An unclassified platelet function disorder associated with bleeding tendency.

A 7-year-old boy with a history of bleeding tendency showed a prolongation of bleeding time and a decrease in platelet adhesiveness. The platelets of the patient, however, had a normal reaction to ADP, collagen, epinephrine, arachidonic acid, bovine fibrinogen, ristocetin, A-23187 and thrombin-induced aggregation, and their shape was determined by electron microscopy to be normal. Therefore, this disorder could not be thought to belong to any known platelet dysfunction. On the other hand, an increase in clot retraction, a reversal of ATP/ADP, a decrease in beta-thromboglobulin and platelet factor 4 in the platelets, and an elevation of plasma levels of released beta-thromboglobulin from the platelets were observed in the patient. We don't know any cases with such an association of hypo- and hyperfunction of platelets.