Type 2A and 2M von Willebrand Disease: Differences in Phenotypic Parameters According to the Affected Domain by Disease-Causing Variants and Assessment of Pathophysiological Mechanisms

2021 ◽  
Author(s):  
Adriana Inés Woods ◽  
Juvenal Paiva ◽  
Débora Marina Primrose ◽  
Alicia Noemí Blanco ◽  
Analía Sánchez-Luceros
Keyword(s):  
Major Bleeding ◽  
Von Willebrand Disease ◽  
Collagen Binding ◽  
Pathophysiological Mechanisms ◽  
In Silico Modeling ◽  
Large Center ◽  
Bleeding Score ◽  
A1 Domain ◽  
Von Willebrand ◽  
A2 Domain

AbstractType 2A and 2M von Willebrand disease (VWD) broadly show similar phenotypic parameters, but involve different pathophysiological mechanisms. This report presents the clinical and laboratory profiles of type 2A and type 2M patients genotypically diagnosed at one large center. Higher bleeding score values and a higher incidence of major bleeding episodes were observed in type 2A compared with type 2M, potentially reflective of the absence of large and intermediate von Willebrand factor (VWF) multimers in 2A. In type 2A, most of disease-causing variants (DCVs) appeared to be responsible for increased VWF clearance and DCV clustered in the VWF-A1 domain resulted in more severe clinical profiles. In type 2M, DCV in the VWF-A1 domain showed different laboratory patterns, related to either reduced synthesis or shortened VWF survival, and DCV in the VWF-A2 domain showed patterns related mainly to shortened survival. VWF-type 1 collagen binding/Ag (C1B/Ag) showed different patterns according to DCV location: in type 2A VWD, C1B/Ag was much lower when DCVs were located in the VWF-A2 domain. In type 2M with DCV in the VWF-A1domain, C1B/Ag was normal, but with DCV in the VWF-A2 domain, C1B/Ag was low. The higher frequency of major bleeding in VWD 2M patients with DCV in the VWF-A2 domain than that with DCV in the VWF-A1 domain could be a summative effect of abnormal C1B/Ag, on top of the reduced VWF-GPIb binding. In silico modeling suggests that DCV impairing the VWF-A2 domain somehow modulates collagen binding to the VWF-A3 domain. Concomitant normal FVIII:C/Ag and VWFpp/Ag, mainly in type 2M VWD, suggest that other nonidentified pathophysiological mechanisms, neither related to synthesis/retention nor survival of VWF, would be responsible for the presenting phenotype.

Platelet Activation and Aggregation Induced by Recombinant von Willebrand Factors Reproducing Four Type 2B von Willebrand Disease Missense Mutations

1998 ◽  
Vol 79 (01) ◽  
pp. 211-216 ◽  
Author(s):  
Lysiane Hilbert ◽  
Claudine Mazurier ◽  
Christophe de Romeuf
Keyword(s):  
Platelet Aggregation ◽  
Platelet Activation ◽  
Von Willebrand Disease ◽  
Platelet Glycoprotein ◽  
Missense Mutations ◽  
Inhibit Platelet Aggregation ◽  
Wild Type ◽  
A1 Domain ◽  
Von Willebrand ◽  
Willebrand Factor

SummaryType 2B of von Willebrand disease (vWD) refers to qualitative variants with increased affinity of von Willebrand factor (vWF) for platelet glycoprotein Ib (GPIb). All the mutations responsible for type 2B vWD have been located in the A1 domain of vWF. In this study, various recombinant von Willebrand factors (rvWF) reproducing four type 2B vWD missense mutations were compared to wild-type rvWF (WT-rvWF) for their spontaneous binding to platelets and their capacity to induce platelet activation and aggregation. Our data show that the multimeric pattern of each mutated rvWF is similar to that of WT-rvWF but the extent of spontaneous binding and the capacity to induce platelet activation and aggregation are more important for the R543Q and V553M mutations than for the L697V and A698V mutations. Both the binding of mutated rvWFs to platelets and platelet aggregation induced by type 2B rvWFs are inhibited by monoclonal anti-GPIb and anti-vWF antibodies, inhibitors of vWF binding to platelets in the presence of ristocetin, as well as by aurin tricarboxylic acid. On the other hand, EDTA and a monoclonal antibody directed against GPIIb/IIIa only inhibit platelet aggregation. Furthermore, the incubation of type 2B rvWFs with platelets, under stirring conditions, results in the decrease in high molecular weight vWF multimers in solution, the extent of which appears correlated with that of plasma vWF from type 2B vWD patients harboring the corresponding missense mutation. This study supports that the binding of different mutated type 2B vWFs onto platelet GPIb induces various degrees of platelet activation and aggregation and thus suggests that the phenotypic heterogeneity of type 2B vWD may be related to the nature and/or location of the causative point mutation.

scholarly journals Evidence for the Misfolding of the A1 Domain within Multimeric von Willebrand Factor in Type 2 von Willebrand Disease

