Von Willebrand Disease (VWD)
Part 3: VWF Activity Assay

VWF Activity Assay by an A1 Domain Conformation-Sensitive Antibody⁶

June 2011

This new assay employs a previously characterized monoclonal antibody that recognizes platelet glycoprotein 1b-binding epitope on the VWF A1 domain. Here is a 3 dimensional presentation of the botrocetin, VWF A1 domain and GPIb alpha. The arrow indicates the functional epitope that is specifically recognized by this antibody. Any conformation change at or around this epitope, particularly in type 2 von Willebrand disease, could affect antibody binding to this site.

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Assay by Conformation-Sensitive Antibody6

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Jump to section:

• Introduction
• Objectives
• History of VWF Ristocetin Cofactor Activity (VWF:RCo) Assay
• Problems with VWF:RCo Assay
• Summary of External Quality Assessment of VWF:RCo
• von Willebrand Disease(VWD) Diagnostic Error Rates Due to Erroneous VWF:RCo Results⁵
• VWF:RCo/Ag Ratio is Insensitive for Aquired von Willebrand Abnormalities (AVWA)
• VWF:RCo is Inadequate for Detecting AVW Abnormality
• The New Automated VWF Activity by Latex-Immunoturbidity Assay (VWF:Lx)
• VWF Activity Assay by an A1 Domain Conformation-Sensitive Antibody⁶
• Performance Characteristics of VWF:Lx
• VWF:Lx and VWF:RCo Method Comparison
• VWF:Lx and VWF:RCo Bias Analysis
• Sample Categorization
• Comparison of VWF:Lx/Ag and VWF:RCo/Ag Ratios
• VWF:Lx and VWF:RCo Errors
• Severe Type 1 vs 2M⁷
• VWF:Lx and RCo Errors
• VWF:Lx/Ag is Sensitive to AVWA with Subtle Loss of Highest HMWM
• ROC Analysis of VWF:Lx/Ag and VWF:RCo/Ag for Detecting AVWA with Loss of HMWMs
• VWF:Lx/Ag vs VWF:RCo/Ag Ratios
• VWF Laboratory Testing Strategy
• Sensitivity and Specificity of the Screening Panel
• von Willebrand Disease Profile
• von Willebrand Disease Profile
• von Willebrand Disease Profile
• von Willebrand Disease Profile
• Limitations of VWF:Lx
• Summary
• References
• Questions?