Mitral regurgitation is associated with similar loss of von Willebrand factor large multimers but lower frequency of anemia compared with aortic stenosis.

Background: Various cardiovascular diseases cause acquired von Willebrand syndrome (AVWS), which is characterized by a decrease in high-molecular-weight (large) von Willebrand factor (VWF) multimers. Mitral regurgitation (MR) has been reported as a cause of AVWS. However, much remains unclear about AVWS associated with MR. Objectives: To evaluate VWF multimers in MR patients and examine their impact on clinical characteristics. Methods: Moderate or severe MR patients (n = 84) were enrolled. VWF parameters such as the VWF large multimer index (VWF-LMI), a quantitative value that represents the amount of VWF large multimers, and clinical data were prospectively analyzed. Results: At baseline, the mean hemoglobin level was 12.9 ± 1.9 g/dL and 58 patients (69.0%) showed loss of VWF large multimers defined as VWF-LMI < 80%. VWF-LMI in patients with degenerative MR was lower than in those with functional MR. VWF-LMI appeared to be restored the day after mitral valve intervention, and the improvement was maintained 1 month after the intervention. Seven patients (8.3%) had a history of bleeding, 6 (7.1%) of whom had gastrointestinal bleeding. Gastrointestinal endoscopy was performed in 23 patients (27.4%) to investigate overt gastrointestinal bleeding, anemia, etc. Angiodysplasia was detected in 2 of the 23 patients (8.7%). Conclusion: Moderate or severe MR is frequently associated with loss of VWF large multimers, and degenerative MR may cause more severe loss compared with functional MR. Mitral valve intervention corrects the loss of VWF large multimers. Gastrointestinal bleeding may be relatively less frequent and hemoglobin level remains stable in MR patients.

Use of crushed tranexamic acid tablets in water for paediatric patients with bleeding disorders.

BACKGROUND: Ε-Aminocaproic acid oral solution (EACA OS) is the only commercially available antifibrinolytic for patients who cannot swallow tablets. Insurance denials and high costs remain barriers to its use. OBJECTIVES: To determine the safety and efficacy of crushed tranexamic acid tablets in water (cTXAw) for children with bleeding disorders. METHODS: We retrospectively reviewed records of children (<10 years) with bleeding disorders who received cTXAw or EACA OS from 1 December 2018, through 31 July 2022, at Mayo Clinic (Rochester, Minnesota). Bleeding outcomes were defined according to ISTH criteria. RESULTS: Thirty-two patients were included (median age, 3 years; male, n = 23). Diagnoses were VWD (n = 17), haemophilia (n = 5), FVII deficiency (n = 3), inherited platelet disorder (n = 4), ITP (n = 2), and combined FV and FVII deficiencies (n = 1). Thirty-two courses of cTXAw (monotherapy 24/32; mean duration 6 days) and fifteen courses of EACA (monotherapy 12/15; mean duration 5 days) were administered. No surgical procedures (n = 28) were complicated by bleeding. Of the 19 bleeding events, 16 had effective haemostasis, two had no reported outcome, and one had no response. cTXAw and EACA were equally effective in preventing and treating bleeding (p value > .1). No patients had adverse effects. Eight of 19 patients (42%) who were initially prescribed EACA OS did not receive it because of cost or insurance denial. The estimated average wholesale price of one treatment was $94 for cTXAw and $905 for EACA OS. CONCLUSIONS: CTXAw appears to be an effective, safe, and low-cost alternative option to EACA OS for young children with bleeding disorders.

A noncanonical splicing variant c.875-5 T > G in von Willebrand factor causes in-frame exon skipping and type 2A von Willebrand disease.

