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

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.

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2B or not 2B? Disparate discrimination of functional VWF discordance using different assay panels or methodologies may lead to success or failure in the early identification of type 2B VWD

Thrombosis and Haemostasis ◽

10.1160/th06-12-0693 ◽

2007 ◽

Vol 98 (08) ◽

pp. 346-358 ◽

Cited By ~ 18

Author(s):

Roslyn Bonar ◽

Muriel Meiring ◽

Alison Street ◽

Katherine Marsden ◽

Emmanuel Favaloro ◽

...

Keyword(s):

Early Identification ◽

Correct Diagnosis ◽

Diagnostic Errors ◽

Von Willebrand Disease ◽

External Quality ◽

Platelet Aggregometry ◽

Von Willebrand ◽

Willebrand Factor

SummaryLaboratory proficiency in the identification of functional von Willebrand factor (VWF) discordance in type 2B von Willebrand disease (VWD) was assessed by external quality assurance surveys conducted by the RCPA Haematology QAP, and using six different type 2B VWD plasma samples (three historical and three previously unpublished) tested by up to 52 laboratories. For the three most recent samples, functional VWF discordance was either not identified in testing or by interpretation with misidentification as ‘normal’ or ‘type 1 VWD’, on average for 25.7% of test occasions when laboratories performed VWF:Ag and VWF:RCo as their primary VWF test panel, but somewhat fewer occasions (10.9%) for laboratories that incorporated VWF:CB as an additional functional VWF assay. VWF assay sub-methodologies also influenced the appropriate identification of samples as potentially type 2 VWD, and VWF functional discordance was more consistently identified when laboratories used (i) automated platelet agglutination for VWF:RCo compared to classical platelet aggregometry, (ii) inhouse VWF:CB assays compared to commercial kit methods, and (iii) automated LIA-based ‘VWF:Activity’ assays compared to ELISA based assays.We conclude that:(i) laboratories are generally proficient in tests for VWD but interpretative diagnostic errors do occur; (ii) correct diagnosis is more likely when test panels are more comprehensive and include the VWF:CB; (iii) sub-methodology influences the appropriate identification of VWF functional discordance. On the basis of these findings, we provide a series of recommendations to enable the appropriate laboratory identification of VWD, in particular type 2B VWD.

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

Journal of Molecular Biology ◽

10.1016/j.jmb.2019.09.022 ◽

2020 ◽

Vol 432 (2) ◽

pp. 305-323 ◽

Cited By ~ 1

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

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Toward Personalized Treatment for Patients with Low von Willebrand Factor and Quantitative von Willebrand Disease

Seminars in Thrombosis and Hemostasis ◽

10.1055/s-0041-1722864 ◽

2021 ◽

Vol 47 (02) ◽

pp. 192-200

Author(s):

James S. O'Donnell

Keyword(s):

Von Willebrand Factor ◽

Bleeding Risk ◽

Von Willebrand Disease ◽

Personalized Treatment ◽

Treatment Plans ◽

Type 3 ◽

Von Willebrand ◽

Willebrand Factor

AbstractThe biological mechanisms involved in the pathogenesis of type 2 and type 3 von Willebrand disease (VWD) have been studied extensively. In contrast, although accounting for the majority of VWD cases, the pathobiology underlying partial quantitative VWD has remained somewhat elusive. However, important insights have been attained following several recent cohort studies that have investigated mechanisms in patients with type 1 VWD and low von Willebrand factor (VWF), respectively. These studies have demonstrated that reduced plasma VWF levels may result from either (1) decreased VWF biosynthesis and/or secretion in endothelial cells and (2) pathological increased VWF clearance. In addition, it has become clear that some patients with only mild to moderate reductions in plasma VWF levels in the 30 to 50 IU/dL range may have significant bleeding phenotypes. Importantly in these low VWF patients, bleeding risk fails to correlate with plasma VWF levels and inheritance is typically independent of the VWF gene. Although plasma VWF levels may increase to > 50 IU/dL with progressive aging or pregnancy in these subjects, emerging data suggest that this apparent normalization in VWF levels does not necessarily equate to a complete correction in bleeding phenotype in patients with partial quantitative VWD. In this review, these recent advances in our understanding of quantitative VWD pathogenesis are discussed. Furthermore, the translational implications of these emerging findings are considered, particularly with respect to designing personalized treatment plans for VWD patients undergoing elective procedures.