2020 ◽  
Vol 432 (2) ◽  
pp. 305-323 ◽  
Author(s):  
Alexander Tischer ◽  
Maria A. Brehm ◽  
Venkata R. Machha ◽  
Laurie Moon-Tasson ◽  
Linda M. Benson ◽  
...  
Keyword(s):  
Von Willebrand Factor ◽  
Von Willebrand Disease ◽  
A1 Domain ◽  
Von Willebrand ◽  
Willebrand Factor

Identification of Type 2 von Willebrand Disease in Previously Diagnosed Type 1 Patients: a Reappraisal Using Phenotypes, Genotypes and Molecular Modelling

2000 ◽  
Vol 84 (12) ◽  
pp. 998-1004 ◽  
Author(s):  
Ioana Nitu-Whalley ◽  
Anne Riddell ◽  
K. Pasi ◽  
Dale Owens ◽  
M. Enayat ◽  
...  
Keyword(s):  
Molecular Modelling ◽  
Correct Diagnosis ◽  
Von Willebrand Disease ◽  
Single Amino Acid ◽  
Elisa Assay ◽  
Modelling Analysis ◽  
A1 Domain ◽  
Von Willebrand

SummaryIn order to investigate the possibility that qualitative type 2 defects in von Willebrand factor (VWF) occurred in patients previously diagnosed with quantitative type 1 von Willebrand disease (VWD), the phenotypes and genotypes were reanalysed in 30 patients who exhibited discrepant VWF activity/VWF:Ag ratios of less than 0.7. The capacity of VWF to bind to glycoprotein Ib (GpIb) was reassessed using the ristocetin co-factor activity (VWF:RiCo) assay compared to an in-house and a commercial ELISA assay (based on a mAb directed against the GpIb binding site on VWF). This was supplemented by multimeric analysis and the amplification and sequencing of a 936 bp fragment of exon 28 of the VWF gene with the aim of identifying mutations in the A1 domain. On reappraisal, using the VWF:RiCo assay all patients demonstrated a disproportionately reduced VWF:RiCo/VWF:Ag ratio, indicative of a qualitative defect, while abnormal ratios were detected in only seven kindreds using the in-house ELISA assay and in only one kindred with the commercial ELISA assay. Eight single amino acid substitutions were found in nine kindreds, four of which were novel candidate VWF mutations and four previously described in association with type 2 VWD. In agreement with the phenotype, the novel VWF mutations were located in the VWF-A1 crystal structure at positions that corresponded to potential type 2M defects. This study underlines the difficulties of correct diagnosis of the subtype of VWD and emphasises the importance of using sensitive phenotypic assays, the relevance of the VWF:RiCo/ VWF:Ag ratio, multimeric analysis and molecular modelling analysis.

scholarly journals THE ROLE OF BLEEDING HISTORY AND CLINICAL MARKERS FOR THE CORRECT DIAGNOSIS OF VWD

2013 ◽  
Vol 5 (1) ◽  
pp. e2013051 ◽  
Author(s):  
Alberto Tosetto
Keyword(s):  
Correct Diagnosis ◽  
Von Willebrand Disease ◽  
Assessment Tools ◽  
Bleeding Tendency ◽  
Clinical Markers ◽  
Web Based ◽  
Bleeding Score ◽  
Bleeding History ◽  
Von Willebrand ◽  
Willebrand Factor

Quantification of the bleeding severity by use of bleeding assessment tools (BAT) and bleeding score (BS) has been consistently shown to improve the clinical diagnosis of von Willebrand disease (VWD) while helping researchers establish phenotype/genotype correlations.  Subjects with a BS equal or higher than 3 may be consider having a bleeding tendency, and should be referred for a laboratory investigation, particularly for VWD. In the diagnosis of type 1 VWD, the use of the BS has been shown to be highly specific (>95%) with reported sensitivities ranging from 40 to 100%. The BS is related to all available measurements of von Willebrand factor activity, including the PFA-100 closure time. Therefore, in clinical practice the use of BAT should always be the first step to standardize the assessment of patients with suspected VWD. The use of the recent ISTH consensus BAT is suggested to harmonize the collection of bleeding symptoms in patients with a suspected or confirmed hemostatic disorder, particularly VWD. The ISTH BAT is also coupled with a Web-based repository of bleeding symptoms, therefore providing an integrated framework for collaboration in the field of clinical evaluation of VWD and mild bleeding disorders.

scholarly journals Collagen Binding Provides a Sensitive Screen for Variant von Willebrand Disease

2013 ◽  
Vol 59 (4) ◽  
pp. 684-691 ◽  
Author(s):  
Veronica H Flood ◽  
Joan Cox Gill ◽  
Kenneth D Friedman ◽  
Pamela A Christopherson ◽  
Paula M Jacobi ◽  
...  
Keyword(s):  
Gel Electrophoresis ◽  
Reference Intervals ◽  
Von Willebrand Disease ◽  
Type Iii Collagen ◽  
Healthy Controls ◽  
Collagen Binding ◽  
Vessel Injury ◽  
Clinical Biology ◽  
Von Willebrand

