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Abstract: Expression of the thrombomodulin (TM) variant c.1611C>A (p.Cys537Stop) leads to the synthesis of a protein with no cytoplasmic tail and a transmembrane domain shortened by 3 amino acids (TM536). However, little is known regarding the release mechanism and properties of TM536. Using umbilical vein endothelial cells and peripheral blood-derived endothelial colony-forming cells from a heterozygous carrier of the TM536 variant as well as overexpression cell models, we demonstrated that TM536 is released from cells by an unusual mechanism. First, TM536 is inserted into the endoplasmic reticulum (ER) membrane, then, because of the low hydrophobicity of its intramembrane domain, it escapes from it and follows the conventional secretory pathway to be released into the extracellular compartment without the involvement of proteolysis. This particular secretion mechanism yields a soluble TM536, which is poorly modified by chondroitin sulfate glycosaminoglycan compared with conventionally secreted soluble forms of TM, and therefore has a suboptimal capacity to mediate thrombin-dependent activation of protein C (PC). We also showed that TM536 cellular trafficking was altered, with retention in the early secretory pathway and increased sensitivity to ER-associated degradation. As expected, activation of ER-associated degradation increased TM536 degradation and reduced its release. The expression of TM536 at the cell surface was low, and its distribution in lipid raft-like membrane microdomains was altered, resulting in low thrombin-dependent PC activation on the cell surface., (© 2024 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)

Introduction: Long term-recurrence risk following a pregnancy associated venous thromboembolism (VTE) is sparsely assessed., Objective: To determine the rate of recurrence after a pregnancy associated VTE, and identify associated risk factors., Method: Five hundred and eighty-seven women with a history of first VTE occurring during pregnancy or until 3 months after delivery were referred to La Timone Hospital, Marseille, France. Women were consecutively included between 2000 and 2015. VTE characteristics and biological parameters were collected at inclusion. During the 2016-2019 period, patients were recontacted to gather information on post-inclusion VTE. A weighted Cox model, adapted to the study's ambispective design, was used to analyse pre- and post-inclusion VTE recurrences., Results: After quality controls, 583 women were analyzed. Incidence of recurrent VTE was 2.4% person-years. Cumulative risk of VTE recurrence was 38% (n=221), with a median follow-up of 31 years (95%CI [27-35]); 6%, 13%, 17%, 30% at 2, 5, 10 and 30 years respectively. Pulmonary embolism (PE) at first event was associated with a 2-fold increased risk of PE at recurrence compared with isolated deep venous thrombosis (DVT, Hazard Ratio (HR)=2.63, 95%CI [1.44-4.82]). Risk factors significantly associated with recurrence were: interrupted pregnancies (HR=1.85, 95%CI [1.18-2.90]; lower limb DVT (HR=2.95, 95%CI [1.16-7.49] and AB blood group (HR=1.71, 95%CI [1.06-2.77])., Conclusion: Although the recurrence risk is low within the first 10 years after a pregnancy associated VTE, 1/3 patients experienced a new event over a 30-year period. Interrupted pregnancies, lower limb DVT, and AB blood group were associated with higher risk of recurrence., (Copyright © 2024. Published by Elsevier Inc.)

Background: Any surgical procedure carries a risk for venous thromboembolism (VTE), albeit variable. Improvements in medical and surgical practices and the shortening of care pathways due to the development of day surgery and enhanced recovery after surgery, have reduced the perioperative risk for VTE., Objective: A collaborative working group of experts in perioperative haemostasis updated in 2024 the recommendations for the Prevention of perioperative venous thromboembolism published in 2011., Methods: The addressed questions were defined by 40 experts (GIHP, SFAR, SFTH and SFMV) and formulated in a PICO format. They performed the literature review and formulated recommendations according to the Grading of GRADE system. Recommendations were then validated by a vote determining the strength of each recommendation. Of note, these recommendations do not cover all surgical specialties. Especially, thromboprophylaxis in cardiac surgery, neurosurgery and obstetrics is not addressed., Results: 78 recommendations were formalized into 17 sections, including patient-related VTE risk factors, types of surgery, extreme body weight, renal impairment, mechanical prophylaxis, distal deep vein thrombosis; 27 were found to have a high level of evidence (GRADE 1) and 41 a low level of evidence (GRADE 2) and 10 were expert opinion. All had strong agreement among the experts., Conclusions: These guidelines help to weigh the perioperative risk for VTE (which includes the risk associated to surgery and the patient-related risk) against the adverse effects of thromboprophylaxis, either pharmacological or mechanical. This includes particularly the bleeding risk induced by antithrombotic drugs as well as costs., (Copyright © 2024. Published by Elsevier Masson SAS.)

