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Background: While bleeding around pregnancy is well described in von Willebrand disease (VWD), the risk of pregnancy loss is less certain., Objectives: We aimed to describe the frequency of pregnancy loss in females with VWD compared with those with a similar mucocutaneous bleeding phenotype and no VWD or compared with nonbleeding disorder controls., Methods: Female patients were consecutively approached in 8 specialty bleeding disorder clinics between 2014 and 2023. The VWD group was defined as having von Willebrand factor (VWF) antigen and VWF activity levels, each <0.50 IU/mL on ≥2 occasions, and a condensed MCMDM-1 score of ≥4. The non-VWD mucocutaneous bleeding disorder group had VWF levels ≥ 0.50 IU/mL on ≥2 occasions and an MCMDM-1 score ≥ 4. A nonbleeding disorder control group was recruited in pregnancy from a low-risk maternity clinic., Results: There were 150 females in the VWD group, 145 in the non-VWD mucocutaneous bleeding disorder group, and 137 in the control group. There was a similar frequency of individuals with ≥1 loss in the VWD group (45.3%, 68/150), the non-VWD group (56.6%; 82/145; -11.2%; 97.5% CI, -24.2%, 1.8%), and the nonbleeding disorder control group (37.2%; 51/137; 8.1%; 97.5% CI, -4.9%, 21.1%). Using a logistic regression, the odds ratio of pregnancy losses in the VWD group vs the non-VWD group was 0.94 (95% CI 0.65, 1.36). All groups experienced more recurrent losses compared with the literature., Conclusion: There was no statistically significant difference in risk of pregnancy loss between females with VWD, females with a similar mucocutaneous bleeding phenotype, and nonbleeding disorder controls., Competing Interests: Declaration of Competing Interests L.S.: research funding by CSL Behring for the current study; honoraria from Leo Pharma and Sanofi; P.J. receives consultancy fees from Star/Vega Therapeutics, Band/Guardian Therapeutics, BioMarin, and Roche; K.U.: research funding by CSL Behring, Roche, Novo Nordisk, and Bayer; honoraria from Takeda, Biocryst, and Novo Nordisk; M.S. received consultancy fees from Star/Vega Therapeutics and honoraria for speaking engagements used to support publication fees/trainee travel for research, and unrestricted research funding from Pfizer, Octapharma, Novo Nordisk, and Sobi; A.C.: consultant for Synergy and the New York Blood Center and has received authorship royalties from UpToDate. M.-C.P.: grant funding from Bayer and CSL-Behring; advisory boards: Bayer, CSL-Behring, KVR Pharma, Novo Nordisk, Octapharma, Pfizer, Roche, SOBI, and Takeda. All other authors report no conflicts of interest., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: Inhibitor eradication to restore factor (F)VIII efficacy is the treatment goal for persons with severe hemophilia A (HA) and inhibitors. Immune tolerance induction (ITI) is demanding and successful in about 70% of people. Until now, it has remained difficult to quantify the probability of ITI success or failure, complicating the decision to initiate or not initiate ITI. Estimating the individual chance of ITI success allows clinicians, patients, and their families to support shared decision-making., Objectives: We aimed to identify clinical predictors of ITI success and to develop a clinical prediction model to estimate the chance of successful ITI in persons with severe HA., Methods: This multicenter study included persons with severe HA who received ITI. Clinical data were collected. Successful ITI was defined by a negative inhibitor titer and an adequate response to FVIII concentrates. A multivariable logistic regression model was developed. Model performance and internal validation were performed., Results: Of 206 participants with a median age of 19.8 months (IQR, 12.1-38.8) at ITI start, 148 (71.8%) achieved ITI success. Our clinical prediction model included 4 predictors of ITI success: cumulative number of FVIII exposure days at inhibitor development, peak inhibitor titer, ethnicity, and F8 mutation type. The C statistic was 0.801 (95% CI, 0.70-0.87)., Conclusion: In our study, including 206 people with severe HA and inhibitors, we developed a clinical prediction model to estimate the chance of successful ITI. After future external validation, this clinical prediction model may be useful for informing clinicians and families., (© 2024 The Author(s).)