INTRODUCTION: A novel variant involving noncanonical splicing acceptor site (c.875-5 T > G) in propeptide coding region of von Willebrand factor (VWF) was identified in a patient with type 2A von Willebrand disease (VWD), who co-inherited with a null variant (p.Tyr271*) and presented characteristic discrepancy of plasma level of VWF antigen and activity, and a selective reduction of both intermediate-molecular-weight (IMWMs) and high-molecular-weight VWF multimers (HMWMs). MATERIALS AND METHODS: VWF mRNA transcripts obtained from peripheral leukocytes and platelets of the patients were investigated to analyze the consequence of c.875-5 T > G on splicing. The impact of the variant on expression and multimer assembly was further analyzed by in vitro expression studies in AtT-20 cells. The intracellular processing of VWF mutant and the Weibel-Palade bodies (WPBs) formation was evaluated by immunofluorescence staining and electron microscopy. RESULTS: The mRNA transcript analysis revealed that c.875-5 T > G variant led to exon 8 skipping and an in-frame deletion of 41 amino acids in the D1 domain of VWF (p.Ser292_Glu333delinsLys), yielding a truncated propeptide. Consistent with the patient's laboratory manifestations, the AtT-20 cells transfected with mutant secreted less VWF, with the VWF antigen level in conditioned medium 47 % of wild-type. A slight retention in the endoplasmic reticulum was observed for the mutant. Almost complete loss of IMWMs and HMWMs in the medium and impaired WPBs formation in the cell, indicating truncated VWF propeptide lost its chaperon-like function for VWF multimerization and tubular storage. CONCLUSIONS: The VWF splicing site variant (c.875-5 T > G) causes propeptide truncation, severely compromising VWF multimer assembly and tubular storage.

Genetic variations of type 2 and type 3 von Willebrand diseases in Thailand.

AIMS: Von Willebrand disease (VWD) is an inherited haemostatic disorder with a wide range of bleeding phenotypes based on von Willebrand factor (VWF) levels. Multiple assays including VWF gene analysis are employed to correctly diagnose VWD and its subtypes. However, data on VWF mutations among Southeast Asian populations are lacking. We, therefore, aimed to explore genetic variations in Thai patients with type 2 and type 3 VWD by whole exome sequencing (WES). METHODS: In this multicentre study, Thai patients with type 2 and type 3 VWD, according to the definitions and VWF levels recommended by the international guidelines, were recruited. WES was performed using DNA extracted from peripheral blood in all cases. The novel variants were verified by Sanger sequencing. RESULTS: Fifteen patients (73% females; median age at diagnosis 3.0 years) with type 2 (n=12) and type 3 VWD (n=3) from 14 families were enrolled. All patients harboured at least one VWF variant. Six missense (p.Arg1374Cys, p.Arg1374His, p.Arg1399Cys, p.Arg1597Trp, p.Ser1613Pro, p.Pro1648Arg) and one splice-site (c.3379+1G>A) variants in the VWF gene were formerly described. Notably, six VWF variants, including three missense (p.Met814Ile, p.Trp856Cys, p.Pro2032Leu), one deletion (c.2251delG) and two splice-site (c.7729+4A>C, c.8115+2delT) mutations were novelly identified. Compound heterozygosity contributed to type 2 and type 3 VWD phenotypes in two and one patients, respectively. CONCLUSIONS: Type 2 and type 3 VWD in Thailand demonstrate the mutational variations among VWF exons/introns with several unique variants. The WES-based approach potentially provides helpful information to verify VWD diagnosis and facilitate genetic counselling in clinical practice.

Patient-relevant health outcomes for von Willebrand disease, platelet function disorders, and rare bleeding disorders: a Delphi study.

Background: To assess patient value, it is essential to regularly measure health outcomes that matter to patients. It is currently unknown which health outcomes are important for patients with autosomal inherited bleeding disorders. Objectives: This study aimed to assess which health outcomes are important for patients with autosomal inherited bleeding disorders, consisting of von Willebrand disease, platelet function disorders, and rare bleeding disorders, as seen from the patients', caregivers', and healthcare professionals' perspectives. Methods: Two panels, one consisting of patients and caregivers, and one consisting of healthcare professionals participated in a Delphi process. A list of 146 health outcomes was identified from the literature. During 3 rounds, both panels rated the importance of health outcomes on a 5-point Likert scale. A health outcome was considered important by a panel if it received a median score of 5 with an IQR of ≤1. Results: In total, 13 patients, 10 caregivers, and 19 healthcare professionals participated in the Delphi study. Both panels reached consensus on the importance of health outcomes related to bleeding episodes, life-threatening complications, and the intensity and impact of menstruation. Patients and caregivers additionally reached consensus on the importance of health outcomes related to menstruation and the impact of the bleeding disorder on their daily lives. Healthcare professionals reached consensus on the importance of health outcomes related to treatment, joint health, and pain. Conclusion: In this study, health outcomes were identified that should be considered when implementing value-based health care in the care of patients with autosomal inherited bleeding disorders.