Background: Factor V (FV) is a key molecular player in the coagulation cascade. FV plasma levels have been associated with several human diseases, including thrombosis, bleeding, and diabetic complications. So far, 2 genes have been robustly found through genome-wide association analyses to contribute to the inter-individual variability of plasma FV levels: structural F5 gene and PLXDC2., Methods and Results: The authors used the underestimated Brown-Forsythe methodology implemented in the QuickTest software to search for non-additive genetic effects that could contribute to the inter-individual variability of FV plasma activity. QUICKTEST was applied to 4 independent genome-wide association studies studies (LURIC [Ludwigshafen RIsk and Cardiovascular Health Study], MARTHA [Marseille Thrombosis Association], MEGA [Multiple Environmental and Genetic Assessment], and RETROVE [Riesgo de Enfermedad Tromboembolica Venosa]) totaling 4505 participants of European ancestry with measured FV plasma levels. Results obtained in the 4 cohorts were meta-analyzed using a fixed-effect model. Additional analyses involved exploring haplotype and gene×gene interactions in downstream investigations. A genome-wide significant signal at the PSKH2 locus on chr8q21.3 with lead variant rs75463553 with no evidence for heterogeneity across cohorts was observed ( P =0.518). Although rs75463553 did not show an association with mean FV levels ( P =0.49), it demonstrated a robust significant ( P =3.38x10 -9 ) association with the variance of FV plasma levels. Further analyses confirmed the reported association of PSKH2 with neutrophil biology and revealed that rs75463553 likely interacts with two loci, GRIN2A and POM121L12 , known for their involvement in smoking biology., Conclusions: This comprehensive approach identifies the role of PSKH2 as a novel molecular player in the genetic regulation of FV, shedding light on the contribution of neutrophils to FV biology.

Hypercoagulable states, also called thrombophilia, can either be congenital or acquired. Congenital thrombophilia, associated mainly with venous thrombosis, is either secondary to coagulation-inhibitor deficiencies, i.e., antithrombin, protein C and Protein S, or gain of function mutations, i.e., factor V Leiden and prothrombin G20210A mutations. Despite the relative frequency of these two mutations, they have not been associated with venous thrombosis recurrence. Most prevalent thrombophilia have a limited impact and usually does not change indications for duration of antithrombotic treatment or prophylaxis compared to decisions based on clinical factors. However, rare inherited thrombophilia such as antithrombin deficiency could justify a long-term anticoagulation. The main acquired thrombophilia, the Antiphospholipid syndrome (APS), is associated with both arterial and venous thrombosis. Its impact on patient management is significant: choice of the anticoagulant (DOAC vs. warfarin), duration of anticoagulation, screening of any organ involvement and systemic autoimmune disease, introduction of immunosuppressive therapy., Competing Interests: Disclosure of interest Dr. Emmerich reports he has no conflicts of interest. Dr. Zuily reports he has no conflicts of interest. Dr. Gouin-Thibault reports board membership or symposia from BMS, Bayer, Leo Pharma, Stago, Viatris. Dr. Couturaud reports having received research grant support from Bayer, Bristol-Myers Squibb/Pfizer, Merck Sharp and Dohme and fees for board memberships or symposia from Bayer, Bristol-Myers Squibb/Pfizer, Merck Sharp and Dohme, GlaxoSmithKline, Chiesi and Astra Zeneca and having received travel support from Bayer, Bristol-Myers Squibb/Pfizer, Merck Sharp and Dohme, Leo Pharma, Sanofi, Chiesi. Dr. Morange reports having research grant support from Bristol-Myers Squibb and fees for board memberships or symposia from Bayer, Bristol-Myers Squibb/Pfizer and Sanofi. Dr. Huisman reports no conflicts of interest., (Copyright © 2024. Published by Elsevier Masson SAS.)

