A Single Base Insertion in F9 Causing Hemophilia B in a Family of Newfoundland-Parti Standard Poodle Hybrid Dogs.

Hemophilia B is an x-linked recessive hereditary coagulopathy that has been reported in various species. We describe a male Newfoundland-Parti Standard Poodle hybrid puppy and its family with hemophilia B from clinical manifestations to the molecular genetic defect. The index case presented for dyspnea was found to have a mediastinal hematoma, while surgical removal and transfusion support brought some relief, progressive hematoma formations led to humane euthanasia. Sequencing the F9 exons revealed a single nucleotide insertion resulting in a frameshift in the last exon (NM_001003323.2:c.821_822insA), predicted to result in a premature stop codon (NP_001003323.1:p.Asn274LysfsTer23) with a loss of 178 of 459 amino acids. The unexpected high residual plasma factor IX activity (3% to 11% of control) was likely erroneous, but no further studies were performed. Both the purebred Newfoundland dam and her sister were heterozygous for the insertion. Five additional male offspring developed severe hemorrhage and were hemizygous for the F9 variant and/or had a prolonged aPTT. In contrast, other male littermates had normal aPTTs and no evidence of bleeding. While they are related to a common Newfoundland granddam, the prevalence of the pathogenic variant in the Newfoundland breed is currently unknown. These clinical to molecular genetic studies illustrate that precision medicine is achievable in clinical companion animal practice.

Gene Therapy in Hemophilia: Recent Advances.

Hemophilia is a monogenic mutational disease affecting coagulation factor VIII or factor IX genes. The palliative treatment of choice is based on the use of safe and effective recombinant clotting factors. Advanced therapies will be curative, ensuring stable and durable concentrations of the defective circulating factor. Results have so far been encouraging in terms of levels and times of expression using mainly adeno-associated vectors. However, these therapies are associated with immunogenicity and hepatotoxicity. Optimizing the vector serotypes and the transgene (variants) will boost clotting efficacy, thus increasing the viability of these protocols. It is essential that both physicians and patients be informed about the potential benefits and risks of the new therapies, and a register of gene therapy patients be kept with information of the efficacy and long-term adverse events associated with the treatments administered. In the context of hemophilia, gene therapy may result in (particularly indirect) cost savings and in a more equitable allocation of treatments. In the case of hemophilia A, further research is needed into how to effectively package the large factor VIII gene into the vector; and in the case of hemophilia B, the priority should be to optimize both the vector serotype, reducing its immunogenicity and hepatotoxicity, and the transgene, boosting its clotting efficacy so as to minimize the amount of vector administered and decrease the incidence of adverse events without compromising the efficacy of the protein expressed.

Consensus Recommendations for Intramuscular COVID-19 Vaccination in Patients with Hemophilia.

BACKGROUND: Currently available coronavirus disease 2019 (COVID-19) vaccines are approved for intramuscular injection and efficacy may not be ensured when given subcutaneously. For years, subcutaneous vaccination was recommended in patients with hemophilia to avoid intramuscular bleeds. Therefore, recommendations for the application of COVID-19 vaccines are needed. METHODS: The Delphi methodology was used to develop consensus recommendations. An initial list of recommendations was prepared by a steering committee and evaluated by 39 hemophilia experts. Consensus was defined as ≥75% agreement and strong consensus as ≥95% agreement, and agreement as a score ≥7 on a scale of 1 to 9. After four rounds, a final list of statements was compiled. RECOMMENDATIONS: Consensus was achieved that COVID-19 vaccines licensed only for intramuscular injection should be administered intramuscularly in hemophilia patients. Prophylactic factor replacement, given on the day of vaccination with a maximum interval between prophylaxis and vaccination of 24 hours (factor VIII and conventional factor IX concentrates) or 48 hours (half-life extended factor IX), should be provided in patients with moderate or severe hemophilia. Strong consensus was achieved that patients with mild hemophilia and residual factor activity greater than 10% with mild bleeding phenotype or patients on emicizumab usually do not need factor replacement before vaccination. Swelling, erythema, and hyperthermia after vaccination are not always signs of bleeding but should prompt consultation of a hemophilia care center. In case of injection-site hematoma, patients should receive replacement therapy until symptoms disappear. CONCLUSIONS: Consensus was achieved on recommendations for intramuscular COVID-19 vaccination after replacement therapy for hemophilia patients depending on disease severity.

