Establishment and characterization of a new and stable collagen‐binding assay for the assessment of von <scp>W</scp>illebrand factor activity

Ni, Yi-Chang; Nesrallah, J.; Agnew, Michael; Geske, F. Jon; Favaloro, Emmanuel J.

doi:10.1111/ijlh.12019

Cited by 18 publications

(12 citation statements)

References 29 publications

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“…Of these, nine patients with low VWF:RCo were given a provisional diagnosis of type 1 VWD by treating physicians; six of these had borderline low levels of VWF:RCo, which could be explained as due to the presence of p.D1472H, thereby potentially invalidating the diagnosis of VWD. Alternative non‐ristocetin‐based assays when widely available may be utilized to clarify and confirm the diagnosis of VWD in such patients . On the contrary, patients with significant bleeding are at risk of misdiagnosis as being healthy, if the lab abnormalities are considered solely due to the effect of the polymorphism.…”

Section: Resultsmentioning

confidence: 99%

Diagnostic challenges in patients with bleeding phenotype and von Willebrand exon 28 polymorphism p.D1472H

et al. 2014

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Exon 28 polymorphism p.D1472H is associated with significantly lower von Willebrand Ristocetin cofactor activity (VWF:RCoF) to von Willebrand antigen (VWF:Ag) ratio compared to normal, but has been reported as not conferring haemorrhagic risk. The impact of this polymorphism while assessing symptomatic patients for von Willebrand disease (VWD) has not been previously analysed. We retrospectively reviewed charts of children with clinically significant bleeding and abnormal VW panel who underwent VW exon 28 analysis. Twenty-three of 63 patients studied had p.D1472H. Of these 23 patients, 6 with borderline low VWF:RCo were given provisional diagnosis of VWD type 1 by treating physicians, which could be alternatively explained as due to the effect of p.D1472H. None of the patients with low VWF:RCo, decreased VWF:RCo/VWF:Ag ratio and p.D1472H had VWD type 2M mutations identified. This study illustrates the challenge in diagnosing VWD using ristocetin-based VW assay in symptomatic patients with p.D1472H.

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Section: Resultsmentioning

confidence: 99%

Diagnostic challenges in patients with bleeding phenotype and von Willebrand exon 28 polymorphism p.D1472H

et al. 2014

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“…This would, however, force to test all the collagen types separately. Secondly, the VWF:CB assay has been shown to be as effective in distinguishing VWD type 1 from type 2 as the VWF:RCo assay . The best distinction between VWD types 1 and 2 has been observed when a mixture of collagen I and III is used.…”

Section: Subtyping Assaysmentioning

confidence: 99%

Developments in the diagnostic procedures for von Willebrand disease

Jong

Eikenboom

2016

Journal of Thrombosis and Haemostasis

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Summary Von Willebrand disease (VWD) is the most common inherited bleeding disorder but its diagnosis can be challenging due to the heterogeneity of the disease. VWD is mainly associated with mild mucocutaneous bleeding, although there are more severe phenotypes with bleeding from the gastrointestinal tract or even the joints. Also, surgical interventions and trauma may lead to critical bleeding events. These bleeding episodes are all related to quantitative or qualitative defects of von Willebrand factor (VWF), a multimeric glycoprotein produced by endothelial cells and megakaryocytes, which mediates platelet adhesion and aggregation and binds factor VIII (FVIII) in the circulation. This review describes the diagnostic procedures required for correct diagnosis. Accurate diagnosis and classification is required for proper treatment and counseling. Assessment of bleeding starts with the medical history. After a positive bleeding or family history, subsequent laboratory investigations will start with a panel of standard screening tests for hemostatic defects. Patients suspected of having VWD will be tested for plasma VWF antigen levels, the ability of VWF to bind platelets and FVIII activity. When VWD is confirmed, a set of subtyping tests can classify the patients as VWD types 1, 2 (A, B, M or N) or 3. The performance of some additional assays and analyses, such as VWF propeptide measurement or genetic analysis, may help in identifying the pathological mechanism behind certain defects or can guide in the choice of treatment.

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“…Collagen binding and multimeric analysis of plasma‐derived type 2N VWD variants was not significantly different from that of wild type variants (Fig. F,G) . The R763A variant retains the 741 amino acid propeptide in approximately 50% of the mature VWF molecules (Fig.…”

Section: Resultsmentioning

confidence: 90%

Abnormal von Willebrand factor secretion, factor VIII stabilization and thrombus dynamics in type 2N von Willebrand disease mice

Swystun

Georgescu

Mewburn

et al. 2017

Journal of Thrombosis and Haemostasis

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Background von Willebrand factor (VWF) and factor VIII (FVIII) circulate as a non-covalent complex, with VWF serving as the carrier for FVIII. VWF indirectly influences secondary hemostasis by stabilizing FVIII and transporting it to the site of primary hemostasis. Type 2N von Willebrand disease involves impaired binding of VWF to FVIII, resulting in decreased plasma levels of FVIII. Objectives In these studies, we characterize the impact of three type 2N VWD variants (R763A, R854Q, R816W) on VWF secretion, FVIII stabilization and thrombus formation in a murine model. Methods Type 2N VWD mice were generated by hydrodynamic injections of mutant murine VWF cDNAs and the influence of these variants on VWF secretion and FVIII binding was evaluated. In vivo hemostasis and the dynamics of thrombus formation and embolization were assessed using a murine tail vein transection hemostasis model and an intravital thrombosis model in the cremaster arterioles. Results Type 2N VWD variants were associated with decreased VWF secretion using cell and animal-based models. FVIII-binding to type 2N variants was impaired in vitro and was variably stabilized in vivo by expressed or infused 2N variant VWF protein. Both transgenic type 2N VWD and FVIII knockout (KO) mice demonstrated impaired thrombus formation associated with decreased thrombus stability. Conclusions The type 2N VWD phenotype can be recapitulated in a murine model and is associated with both quantitative and qualitative VWF deficiencies and impaired thrombus formation. Patients with type 2N VWD may have normal primary hemostasis formation but decreased thrombus stability related to ineffective secondary hemostasis.

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Establishment and characterization of a new and stable collagen‐binding assay for the assessment of von Willebrand factor activity

Cited by 18 publications

References 29 publications

Diagnostic challenges in patients with bleeding phenotype and von Willebrand exon 28 polymorphism p.D1472H

Diagnostic challenges in patients with bleeding phenotype and von Willebrand exon 28 polymorphism p.D1472H

Developments in the diagnostic procedures for von Willebrand disease

Abnormal von Willebrand factor secretion, factor VIII stabilization and thrombus dynamics in type 2N von Willebrand disease mice

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