Health-related quality of life is impaired in bleeding disorders of unknown cause: results from the Vienna Bleeding Biobank.

Background: Bleeding disorder of unknown cause (BDUC) is a diagnosis of exclusion after extensive investigation of coagulation and platelet function and is commonly seen among patients with mild-to-moderate bleeding disorders. Despite increasing awareness among treating physicians, little is known about the health-related quality of life (HrQoL) in BDUC. Objectives: To investigate HrQoL in patients with BDUC in comparison to the general population and patients diagnosed with other established bleeding disorders. Methods: Patients with mild-to-moderate bleeding disorders from the Vienna Bleeding Biobank, a prospective cohort study, were contacted via mail and phone to complete the 36-Item Health Survey Questionnaire form. Results: In total, 333/657 (50.7%) patients completed the 36-Item Health Survey Questionnaire. Patients with BDUC (n = 207, 62%) had significantly impaired HrQoL both in physical (47.8 vs 49.2) and mental health parameters (42.9 vs 51.0) compared to the general population (n = 2914, 56% females), which remained after adjustment for sex and age in multivariable linear regression. The impairment in HrQoL, compared to patients with von Willebrand disease, platelet function defects, or mild clotting factor deficiencies, did not prevail after adjustment for age and sex. In patients with BDUC, age and the presence of at least 1 comorbidity were associated with impaired physical health but not sex or bleeding severity. Of all analyzed bleeding symptoms, only joint bleeding was associated with impaired physical health and gastrointestinal bleeding with mental health in BDUC. Conclusion: The impairments in HrQoL in patients with BDUC emphasize the burden of BDUC on mental and physical well-being, encouraging early recognition and better counseling of patients with BDUC.

Desmopressin as a Treatment in Patients With Von Willebrand Disease: A Systematic Review.

Von Willebrand disease (VWD) and hemophilia A are the most common inherited bleeding disorders. Quantitative or qualitative von Willebrand factor (VWF) anomalies cause this disorder in men and women. VWF, a plasma glycoprotein, relies on platelets for primary hemostasis. It also carries and stabilizes factor VIII in the blood. VWD has several categories. Types 1 and 3 have partial or total VWF quantitative deficiencies. However, type 2 and its subtypes have VWF quality issues. The major treatment is desmopressin (DDAVP), which replaces endogenous VWF and factor VIII (FVIII). Plasma-derived VWF/FVIII products may also be substituted exogenously. Treatment with plasma-derived or recombinant VWF concentrates without FVIII is also possible. The purpose of this retrospective, single-center research was to evaluate DDAVP's efficacy in treating VWD based on many criteria established in the current literature. We looked at the results on Google Scholar, the Cochrane Library, and PubMed/Medline. There were a total of 10 papers found, evaluated, and accepted for inclusion in this study. A comprehensive analysis of DDVAP's role in VWD was compiled from the aforementioned papers. Various aspects of DDVAP were captured by including an analysis of complementary treatments used in surgical and clinical settings. We also describe the treatment's intended impact on the different variations of the disease. Given these results, further investigation is required to determine the most effective method for managing VWD so that it may be included in standard clinical practice.

Impact of transcatheter aortic valve implantation on circulating von Willebrand factor in patients with severe aortic stenosis.

