[Thrombocytopathia with cyclo-oxygenase deficiency]

In four patients, platelet aggregation with arachidonate was absent but was normal with "Labile Aggregation Stimulating Substance". ADP (10muM) aggregation was always reversible; collagen aggregation was absent and those induced by thrombin and ristocetin were normal. Collagen did not induce 14C-serotonin release but there was some release with thrombin. There was no thromboxan B2 synthesis in these platelets. Two patients showed hereditary hemostasis defect and the others acquired cyclo-oxygenase deficiency.