The von Willebrand syndrome.

Five patients with an original diagnosis of von Willebrand's disease are described because of their levels of factor VIII related protein, Ristocetin-induced platelet aggregation and/or family studies differed from the main group of patients with classical von Willebrand's disease. Two had normal levels of factor VIII related protein with reduced Ristocetin aggregation when this was tested in platelet rich plasma. In one, however, this was due to a plasma defect and in the other to a platelet abnormality. After cryoprecipitate infusion all abnormal tests were corrected in both these patients. The first patient, however, failed to show a secondary rise of factor VIII whereas the second showed a secondary rise of both factor VIII and of factor VIII related protein. The other three cases, who were all very severely affected, have been separated from the main group as none of their families was segregating for classical von Willebrand's disease. It is suggested that the term von Willebrand's disease should be confined to those patients who have reduced factor VIII related protein and Ristocetin aggregation, and that von Willebrand's syndrome should be used for the various sub-groups that are emerging.