INTRODUCTION: Severe aortic stenosis (AS) can lead to degradation of high molecular weight (HMW) von Willebrand factor (VWF) which can result in haemostatic abnormalities. While studies have explored changes in VWF profiles before and after surgical aortic valve replacement (SAVR), the longer-term changes in VWF profiles pre- and post-transcatheter aortic valve implantation (TAVI) are less understood. AIM: Our primary objective was to identify differences in VWF multimer profiles and VWF function pre-TAVI and 1-month post-TAVI. Our secondary objective was to correlate VWF markers with measures of AS severity. METHODS: Adult patients with severe AS referred for TAVI at our institution were prospectively enrolled in this cohort study. Blood samples were collected for plasma analysis at three time points for all patients: 1 day pre-TAVI, 3 days post-TAVI, and 1-month post-TAVI. VWF antigen, activity, propeptide, collagen binding, multimers, and factor VIII coagulant activity were determined at each time point. Correlations between VWF parameters and severity of AS were assessed. RESULTS: Twenty participants (15 males, five females) with severe AS were recruited for the study. There was a significant increase in HMW VWF between pre-procedure and 1-month post-TAVI (p < .05). There was a transient increase in VWF antigen levels and activity at 3-days post TAVI that decreased to pre-TAVI levels at 1-month. There were no statistically significant correlations between VWF markers and AS severity. CONCLUSIONS: This is the first study to elucidate longer-term (>1 week) improvements in HMW VWF after a TAVI procedure in severe AS patients.

HRQoL and psychosocial aspects of burden on caregivers to children with moderate or severe von Willebrand disease.

INTRODUCTION: Von Willebrand disease (VWD) is the most widespread congenital bleeding disorder. Caregivers are highly involved in its treatment, and from the time of the child's bleeding diagnosis, they face new demands such as recognition of bleeds and treatment options. AIM: The aim of this study was to assess Health related quality of life (HRQoL) in caregivers of children with moderate and severe VWD in Sweden, and to describe the impact of psychosocial aspects on the burden. METHODS: A multicentre, cross-sectional study. The Short Form 36 Health Survey (SF-36) was used to assess HRQoL. Caregiver burden was measured using The HEMOphilia associated Caregiver Burden scale (HEMOCAB). Children´s clinical data were collected from the Swedish national registry for bleeding disorders. RESULTS: Seventy caregivers of children with moderate or severe VWD were included. Caregivers of children with moderate VWD scored significantly lower in the mental health domains on SF-36, compared to matched normative data. Psychosocial aspects that significantly impacted the caregiver burden negatively measured by HEMOCAB total score were: if the caregiver reported that VWD affected their life in general (p = .001), if the child was absent from preschool/school ≥2 day/12 months due to VWD (p = .002) or that VWD had a financial impact on the family (p = .001). CONCLUSION: This study contributes to knowledge about caregivers' HRQoL and highlights the situation of caregivers of children with moderate VWD. Furthermore, the caregiver burden was negatively affected by psychosocial aspects. Clinical follow-ups should include assessment of psychosocial aspects to identify caregivers that are at risk of high burden.

Desmopressin (DDAVP) use in patients with von Willebrand disease: A single-centre retrospective review of test response and clinical outcomes.

INTRODUCTION: Peri-procedural management of von Willebrand disease (VWD) utilizes von Willebrand factor (VWF) concentrates or desmopressin (DDAVP) to increase VWF levels. DDAVP is safe, easily administered, and inexpensive. Currently, a consensus definition for adequate DDAVP response is lacking, and outcomes of peri-procedural DDAVP use in VWD patients are seldom reported. AIM: This single-centre retrospective review aims to characterize DDAVP-responsiveness and assess clinical outcomes of peri-procedural DDAVP use in VWD. PATIENTS AND METHODS: We reviewed records for all our adult VWD patients (age ≥18 years) who underwent DDAVP challenge testing between January 2007 and January 2022. DDAVP-responsiveness was assessed using six definitions. Bleeding outcomes following procedures covered by DDAVP were classified as excessive or expected bleeding. RESULTS: Eighty-four of 94 (89.4%) patients were DDAVP-responsive by our definition (1-h VWF Activity/Factor VIII ≥0.50 IU/mL). However, the proportion of DDAVP-responders varied from 53.2% to 91.5%, depending on the literature definition used. Ninety-nine procedures pre-treated with DDAVP were performed during the study period. Eighty-six (86.7%) procedures (31 major; 55 minor) were covered with only DDAVP ± tranexamic acid (TXA). Excessive bleeding occurred following 4/31 major procedures and 2/55 minor procedures (both performed in a single patient with a bleeding score of 16). When covered with DDAVP+Factor ± TXA, one each of 10 major and 3 minor procedures (performed in 2 patients with bleeding scores 15-16) resulted in post-procedural bleeding. CONCLUSIONS: Peri-procedural DDAVP prophylaxis appears to be effective among individuals with VWD. Beyond DDAVP-responsiveness, patient bleeding history and procedure invasiveness should be considered in determining suitability for DDAVP prophylaxis.