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Recessive von Willebrand Disease Type 2 Normandy: Variable Expression of Mild Hemophilia and VWD Type 1

Acta Haematologica ◽

10.1159/000214852 ◽

2009 ◽

Vol 121 (2-3) ◽

pp. 119-127 ◽

Cited By ~ 3

Author(s):

Jan Jacques Michiels ◽

Alain Gadisseur ◽

Inge Vangenegten ◽

Wilfried Schroyens ◽

Zwi Berneman

Keyword(s):

Disease Type ◽

Von Willebrand Disease ◽

Variable Expression ◽

Von Willebrand

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Molecular Background of “Smeary” von Willebrand Factor Multimers.

Blood ◽

10.1182/blood.v110.11.2711.2711 ◽

2007 ◽

Vol 110 (11) ◽

pp. 2711-2711

Author(s):

Reinhard Schneppenheim ◽

Olivier Marggraf ◽

Heike Eckert ◽

Tobias Obser ◽

Florian Oyen ◽

...

Keyword(s):

Von Willebrand Factor ◽

Disulfide Bonds ◽

Von Willebrand Disease ◽

Molecular Testing ◽

Functional Deficits ◽

Intermolecular Disulfide Bonds ◽

A1 Domain ◽

Von Willebrand ◽

Willebrand Factor

Abstract Background: Multimer analysis of von Willebrand factor (VWF) is a most important technique to classify patients with von Willebrand disease (VWD) type 2. Besides “classical” multimer patterns a “smeary” appearance of individual VWF oligomers is increasingly observed and has previously been regarded as a pre-analytical artifact. Objective: To phenotypically and genotypically assess the molecular background of “smeary” VWF multimers. Patients and methods: Samples of 8 VWD patients were analyzed in our reference lab (UB) for further classification and molecular testing. Multimer profiles were assessed by intermediate resolution gels. VWF:CB and VWF:GpIb binding were used as functional assays. VWF gene mutation analysis was performed in all index cases (IC). The causal relationship between genotype and phenotype was studied by analyzing recombinant mutants in comparison to wildtype VWF. Results: In all IC the phenotype correlated with particular mutations in the VWF D3 domain (G1172D), the A1 domain (R1315C, R1374S, R1374C, R1399C), the D4 domain (C2257R), the C1 domain (R2464C) and in the region close to the CK domain (C2671Y), respectively. The multimer patterns of recombinant mutant VWF was of a “smeary” appearance and closely resembled those of mutant plasma VWF. Mutations in the A1 domain additionally correlated with severe GpIb binding deficiency. Conclusions: Our data suggest a molecular cause of the “smeary” multimer structure rather than pre-analytical artifacts. Most of the mutations identified involved cysteine residues suggesting an influence on the VWF secondary structure which is determined by intra- and intermolecular disulfide bonds. This could explain the peculiar multimer appearance. The functional deficits, however, seem to depend on the location of the mutations with a significant impact on GpIb binding of mutants in the A1 domain.

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Limitations of Current Plasma VonWillebrand Factor (VWF) Activity Tests: A Comprehensive Comparison of Five VWF Activity Assays.

Blood ◽

10.1182/blood.v112.11.3376.3376 ◽

2008 ◽

Vol 112 (11) ◽

pp. 3376-3376

Author(s):

Dong Chen ◽

Rajiv Pruthi ◽

William L. Nichols ◽

John A. Heit

Keyword(s):