Rare missense mutations in the von Willebrand factor (VWF) A3 domain that disrupt collagen binding have been found in patients with a mild bleeding phenotype. However, the analysis of these aberrant VWF-collagen interactions has been limited. Here, we have developed mouse models of collagen-binding mutants and analyzed the function of the A3 domain using comprehensive in vitro and in vivo approaches. Five loss-of-function (p.S1731T, p.W1745C, p.S1783A, p.H1786D, A3 deletion) and 1 gain-of-function (p.L1757A) variants were generated in the mouse VWF complementary DNA. The results of these various assays were consistent, although the magnitude of the effects were different: the gain-of-function (p.L1757A) variant showed consistent enhanced collagen binding whereas the loss-of-function mutants showed variable degrees of functional deficit. We further analyzed the impact of direct platelet-collagen binding by blocking glycoprotein VI (GPVI) and integrin α2β1 in our ferric chloride murine thrombosis model. The inhibition of GPVI demonstrated a comparable functional defect in thrombosis formation to the VWF(-/-) mice whereas α2β1 inhibition demonstrated a milder bleeding phenotype. Furthermore, a delayed and markedly reduced thrombogenic response was still evident in VWF(-/-), GPVI, and α2β1 blocked animals, suggesting that alternative primary hemostatic mechanisms can partially rescue the bleeding phenotype associated with these defects., (© 2014 by The American Society of Hematology.)

Genetic variation in or near the C-type lectin domain family 4 member M (CLEC4M) has been associated with plasma levels of von Willebrand factor (VWF) in healthy individuals. CLEC4M is a lectin receptor with a polymorphic extracellular neck region possessing a variable number of tandem repeats (VNTR). A total of 491 participants (318 patients with type 1 von Willebrand disease [VWD] and 173 unaffected family members) were genotyped for the CLEC4M VNTR polymorphism. Family-based association analysis on kindreds with type 1 VWD demonstrated an excess transmission of VNTR 6 to unaffected individuals (P = .0096) and an association of this allele with increased VWF:RCo (P = .029). CLEC4M-Fc bound to VWF. Immunofluorescence and enzyme-linked immunosorbent assay demonstrated that HEK 293 cells transfected with CLEC4M bound and internalized VWF. Cells expressing 4 or 9 copies of the CLEC4M neck region VNTR showed reduced interaction with VWF relative to CLEC4M with 7 VNTR (CLEC4M 4%-60% reduction, P < .001; CLEC4M 9%-45% reduction, P = .006). Mice expressing CLEC4M after hydrodynamic liver transfer have a 46% decrease in plasma levels of VWF (P = .0094). CLEC4M binds to and internalizes VWF, and polymorphisms in the CLEC4M gene contribute to variable plasma levels of VWF.

A personal history of excessive mucocutaneous bleeding is a key component in the diagnosis of a number of mild bleeding disorders, including von Willebrand disease (VWD), platelet function disorders (PFD), and coagulation factor deficiencies. However, the evaluation of hemorrhagic symptoms is a well-recognized challenge for both patients and physicians, because the reporting and interpretation of bleeding symptoms is subjective. As a result, bleeding assessment tools (BATs) have been developed and studied in a variety of clinical settings. This work has been pioneered by a group of Italian researchers, and the resultant 'Vicenza Bleeding Questionnaire' stands as the original BAT. In this review, we will discuss the modifications of the Vicenza Bleeding Questionnaire that have taken place over the years, as well as the validation studies that have been published. Other BATs that have been developed and published will be reviewed, as will the special situations of assessing pediatric bleeding as well as menorrhagia. Lastly, the clinical utility of BATs will be discussed including remaining challenges and future directions for the field., (© 2012 International Society on Thrombosis and Haemostasis.)