Genetic studies have identified numerous regions associated with plasma fibrinogen levels in Europeans, yet missing heritability and limited inclusion of non-Europeans necessitates further studies with improved power and sensitivity. Compared with array-based genotyping, whole genome sequencing (WGS) data provides better coverage of the genome and better representation of non-European variants. To better understand the genetic landscape regulating plasma fibrinogen levels, we meta-analyzed WGS data from the NHLBI's Trans-Omics for Precision Medicine (TOPMed) program (n=32,572), with array-based genotype data from the Cohorts for Heart and Aging Research in Genomic Epidemiology (CHARGE) Consortium (n=131,340) imputed to the TOPMed or Haplotype Reference Consortium panel. We identified 18 loci that have not been identified in prior genetic studies of fibrinogen. Of these, four are driven by common variants of small effect with reported MAF at least 10 percentage points higher in African populations. Three signals (SERPINA1, ZFP36L2, and TLR10) contain predicted deleterious missense variants. Two loci, SOCS3 and HPN, each harbor two conditionally distinct, non-coding variants. The gene region encoding the fibrinogen protein chain subunits (FGG;FGB;FGA), contains 7 distinct signals, including one novel signal driven by rs28577061, a variant common in African ancestry populations but extremely rare in Europeans (MAFAFR=0.180; MAFEUR=0.008). Through phenome-wide association studies in the VA Million Veteran Program, we found associations between fibrinogen polygenic risk scores and thrombotic and inflammatory disease phenotypes, including an association with gout. Our findings demonstrate the utility of WGS to augment genetic discovery in diverse populations and offer new insights for putative mechanisms of fibrinogen regulation., (Copyright © 2024 American Society of Hematology.)

Venous thromboembolism (VTE) is a significant contributor to morbidity and mortality, with large disparities in incidence rates between Black and White Americans. Polygenic risk scores (PRSs) limited to variants discovered in genome-wide association studies in European-ancestry samples can identify European-ancestry individuals at high risk of VTE. However, there is limited evidence on whether high-dimensional PRS constructed using more sophisticated methods and more diverse training data can enhance the predictive ability and their utility across diverse populations. We developed PRSs for VTE using summary statistics from the International Network against Venous Thrombosis (INVENT) consortium genome-wide association studies meta-analyses of European- (71 771 cases and 1 059 740 controls) and African-ancestry samples (7482 cases and 129 975 controls). We used LDpred2 and PRS-CSx to construct ancestry-specific and multi-ancestry PRSs and evaluated their performance in an independent European- (6781 cases and 103 016 controls) and African-ancestry sample (1385 cases and 12 569 controls). Multi-ancestry PRSs with weights tuned in European-ancestry samples slightly outperformed ancestry-specific PRSs in European-ancestry test samples (e.g. the area under the receiver operating curve [AUC] was 0.609 for PRS-CSx_combinedEUR and 0.608 for PRS-CSxEUR [P = 0.00029]). Multi-ancestry PRSs with weights tuned in African-ancestry samples also outperformed ancestry-specific PRSs in African-ancestry test samples (PRS-CSxAFR: AUC = 0.58, PRS-CSx_combined AFR: AUC = 0.59), although this difference was not statistically significant (P = 0.34). The highest fifth percentile of the best-performing PRS was associated with 1.9-fold and 1.68-fold increased risk for VTE among European- and African-ancestry subjects, respectively, relative to those in the middle stratum. These findings suggest that the multi-ancestry PRS might be used to improve performance across diverse populations to identify individuals at highest risk for VTE., (© The Author(s) 2024. Published by Oxford University Press.)