BACKGROUND von Willebrand factor (VWF) is a multimeric protein that binds platelets and collagen, facilitating hemostasis at sites of vessel injury. Measurement of VWF multimer distribution is critical for diagnosis of variant von Willebrand disease (VWD), particularly types 2A and 2B, but the typical measurement by gel electrophoresis is technically difficult and time-consuming. A comparison of VWF collagen binding (VWF:CB) and VWF multimer distribution was performed to evaluate the utility of VWF:CB as a diagnostic test. METHODS Participants were enrolled in the Zimmerman Program for the Molecular and Clinical Biology of VWD. VWF:CB was analyzed with type III collagen and multimer distribution by agarose gel electrophoresis. The study population included 146 healthy controls, 351 individuals with type 1 VWD, and 77 with type 2 VWD. Differences between individuals with multimer group results within (controls) and outside the reference intervals were assessed with Mann–Whitney tests. RESULTS The mean VWF:CB/VWF antigen ratio was 1.10 for individuals with multimer distribution within the reference intervals and 0.51 for those with multimer distribution outside the reference intervals (P < 0.001). Sensitivity of VWF:CB for multimer abnormalities was 100% for healthy controls, 99% for patients with type 1, and 100% for patients with type 2A and type 2B VWD using a VWF:CB/VWF antigen cutoff ratio of 0.6, and decreased to 99% for all patients with a ratio of 0.7. With the exception of individuals with novel or unclassified mutations, the VWF:CB was able to correctly categorize participants with variant VWD. CONCLUSIONS These findings suggest that VWF:CB may substitute for multimer distribution in initial VWD testing, although further studies are needed to validate the clinical utility of VWF:CB.

Effect of recombinant von Willebrand factor reproducing type 2B or type 2M mutations on shear-induced platelet aggregation

Blood ◽  
2000 ◽  
Vol 95 (12) ◽  
pp. 3796-3803 ◽  
Author(s):  
Nadine Ajzenberg ◽  
Anne-Sophie Ribba ◽  
Ghassem Rastegar-Lari ◽  
Dominique Meyer ◽  
Dominique Baruch
Keyword(s):  
Platelet Aggregation ◽  
Von Willebrand Factor ◽  
Von Willebrand Disease ◽  
High Shear ◽  
Shear Rates ◽  
High Shear Rates ◽  
Consistent Increase ◽  
A1 Domain ◽  
Von Willebrand ◽  
Willebrand Factor

Abstract The aim was to better understand the function of von Willebrand factor (vWF) A1 domain in shear-induced platelet aggregation (SIPA), at low (200) and high shear rate (4000 seconds-1) generated by a Couette viscometer. We report on 9 fully multimerized recombinant vWFs (rvWFs) expressing type 2M or type 2B von Willebrand disease (vWD) mutations, characterized respectively by a decreased or increased binding of vWF to GPIb in the presence of ristocetin. We expressed 4 type 2M (-G561A, -E596K, -R611H, and -I662F) and 5 type 2B (rvWF-M540MM, -V551F, -V553M, -R578Q, and -L697V). SIPA was strongly impaired in all type 2M rvWFs at 200 and 4000 seconds-1. Decreased aggregation was correlated with ristocetin binding to platelets. In contrast, a distinct effect of botrocetin was observed, since type 2M rvWFs (-G561A, -E596K, and -I662F) were able to bind to platelets to the same extent as wild type rvWF (rvWF-WT). Interestingly, SIPA at 200 and 4000 seconds-1 confirmed the gain-of-function phenotype of the 5 type 2B rvWFs. Our data indicated a consistent increase of SIPA at both low and high shear rates, reaching 95% of total platelets, whereas SIPA did not exceed 40% in the presence of rvWF-WT. Aggregation was completely inhibited by monoclonal antibody 6D1 directed to GPIb, underlining the importance of vWF-GPIb interaction in type 2B rvWF. Impaired SIPA of type 2M rvWF could account for the hemorrhagic syndrome observed in type 2M vWD. Increased SIPA of type 2B rvWF could be responsible for unstable aggregates and explain the fluctuant thrombocytopenia of type 2B vWD.

scholarly journals Variability in platelet- and collagen-binding defects in type 2M von Willebrand disease

Haemophilia ◽  
2013 ◽  
Vol 19 (4) ◽  
pp. 590-594 ◽  
Author(s):  
D. M. Larsen ◽  
S. L. Haberichter ◽  
J. C. Gill ◽  
A. D. Shapiro ◽  
V. H. Flood
Keyword(s):  
Von Willebrand Disease ◽  
Collagen Binding ◽  
Von Willebrand
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