Development of a Rapid and Fully Automated Factor VIII-Inhibitor Assay, Insensitive for Emicizumab, and a Lowest Level of Quantification of 0.2BU/mL.

BACKGROUND: Factor VIII inhibitors are measured using labour and resource expensive Nijmegen or Bethesda assays, which lack sensitivity for low-titre-inhibitors, and show high variations in quality surveys, mainly because of manual assay procedures. METHODS: A new rapid, fully automated, factor VIII inhibitor assay is presented, the core of which is use of full-length recombinant FVIII (rFVIII) (Kovaltry®) as inhibitor substrate instead of plasma FVIII, resulting in rapid binding of inhibitors to rFVIII due to absence of VWF. Dramatic shortening of incubation time facilitated full automation on an analyser capable of three subsequent sample dilution steps and three reagent additions. Equal volume mixtures of sample and rFVIII (1.0 U/mL) were incubated 10 minutes/37°C, whereafter remaining FVIII-activity was analysed with a kinetic chromogenic assay, allowing inhibitor-activity calculation without preceding FVIII-activity calibration, using a Ceveron s100 analyser. RESULTS: Mean titre in 60 non-haemophiliacs was 0.0BU/mL (SD 0.1), yielding a Limit-of-Blank of 0.1BU/mL and Lower-Limit-of-Quantification of 0.2BU/mL. Analyses were performed with the new method and a Nijmegen Assay in 28 inhibitor-positive clinical samples, 14 containing emicizumab and 14 without. Correlation coefficient in emicizumab-free type-I-inhibitor samples was r=1.0. Emicizumab dependency of the method was excluded in spiking experiments with inhibitor-positive-samples. Reproducibility was tested by analysing seven samples in three laboratories on five days, twice daily; CV of all samples were <15%. CONCLUSION: We present development data of a sensitive and specific, rapid, automated FVIII inhibitor assay generating results within 20 minutes, is less resource intensive than standard assays, with potential to improve assay variability.

Genotype-phenotype analyses of Iranian patients with hemophilia B (Leyden -) and hemophilia B (Leyden +): A single-center study.

BACKGROUND: There is a high prevalence of inherited bleeding disorders in Iran, such as hemophilia A (HA) and hemophilia B (HB). This study aimed to analyze the molecular and clinical profiles of patients with HB. METHODS: A single-center study was conducted among patients with severe HB between March 20, 2000, and June 31, 2023. The polymerase chain reaction (PCR) amplification was used for all of the major regions, such as the promoter, the exons, the adjacent intronic regions, and the untranslated regions of the F9 gene. Finally, Sanger sequencing was performed on the PCR products. RESULTS: A total of 111 HB patients (17 with HB [Leyden +] and 94 with HB [Leyden -]) were enrolled in this study. Among 94 patients with HB (Leyden -), 59 (62.8 %) had missense, 21 (22.3 %) had nonsense, and 8 (8.5 %) had frameshift mutations. Moreover, the most frequent pathogenic variant in HB (Leyden +) was c.-17 A>G in this study. CONCLUSION: The results of this study confirm that HB is caused by a wide range of molecular defects in Iran. Thus, by knowing the genotypes and phenotypes, we would be able to stratify the patients which is important in terms of their management and outcome.

A Rare Case of Acquired Factor VIII Inhibition in an Elderly Female.

Acquired hemophilia A is a rare condition characterized by the development of autoantibodies against coagulation factor VIII. It often initially presents as serious bleeding in the absence of risk factors and carries high morbidity and mortality if not diagnosed early. Due to its rare nature, data is limited, and guidelines are primarily based on expert opinion. Here we present a case of an elderly patient with severe gastrointestinal bleeding found to have activated partial thromboplastin times, plasma mixing studies, and coagulation factor activity levels consistent with acquired hemophilia A. We hope to bring awareness of this rare disease and promote its consideration in the differential of unexpected bleeding to improve safety outcomes.

[Novel treatment strategies for acquired hemophilia A].