Venous thromboembolism (VTE) is a common, serious condition that requires anticoagulation for at least three months to prevent recurrence and long-term complications. After this initial period, the decision to continue or stop anticoagulation depends on the balance between the risk of recurrent VTE and the risk of bleeding. Established guidelines suggest short-term anticoagulation for VTE caused by transient factors and indefinite anticoagulation for recurrent or cancer-associated VTE. However, for a first unprovoked VTE, decision-making remains challenging. Current predictive scores for recurrence and bleeding are not sufficiently reliable, and the safety and efficacy of reduced-dose anticoagulation remain unclear. In the future, precision and patient-centred medicine may improve treatment decisions in this area., Competing Interests: Declaration of competing interest Dr. Couturaud reports having received research grant support from Bayer, Bristol-Myers Squibb/Pfizer, Merck Sharp and Dohme and fees for board memberships or symposia from Bayer, Bristol-Myers Squibb/Pfizer, Merck Sharp and Dohme, GlaxoSmithKline, Chiesi and Astra Zeneca and having received travel support from Bayer, Bristol-Myers Squibb/Pfizer, Merck Sharp and Dohme, Leo Pharma, Sanofi, Chiesi. Dr.Morange reports having research grant support from Bristol-Myers Squibb and fees for board memberships or symposia from Bayer, Bristol-Myers Squibb/Pfizer and Sanofi. Dr Sevestre reports fees and travel support from Bristol-Myers Squibb, Viatris, Leo Pharma and Novartis. Dr. Meneveau declares he has no conflict of interest., (Copyright © 2024 Elsevier Masson SAS. All rights reserved.)

Background: The thrombin generation assay (TGA) evaluates the potential of plasma to generate thrombin over time, providing a global picture of an individual's hemostatic balance., Objectives: This study aimed to identify novel biological determinants of thrombin generation using a multiomics approach., Methods: Associations between TGA parameters and plasma levels of 377 antibodies targeting 236 candidate proteins for cardiovascular risk were tested using multiple linear regression analysis in 770 individuals with venous thrombosis from the Marseille Thrombosis Association (MARTHA) study. Proteins associated with at least 3 TGA parameters were selected for validation in an independent population of 536 healthy individuals (Etablissement Français du Sang Alpes-Méditerranée [EFS-AM]). Proteins with strongest associations in both groups underwent additional genetic analyses and in vitro experiments., Results: Eighteen proteins were associated (P < 1.33 × 10⁻ 4 ) with at least 3 TGA parameters in MARTHA, among which 13 demonstrated a similar pattern of associations in EFS-AM. Complement proteins C5 and C9 had the strongest associations in both groups. Ex vivo supplementation of platelet-poor plasma with purified C9 protein had a significant dose-dependent effect on TGA parameters. No effect was observed with purified C5. Several single nucleotide polymorphisms associated with C5 and C9 plasma levels were identified, with the strongest association for the C5 missense variant rs17611, which was associated with a decrease in C5 levels, endogenous thrombin potential, and peak in MARTHA. No association of this variant with TGA parameters was observed in EFS-AM., Conclusion: This study identified complement proteins C5 and C9 as potential determinants of thrombin generation. Further studies are warranted to establish causality and elucidate the underlying mechanisms., Competing Interests: Declaration of competing interests There are no competing interests to disclose., (Copyright © 2024 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

