Health-related quality of life following valoctocogene roxaparvovec gene therapy for severe hemophilia A in the phase 3 trial GENEr8-1.

BACKGROUND: Severe hemophilia A (HA) negatively impacts health-related quality of life (HRQOL). OBJECTIVES: We aimed to analyze HRQOL in adult men with severe HA without inhibitors after valoctocogene roxaparvovec gene transfer in the phase 3 trial GENEr8-1. METHODS: Participant-reported outcomes were the hemophilia-specific quality of life questionnaire for adults (Haemo-QOL-A), the EQ-5D-5L instrument, the Hemophilia Activities List (HAL), and the Work Productivity and Activity Impairment Questionnaire: Hemophilia Specific (WPAI+CIQ:HS). Participants completed the questionnaires at baseline and through 104 weeks postinfusion with 6 × 1013 vg/kg of valoctocogene roxaparvovec. Scores were analyzed per participant characteristics and outcomes. RESULTS: For 132 HIV-negative participants, mean change from baseline in Haemo-QOL-A Total Score met the anchor-based clinically important difference (CID: 5.5) by week 12; the mean (SD) increase was 7.0 (12.6) at week 104. At week 104, improvement in Consequences of Bleeding, Treatment Concern, Worry, and Role Functioning domain scores exceeded the CID (6). EQ-5D-5L Utility Index scores improved above the CID at week 52, but not at week 104. EQ-5D-5L visual analog scale and HAL scores increased from baseline to week 104. Participants reported less activity and work impairment at week 104 than baseline. Participants with problem joints had lower mean baseline Haemo-QOL-A Total and domain scores than those without them, but improved over 104 weeks, except for 11 participants with ≥3 problem joints. Participants with 0 bleeds during the baseline prophylaxis period reported Haemo-QOL-A score improvements above the CID, including in the Consequences of Bleeding domain. CONCLUSION: Valoctocogene roxaparvovec provided clinically meaningful HRQOL improvement for men with severe HA.

Emicizumab for acquired haemophilia A: A case series.

BACKGROUND: Emicizumab is approved to prevent bleeding in patients with congenital haemophilia A with or without inhibitors. However, no randomized trials addressed the efficacy of emicizumab in acquired haemophilia A (AHA). AIMS: To report the clinical and biochemical response of emicizumab in AHA. METHODS: This single-centre retrospective study included seven adults with AHA between November 2020 and May 2022. We collected patient characteristics, laboratory coagulation parameters, the use of haemostatic agents, bleeds and thrombotic events. Treatment was monitored using chromogenic FVIII assays. The assay with human reagents assesses both the emicizumab FVIII-like-activity and native patient FVIII-activity. The assay with bovine reagents only measures the patients' native FVIII-activity as emicizumab does not bind to bovine reagents. RESULTS: Patients presented with spontaneous hematoma (n = 7), intramuscular bleeding (n = 2), haematuria (n = 2) and/or gastro-intestinal bleeding (n = 2). Six patients had major bleedings. At diagnosis, APTT was prolonged (91 seconds, IQR 73-103), FVIII activity was 0% (IQR 0-1) and FVIII inhibitor 182 BU/mL (IQR 104-228). Emicizumab was administered weekly (3 mg/kg) for 4 weeks, and thereafter every 2 weeks until regression of the inhibitor. Three patients received activated FVIIa (cumulative dose of 1.7 mg/kg, IQR 1.2-2.2). All bleedings were controlled after treatment initiation, without further bleeds. After starting emicizumab, FVIII-like activity reached ≥5% at 12 days (IQR 7-14), whereas recovery of the intrinsic FVIII-activity ≥5% occurred at 128 days (IQR 88-173), coinciding with the disappearance of the FVIII inhibitor. There were no safety issues. CONCLUSION: In this AHA case series, no new clinically relevant bleeds were observed after initiation of emicizumab in conjunction with standard immunosuppressive therapy.

Ribosome dysfunction underlies SLFN14-related thrombocytopenia.