The contribution of the sinusoidal endothelial cell receptors CLEC4M, stabilin-2, and SCARA5 to VWF-FVIII clearance in thrombosis and hemostasis.

Quantitative abnormalities in factor VIII (FVIII) and its binding partner, von Willebrand factor (VWF), are associated with an increased risk of bleeding or thrombosis, and pathways that regulate the clearance of VWF-FVIII can strongly influence their plasma levels. In 2010, the Cohorts for Heart and Aging Research in Genome Epidemiology (CHARGE) on genome-wide association study meta-analysis identified variants in the genes for the sinusoidal endothelial receptors C-type lectin domain family 4 member M (CLEC4M), stabilin-2, and scavenger receptor class A member 5 (SCARA5) as being associated with plasma levels of VWF and/or FVIII in normal individuals. The ability of these receptors to bind, internalize, and clear the VWF-FVIII complex from the circulation has now been reported in a series of studies using in vitro and in vivo models. The receptor stabilin-2 has also been shown to modulate the immune response to infused VWF-FVIII concentrates in a murine model. In addition, the influence of genetic variants in CLEC4M, STAB2, and SCARA5 on type 1 von Willebrand disease/low VWF phenotype, FVIII pharmacokinetics, and the risk of venous thromboembolism has been described in a number of patient-based studies. Understanding the role of these receptors in the regulation of VWF-FVIII clearance has led to significant insights into the genomic architecture that modulates plasma VWF and FVIII levels, improving the understanding of pathways that regulate VWF-FVIII clearance and the mechanistic basis of quantitative VWF-FVIII pathologies.

Colorectal cancer screening in patients with inherited bleeding disorders: high cancer detection rate in hemophilia patients.

BACKGROUND: The population-based colorectal cancer (CRC) screening program in individuals aged 55 to 75 years in the Netherlands uses fecal immunochemical testing (FIT), to detect hemoglobin in feces, followed by colonoscopy in individuals with a positive FIT. OBJECTIVES: The objectives of this study are to assess the false-positive rate, detection rate, and positive predictive value of FIT for CRC and advanced adenoma (AA) in patients with Von Willebrand disease (VWD) or hemophilia. METHODS: We performed a multicenter, nationwide cross-sectional study embedded in 2 nationwide studies on VWD and hemophilia in the Netherlands. RESULTS: In total, 493 patients with hemophilia (n = 329) or VWD (n = 164) were included, of whom 351 patients participated in the CRC screening program (71.2%). FIT positivity and false-positive rate in patients with hemophilia and VWD were significantly higher than those in the general population (14.8% vs. 4.3%, p < .001 and 10.3% vs. 2.3%, p <.001, respectively). In patients with hemophilia, the detection rate of CRC/AA was significantly higher than that in the general male population (4.5% vs. 1.8%, p = .02), and the positive predictive value of FIT for CRC/AA was comparable (32.3% vs. 39.7%, n.s.). In patients with VWD, the detection rate was similar to that of the general population (0.8% vs. 1.4%, n.s.), whereas the positive predictive value was significantly lower than that in the general population (6.3% vs. 36.8%, p = .02). CONCLUSION: This study indicates that despite a high false-positive rate of FIT in patients with inherited bleeding disorders, the detection rate of CRC and/or AA in hemophilia patients is high. FIT performs different in patients with hemophilia or VWD compared with the general population.