Acquired hemophilia A (AHA) is a bleeding disorder caused by autoantibody (inhibitor) production targeting blood coagulation factor VIII (FVIII). It is characterized by sudden onset, and often causes extensive and severe bleeding in soft tissue. Acquired hemophilia A is diagnosed when coagulation tests show normal PT, prolonged APTT, decreased FVIII activity, normal VWF activity, and positive FVIII inhibitor. Hemostatic therapy mainly consists of bypass therapy, which activates the extrinsic coagulation pathway, bypassing the need for FVIII or factor IX. Emicizumab, a bispecific antibody that substitutes for FVIII function, can be used to prevent bleeding. Immunosuppressive therapy is necessary to suppress or eradicate inhibitors. The majority of patients go into remission with treatment, but some die from bleeding symptoms or infections associated with immunosuppressive therapy.

First-line immunosuppressive therapies for acquired hemophilia A: A 25-year cohort experience and network meta-analysis.

Acquired hemophilia A (AHA) presents a significant bleeding risk. Management involves bleeding control and immunosuppressive therapy (IST) to eliminate inhibitors. This study, encompassing a retrospective cohort of 76 newly diagnosed AHA patients (1997-2022), evaluated IST outcomes such as complete remission (CR), relapse, and mortality rates, alongside influencing factors. Supplementing these findings, a systematic review and network meta-analysis compared CR and relapse rates across ISTs, sourcing from Embase, Scopus, and ScienceDirect up to November 2023. In our cohort, demarcated by a 20 Bethesda-unit titer threshold, cyclophosphamide plus prednisolone (CP; n = 64) was the predominant initial IST. Lower inhibitor levels significantly correlated with higher CR rates (86.8 % vs 62.2 %; P = .014) and showed an odds ratio of 0.26 for CR (P = .021). Median relapse-free survival (RFS) extended to 37.13 months, significantly enhanced by CP (hazard ratio, 0.24; 95 % confidence interval, 0.10-0.60; P = .002). Our network meta-analysis, including 1476 CR and 636 relapse patients, indicated CP and rituximab-based ISTs significantly outperformed steroid monotherapy in terms of CR and lower relapse rates (risk differences of 0.15 and -0.13/-0.15, respectively; P < .05), without significant differences between CP and rituximab. Moreover, adding rituximab to the front-line treatment did not produce superior outcomes compared to the CP regimen alone, positioning CP as a viable first-line choice, particularly where rituximab is less accessible. The consideration of IST toxicity remains critical in treatment decisions.

F8 variants and their genotype-phenotype correlations in Thai patients with haemophilia A: a nationwide multicentre study.

AIMS: Analysis of the F8 gene helps predict the risk of developing factor VIII (FVIII) inhibitors and the depth of phenotype in haemophilia A (HA) patients. Since data in Southeast Asian countries remain scarce, we aim to study F8 variation correlated with HA phenotypes in Thailand. METHODS: Thai patients with HA were enrolled from seven haemophilia treatment centres during 2022-2023. Using peripheral blood DNA, inverse shifting-polymerase chain reaction (IS-PCR) for F8-intron 22 inversion (Inv22) and F8-intron 1 inversion (Inv1) was performed. Whole exome sequencing (WES) was explored in cases without Inv22/Inv1. RESULTS: Of 124 patients with HA, 91.9% were detected with a causative F8 variant, including Inv22 (30.6%), Inv1 (1.6%), missense (23.4%), nonsense (16.9%) and small insertion/deletion (16.1%) mutations. Inv22, small insertion/deletion and nonsense were associated with severe HA, compared with missense variants, by the ORs of 13.9 (95% CI, 4.2 to 56.7), 14.7 (95% CI, 3.4 to 104.7) and 15.6 (95% CI, 3.6 to 110.2), respectively. While nonsense variants affecting the light chain increased the risk of developing FVIII inhibitors (OR, 6.8; 95% CI, 1.5 to 32.6) compared with the low-risk (small insertion/deletion, missense and splice-site) variants. Twelve patients (9.7%) harboured novel F8 variants, comprising five missense (p.Pro540Leu, p.Ser564Pro, p.Leu668Pro, p.Ala1721Glu, p.His2024Pro), five small insertion/deletion (p.Val502SerfsTer13, p.Ile522PhefsTer13, p.Phe992LysfsTer11, p.Leu1223PhefsTer18, c.6427_6429+3delATGGTA) and one nonsense mutations (p.Glu1292Ter). CONCLUSIONS: IS-PCR followed by WES successfully assesses F8 alterations in most HA cases. With several unique variants, severe HA in Thailand is considerably caused by Inv22, small insertion/deletion and nonsense, whereas missense variants are more responsible for nonsevere HA phenotypes.

