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

A New von Willebrand Factor Activity Assay and Testing Algorithm

Severe Type 1 vs 2M7

Slide 17

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


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