Variability in International Society on Thrombosis and Haemostasis-Scientific and Standardization Committee endorsed Bleeding Assessment Tool (ISTH-BAT) score with normal aging in healthy females: contributory factors and clinical significance.

BACKGROUND: Bleeding assessment tools are key screening tests used in the evaluation of patients with suspected inherited bleeding disorders. The International Society on Thrombosis and Haemostasis-Scientific and Standardization Committee endorsed Bleeding Assessment Tool (ISTH-BAT) has differing reference ranges for adult males (0-3), adult females (0-5), and children (0-2), reflecting differing bleeding symptoms and exposure to hemostatic challenges in these healthy population subgroups. Age is known to markedly impact bleeding score in individuals with von Willebrand disease. However, the influence of age on bleeding score in healthy adult controls is poorly understood. OBJECTIVES: We aimed to assess variability in ISTH-BAT score with age among healthy control females. METHODS: We used the legacy "Merging Project" dataset of normal healthy controls upon which current ISTH-BAT normal ranges are based. We included women, totaling 646 individuals. The normal range (middle 95th percentile) of total ISTH-BAT and grouped subdomain scores between age quartiles was assessed. RESULTS: The normal range of ISTH-BAT scores increased with age, ranging from 0 to 4 in the youngest quartile (age range, 18-30) to 0 to 6 in the oldest (age range, 52-88). This increased variability with aging was related both to high menorrhagia domain scores in older women and an increase in postprocedural bleeding with accumulated exposure to hemostatic challenges. CONCLUSIONS: Cumulatively, our data highlight that normal aging leads to increased variability in bleeding scores in healthy adult females. Further refinement of the ISTH-BAT with age-adjusted reference ranges may improve the sensitivity and specificity of the tool among females.

Investigating patients for bleeding disorders when most of the "usual" ones have been ruled out.

A State of the Art lecture titled "Investigating Patients for Bleeding Disorders When Most of the Usual Ones Have Been Ruled Out" was presented at the International Society on Thrombosis and Haemostasis Congress in 2023. Mild to moderate bleeding disorders (MBDs) in patients in whom no diagnosis of an established disorder, such as platelet function defect, von Willebrand disease, or a coagulation factor deficiency, can be identified are classified as bleeding disorders of unknown cause (BDUCs). Prospective data from the Vienna Bleeding Biobank and other studies have revealed a high proportion of BDUCs of up to 70% among patients with MBD who have a similar bleeding phenotype as other MBDs. As BDUC is a diagnosis of exclusion, the accuracy of the diagnostic workup is essential. For example, repeated testing for von Willebrand disease should be considered if von Willebrand factor values are <80 IU/dL. Current evidence does not support the clinical use of global assays such as thromboelastography, platelet function analyzer, or thrombin generation potential. Rare and novel bleeding disorders due to genetic variants in fibrinolytic factors or natural anticoagulants are rare and should only be analyzed in patients with specific phenotypes and a clear family history. In BDUC, blood group O was identified as a risk factor for increased bleeding severity and bleeding risk after hemostatic challenges. Future studies should improve the phenotypical characterization and ideally identify novel risk factors in BDUC, as a multifactorial pathogenesis is suspected. Finally, we summarize relevant new data on this topic presented during the 2023 International Society on Thrombosis and Haemostasis Congress.

Pseudotumor of the Maxillary Sinus in a Child with Von Willebrand Disease.

Introduction: Mandibular pseudotumors, also known as blood cysts, are rare complications which occur more frequently in patients with an associated bleeding disorder such as hemophilia. Case Report: We present a case of a 2-year and 6-month-old patient with a hemophilic pseudotumor associated with Von Willebrand's disease, who consulted the emergency room due to spontaneous increase in volume of the left maxillary region, with no previous relevant medical history. Conclusions: Different imaging studies were carried out to characterize the lesion, providing the necessary information for the correct approach. Due to the low prevalence of this complication, we believe it is of vital importance to understand the adequate management in this patient population.

Polyphosphate Activates von Willebrand Factor Interaction with Glycoprotein Ib in the Absence of Factor VIII In Vitro.