Pathogenic missense variants in SLFN14, which encode an RNA endoribonuclease protein that regulates ribosomal RNA (rRNA) degradation, are known to cause inherited thrombocytopenia (TP) with impaired platelet aggregation and adenosine triphosphate secretion. Despite mild laboratory defects, the patients displayed an obvious bleeding phenotype. However, the function of SLFN14 in megakaryocyte (MK) and platelet biology remains unknown. This study aimed to model the disease in an immortalized MK cell line (imMKCL) and to characterize the platelet transcriptome in patients with the SLFN14 K219N variant. MK derived from heterozygous and homozygous SLFN14 K219N imMKCL and stem cells of blood from patients mainly presented with a defect in proplatelet formation and mitochondrial organization. SLFN14-defective platelets and mature MK showed signs of rRNA degradation; however, this was absent in undifferentiated imMKCL cells and granulocytes. Total platelet RNA was sequenced in 2 patients and 19 healthy controls. Differential gene expression analysis yielded 2999 and 2888 significantly (|log2 fold change| >1, false discovery rate <0.05) up- and downregulated genes, respectively. Remarkably, these downregulated genes were not enriched in any biological pathway, whereas upregulated genes were enriched in pathways involved in (mitochondrial) translation and transcription, with a significant upregulation of 134 ribosomal protein genes (RPGs). The upregulation of mitochondrial RPGs through increased mammalian target of rapamycin complex 1 (mTORC1) signaling in SLFN14 K219N MK seems to be a compensatory response to rRNA degradation. mTORC1 inhibition with rapamycin resulted in further enhanced rRNA degradation in SLFN14 K219N MK. Taken together, our study indicates dysregulation of mTORC1 coordinated ribosomal biogenesis is the disease mechanism for SLFN14-related TP.

Gene Therapy with Etranacogene Dezaparvovec for Hemophilia B.

BACKGROUND: Moderate-to-severe hemophilia B is treated with lifelong, continuous coagulation factor IX replacement to prevent bleeding. Gene therapy for hemophilia B aims to establish sustained factor IX activity, thereby protecting against bleeding without burdensome factor IX replacement. METHODS: In this open-label, phase 3 study, after a lead-in period (≥6 months) of factor IX prophylaxis, we administered one infusion of adeno-associated virus 5 (AAV5) vector expressing the Padua factor IX variant (etranacogene dezaparvovec; 2×1013 genome copies per kilogram of body weight) to 54 men with hemophilia B (factor IX activity ≤2% of the normal value) regardless of preexisting AAV5 neutralizing antibodies. The primary end point was the annualized bleeding rate, evaluated in a noninferiority analysis comparing the rate during months 7 through 18 after etranacogene dezaparvovec treatment with the rate during the lead-in period. Noninferiority of etranacogene dezaparvovec was defined as an upper limit of the two-sided 95% Wald confidence interval of the annualized bleeding rate ratio that was less than the noninferiority margin of 1.8. Superiority, additional efficacy measures, and safety were also assessed. RESULTS: The annualized bleeding rate decreased from 4.19 (95% confidence interval [CI], 3.22 to 5.45) during the lead-in period to 1.51 (95% CI, 0.81 to 2.82) during months 7 through 18 after treatment, for a rate ratio of 0.36 (95% Wald CI, 0.20 to 0.64; P<0.001), demonstrating noninferiority and superiority of etranacogene dezaparvovec as compared with factor IX prophylaxis. Factor IX activity had increased from baseline by a least-squares mean of 36.2 percentage points (95% CI, 31.4 to 41.0) at 6 months and 34.3 percentage points (95% CI, 29.5 to 39.1) at 18 months after treatment, and usage of factor IX concentrate decreased by a mean of 248,825 IU per year per participant in the post-treatment period (P<0.001 for all three comparisons). Benefits and safety were observed in participants with predose AAV5 neutralizing antibody titers of less than 700. No treatment-related serious adverse events occurred. CONCLUSIONS: Etranacogene dezaparvovec gene therapy was superior to prophylactic factor IX with respect to the annualized bleeding rate, and it had a favorable safety profile. (Funded by uniQure and CSL Behring; HOPE-B ClinicalTrials.gov number, NCT03569891.).

