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Updated: Feb 19, 2026
08:30
Investigating von Willebrand Factor Pathophysiology Using a Flow Chamber Model of von Willebrand Factor-platelet String Formation
Published on: August 14, 2017
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Type 2N von Willebrand disease: Characterization and diagnostic difficulties
A Casonato1, E Galletta1, L Sarolo1
1Department of Medicine, Hemorrhagic and Thrombotic Disorders Unit, University of Padua Medical School, Padua, Italy.
Summary
Diagnosing type 2N von Willebrand disease (VWD) requires the VWF FVIII binding (VWF:FVIIIB) assay. This test is crucial for identifying VWF:FVIIIB ratio abnormalities, especially when combined with quantitative VWF mutations.
Area of Science:
- Hematology
- Genetics
- Clinical Diagnostics
Background:
- Type 2N von Willebrand disease (VWD) is characterized by abnormal factor VIII (FVIII) binding capacity of von Willebrand factor (VWF).
- Diagnosis typically relies on the VWF FVIII binding (VWF:FVIIIB) assay, specifically the VWF:FVIIIB/VWF:Ag ratio.
Purpose of the Study:
- To report on a 15-year experience in diagnosing type 2N VWD.
- To evaluate the utility of the VWF:FVIIIB assay in a large cohort.
Main Methods:
- Conducted 2178 VWF:FVIIIB assays in patients with bleeding disorders and healthy individuals.
- Analyzed VWF:FVIIIB ratios to identify type 2N VWD and carriers.
Main Results:
- Identified 60 cases with low VWF:FVIIIB ratios (<0.74) out of 682 with reduced VWF:FVIIIB.
- Characterized mutations including p.R854Q homozygotes and heterozygotes, some with concurrent quantitative VWF mutations.
- Found 5.2% heterozygosity for the p.R854Q mutation in the general population of Northeast Italy.
Conclusions:
- Type 2N VWD diagnosis can be challenging with routine tests alone, particularly when VWF mutations are quantitative.
- The VWF:FVIIIB assay is essential for accurate diagnosis and should be included in the VWD workup.
- Prevalence of type 2N VWD in the cohort was 2.5%.
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