Joint health and pain in the changing hemophilia treatment landscape.

INTRODUCTION: Hemophilia is an inherited bleeding disorder. Bleeding, and in particular joint hemorrhage results in chronic arthropathy and disability. Acute and chronic pain are frequent and limit activity and participation and result in decreased health-related quality of life. Remarkable progress has been made in the diagnosis and treatment of hemophilia but bleeding continues to prove recalcitrant to currently available treatments and joint disease remains problematic. Physiotherapy and pain management are mainstays of current multidisciplinary integrated care of people with hemophilia (PWH). The focus of this review is on preservation of joint health in the era of new and innovative therapies. AREAS COVERED: A search of the PubMed Central was conducted on 1 February 2024 using the MeSH Major Topic terms identified as key words for the manuscript. This review will highlight what is known and unknown about joint bleeding and arthropathy, including insights on pain as a related complication. EXPERT OPINION: Recent advances in therapeutic interventions aimed at promoting healthy joints in PWH will be discussed, including both the pharmacological treatment landscape and related strategies to promote joint health.

Emicizumab as first-line therapy in acquired hemophilia A.

Acquired hemophilia A (AHA) is a rare autoimmune disease resulting from the development of autoantibodies directed against endogenous factor (F)VIII, leading to bleeding manifestations that can be life-threatening. The current standard hemostatic treatment involves the use of bypassing agents that circumvent FVIII (recombinant activated FVII, activated prothrombin complex concentrate, and recombinant porcine FVIII) that must be administered intravenously and possess a short half-life. These limitations and the risk of potentially fatal bleeding complications justify the early initiation of immunosuppressive treatment (IST) aimed at promptly eradicating the autoantibodies. IST is not without side effects, sometimes severe and possibly fatal, especially in persons with AHA who are generally older and have multiple comorbidities. Emicizumab, a bispecific antibody that mimics the action of FVIII, has emerged as an effective hemostatic therapy among persons with congenital hemophilia, whether complicated by the presence of anti-FVIII antibodies or not. Numerous arguments from recent clinical experiences suggest positioning emicizumab as a first-line treatment for AHA. This strategy has the potential to reduce bleeding complications and, importantly, the side effects associated with IST, which can be delayed and tailored to each patient.

Reconstruction of the historic time course of blood-borne virus contamination of clotting factor concentrates, 1974-1992.

Factor VIII and IX clotting factor concentrates manufactured from pooled plasma have been identified as potent sources of virus infection in persons with hemophilia (PWHs) in the 1970s and 1980s. To investigate the range and diversity of viruses over this period, we analysed 24 clotting factor concentrates for several blood-borne viruses. Nucleic acid was extracted from 14 commercially produced clotting factors and 10 from nonremunerated donors, preserved in lyophilized form (expiry dates: 1974-1992). Clotting factors were tested by commercial and in-house quantitative PCRs for blood-borne viruses hepatitis A, B, C and E viruses (HAV, HBV, HCV, HEV), HIV- types 1/2, parvoviruses B19V and PARV4, and human pegiviruses types 1 and 2 (HPgV-1,-2). HCV and HPgV-1 were the most frequently detected viruses (both 14/24 tested) primarily in commercial clotting factors, with frequently extremely high viral loads in the late 1970s-1985 and a diverse range of HCV genotypes. Detection frequencies sharply declined following introduction of virus inactivation. HIV-1, HBV, and HAV were less frequently detected (3/24, 1/24, and 1/24 respectively); none were positive for HEV. Contrastingly, B19V and PARV4 were detected throughout the study period, even after introduction of dry heat treatment, consistent with ongoing documented transmission to PWHs into the early 1990s. While hemophilia treatment is now largely based on recombinant factor VIII/IX in the UK and elsewhere, the comprehensive screen of historical plasma-derived clotting factors reveals extensive exposure of PWHs to blood-borne viruses throughout 1970s-early 1990s, and the epidemiological and manufacturing parameters that influenced clotting factor contamination.

