Prolonged bleeding times with factor IX and XI deficiency von Willebrand's syndromes.

This report describes three patients with a prolonged bleeding time and reduced platelet retention on glass beads, two of the three established criteria for conventional von Willebrand's disease (vWd). However, the third standard, the diminution of factor VIII, was replaced by a decrease of factor IX or XI in the first two instances, respectively, and combined factor VII and IX deficiency was present in the last patient. These associations suggest that the vW (bleeding time/platelet retention) factor is not necessarily homogeneous, may not be dependent on a single genetic determinant, and may be present in a molecular complex composed not only of factor VIII but of other blood clotting proteins as well. Although simulating classic vW, these homologues may more appropriately be called von Willebrand syndromes. Finally, unusual as they may be, their clinical recognition is important to insure that such patients receive not only factor VIII concentrates in treatment since these materials do not contain factors IX and XI and may not even be a suitable source of platelet retention factor under these modified circumstances.