Polyphosphate (polyP), a phosphate polymer released by activated platelets, may modulate various stages of hemostasis by binding to blood proteins. In this context, we previously reported that polyP binds to the von Willebrand factor (VWF). One of the most significant functions of VWF is to bind to and protect the blood circulating Factor VIII (FVIII). Therefore, here, we study the role of polyP in the VWF-FVIII complex in vitro and suggest its biological significance. Surface plasmon resonance and electrophoretic mobility assays indicated that polyP binds dynamically to VWF only in the absence of FVIII. Using the VWF Ristocetin Cofactor assay, the most accepted method for studying VWF in platelet adhesion, we found that polyP activates this role of VWF only at low levels of FVIII, such as in plasmas with chemically depleted FVIII and plasmas from severe hemophilia A patients. Moreover, we demonstrated that FVIII competes with polyP in the activation of VWF. Finally, polyP also increases the binding of VWF to platelets in samples from patients with type 2 and type 3 von Willebrand disease. We propose that polyP may be used in designing new therapies to activate VWF when FVIII cannot be used.

Structure and Function of Recombinant versus Plasma-Derived von Willebrand Factor and Impact on Multimer Pharmacokinetics in von Willebrand Disease.

Background: Recombinant von Willebrand factor (rVWF, vonicog alfa) is a purified VWF concentrate produced from Chinese hamster ovary cells. rVWF is not exposed to the VWF-cleaving protease ADAMTS13 and so is not subject to proteolytic degradation of large (L) and ultra-large (UL) VWF multimers by that enzyme. Purpose: To compare the structure and function of rVWF with the human plasma-derived VWF [pdVWF] concentrates Haemate P®/Humate-P®, Voncento®, Wilate®/Eqwilate®, and Wilfactin®/Willfact®; to investigate the relationship between VWF multimeric pattern and VWF:ristocetin cofactor (VWF:RCo) activity through population pharmacokinetic (PK) modeling in patients with severe von Willebrand disease (VWD) treated with rVWF. Methods: Analyses included VWF:RCo activity, VWF:collagen-binding activity, VWF:platelet glycoprotein Ib receptor binding, factor VIII (FVIII) binding capacity, and VWF-mediated platelet adhesion under flow conditions. VWF multimeric structure was determined by agarose gel electrophoresis. Population PK models describing the activity-time profile of small, medium, and L/UL multimers following intravenous administration of rVWF in patients with severe VWD were developed. Results: Findings demonstrate that rVWF contains a non-degraded VWF multimer pattern including the UL multimers not present in pdVWF concentrates. rVWF displayed higher specific platelet-binding activity, and faster mediation of platelet adhesion to collagen under shear stress versus pdVWF concentrates. rVWF also demonstrated higher FVIII binding capacity than Haemate P®, Voncento® and Wilate®. Modeling provided evidence that VWF:RCo activity in patients with severe VWD treated with rVWF is associated with L/UL VWF multimers in the circulation. Conclusions: Findings suggest that the L and UL multimers preserved in rVWF contribute to high biological activity and might be important for providing hemostatic efficacy.

The Cardioprotective Potential of von Willebrand Disease in Ischemic Heart Disease.

von Willebrand factor (vWF) aids coagulation at sites of vessel injury. Elevated vWF levels have been associated with an increased risk of ischemic heart disease (IHD); however, it is unclear whether vWF deficiency, seen in patients with von Willebrand disease (vWD), protects people against IHD. We determined and compared the prevalence and risk of IHD in patients with versus without vWD by using data from the National Inpatient Sample (2009-2014), excluding patients younger than 18 and older than 75 years. The primary outcome was the odds ratio (OR) of IHD in patients with versus without vWD. Secondary outcomes were major medical comorbidities and demographic characteristics in patients with vWD. Of 224,475,443 weighted hospital-discharge samples, we identified 82,809 patients with a vWD diagnosis. The odds of IHD were lower in patients with vWD than in those without (OR=0.54; 95% CI, 0.52-0.56). After multivariable logistic regression analysis and adjustment for age, sex, and typical IHD risk factors (hypertension, smoking, diabetes, hyperlipidemia, chronic kidney disease, obesity, and family history of IHD), the likelihood of IHD remained lower in patients with vWD than in patients without (OR=0.65; 95% CI, 0.63-0.67). Our study shows that vWF deficiency, as seen in patients with vWD, is associated with a decreased prevalence of IHD. Further investigation may confirm these findings.