Background: Increased risk of venous thromboembolism (VTE) is a life-threatening side effect for users of oral contraceptives (OCs) or hormone therapy (HT)., Objectives: To investigate the potential for genetic predisposition to VTE in OC or HT users, we conducted a gene-by-environment case-only meta-analysis of genome-wide association studies (GWAS)., Methods: Use or nonuse of OCs (7 studies) or HT (8 studies) at the time of the VTE event was determined by pharmacy records or self-report. A synergy index (SI) was modeled for each variant in each study and submultiplicative/supramultiplicative gene-by-environment interactions were estimated. The SI parameters were first meta-analyzed across OC and HT studies and subsequently meta-analyzed to obtain an overall estimate. The primary analysis was agnostic GWAS and interrogated all imputed genotypes using a P value threshold of <5.0 × 10 -8 ; secondary analyses were candidate-based., Results: The VTE case-only OC meta-analysis included 2895 OC users and 6607 nonusers; the case-only HT meta-analysis included 2434 HT users and 12 793 nonusers. In primary GWAS meta-analyses, no variant reached genome-wide significance, but the smallest P value approached statistical significance: rs9386463 (P = 5.03 × 10 -8 ). We tested associations for 138 candidate variants and identified 2 that exceeded statistical significance (0.05/138 = 3.62 × 10 -4 ): F5 rs6025 (P = 1.87 × 10 -5 ; SI, 1.29; previously observed) and F11 rs2036914 (P = 2.0 × 10 -4 ; SI, 0.91; new observation)., Conclusion: The candidate variant approach to identify submultiplictive/supramultiplicative associations between genetic variation and OC and HT use identified a new association with common genetic variation in F11, while the agnostic interrogations did not yield new discoveries., Competing Interests: Declaration of competing interests T.N. receives speaking honoraria from Servier Finland and AstraZeneca. All other authors have no relevant disclosures., (Copyright © 2024 International Society on Thrombosis and Haemostasis. Published by Elsevier Inc. All rights reserved.)

This invited review follows the oral presentation "To Sequence or Not to Sequence, That Is Not the Question; But 'When, Who, Which and What For?' Is" given during the State of the Art session "Translational Genomics in Thrombosis: From OMICs to Clinics" of the International Society on Thrombosis and Haemostasis 2023 Congress. Emphasizing the power of next-generation sequencing technologies and the diverse strategies associated with DNA variant analysis, this review highlights the unresolved questions and challenges in their implementation both for the clinical diagnosis of venous thromboembolism and in translational research., Competing Interests: Declaration of competing interests There are no competing interests to disclose., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Abstract: Coagulation factor VIII (FVIII) and its carrier protein von Willebrand factor (VWF) are critical to coagulation and platelet aggregation. We leveraged whole-genome sequence data from the Trans-Omics for Precision Medicine (TOPMed) program along with TOPMed-based imputation of genotypes in additional samples to identify genetic associations with circulating FVIII and VWF levels in a single-variant meta-analysis, including up to 45 289 participants. Gene-based aggregate tests were implemented in TOPMed. We identified 3 candidate causal genes and tested their functional effect on FVIII release from human liver endothelial cells (HLECs) and VWF release from human umbilical vein endothelial cells. Mendelian randomization was also performed to provide evidence for causal associations of FVIII and VWF with thrombotic outcomes. We identified associations (P < 5 × 10-9) at 7 new loci for FVIII (ST3GAL4, CLEC4M, B3GNT2, ASGR1, F12, KNG1, and TREM1/NCR2) and 1 for VWF (B3GNT2). VWF, ABO, and STAB2 were associated with FVIII and VWF in gene-based analyses. Multiphenotype analysis of FVIII and VWF identified another 3 new loci, including PDIA3. Silencing of B3GNT2 and the previously reported CD36 gene decreased release of FVIII by HLECs, whereas silencing of B3GNT2, CD36, and PDIA3 decreased release of VWF by HVECs. Mendelian randomization supports causal association of higher FVIII and VWF with increased risk of thrombotic outcomes. Seven new loci were identified for FVIII and 1 for VWF, with evidence supporting causal associations of FVIII and VWF with thrombotic outcomes. B3GNT2, CD36, and PDIA3 modulate the release of FVIII and/or VWF in vitro.