Clinical application of multigene panel testing for bleeding, thrombotic, and platelet disorders: a 3-year Belgian experience.

BACKGROUND: The international study ThromboGenomics has evaluated the diagnostic rate using a targeted multigene panel test for the screening of inherited bleeding, thrombotic and platelet disorders. OBJECTIVES: We retrospectively analyzed the results of the implementation of genetic testing for inherited bleeding, thrombotic and platelet disorders in Belgian clinical practice and evaluated possible reclassification of reported variants. PATIENTS/METHODS: We implemented a Thrombosis-Hemostasis multigene panel test using whole exome sequencing to diagnose 487 patients recruited by 27 different Belgian hospitals with the implementation of stringent laboratory accreditation standards and by studying up to 100 diagnostic-grade genes. RESULTS: This Thrombosis-Hemostasis multigene panel test was able to detect at least one genetic variant in 58% of the 487 patients of which 50% were (likely) pathogenic variants and the others were variants of unknown significance. Polygenic variants were detected in 65 patients (13%). A multi-step workflow for results discussion by multidisciplinary team meetings and patients' recalls for segregation studies and additional laboratory testing was set up. Variants were also submitted to the GoldVariants database from the International Society on Thrombosis and Haemostasis (ISTH). The aim of these approaches is to optimize variant interpretation and to (re)classify variants of unknown significance as (likely) pathogenic or (likely) benign. CONCLUSIONS: The growing implementation of multigene panel tests in clinical diagnostics comes with difficulties in interpreting genetic results. Additional efforts are needed to continuously optimize the diagnostic outcome.

Thromboprophylaxis in COVID-19: Weight and severity adjusted intensified dosing.

Background: Venous thromboembolism (VTE) frequently occurs in hospitalized patients with coronavirus disease 2019 (COVID-19). The optimal dose of anticoagulation for thromboprophylaxis in COVID-19 is unknown. Aims: To report VTE incidence and bleeding before and after implementing a hospital-wide intensified thromboprophylactic protocol in patients with COVID-19. Methods: On March 31, 2020, we implemented an intensified thromboprophylactic protocol consisting of 50 IU anti-Xa low molecular weight heparin (LMWH)/kg once daily at the ward, twice daily at the intensive care unit (ICU). We included all patients hospitalized in a tertiary care hospital with symptomatic COVID-19 between March 7 and July 1, 2020. The primary outcome was the incidence of symptomatic or subclinical VTE and major bleeding during admission. Routine ultrasound screening for VTE was performed whenever logistically possible. Results: We included 412 patients, of which 116 were admitted to the ICU. Of 219 patients with standard a prophylactic dose of LMWH, 16 (7.3%) had VTE, 10 of which were symptomatic (4.6%). Of 193 patients with intensified thromboprophylaxis, there were no symptomatic VTE cases, three incidental deep venous thrombosis cases (1.6%), and one incidental pulmonary embolism (0.5%). The major bleeding rate was 1.2% in patients with intensified thromboprophylaxis and 7.7% when therapeutic anticoagulation was needed. Conclusion: In hospitalized patients with COVID-19, there were no additional symptomatic VTEs and a reduction in incidental deep vein thrombosis after implementing systematic thromboprophylaxis with weight-adjusted prophylactic (ward) to intermediate (ICU), but not therapeutic dosed anticoagulation. This intensified thromboprophylaxis was associated with a lower risk of major bleeding compared with therapeutic dosed anticoagulation.

Valoctocogene Roxaparvovec Gene Therapy for Hemophilia A.