Activity Ratio ◽

Light Transmission ◽

Von Willebrand Disease ◽

Assay Method ◽

Type I ◽

Platelet Activity ◽

Platelet Aggregometry ◽

Von Willebrand

Abstract Accurate measurement of plasma von Willebrand factor (VWF) activity is essential for the laboratory diagnosis and treatment monitoring of von Willebrand disease (VWD). Currently available VWF activity assays include VWF ristocetin cofactor activity by manual light transmission platelet aggregometry (VWF:RCo–Agg) or flow cytometry (VWF:RCo–FL), collagen I and III binding activity (VWF:Co–I and –III) (Technozym), and platelet activity by latex agglutination (VWF:Lx) (Instrumental Laboratory). In this study we evaluated and compared the accuracy and precision of these 5 assay methods. Plasma samples from 11 normal donors and 41 patients categorized as type 1 (n=20) or type 2 (n=21) VWD based on clinical evaluation, fVIII:C activity, VWF:RCo–Agg, VWF antigen (VWF:Ag) level and plasma VWF multimer analysis by agarose gel electrophoresis were assayed for VWF activity by VWF:RCo–FL, VWF:Co–I, VWF:Co–III and VWF:Lx methods. The VWF:Ag/VWF activity ratio by VWF activity assay method was calculated for each sample. For normal donors and type I VWD patients, VWF:RCo–FL and VWF:Lx correlated well with VWF:RCo–Agg (R2=0.87, and 0.97, respectively), while VWF:Co–I and –III were lower compared to VWF:RCo-Agg. For type 2 VWD patients, different VWF:Ag/VWF activity ratio cutoffs (range 0.3–0.7) were used (Figure). Both VWF:RCo–Agg and –FL were sensitive (95%) and specific (97%) for type 2 VWD while the VWF:Lx was slightly less sensitive (81%) but was very specific (100%). VWF:Co–I and –III were the least sensitive (<90%) and specific (<90%); both methods had high false positive and negative rates for type 2 VWD. In Summary, for normals and type 1 VWD patients, VWF:RCo–FL and VWF:Lx correlate well with VWF:RCo–Agg and have similar sensitivities and specificities for type 2 VWD. VWF:Co–I and –III are unreliable for assessing plasma VWF activity.

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Wish-Qol Study - Assessment of Health-Related Quality of Life (HRQoL) and Health-Economic Aspects in Patients with Von Willebrand Disease (VWD) in France: Results of the Women Cohort

Blood ◽

10.1182/blood.v128.22.1395.1395 ◽

2016 ◽

Vol 128 (22) ◽

pp. 1395-1395

Author(s):

Annie Borel-Derlon ◽

Jenny Goudemand ◽

Dominique Desprez ◽

Fabienne Volot ◽

Yves Gruel ◽

...

Keyword(s):

Interim Analysis ◽

Research Funding ◽

Von Willebrand Disease ◽

Female Group ◽

Bleeding Score ◽

Type 3 ◽

Von Willebrand

Abstract Background: Von Willebrand disease (VWD) is the most common inherited bleeding disorder with a prevalence of 1% in the general population. VWD results from a deficiency in or a dysfunction of von Willebrand factor which is a protein that is necessary for normal platelet adhesion and protection of factor VIII from proteolysis in the circulation. Nevertheless, prevalence of the most symptomatic forms such as bleeds requiring replacement treatment and /or hospitalization is about 0.01%. Although VWD affects both genders, there is a higher proportion in females than in males.VWD seems to be more symptomatic in women because of their reproductive life. Women with VWD have an increased bleeding risk in numerous situations including anemia, menorrhagia, bleeding during pregnancy, postpartum