Sections View Full Chapter Figures Tables Videos Annotate Full Chapter Figures Tables Videos Supplementary Content + Download Section PDF Listen ++ For further information, see CMDT 14-06: Congenital Disorders of Platelet Function + Key Features Download Section PDF Listen +++ ++ Rare autosomal recessive disorder Due to reduced or abnormal platelet membrane expression of glycoprotein Ib/IX (von Willebrand [vWF] receptor) + Clinical Findings Download Section PDF Listen +++ ++ Often severe mucosal and postoperative bleeding Bleeding due to defective platelets is classically mucocutaneous, but is not limited to mucocutaneous surfaces + Diagnosis Download Section PDF Listen +++ ++ Presence of abnormally large platelets (approaching the size of red cells) Moderate thrombocytopenia Prolonged bleeding time Platelet aggregation studies show a marked defect in response to ristocetin, whereas aggregation in response to other agonists is normal Addition of normal platelets corrects the abnormal aggregation Platelet flow cytometry confirms the diagnosis + Treatment Download Section PDF Listen +++ ++ Platelet transfusion when necessary Desmopressin acetate (DDAVP), antifibrinolytic agents, and recombinant human activated factor VII also have been used successfully