The Progression of Hemophilic Arthropathy: The Role of Biomarkers.

BACKGROUND: Hemophilia A and B are X-linked congenital bleeding disorders characterized by recurrent hemarthroses leading to specific changes in the synovium and cartilage, which finally result in the destruction of the joint: this process is called hemophilic arthropathy (HA). This review highlights the most prominent molecular biomarkers found in the literature to discuss their potential use in the clinical practice to monitor bleeding, to assess the progression of the HA and the effectiveness of treatments. METHODS: A review of the literature was performed on PubMed and Embase, from 3 to 7 August 2020. Study selection and data extraction were achieved independently by two authors and the following inclusion criteria were determined a priori: English language, available full text and articles published in peer-reviewed journal. In addition, further articles were identified by checking the bibliography of relevant articles and searching for the studies cited in all the articles examined. RESULTS: Eligible studies obtained at the end of the search and screen process were seventy-three (73). CONCLUSIONS: Despite the surge of interest in the clinical use of biomarkers, current literature underlines the lack of their standardization and their potential use in the clinical practice preserving the role of physical examination and imaging in early diagnosis.

Development of a Clinical Candidate AAV3 Vector for Gene Therapy of Hemophilia B.

Although recombinant adeno-associated virus serotype 8 (AAV8) and serotype 5 (AAV5) vectors have shown efficacy in Phase 1 clinical trials for gene therapy of hemophilia B, it has become increasingly clear that these serotypes are not optimal for transducing primary human hepatocytes. We have previously reported that among the 10 most commonly used AAV serotypes, AAV serotype 3 (AAV3) vectors are the most efficient in transducing primary human hepatocytes in vitro as well as in "humanized" mice in vivo, and suggested that AAV3 vectors expressing human coagulation factor IX (hFIX) may be a more efficient alternative for clinical gene therapy of hemophilia B. In the present study, we extended these findings to develop an AAV3 vector incorporating a compact yet powerful liver-directed promoter as well as optimized hFIX cDNA sequence inserted between two AAV3 inverted terminal repeats. When packaged into an AAV3 capsid, this vector yields therapeutic levels of hFIX in hemophilia B and in "humanized" mice in vivo. Together, these studies have resulted in an AAV3 vector predicted to achieve clinical efficacy at reduced vector doses, without the need for immune-suppression, for clinical gene therapy of hemophilia B.

Hemophilia B - Mutation Rates and Incidence - A Simulation Study.

The dynamics of rare X-linked recessive traits is explored by simulation. The model follows the prevalence of affected males and carrier females as separate but correlated variables. Different mutation rates and selection coefficients are introduced for males and females. A virtual population based on a published study of hemophilia B in the west of Scotland is followed at weekly intervals over many years. Speculative values of critical parameters to mimic the real population are proposed.

Hemophilia A and B mice, but not VWF-/-mice, display bone defects in congenital development and remodeling after injury.

