Von willebrands disease all are true except – a) Factor VIII C deficiencyb) B.T. Prolongedc) Normal Ristocetin testd) Defective aggregation

Von Willebrand disease is characterized by the deficiency of vWF, while the synthesis of factor VIIIc is normal. VWF has two major functions - Helps in platelet adhesion Stabilizes factor VIIIc So, deficiency of vWF results in manifestation of both - 1) Platelet adhesion defect Bleeding from small venules and capillaries of skin and mucous membrane e.g. epistaxis. a Menorrhagia and GI bleeding Prolonged bleeding time 2)   Coagulation defect (due to factor VIII dysfunction) Bleeding into weight bearing joints Large post traumatic ecchymoses or hematoma Prolonged bleeding after any form of surgical procedure or a laceration. Prolonged PTT VWF can be assayed by ristocetin agglutination test which measures the ability of ristocetin to promote the interaction between VWF and platelet membrane glycoprotein Ib-IX.