title: Type IIB von Willebrand's disease associated with a complex thrombocytopenic thrombocytopathy.
abstract: A familial bleeding disorder characterized by an association of Type IIB von Willebrand's disease (vWD) with a complex thrombocytopenic thrombocytopathy is described in two patients from the same generation. Findings typical of type IIB vWD included enhanced ristocetin-induced binding of patient von Willebrand factor (vWF) to platelets of patients and normal individuals in association with the absence of larger multimers from plasma. Abnormalities in platelet function included deficient platelet aggregation to ADP, collagen, epinephrine, and arachidonic acid; and defective release of 14C-serotonin, vWF, and platelet factor 4 (PF4) in response to thrombin, collagen, or ADP. Platelet factor 4 and platelet vWF were decreased when measured per mg of total platelet protein. In addition, the binding of normal vWF to patient platelets stimulated with thrombin was decreased. Platelet size was increased with a very heterogeneous distribution width. Electron microscopic evaluation showed giant platelets with dense and alpha bodies present. The platelet count was borderline or slightly decreased in the resting state and declined to frankly thrombocytopenic levels at the time of acute bleeding episodes; this state was associated with the presence of platelet aggregates in blood smears.
authors.affiliation: Department of Hematology, Hospital Juan Canalejo, La Coruña, Spain.
authors.forename: M F
authors.initials: MF
authors.lastname: López-Fernández
authors.forename: C
authors.initials: C
authors.lastname: López-Berges
authors.forename: J A
authors.initials: JA
authors.lastname: Martín-Bernal
authors.forename: R
authors.initials: R
authors.lastname: Sánchez
authors.forename: L G
authors.initials: LG
authors.lastname: Villarón
authors.forename: J
authors.initials: J
authors.lastname: Díez-Jarilla
authors.forename: J
authors.initials: J
authors.lastname: Batlle
mesh_terms: D000911:Antibodies, Monoclonal; D001792:Blood Platelets / Q000502:physiology*; D005260:Female; D006801:Humans; D007700:Kinetics; D008297:Male; D010375:Pedigree; D010974:Platelet Aggregation; D012016:Reference Values; D012310:Ristocetin; D013921:Thrombocytopenia / Q000097:blood* / Q000150:complications; D014842:von Willebrand Diseases / Q000097:blood* / Q000150:complications / Q000235:genetics; D014841:von Willebrand Factor / Q000032:analysis
chemical_list: D000911:Antibodies, Monoclonal; D014841:von Willebrand Factor; D012310:Ristocetin