While joint damage is the primary co-morbidity of hemophilia, osteoporosis and osteopenia are also observed. Coagulation factor VIII deficient (FVIII-/-) mice develop an osteoporotic phenotype in the absence of induced hemarthrosis that is exacerbated two weeks after an induced joint injury. Here we have compared comprehensively the bone health of clotting factor VIII, factor IX, and Von Willebrand Factor knockout (FVIII-/-, FIX-/-, and VWF-/- respectively) mice both in the absence of joint hemorrhage and following induced joint injury. We found FVIII-/- and FIX-/- mice, but not VWF-/- mice, developmentally have an osteoporotic phenotype. Unilateral induced hemarthrosis causes further bone damage in both FVIII-/- and FIX-/- mice, but has little effect on VWF-/- bone health, indicating that the FVIII.VWF complex is not required for normal bone remodeling in vivo. To further investigate the bone healing following hemarthrosis in hemophilia we examined a two week time course using microCT, serum chemistry, and histological analysis. Elevated ratio of osteoprotegerin (OPG)/receptor activator of nuclear factor-kappa B ligand (RANKL), increased osterix+ osteoblastic cells, and decreased smoothness of the cortical bone surface were evident within several days of injury, indicative of acute heterotopic mineralization along the cortical surface. This was closely followed by increased interleukin-6 (IL-6) levels, increased osteoclast numbers, and significant trabecular bone loss. Uncoupled and disorganized bone formation and resorption continued for the duration of the study resulting in significant deterioration of the joint. Further elucidation of the shared mechanisms underlying abnormal bone homeostasis in the absence of FVIII or FIX is needed to guide evidence-based approaches to the screening and treatment of the prevalent bone defects in hemophilia A and B.

Genetic-Based Approaches to Inherited Metabolic Liver Diseases.

In vertebrates, the liver is the central metabolic organ of the body, which carries out an estimated 500 functions that range from general detoxification to protein synthesis, bile production, metabolism of fats, carbohydrates, proteins, bilirubin, vitamin and mineral storage and it even has an immune function. Hepatocytes are considered the professional liver cells, which carry out all of these functions. With such a variety of tasks to perform, it is not surprising that more than 400 rare monogenic disorders of hepatic origin have been described. For many of these, liver transplantation remains the only curative strategy, however, this is limited by organ availability and requires lifelong immune suppression. The fact that liver transplantation is curative led to the assumption that the restoration of the expression of the defective gene would result in the resolution of the disease. Indeed, liver-directed gene therapy trials for hemophilia A and B have demonstrated the potential of gene therapy to provide long-lasting clinical benefit in the treatment of monogenic liver disorders. Thus, liver-directed gene therapy and gene editing strategies have emerged as promising alternatives to transplantation in inherited monogenic liver disorders. Herein, we review the advances and limitations of gene therapy for such disorders, covering therapeutic strategies based on gene addition and gene editing and the exciting clinical results obtained with the use of ribonucleic acid as therapeutic molecules.

Phenotypic characterization of haemophilia B - Understanding the underlying biology of coagulation factor IX.

Haemophilia B is a recessive, X-linked bleeding disorder due to inherited deficiency in vitamin K-dependent coagulation factor IX (FIX). FIX activity levels, as a basis for the definition of disease severity, do not clearly correlate with bleeding phenotype, likely due to the multiple steps regulating coagulation. Timely, with the availability of extended half-life products and successful steps in gene therapy, haemophilia B therapy is in an active developmental phase. Therefore, increased knowledge of the factors contributing to the variation of haemostatic and clinical outcome and response to therapy is welcomed. FIX acts at the crossroads of both the extrinsic and intrinsic pathways, and on the platelet procoagulant membrane at the site of vascular injury, and therefore, FIX biology is targeted for multiple effectors and regulators. The synthesis, cellular and molecular interactions, and elimination routes of FIX are not as well studied as for FVIII. The specific roles of magnesium in both platelet adhesion and FIX activation, and of vascular collagen at the haemostatic site of platelet adhesion and FIX residence are of particular interest. Biochemical and translational research on these issues should improve our understanding of the mechanisms involved, leading to the development of relevant assays that measure both haemostasis and treatment response. The latter is becoming increasingly important in the new era of haemophilia management and ultimately may lead to improved treatment strategies individually tailored to a patient's needs and cost-efficiency.

Timely and large dose of clotting factor IX provides better joint wound healing after hemarthrosis in hemophilia B mice.