Reduced Volume and Faster Infusion Rate of Activated Prothrombin Complex Concentrate: A Phase 3b/4 Trial in Adults with Hemophilia A with Inhibitors.

Background Activated prothrombin complex concentrate (aPCC) is indicated for bleed treatment and prevention in patients with hemophilia with inhibitors. The safety and tolerability of intravenous aPCC at a reduced volume and faster infusion rates were evaluated. Methods This multicenter, open-label trial (NCT02764489) enrolled adults with hemophilia A with inhibitors. In part 1, patients were randomized to receive three infusions of aPCC (85 ± 15 U/kg) at 2 U/kg/min (the approved standard rate at the time of the study), in a regular or 50% reduced volume, and were then crossed over to receive three infusions in the alternative volume. In part 2, patients received three sequential infusions of aPCC in a 50% reduced volume at 4 U/kg/min and then at 10 U/kg/min. Primary outcome measures included the incidence of adverse events (AEs), allergic-type hypersensitivity reactions (AHRs), infusion-site reactions (ISRs), and thromboembolic events. Results Of the 45 patients enrolled, 33 received aPCC in part 1 and 30 in part 2. In part 1, 24.2 and 23.3% of patients with regular and reduced volumes experienced AEs, respectively; 11 AEs in eight patients were treatment related. AHRs and ISRs occurred in four (12.1%) and two (6.1%) patients, respectively. In part 2, 3.3 and 14.3% of patients with infusion rates of 4 and 10 U/kg/min experienced AEs, respectively; only one AE in one patient was treatment related; no AHRs or ISRs were reported. Most AEs were mild/moderate in severity. Overall, no thromboembolic events were reported. Conclusions aPCC was well tolerated at a reduced volume and faster infusion rates, with safety profiles comparable to the approved regimen.

COVID-19 in the Setting of HIV and Severe Hemophilia A: A Case Report.

Introduction: A hyperactive immune response is the driving force behind severe Coronavirus disease 2019 (COVID-19). Complications of severe COVID-19 include acute respiratory distress syndrome, acute respiratory failure, and increased risk of venous thromboembolism (VTE). The management of patients with COVID-19 includes respiratory support, decreasing immune response to the virus to prevent the progression of disease, and anticoagulation to prevent VTE. Case Presentation: We present the case of a patient with a history of human immunodeficiency virus (HIV) and hemophilia A admitted with COVID-19. This case demonstrates the difficulties present when managing COVID-19 in patients with specific comorbidities. Anticoagulation is a recommended component of COVID-19 treatment but is contraindicated in patients with severe hemophilia due to increased risk for bleeding. Research has also shown that dexamethasone decreases mortality in patients with COVID-19, but doctors should use dexamethasone cautiously in patients with HIV since it is an immunosuppressant. Taking certain antiretroviral therapies, such as rilpivirine, also contraindicates the use of dexamethasone. Conclusion: In this case, it is important to monitor for the risk and presence of superimposed bacterial or opportunistic infections. Treating a patient with these comorbidities who is infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) highlights the importance of balancing the risks and benefits.

Artificial intelligence-assisted ultrasound imaging in hemophilia: research, development, and evaluation of hemarthrosis and synovitis detection.