Introduction: Bleeding severity in severe haemophilic patients, with low thrombin generation (TG) capacity, can vary widely between patients, possibly reflecting differences in tissue factor pathway inhibitor (TFPI) level., Aim: To compare free TFPI (fTFPI) levels in patients with severe haemophilia A (sHA) and severe haemophilia B (sHB) and to investigate in these patients as a whole the relationships between bleeding and TG potential, between TG potential and fTFPI level and between fTFPI level and bleeding tendency., Methods: Data on bleeding episodes retrospectively recorded during follow-up visits over 5-10 years were collected and used to calculate the annualised joint bleeding rate (AJBR). fTFPI levels and basal TG parameters were determined in platelet-poor plasma (PPP) and platelet-rich plasma (PRP) using calibrated automated tomography (CAT)., Results: Mean fTFPI levels did not differ significantly between sHA (n = 34) and sHB (n = 19) patients. Mean values of endogenous thrombin potential (ETP) and thrombin peak (peak) in PPP and PRP were two-fold higher when fTFPI levels < 9.4 versus > 14.3 ng/mL. In patients treated on demand, ETP and peak in PRP were doubled when AJBR was ≤ 4.9 $ \le 4.9$ , AJBR being halved in patients with a low fTFPI level (9.4 ng/mL). In patients on factor prophylaxis, no association was found between TG parameters and either fTFPI level or AJBR., Conclusion: In patients treated on demand, bleeding tendency was influenced by fTFPI levels, which in turn affected basal TG potential. In patients on prophylaxis, bleeding tendency is probably determined primarily by the intensity of this treatment., (© 2024 The Authors. Haemophilia published by John Wiley & Sons Ltd.)

Background: Inherited bleeding, thrombotic, and platelet disorders (BTPDs) are a heterogeneous set of diseases, many of which are very rare globally. Over the past 5 decades, the genetic basis of some of these disorders has been identified, and recently, high-throughput sequencing has become the primary means of identifying disease-causing genetic variants., Objectives: Knowledge of the clinical validity of a gene-disease relationship is essential to provide an accurate diagnosis based on results of diagnostic gene panel tests and inform the construction of such panels. The Scientific and Standardization Committee for Genetics in Thrombosis and Hemostasis undertook a curation process for selecting 96 TIER1 genes for BTPDs. The purpose of the process was to evaluate the evidence supporting each gene-disease relationship and provide an expert-reviewed classification for the clinical validity of genes associated with BTPDs., Methods: The Clinical Genome Resource (ClinGen) Hemostasis/Thrombosis Gene Curation Expert Panel assessed the strength of evidence for TIER1 genes using the semiquantitative ClinGen gene-disease clinical validity framework. ClinGen Lumping and Splitting guidelines were used to determine the appropriate disease entity or entities for each gene, and 101 gene-disease relationships were identified for curation., Results: The final outcome included 68 Definitive (67%), 26 Moderate (26%), and 7 Limited (7%) classifications. The summary of each curation is available on the ClinGen website., Conclusion: Expert-reviewed assignment of gene-disease relationships by the ClinGen Hemostasis/Thrombosis Gene Curation Expert Panel facilitates accurate molecular diagnoses of BTPDs by clinicians and diagnostic laboratories. These curation efforts can allow genetic testing to focus on genes with a validated role in disease., Competing Interests: Declaration of competing interests The following authors are employee, trainee, or consultant for a commercial laboratory offering genetic testing related to disorders of hemostasis/thrombosis: L.B., K.F., P.G., C.K., J.P.B., M.S., and J.Z. The following authors have made substantial contributions to the literature on gene-disease relationships relevant to this work: L.B., K.D., K.F., P.G., C.K., M.L., K.M., P.M., N.M., J.P.B., N.S., and K.Z. Additionally, K.F. chairs the Scientific and Standardization Committee for Genetics in Thrombosis and Hemostasis of the International Society on Thrombosis and Hemostasis. The other authors declare no conflicts of interest., (Copyright © 2023 International Society on Thrombosis and Haemostasis. All rights reserved.)