Bleeding into the joints represents the major morbidity of severe hemophilia and predisposes it to hemophilic arthropathy (HA). In a reproducible hemarthrosis mouse model, we found distinct changes in thrombin activity in joint tissue homogenate following exposure of the joint to blood in wide type (WT) and hemophilic B mice. Specifically, at early time points (4 h and 24 h) after hemarthrosis, thrombin activity in WT mice quickly peaked at 4 h, and returned to baseline after 1 week. In hemophilia B mice, there was no/minimal thrombin activity in joint tissues at 4 h and 24 h, whereas at 72 h and thereafter, thrombin activity kept rising, and persisted at a higher level. Nevertheless, prothrombin had not decreased in both WT and hemophilia. The pattern was also confirmed by Western blotting and immunostaining. To optimize the protection against development of HA, we tested different treatment regimens by administration of clotting factor IX into hemophilia B mouse after hemarthrosis induction, including a total of 600 IU/kg FIX within the first 24 h or the whole 2-week period. We concluded that timely (in the first 24 h) and sufficient hemostasis correction is critical for a better protection against the development of hemophilic arthropathy.

Safety of buccal infiltration local anaesthesia for dental procedures.

AIM: To assess the safety of buccal infiltration local anaesthetic (LA) without additional factor replacement in patients with haemophilia (PWH) and association with clinical experience of the operator. METHODS: A consecutive sample of participants with mild, moderate and severe haemophilia scheduled to have dental treatment were recruited from a comprehensive care centre in Ireland. Infiltration LA was administered using a standard technique. Safety was defined as any adverse event at time of administration, immediate postoperative, or postoperative period. Clinical experience was dichotomized into fewer or greater than three years clinical experience. RESULTS: N = 135 buccal infiltration LAs without additional factor replacement were provided to N = 71 participants with mild (n = 20; 28%) and moderate to severe haemophilia (n = 51; 72%). Successful local anaesthesia was achieved in n = 133 cases (99%). No (0%) adverse bleeding events were recorded for any participants at time of administration of LA or during follow-up. Three out of 135 (2.2%) LAs recorded superficial bleeding 30 seconds after administration of LA, all of which resolved within 2 minutes with application of pressure; 4 out of 135 (3%) LAs produced a superficial haematoma at the site of injection no greater than 2 mm all of which resolved at 4 minutes. There were no differences in bleeding rates between clinicians by level of experience (P = 0.435) or by severity of bleeding disorder (P = 1.0). CONCLUSION: Local anaesthetic is safe to administer via buccal infiltration for people with mild, moderate and severe haemophilia without additional factor cover. This finding holds true regardless of operator experience.

Outcomes indicators and processes in transitional care in adolescents with haemophilia: A Delphi survey of Canadian haemophilia care providers.

INTRODUCTION: It is unclear which outcome indicators should be used to measure the success of haemophilia transition programs, and what are key elements of a haemophilia transition program to ensure success. AIM: To establish by expert consensus a list of important and feasible outcome indicators of successful haemophilia transition, and a list of key elements of transition planning. METHODS: A modified two-stage Delphi survey was developed and disseminated among a panel of Canadian interdisciplinary haemophilia care providers. Participants were asked to rate the importance and feasibility of outcome indicators of effective haemophilia transition and elements of haemophilia transition program. In the second round, participants were asked to choose the top five outcomes suitable for inclusion in a core outcome set of transition effectiveness, and the top five elements that are important and feasible for implementation within the next 5 years. RESULTS: In total, 34/73 (47%) of participants completed the first round and 33 completed the second round, representing a variety of disciplines. Top outcome indicators recommended for a core outcome set include measurement of adherence, change in bleeding rate, self-efficacy skills, haemophilia knowledge, patient and caregiver satisfaction, time gap between last paediatric and first adult clinic, and number of emergency room or hospital admissions. Fourteen elements of transition achieved consensus in importance ratings, while eight were felt to be feasible for implementation within next 5 years. CONCLUSIONS: Results will contribute towards the development of a haemophilia transition outcome instrument and provide guidance for future studies of the effectiveness of transition programs.

Erectile dysfunction in patients with haemophilia.

