Biological findings in Von Willebrand's pedigrees: implications for inheritance.

Thirty-one subjects from three families affected by Von Willebrand's disease have been investigated with the following tests: Ivy's bleeding time; platelet adhesiveness according to Salzman; two-stage factor VIII assay. Twelve patients have a complete form of the disease, i.e., a prolonged bleeding time with low platelet adhesiveness, and a reduced factor VIII level. Eight subjects have an isolated low platelet adhesiveness associated in three cases with a prolonged bleeding time. The low platelet adhesiveness in these subjects was corrected, as in Von Willebrand's disease, by infusion of haemophilia A plasma. The dominant autosomal mode of inheritance appears to be due to a pleiotropic gene, expressed in a variety of ways