BACKGROUND: Valoctocogene roxaparvovec (AAV5-hFVIII-SQ) is an adeno-associated virus 5 (AAV5)-based gene-therapy vector containing a coagulation factor VIII complementary DNA driven by a liver-selective promoter. The efficacy and safety of the therapy were previously evaluated in men with severe hemophilia A in a phase 1-2 dose-escalation study. METHODS: We conducted an open-label, single-group, multicenter, phase 3 study to evaluate the efficacy and safety of valoctocogene roxaparvovec in men with severe hemophilia A, defined as a factor VIII level of 1 IU per deciliter or lower. Participants who were at least 18 years of age and did not have preexisting anti-AAV5 antibodies or a history of development of factor VIII inhibitors and who had been receiving prophylaxis with factor VIII concentrate received a single infusion of 6×1013 vector genomes of valoctocogene roxaparvovec per kilogram of body weight. The primary end point was the change from baseline in factor VIII activity (measured with a chromogenic substrate assay) during weeks 49 through 52 after infusion. Secondary end points included the change in annualized factor VIII concentrate use and bleeding rates. Safety was assessed as adverse events and laboratory test results. RESULTS: Overall, 134 participants received an infusion and completed more than 51 weeks of follow-up. Among the 132 human immunodeficiency virus-negative participants, the mean factor VIII activity level at weeks 49 through 52 had increased by 41.9 IU per deciliter (95% confidence interval [CI], 34.1 to 49.7; P<0.001; median change, 22.9 IU per deciliter; interquartile range, 10.9 to 61.3). Among the 112 participants enrolled from a prospective noninterventional study, the mean annualized rates of factor VIII concentrate use and treated bleeding after week 4 had decreased after infusion by 98.6% and 83.8%, respectively (P<0.001 for both comparisons). All the participants had at least one adverse event; 22 of 134 (16.4%) reported serious adverse events. Elevations in alanine aminotransferase levels occurred in 115 of 134 participants (85.8%) and were managed with immune suppressants. The other most common adverse events were headache (38.1%), nausea (37.3%), and elevations in aspartate aminotransferase levels (35.1%). No development of factor VIII inhibitors or thrombosis occurred in any of the participants. CONCLUSIONS: In patients with severe hemophilia A, valoctocogene roxaparvovec treatment provided endogenous factor VIII production and significantly reduced bleeding and factor VIII concentrate use relative to factor VIII prophylaxis. (Funded by BioMarin Pharmaceutical; GENEr8-1 ClinicalTrials.gov number, NCT03370913.).

Coagulation Factors Accumulate During Normothermic Liver Machine Perfusion Regardless of Donor Type and Severity of Ischemic Injury.

BACKGROUND: Coagulation factors may inform on liver function during normothermic machine perfusion (NMP). We investigated whether graft ischemic injury impairs the accumulation of anticoagulation factors during NMP of porcine and human livers. METHODS: Dynamics of FV, FVII, FVIII, FIX, and FX during NMP and their correlation with graft injury was investigated in porcine livers with minimal (no warm ischemia, n = 5) or severe injury (60 min warm ischemia, n = 5). Next, FV, FVIII, FIX, fibrinogen, and antithrombin were measured in 35 matched human liver NMPs from the COPE trial. Correlation of these factors with outcomes was explored. Livers were categorized in to 4 groups depending on donor type and posttransplant peak aspartate aminotransferase (AST) as surrogate of minimal (peak < 500 IU/L) or moderate injury (peak > 1000 IU/L). RESULTS: Factor concentrations increased significantly during NMP regardless of severity of injury. In porcine livers, factor concentrations were 2- to 6-fold lower in severely injured grafts (all P < 0.05). All factors negatively correlated with AST (coefficient range: from -0.50 to -0.93; all P < 0.05) and lactate (range: from -0.51 to -0.67; all P < 0.05). In human livers, no difference in factor accumulation rates and no correlation with other markers were observed. One graft with primary nonfunction had low rate of factor accumulation. CONCLUSIONS: Anticoagulation factors accumulate during NMP regardless of donor type and severity of injury. In pigs, severe ischemic injury resulted in significantly lower factor concentrations. In human livers with life-sustaining function, they do not correlate with hepatic injury. Whether low concentrations predict nonfunction in high-risk livers with severe injury requires further investigation.

