Von Willebrand’s Disease
Clinical Manifestations
Classic hemophilia is not the only hereditary deficiency of antihemophilic factor. Von Willebrand’s disease is a bleeding disorder of both sexes which in its usual form is present in successive generations; thus, it is inherited as an autosomal dominant trait.
The plasma of affected individuals is deficient in both parts of the antihemophilic factor complex — that is, the coagulant portion (factor VIII) and von Willebrand factor (vWf). The bleeding time - the duration of bleeding from a deliberately incised wound - is abnormally long, distinguishing von Willebrand’s disease from classic hemophilia or Christmas disease. The disorder is usually mild, although variants have been observed in which severe bleeding episodes are frequent. Inheritance in these cases is probably recessive in nature.Geography
The prevalence of von Willebrand’s disease is uncertain because mild cases are easily overlooked. Using Ohio as something of a proxy for the United States, von Willebrand’s disease is about one-fourth as prevalent as classic hemophilia, meaning about 2 or 3 cases per 100,000 individuals. Estimates of 3 to 6 cases per 100,000 have been made in the United Kingdom and Switzerland, whereas the prevalence is somewhat higher in Sweden, about 12 per 100,000. A study conducted in northern Italy on a population of school children revealed that 10 of 1,218 had laboratory evidence of the disease as well as a family history of hemorrhagic problems. By contrast, the disorder is relatively uncommon in blacks. Similarly, although the severe, autosomal recessive form of von Willebrand’s disease is unusual in most individuals of European extraction (perhaps 1 per 1 million), it is particularly prevalent among Israeli Arabs, in whom it can be detected in about 5 individuals per 100,000, and in Scandinavia.