Functional and Ultrastructural Abnormalities of Platelets in Ehlers-Danlos Syndrome

Abstract

Etiology of the bleeding tendency in Ehlers-Danlos syndrome (E-D) is incompletely understood. It has generally been attributed to a connective tissue defect within and outside the blood vessel wall. Tests of coagulation in the past have demonstrated variable and inconsistent results. The present paper is based on hemostatic and platelet ultrastructural studies in 3 unrelated patients with Ehlers-Danlos syndrome (E-D.) An abnormal prothrombin consumption time was noted in all 3 patients. A defective thromboplastin generation test on platelets in 2 of them indicated a defect in platelet function. The thromboplastin generation teat returned to normal after platelets were treated with sonic oscillation suggesting a normal content of platelet factor 3, but a suboptimal release. Electron microscopic study of the platelets in all 3 patients as well as in 4 children of one of the probands, uncovered consistent and distinct changes. There were reduction in the dendritic platelet forms and a marked increase in the spread forms with marked viscous metamorphosis and osmiophilic retention. These ultrastructural alterations of the platelets in E-D, together with their functional abnormality, are similar to those seen in thrombocytopathy A. It is suggested that the described platelet abnormality may contribute to the bleeding dyscrasia in E-D.