hemorrhage and impairments in their quality of life (QoL).The prevalence of menorrhagia in women with VWD is 74-92%. According to the Francecoag Network, the referral-based prevalence of moderate-to-severe VWD patients is about 1,750 cases in France. Aim: Since the disease and its treatment can affect every-day life of patients and their families, a French HRQoL Study (WiSH-QoL) exploring this impact started 22 months ago. Methods: This non-interventional 5-year study evaluates patients HRQoL and costs of care in France. At least 350 patients will be followed for 24 months in minimum 30 centers. HRQoL is assessed with the generic SF-36 and the disease-specific VWD-QoL questionnaires. Bleeding severity was measured using the Tosetto Bleeding Score (BS). Results: Since October 2014, 245 patients have been included. We present here the first interim analysis with a focus on the female group. At the first interim analysis, data from 140 patients were documented: 91 adults with a median age of 40.0 years [18.3-78.0] and 49 children with a median age of 10.1 years [2.9-17.5]. VWD Types were already identified for 122 (87%) of these patients: 33 with VWD type 1 (27%) including 5 type 1 Vicenza; 76 type 2 (62%) and 13 type 3 (11%). The median Tosetto bleeding score reported for 124 patients (males and females) was +7 ranging from -1 to +28. From the 95 female patients, 70 were aged ≥18 years, 21 were adolescents between 8-17 years and 4 were girls below 4 years of age. Median age was 29.4 (range 4.3-78.0) years. A total of 25 women had type 1 VWD (31%), 49 had type 2 VWD (60%), and 7 had type 3 VWD (9%), for 14 patients VWD type is undetermined. The median Tosetto bleeding score of the female group was +8 ranging from -1 to +28. Out of 95 patients, 45 patients (47.4%) have received a concomitant treatment due to menorrhagia, such as iron therapy, oral contraceptive, levonorgestrel intrauterin system: 5/21 patients in the group between 8 and 17 years and 40/70 in the group ≥18 years. Out of the 60 women of childbearing potential defined as age between 15-50 years, 6 women were pregnant at time of inclusion. A total of 46 patients, aged 18 years or more have had obstetrical history prior to study inclusion. The mean number of childbirth was more than 2 i.e 2.39 range (1-8) per woman, 75% of these deliveries were natural delivery and 25% were caesarean section. Out of 108 deliveries, 28 (26%) were experienced with post-partum hemorrhages. Conclusions: With the results of the WiSH-QoL study, the first prospective study of von Willebrand disease conducted in France, especially the VWD-specific evaluation of HRQoL and treatment satisfaction a deeper insight will be gathered into the patients' daily life, their perception of well-being and their specific health care needs. With the additional domain 'pregnancy' included in the French version of the VWD-QoL questionnaire for female adult patients, it will possible to better understand how women may be affected by VWD during childbearing years. Disclosures Borel-Derlon: LFB: Other: Reference expert and national coordinator for VWD; Octapharma: Research Funding; NovoNordisk: Other: Expert for scientific committee; Shire - Baxalta: Research Funding. Chatelanaz:LFB Biomedicaments: Employment. Doriat-Robin:LFB Biomedicaments: Employment. von Mackensen:SOBI: Research Funding; Shire: Research Funding.

