CONGENITAL BLEEDING DISORDERS WITH LONG BLEEDING TIME AND NORMAL PLATELET COUNT .2. VONWILLEBRANDS DISEASE (REPORT OF 37 PATIENTS)

The hemostatic data on thirty-seven patients with von Willebrand's disease are reported. The diagnostic criteria included prolonged bleeding time, low platelet adhesiveness to glass beads and factor VIII deficiency. This study of our patients supports the view that von Willebrand's disease is heterogeneous, since the bleeding time may be normal and factor VII level very variable in some patients. The behavior of platelet-rich plasma in the presence of low concentrations of adenosine diphosphate (ADP) was found to be abnormal except in two families. Platelet adhesiveness to glass beads was consistently abnormal. The dominant autosomal mode of inheritance, due to a pleiotropic gene, is expressed in a variety of ways, as illustrated by a study of the relatives of the patients in this series. In vivo experiments confirm the existence of an underlying plasmatic defect since prolonged bleeding time and factor VIII deficiency are corrected by infusion of normal or hemophilic platelet-poor plasma. The same biochemical defect may be responsible for both anomalies, although the Willebrand factor" and the precursor of factor VIII remain unidentified. © 1968."