Background: Joint bleeding can lead to synovitis and arthropathy in people with hemophilia, reducing quality of life. Although early diagnosis is associated with improved therapeutic outcomes, diagnostic ultrasonography requires specialist experience. Artificial intelligence (AI) algorithms may support ultrasonography diagnoses. Objectives: This study will research, develop, and evaluate the diagnostic precision of an AI algorithm for detecting the presence or absence of hemarthrosis and synovitis in people with hemophilia. Methods: Elbow, knee, and ankle ultrasound images were obtained from people with hemophilia from January 2010 to March 2022. The images were used to train and test the AI models to estimate the presence/absence of hemarthrosis and synovitis. The primary endpoint was the area under the curve for the diagnostic precision to diagnose hemarthrosis and synovitis. Other endpoints were the rate of accuracy, precision, sensitivity, and specificity. Results: Out of 5649 images collected, 3435 were used for analysis. The area under the curve for hemarthrosis detection for the elbow, knee, and ankle joints was ≥0.87 and for synovitis, it was ≥0.90. The accuracy and precision for hemarthrosis detection were ≥0.74 and ≥0.67, respectively, and those for synovitis were ≥0.83 and ≥0.74, respectively. Analysis across people with hemophilia aged 10 to 60 years showed consistent results. Conclusion: AI models have the potential to aid diagnosis and enable earlier therapeutic interventions, helping people with hemophilia achieve healthy and active lives. Although AI models show potential in diagnosis, evidence is unclear on required control for abnormal findings. Long-term observation is crucial for assessing impact on joint health.

Exploring nonreplacement therapies' impact on hemophilia and other rare bleeding disorders.

The management of hemophilia, von Willebrand disease (VWD), and rare coagulation disorders traditionally relied on replacement therapies, such as factor concentrates, to address clotting factor deficiencies. However, in recent years, the emergence of nonreplacement therapies has shown promise as an adjunctive approach, especially in hemophilia, and also for patients with VWD and rare bleeding disorders. This review article offers an overview of nonreplacement therapies, such as FVIII-mimicking agents and drugs aimed at rebalancing hemostasis by inhibiting natural anticoagulants, particularly in the management of hemophilia. The utilization of nonreplacement therapies in VWD and rare bleeding disorders has recently attracted attention, as evidenced by presentations at the International Society on Thrombosis and Haemostasis 2023 Congress. Nonreplacement therapies provide alternative methods for preventing bleeding episodes and enhancing patients' quality of life, as many of them are administered subcutaneously and allow longer infusion intervals, resulting in improved quality of life and comfort for patients.

Elevated memory T-cell conversion in a preclinical mouse model of hemophilia A.

One of the major challenges in the choice of the best therapeutic approach for the treatment of patients affected by hemophilia A (HA) is the definition of criteria predicting the formation of factor VIII (FVIII) neutralizing antibodies, called inhibitors. Both genetic and environmental elements influencing the immune response toward FVIII have been identified but still not all the factors causing the pathological rejection of FVIII have been identified. Since there is a connection between coagulation and inflammation, here we assessed the role played by the FVIII deficiency in shaping the humoral and cellular response toward an antigen other than FVIII itself. To this aim, we challenged both HA and wild-type (WT) mice with either FVIII or ovalbumin (OVA) and followed antigen-specific antibody level, immune cell population frequency and phenotype up to 9 weeks after the last antigen booster. The activation threshold was evaluated in vitro by stimulating the murine T cells with a decreasing dose of α-CD3. The humoral response to FVIII was similar between the two groups while both the in vivo and in vitro experiments highlighted an antigen-independent sensitivity of HA compared with WT T cells causing an increase in memory T-cell conversion and proliferation capability.

Emicizumab versus immunosuppressive therapy for the management of acquired hemophilia A.

BACKGROUND: Acquired hemophilia A (AHA) is an autoimmune bleeding disorder caused by neutralizing antibodies against coagulation factor VIII (FVIII). Immunosuppressive therapy (IST) is standard of care to eradicate autoantibody production and protect from further bleeding but carries a risk of severe infection and mortality in frail patients with AHA. Recently, emicizumab has been studied for its potential to reduce the need for early and aggressive IST. OBJECTIVE: To compare outcomes of two studies that used either IST (GTH-AH 01/2010; n=101) or prophylaxis with emicizumab (GHT-AHA-EMI; n=47) early after diagnosis of AHA. METHODS: Baseline characteristics were balanced by propensity score matching. Primary endpoint was the rate of clinically relevant new bleeds during the first 12 weeks; secondary endpoints were adverse events and overall survival. RESULTS: The negative binominal model-based bleeding rate was 68% lower with emicizumab as compared with IST (incident rate ratio 0.325, 95% confidence interval (CI) 0.182-0.581). No difference was apparent in the overall frequency of infections (emicizumab 21%, IST 29%) during the first 12 weeks, but infections were less often fatal in emicizumab treated patients (0%) compared with IST treated patients (11%). Thromboembolic events occurred less often with emicizumab (2%) than IST (7%). Overall survival after 24 weeks was better with emicizumab (90% versus 76%, HR 0.44; 95% CI 0.24-0.81). CONCLUSION: Using emicizumab instead of IST in the early phase after initial diagnosis of AHA reduced bleeding and fatal infections, and improved overall survival.