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Semiautomatic VWF Multimer Densitometric Analysis: Validation of the Clinical Accuracy and Clinical Implications in Von Willebrand Disease

Blood ◽

10.1182/blood-2020-142287 ◽

2020 ◽

Vol 136 (Supplement 1) ◽

pp. 15-16

Author(s):

Ferdows Atiq ◽

Johan Boender ◽

Marjon H. Cnossen ◽

Johanna G van der Bom ◽

Karin Fijnvandraat ◽

...

Keyword(s):

Clinical Practice ◽

Research Funding ◽

Von Willebrand Disease ◽

Densitometric Analysis ◽

Travel Grant ◽

Bleeding Score ◽

Type 3 ◽

Von Willebrand

Introduction Von Willebrand factor (VWF) multimer analysis is an essential tool in the diagnosis and classification of von Willebrand disease (VWD). Current visual VWF multimer analysis is observer dependent, time consuming and is inaccurate in detecting subtle changes in multimer patterns. Therefore, recent studies have investigated VWF multimer quantification using semiautomatic densitometric analysis. The accuracy of VWF multimer densitometric analysis in clinical practice needs further investigation before it can be widely used. The aim of the study was to validate the accuracy of VWF multimer densitometric analysis in clinical practice. Additionally, we aimed to identify patient characteristics associated with VWF multimer densitometry outcomes in type 1 and type 2 VWD patients, and we investigated whether subtle differences in VWF multimer pattern are associated with the bleeding phenotype of VWD patients. Methods We included patients from the nationwide Willebrand in the Netherlands (WiN) study. The inclusion criteria of the WiN study were a personal hemorrhagic diathesis or family history of VWD, and historically lowest VWF antigen (VWF:Ag), VWF activity (measured with the monoclonal antibody assay: VWF:Ab) or VWF collagen binding (VWF:CB) ≤0.30 IU/mL or FVIII activity (FVIII:C) ≤0.40 IU/mL in case of type 2N VWD. At inclusion in the WiN study, blood was drawn and patients filled in an extensive questionnaire containing a self-administered Tosetto bleeding score (BS). For multimer analysis, citrated blood samples were separated on 0.9% agarose gel and visualized by Western blotting. We used IMAGEJ for densitometric analysis. The five smallest bands on densitometric images were defined as small multimers, next five bands were defined as medium multimers and the remaining bands were defined as large multimers. Medium-large VWF multimer index was calculated by dividing the patient's multimer ratio (intensity of the medium and large multimers divided by the total intensity of all multimers) by the multimer ratio of a normal control in the same western blot. If no multimers could be detected, the multimer index was set as 0. Results We included 561 VWD patients: 328 type 1, 211 type 2 and 21 type 3 patients. The median age was 44 [IQR 29-58] and 351 patients (62.7%) were female (Table 1). Figure 1 illustrates typical densitometric outcomes of a type 1 VWD patient with normal VWF multimers (A) and a type 2A patient with reduced high-molecular-weight (HMW) VWF multimers (B). Medium-large VWF multimer index was 1.06 [0.99-1.12] in type 1 and 0.53 [0.29-0.89] in type 2 and 0.00 [0.00-0.00] in type 3 VWD. Medium-large VWF multimer index was in patients visually classified as normal, reduced and absent HMW VWF multimers, respectively 1.07 [1.02-1.12], 0.84 [0.71-0.91] and 0.31 [0.20-0.44] (p<0.001, Figure 2A). With visual examination as gold standard, medium-large VWF multimer index had a very good accuracy in distinguishing normal VWF multimers from reduced HMW VWF multimers (AUC: 0.96 (0.94-0.98) p<0.001, Figure 2B). It could also accurately distinguish reduced HMW VWF multimers from absence of HMW multimers, with an AUC of 0.95 (0.92-0.97, p<0.001), and type 2A and 2B from type 2M and 2N (AUC: 0.96 (0.94-0.99), p<0.001, Figure 2C and 2D). From VWF activity measurements, medium-large VWF multimer index was strongest correlated with VWF:CB (ρ=0.79, p<0.001). From the ratio of the various functional VWF measurements (divided by VWF:Ag), the strongest correlation was again found for VWF:CB/VWF:Ag ratio (ρ=0.80, p<0.001). In type 1 VWD, an increased clearance of VWF (defined as VWFpropeptide/VWF:Ag ratio ≥2.2) was independently associated with lower medium-large VWF multimer index (β=-0.10 (-0.14; -0.07), p<0.001). Also, type 1 VWD patients with a VWF gene variant had relatively lower medium-large VWF multimer index compared to type 1 patients without a VWF variant, respectively 1.03 [0.95-1.10] vs 1.08 [1.04-1.12] (p<0.001). In the total population, higher medium-large VWF multimer index was associated with a lower bleeding score: β=-4.6 (-7.2; -2.0), p=0.001, adjusted for age, sex, blood group and type of VWD. Conclusion Semiautomatic densitometric analysis of VWF multimers has an excellent accuracy in clinical practice, and may have an additional value in providing a better understanding of the clinical features such as the bleeding phenotype of VWD patients. Disclosures Atiq: CSL Behring: Research Funding; SOBI: Other: travel grant. Boender:SOBI: Current Employment; CSL Behring: Research Funding. Cnossen:Bayer: Research Funding; Novo Nordisk: Research Funding; Nordic Pharma: Research Funding; Sobi: Research Funding; Takeda: Research Funding; CSL behring: Research Funding; Pfizer: Research Funding; Shire: Research Funding; Baxter: Research Funding. van der Bom:Bayer: Speakers Bureau. Fijnvandraat:SOBI: Research Funding; NovoNordisk: Consultancy; Grifols: Consultancy; Takeda: Consultancy; Roche: Consultancy; CSL Behring: Research Funding; NovoNordisk: Research Funding. Van Galen:Bayer: Research Funding; Takeda: Speakers Bureau; CSL Behring: Research Funding. Laros-Van Gorkom:Baxter: Other: Educational grant; CSL Behring: Other: Educational grant. Meijer:Bayer: Research Funding; Sanquin: Research Funding; Pfizer: Research Funding; Bayer: Speakers Bureau; Sanquin: Speakers Bureau; Boehringer Ingelheim: Speakers Bureau; BMS: Speakers Bureau; Aspen: Speakers Bureau; Uniqure: Consultancy. Eikenboom:CSL Behring: Research Funding; Roche: Other: Teacher on educational activities. Leebeek:Roche: Other: DSMB member for a study; SOBI: Other: Travel grant; Novo Nordisk: Consultancy; Shire/Takeda: Consultancy; Uniqure: Consultancy; Shire/Takeda: Research Funding; CSL Behring: Research Funding.