INTRODUCTION: Patients with haemophilia (PWH) are experiencing a nearly normal life span with safe factor replacement therapy and effective antiviral treatments for co-infections. As a result, many ageing-related health issues are starting to emerge. One rarely discussed health issue is erectile dysfunction (ED). ED can affect overall well-being and predict future cardiac events, but is not well studied in PWH. AIM: This prospective study aims to examine the prevalence and risk factors for ED in PWH using the validated International Index of Erectile Function (IIEF) questionnaire. METHODS: Patients with haemophilia A and B at all severities were invited to participate in IIEF questionnaire at the provincial Hemophilia Treatment Centre. Risk factors for ED including cardiovascular risk factors, prior surgeries, viral infections, medications and haemophilia-specific factors were obtained. Fasting laboratory tests including but not limited to renal function, haemoglobin, lipid profile, glucose and CRP were performed the same day. Blood pressure and anthropomorphic indices were measured. Endothelial function was assessed by brachial artery flow-mediated dilation (FMD and hyperaemic velocity time integral [VTI]). RESULTS: Out of the 56 subjects approached, 44 completed the IIEF. Median age was 49 years. About 38.6% of the cohort reported ED symptoms. There was no significant difference in endothelial function measured by FMD and VTI between patient with ED and without. IIEF score correlated with age in multivariable analysis. CONCLUSION: Erectile dysfunction symptoms appear prevalent in PWH, particularly in the older group. This disorder along with the underlying causes needs to be explored further in future larger observational study.

Haemophilia in Côte d'Ivoire (the Ivory Coast) in 2017: Extensive data collection as part of the World Federation of Hemophilia's twinning programme.

INTRODUCTION: In sub-Saharan African countries, research on haemophilia is limited. Since 2015, a partnership has been established through the World Federation of Hemophilia (WFH)'s twinning programme between the haemophilia treatment centre (HTC) of the Centre Hospitalier universitaire of Yopougon in Abidjan, Côte d'Ivoire, and the Cliniques universitaires Saint-Luc of Brussels, Belgium. AIM: This study sought to collect accurate, and detailed demographic, clinical, and laboratory data on the whole identified Ivorian haemophilia population. METHODS: A prospective study was conducted in 2017 in Yopougon's HTC. Participants were assessed through multidisciplinary workups including interviews, logbook review, pedigree establishment, clinical examination and laboratory testing. RESULTS: Data on 81 patients with haemophilia (PWH) (78 severe and moderate) were collected. Postcircumcision bleeding was the most common diagnosis reason (32%). Mouth bleeds and skin wounds accounted for 55.2% of bleeds. Pedigrees revealed 63 deaths in affected relatives among 33 families. Most PWHs (76.5%) were treated on demand, and 21% had never been exposed to clotting factor. Non-substitutive therapies (tranexamic acid [43%], physiotherapy [11%] and DDAVP [0%]) were underused. Overweight was uncommon. Knees were the most clinically affected joints at the Hemophilia Joint Health Score. Inhibitors were present in 7.8% of previously treated PWHs. CONCLUSIONS: This study highlights the value of simple, feasible and inexpensive tools to collect data in the Ivorian haemophilia population and provides the basis for developing and implementing locally appropriate strategies to improve screening, diagnosis, preventive care, treatment and education. It demonstrated the WFH twinning programme benefits for haemophilia care in the developing world.

The impact of haemophilia on the social status and the health-related quality of life in adult Lebanese persons with haemophilia.