Identifying hemophilia B carriers: Utility of aPTT, factor IX levels and ratios of factor IX to other Vitamin K dependent factors.

INTRODUCTION: Diagnosing hemophilia B (HB) carrier status is important to manage bleeding in carriers and to prevent bleeding in potential offspring. Without a family history of hemophilia, diagnosing HB carrier status is challenging. Genetic testing is the gold-standard, however it is reserved for individuals with a high suspicion of carrier status. AIMS: To describe the distribution of activated partial thromboplastin time (aPTT) and factor IX coagulant (FIX:C) levels in HB carriers and assess the ratio of FIX:C to other Vitamin K dependent factors (FII:C, FVII:C, FX:C) as an indicator of HB carrier status. METHODS: In this retrospective, single-centre cohort study, subjects were included if they were obligate or genetically proven HB carriers. Distributions of aPTT and FIX:C were described and the relationship between FIX:C levels in carriers and severity of familial HB was analysed. Ratios of FIX:C to FII:C, FVII:C, FX:C were calculated. RESULTS: Seventy-two female HB carriers (median age: 34 years; IQR 24-43) were included. Median aPTT and FIX:C levels were 33.0 s [IQR 30.0-37.0] and 57 IU/dL [IQR 43-74]. Fifteen carriers (21%) had mild HB (FIX:C levels of 10-40 IU/dL). FIX:C levels trended higher in carriers of mild HB versus carriers of moderate/severe HB. In six carriers, the median ratio of FIX:C to other Vitamin K dependent factors was 0.44, with 92% of ratios being ≤ 0.75. CONCLUSION: aPTT and FIX:C levels were unreliable in diagnosing HB carrier status. A low ratio of FIX:C to other Vitamin K dependent factors may be a useful marker of HB carrier status.

Regular prophylaxis with activated prothrombin complex concentrates in pediatric hemophilia.

BACKGROUND: Regular prophylaxis with activated prothrombin complex concentrates (aPCCs) is effective in adult patients with hemophilia with inhibitors; however, data in children are scarce. METHODS: This was a single-center retrospective study at Saitama Children's Medical Center. Patients with severe and moderate hemophilia with inhibitors aged <15 years at the start of aPCCs prophylaxis were included. Medical records were retrospectively reviewed. RESULTS: We treated nine pediatric patients with hemophilia with inhibitors (median age, 1.9 years; age range, 1.3-12.9 years; inhibitor titers before treatment with aPCCs, 5.9-69 BU/mL) using prophylactic aPCCs (doses, 50-100 U/kg; 2-3 times/week). The median prophylactic period was 13 months (range: 5-31 months). The median annualized bleeding rate (ABR) during prophylactic treatment with aPCCs was 2 (range, 0-17). In four patients, ABR was reduced by 19%-100% with prophylactic aPCCs compared to on-demand aPCCs. An adverse effect of treatment was that a patient with hemophilia B developed nephrotic syndrome 34 months after starting regular prophylaxis with aPCCs. CONCLUSIONS: Regular prophylactic aPCCs reduced the ABR even in younger children with hemophilia A and B. Serious adverse events include nephrotic syndrome, which requires caution.

Deletion of Tissue Factor Pathway Inhibitor Isoform Beta or Gamma, but not Alpha, Improves Clotting in Hemophilia Mice.

