<prompt> Von Wiliebrand disease is associated with -PTT; PT; BT ; CTPTT; PT; BT ; CTPTT; Normal PT; BT; Normal CTPTT; Normal PT; BT; CT  <response>: Ans. is d i.e., PTT; Normal PT; BT; CT LABORATORY DIAGNOSIS OF VON WILLEBRANDS DISEASE.Screening testsVon Vilebrand diseaseDeficiency ofVonvilebrand factordefect in factor VIIIcVWf carries VIIIcLeads to plateletdysfunctionLeads to defect inintrinsic coagulation pathwayo Increased bleeding timeQo Increased PTTQo Normal PTQo Increased clotting timeQ Laboratory findings in Von wilebrand diseaseo Tourniquet test Hess test- Is positive because of defective platelet adhesionso Bleeding time- Prolonged because of platelet function defecto APTT- Prolonged because of secondarily reduced VIIIc activityo VWF assay- levelso Ristocetin induced aggregation is defective- It Is diagnostic of vWD. This is insensitive to mild deficiency of vWF. However in platelet type vWD - Ristocetin induced platelet aggregation is increasedo vWF immunoassay- Levels of VWF antigen VWF: Ag axe assayed by EUSAor automated assays and are reduced in type vWD while in type 2 vWD, the vWF: Ag levels may be normal indicating that just measuring VWF: Ag is not enough for diagnosing vWDo Muitimeric analysis of vWF o Genetic studies of specific CDNA regions 