specific receptor site for fibrinogen at the GP IIb-IIIa level. However, platelet fibrinogen is normal as is the clot retraction. The study of this variant allows new concepts on platelet aggregation and clot retraction.