Von Willebrand Disease (VWD)
Part 3: VWF Activity Assay
A New von Willebrand Factor Activity Assay and Testing Algorithm
Severe Type 1 vs 2M7
June 2011
Let us look at this group in detail. We used VWF ristocetin cofactor activity by flow cytometry and antigen ratios to classify these samples. At a cut off of 0.5, 6 samples were classified as 2M and 2 samples as severe type 1. Interestingly, 7 of the 8 samples showed concordant VWF latex activity over antigen ratios, with exception of one lipemic sample. 4 samples in the 2M VWD group were from 2 families whose genotyping studies showed a cytosine to thymine mutation at nucleotide 4120. This variant is now classified as 2M and their VWF multimer usually show no loss of high molecular weight multimer, but instead frequently demonstrate ultra-large multimers and smeary multimer pattern.
Severe Type 1 vs 2M7 |
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?
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