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PFA-100 monitoring of von Willebrand factor (VWF) responses to desmopressin (DDAVP) and factor VIII/VWF concentrate substitution in von Willebrand disease type 1 and 2

Thrombosis and Haemostasis ◽

10.1160/th07-08-0527 ◽

2008 ◽

Vol 100 (09) ◽

pp. 462-468 ◽

Cited By ~ 23

Author(s):

Huub H. D. M. van Vliet ◽

Mies C. Kappers-Klunne ◽

Jan J. Michiels ◽

Frank W. G. Leebeek

Keyword(s):

Von Willebrand Factor ◽

Von Willebrand Disease ◽

Response Relationship ◽

Dose Response Relationship ◽

Before And After ◽

Von Willebrand ◽

Willebrand Factor

SummaryDose-response relationship was studied between PFA-100 closure times (PFA CTs) and factor (F)VIII-von Willebrand factor (VWF) parameters in patients with von Willebrand disease (VWD) type 1 and type 2 before and after treatment with DDAVP (n=84) or FVIII/VWF concentrate (n=38). DDAVP treatment of patients with VWD type 1 normalised the PFA CTs by increasing VWF levels to normal. Of the 14 patients with VWD type 2, PFA CTs did not normalize in eight. Haemate-P substitution in patients with VWD type 1 induced a less favourable response as compared to DDAVP, because PFA CTs did not correct in all patients. Of 12 patients with VWD type 2 treated with Haemate-P, six showed a correction of PFA CTs (<250 sec), which correlated with the normalisation of the VWF CB/ Ag ratio. In-vitro studies were performed by using whole blood of patients with VWD and adding various amounts of FVIII/VWF concentrate. Addition of Haemate-P induced an increase of the VWF CB/Ag ratio from 0.30 to 0.70 in blood of patients with VWD type 2 with correction of the PFA CTs. Immunate did not result in an increase of VWF CB/Ag ratio in blood of VWD type 2 patients, and the PFA CTs remained prolonged. We conclude that PFA-100 might be an adequate instrument not only for diagnosis but also for monitoring of DDAVP responses and FVIII/ VWF substitution of patients with VWD type 1 and 2,but this is dependent upon the type of VWD and the concentrate used.

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Analysis of von Willebrand Disease in the South Moravian Population (Czech Republic): Results from the BRNO-VWD Study

Thrombosis and Haemostasis ◽

10.1055/s-0039-1678528 ◽

2019 ◽

Vol 119 (04) ◽

pp. 594-605 ◽

Cited By ~ 2

Author(s):

Inge Vangenechten ◽

Petr Smejkal ◽

Ondrej Zapletal ◽

Jan Jacques Michiels ◽

Zwi Berneman ◽

...

Keyword(s):

Czech Republic ◽

Von Willebrand Disease ◽

University Hospital ◽

Cross Sectional ◽

Mutation Database ◽

Family Based ◽

Von Willebrand ◽

Willebrand Factor

Background von Willebrand disease (VWD) is an inherited bleeding disorder caused by a quantitative (type 1 and 3) or qualitative (type 2) defect of von Willebrand factor (VWF). The heterogeneity of laboratory phenotyping makes diagnosing difficult. Objective A cross-sectional, family-based VWD study in a collaboration between University Hospital Brno (Czech Republic) and Antwerp University Hospital (Belgium) to improve the understanding of laboratory phenotype/genotype correlation. Patients and Methods A total of 205 patients with suspected VWD were identified from historical records. Complete laboratory analysis was established using all available VWD assays including VWF multimers and genetic analysis. Results Based on the current International Society of Thrombosis and Haemostasis (ISTH) – Scientific and Standardization Committee VWD classification and type 2A sub-division into 2A/IIA, IID, IIC and IIE, the majority was characterized as a type 1 VWD, followed by type 2. Proposed laboratory phenotypes were confirmed by their multimeric pattern within 98% of this cohort. All type 2, 3 and 75% of type 1 VWD patients were confirmed by underlying causative mutations. Forty-six different causal mutations (117 not previously described in the literature) could be identified. Fifty per cent of all cases was represented by eight individual mutations, mainly p.Pro812ArgfsX31. Thirteen patients had a large heterozygous gene alteration. Conclusion Although an extensive panel of tests was used, VWD classification and (sub)typing remains difficult and fluid. This study provides a cross-sectional overview of the VWD population in the Czech Republic and provides important data to the ISTH/European Association for Haemophilia and Allied Disorders VWD mutation database in linking causal mutations with unique VWD (sub)types. It also identifies new, as not previously described in the literature, causal mutations.

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