[Paris-I-Lariboisière variant thrombasthenia. Functional disorder of human platelet aggregation, glycoprotein-independent].

The present case of constitutional thrombasthenia is unique. It demonstrates the importance of the three major steps of human platelet aggregation: 1. binding of agonists to their respective membrane sites; 2. transmission of a message probably membrane Ca++ dependent, 3. exposure of the preformed GP IIb-III a complex allowing fibrinogen binding. We postulate that in this case the second step is impaired while in the classical thrombasthenia, the third one is abnormal by absence, strong reduction or functional abnormality of the GP II b-III a complex.