Postpartum Hemorrhage in Women with von Willebrand Disease: Consider Other Etiologies.

OBJECTIVE: Higher rates of postpartum hemorrhage (PPH) have been reported for women with von Willebrand disease (VWD). Comprehensive multidisciplinary care reduces these rates; thus PPH may not be secondary to VWD. METHODS: We conducted a retrospective review for the period of 2009-2018, including all VWD pregnancies at 2 tertiary care academic hospitals to determine rates, etiology, and timing of PPH. RESULTS: A total of 63 women with 80 pregnancies were included. Three women had twin pregnancies. Sixty-six pregnancies (82.5%) involved type 1 VWD; 4 (5.0%), type 2 (unclear subtype); 3 (3.8%) type 2A; 3 (3.8%) type 2B; and 2 (2.5%), type 2M. Median age of patients was 32.9 years (range 19-43 y). Most patients were blood type O (65%), and 33 of 80 pregnancies (41.3%) were nulliparous. The mean bleeding assessment score was 8 (range 0-16). Thirty-seven pregnancies (46.3%) received prophylactic hemostatic treatment prior to delivery. Seventy-four percent of pregnancies were delivered vaginally, and 88% received epidural anaesthesia. The majority of pregnancies (78.8%) had von Willebrand factor (VWF) levels assessed during the third trimester, with most (71.3%) achieving VWF levels above 1.00 IU/mL. Four pregnancies (5.2%) were complicated by primary PPH; uterine atony in 2 and placenta previa in 1. Delayed postpartum bleeding occurred in 5 pregnancies (6.3%). CONCLUSION: Multidisciplinary care of pregnancies with VWD improves outcomes. Rates of primary and delayed PPH in this study are lower than previously described and are similar to those of women without VWD. In women with VWD, uterine etiologies for primary PPH need to be considered, in a manner similar to the assessment of women without VWD, to ensure hemostasis is achieved.

VWF-Gly2752Ser, a novel non-cysteine substitution variant in the CK domain, exhibits severe secretory impairment by hampering C-terminal dimer formation.

BACKGROUND: Von Willebrand factor (VWF) is a multimeric glycoprotein that plays important roles in hemostasis and thrombosis. C-terminal interchain-disulfide bonds in the cystine knot (CK) domain are essential for VWF dimerization. Previous studies have reported that missense variants of cysteine in the CK domain disrupt the intrachain-disulfide bond and cause type 3 von Willebrand disease (VWD). However, type 3 VWD-associated noncysteine substitution variants in the CK domain have not been reported. OBJECTIVE: To investigate the molecular mechanism of a novel non-cysteine variant in the CK domain, VWF c.8254 G>A (p.Gly2752Ser), which was identified in a patient with type 3 VWD as homozygous. METHODS: Genetic analysis was performed by whole exome sequencing and Sanger sequencing. VWF multimer analysis was performed using SDS-agarose electrophoresis. VWF production and subcellular localization were analyzed using ex vivo endothelial colony forming cells (ECFCs) and an in vitro recombinant VWF (rVWF) expression system. RESULTS: The patient was homozygous for VWF-Gly2752Ser. Plasma VWF enzyme-linked immunosorbent assay showed that the VWF antigen level of the patient was 1.2% compared with healthy subjects. A tiny amount of VWF was identified in the patient's ECFC. Multimer analysis revealed that the circulating VWF-Gly2752Ser presented only low molecular weight multimers. Subcellular localization analysis of VWF-Gly2752Ser-transfected cell lines showed that rVWF-Gly2752Ser was severely impaired in its ER-to-Golgi trafficking. CONCLUSION: VWF-Gly2752Ser causes severe secretory impairment because of its dimerization failure. This is the first report of a VWF variant with a noncysteine substitution in the CK domain that causes type 3 VWD.