INTRODUCTION: Health-related quality of life (HRQoL) studies are increasingly needed to prevent and improve the medical care of persons with haemophilia (PWH). AIM: We assessed the impact of haemophilia on HRQoL and social status of adult Lebanese PWH compared to a reference population. METHODS: In this case-control study, 60 severe and moderate PWH were compared to 112 healthy controls. Detailed socio-demographic data and disease characteristics were collected, and HRQoL was assessed using the SF-36 questionnaire. RESULTS: Age, body mass index and the percentage of married people were similar in PWH and controls. A greater proportion of controls attained a higher educational level than cases (88.4% vs 59.3%, respectively, P < 0.001). PWH were more likely to have a job requiring physical activity than controls (55.9% vs 31.4%) and more likely to be unemployed (10.2% vs 1.0%), whereas more controls had higher socio-economic jobs (10.5% vs 1.7%). PWH had significantly (P < 0.001) worse scores in all SF-36 domains except for energy/fatigue. Affected targeted joints (2.7 ± 1.5) and monthly bleeding frequency (2.9 ± 2.4) were inversely correlated with almost all SF-36 domains. Only 26.7% of PWH walk normally, and walking abnormalities were inversely correlated with all SF-36 domains except role-emotional and emotional well-being. CONCLUSION: As compared with controls, the majority of Lebanese PWH has difficulties in social integration, has severe physical limitations and psychological impairments.

Neuromuscular control during gait in people with haemophilic arthropathy.

INTRODUCTION: Effects of haemophilic arthropathy on neuromuscular control during gait are currently unknown. AIMS: (a) To assess how haemophilic arthropathy affects the complexity of neuromuscular control during gait; (b) To investigate the relationship between complexity of neuromuscular control and joint impairment. METHODS: Thirteen control subjects (CG) walked overground at their preferred and a slow velocity and thirteen people with haemophilic arthropathy (PWHA) walking at their preferred velocity. Surface electromyography (EMG) was collected from eleven leg muscles. Electromyography variance explained by muscle synergies (sets of co-activated muscles that can be recruited by a single signal) was calculated by the total variance accounted (tVAF). Three measures were used to evaluate complexity of neuromuscular control: (a) the number of synergies required for tVAF > 90%, (b) tVAF as a function of the number of muscle synergies, and (c) the dynamic motor control index (Walk-DMC). Impairment of ankle and knee joints was determined by the Haemophilia Joint Health Score (HJHS). RESULTS: The same number of the muscle synergies was found for each group (P > 0.05). For both walking velocities tested, tVAF1 was higher in PHWA (P < 0.05). The Walk-DMC of PWHA was lower than that of the CG for both walking velocities (P < 0.05). For PWHA, no significant correlation was found between HJHS (sum knee and ankle) and Walk-DMC index (r = -0.32, P = 0.28). CONCLUSIONS: These results indicate differences between PWHA and CG in the neuromuscular control of gait. The Walk-DMC and tVAF1 may be useful measures to assess changes in neuromuscular control in response to treatment.

Tissue factor pathway inhibitor is the main determinant of thrombin generation in haemophilic patients.

The thrombin generation (TG) assay evaluates haemostatic balance, which is influenced by the levels of many coagulation factors and inhibitors. Our objective was to identify the determinant factors of TG in haemophilia A (HA) and haemophilia B (HB) patients and to compare them to those in healthy controls. Coagulation factor and inhibitor levels, and TG, were measured in platelet-poor plasma from 40 patients with HA, 32 patients with HB and 40 healthy subjects. Data were analysed using multiple regression models. In HA patients, factor VIII was a positive determinant of endogenous thrombin potential (ETP) and peak, whereas tissue factor pathway inhibitor (TFPI) and factor V were negative determinants of ETP and peak. In HB patients, FIX was a positive determinant of ETP and peak, FVII being a positive determinant of peak. Antithrombin and protein S (PS) were negative determinants of ETP while FX was a negative determinant of peak. Above all, in HB patients, TFPI was a negative determinant of ETP and peak. In healthy subjects, FVIII was a positive determinant of ETP and peak, whereas FX and protein S were negative determinants of these parameters. TFPI was not a negative determinant of either peak or ETP. In haemophilic patients, the determinant factors of TG are all implicated in FXa generation and inhibition, the crucial determinant factor being TFPI whatever the type of haemophilia, A or B. These findings contribute to the rationale that recently place TFPI as a target for innovative therapies of haemophilia.