New families with von Willebrand disease type 2M (Vicenza).

The variant von Willebrand disease (vWd) variant type 2M (Vicenza) was identified in 13 patients of 7 unrelated families. 11 patients were from different parts of germany and 2 patients from Turkey. Hitherto this variant of vWd has been described only in two families originating from the province of Vicenza in Northern Italy. Characteristically this type of vWd shows the supranormal multimers of von Willebrand factor (vWf) in plasma similar to those seen in normal plasma after desmopressin infusion. Clinically, the patients present with bleeding symptoms. Other laboratory abnormalities include reduced values for vWf antigen (vWf: Ag), factor VIII coagulant activity (VII:C), ristocetin cofactor activity (RiCof) and collagen binding activity (vWf: CBA). The hereditary transmission of this variant is consistent with an autosomal dominant mode of inheritance. The patients with vWd type 2M (Vicenza) could be allocated into two subgroups: type "platelet normal" with normal vWf properties in platelets and type "platelet low" with reduced vWf: Ag levels in platelets.