BACKGROUND: Tissue factor pathway inhibitor (TFPI) regulates tissue factor (TF)-triggered coagulation. Humans and mice express transcripts encoding for multi-distributed (endothelial, platelet, and plasma) 3-Kunitz domain TFPIα and endothelial membrane-anchored 2-Kunitz TFPIß. Mice express a third transcript, γ, that encodes plasma lipoprotein-associated 2-Kunitz TFPI. In humans, proteolysis of α and/or ß produces plasma lipoprotein-associated 2-Kunitz TFPI at lower levels. In clinical trials, monoclonal antibodies that target all TFPI isoforms extend coagulation and correct bleeding in hemophilia patients but with some thrombosis risks. OBJECTIVES: Determine the impact of TFPI isoform-specific deletions on promoting clotting in hemophilia mice. METHODS: Engineered TFPI isoform-specific, hemophilia (FVIII-null) mice were evaluated for clotting. RESULTS: Mice expressing any single TFPI isoform are healthy. Thrombin generation assays identified TFPIγ as the dominant anticoagulation isoform in mouse plasma. Hemostasis was assessed by serial bleeding times from a tail vein laceration. Repeatedly, after a clot forms, it is manually disrupted; the number of clots/disruptions occurring over a 15-minute period is reported. C57BL/6 and hemophilia mice clot on average 25.6 versus 5.4 times, respectively. On a hemophilia background, TFPIß or TFPIγ-specific deletion improves clotting to 14.6 and 15.2 times, respectively (p<0.0001). TFPIα-specific deletion is without impact, clotting 5.1 times. Heterozygous deletion of TFPIß is effective, clotting 11.8 times (p<0.0001). Heterozygous deletion of TFPIα or TFPIγ alone is ineffective clotting 3.0 and 6.1 times, respectively; but heterozygous TFPIαγ deletion improves clotting to 11.2 times (p<0.001). CONCLUSION: In hemophilia mice, endothelial TFPIß and plasma γ-derived 2-Kunitz TFPI individually contribute more to bleeding than total TFPIα.

Genetics and Epigenetics in Acquired Hemophilia A: From Bench to Bedside.

Acquired hemophilia A (AHA) is a bleeding disorder characterized by the immunological inhibition of factor VIII (FVIII) of the hemostatic pathway leading to hemorrhagic events. Different domains of FVIII are the target of autoantibodies (mainly immunoglobulin (Ig) G) leading to the deficiency of FVIII. Several factors have been associated with the activation of the auto-immunity towards FVIII. Emerging evidence implicates CD4+ T cell activation in mediating this autoimmune response, with their involvement like that observed in congenital hemophilia A. Several genes such as HLA II DRB*16, DQB1*0502, and CTLA-4 + 49 are responsible for the pathogenesis of AHA. Epigenetic modifications and mainly long-coding RNAS (lncRNAs) are potentially contributing to the pathogenesis of AHA. The treatment approach of AHA includes the management of acute bleeding events and the administration of immunosuppressive medications. This review aimed to summarize the published data on the genetics and epigenetics of AHA. The severity and the mortality of this disease are creating an emerging need for further research in the field of the genetics and epigenetics of acquired hemorrhagic disorder.

Surgical procedures and complications in placement of totally implantable venous access port in pediatric hemophilia patients: A retrospective analysis.

This retrospective study at Beijing Children's Hospital (2020-2023) analyzed surgical procedures and complications in 24 pediatric hemophilia patients undergoing Totally Implantable Venous Access Port (TIVAP) insertion, primarily in the right jugular vein (RJV). We detailed the surgical process, including patient demographics and intraoperative imaging use. The choice of the RJV for TIVAP placement was influenced by its larger diameter and superficial anatomical position, potentially reducing risks like thrombosis and infection. Our findings support the RJV as a safer alternative for port placement in pediatric patients, aligning with current literature. Statistical analysis revealed no significant correlation between complications and baseline characteristics like weight and diagnosis type. However, the length of hospital stay and implant brand were significant risk factors for catheter or port displacement and removal. The limited patient number may introduce bias, suggesting a need for further studies with larger samples. Despite a 14.7 %-33 % complication rate and 5 port removals, the advantages of TIVAP, including reliable venous access, reduced discomfort, and treatment convenience, were evident. Most complications improved with symptomatic treatment, and there were no deaths due to port-related complications, underscoring the impact of TIVAP on improving pediatric hemophilia treatment.