Patient preferences for gene therapy in haemophilia: Results from the PAVING threshold technique survey.

OBJECTIVES: The aim of the Patient preferences to Assess Value IN Gene therapies (PAVING) study was to investigate trade-offs that adult Belgian people with haemophilia (PWH) A and B are willing to make when choosing between prophylactic factor replacement therapy (PFRT) and gene therapy. METHODS: The threshold technique was used to quantify the minimum acceptable benefit (MAB) of a switch from PFRT to gene therapy in terms of 'Annual bleeding rate' (ABR), 'Chance to stop prophylaxis' (STOP), and 'Quality of life' (QOL). The design was supported by stakeholder involvement and included an educational tool on gene therapy. Threshold intervals were analysed using interval regression models in Stata 16. RESULTS: A total of 117 PWH completed the survey. Mean thresholds were identified for all benefits, but substantial preference heterogeneity was observed; especially for the STOP thresholds, where the distribution of preferences was bimodal. Time spent on the educational tool and residence were found to impact MAB thresholds. The most accepted (88% of PWH) gene therapy profile investigated in this study comprised of zero bleeds per year (vs. six for PFRT), 90% chance to stop prophylaxis, no impact on QoL, and 10 years of follow-up on side effects (vs. 30 for PFRT). CONCLUSIONS: Results from this study proved the value of educating patients on novel treatments. Moreover, preference heterogeneity for novel treatments was confirmed in this study. In gene therapy decision-making, preference heterogeneity and the impact of patient education on acceptance should be considered.

Venous Thromboembolism in Patients Discharged after COVID-19 Hospitalization.

BACKGROUND: Venous thromboembolism (VTE) is a frequent complication of COVID-19, so that the importance of adequate in-hospital thromboprophylaxis in patients hospitalized with COVID-19 is well established. However, the incidence of VTE after discharge and whether postdischarge thromboprophylaxis is beneficial and safe are unclear. In this prospective observational single-center study, we report the incidence of VTE 6 weeks after hospitalization and the use of postdischarge thromboprophylaxis. METHODS: Patients hospitalized with confirmed COVID-19 were invited to a multidisciplinary follow-up clinic 6 weeks after discharge. D-dimer and C-reactive protein were measured, and all patients were screened for deep vein thrombosis with venous duplex-ultrasound. Additionally, selected high-risk patients received computed tomography pulmonary angiogram or ventilation-perfusion (V/Q) scan to screen for incidental pulmonary embolism. RESULTS: Of 485 consecutive patients hospitalized from March through June 2020, 146 patients were analyzed, of which 39% had been admitted to the intensive care unit (ICU). Postdischarge thromboprophylaxis was prescribed in 28% of patients, but was used more frequently after ICU stay (61%) and in patients with higher maximal D-dimer and C-reactive protein levels during hospitalization. Six weeks after discharge, elevated D-dimer values were present in 32% of ward and 42% of ICU patients. Only one asymptomatic deep vein thrombosis (0.7%) and one symptomatic pulmonary embolism (0.7%) were diagnosed with systematic screening. No bleedings were reported. CONCLUSION: In patients who had been hospitalized with COVID-19, systematic screening for VTE 6 weeks after discharge revealed a low incidence of VTE. A strategy of selectively providing postdischarge thromboprophylaxis in high-risk patients seems safe and potentially effective.

Optimization of the detection of inhibitory autoantibodies against the VWF-cleaving protease ADAMTS13 with an automated chemiluminescent ADAMTS13 activity immunoassay.

INTRODUCTION: Acquired thrombotic thrombocytopenic purpura is a rare disease associated with the production of autoantibodies against the VWF-cleaving protease ADAMTS13. The detection of these antibodies is made difficult by the instability of ADAMTS13 in citrated plasma and the time-consuming ADAMTS13 assays. The aim of our study was to evaluate the optimal conditions for detecting anti-ADAMTS13 inhibitory antibodies with the novel automated chemiluminescent immunoassay HemosILR AcuStar ADAMTS13 Activity assay. METHODS: The parallelism between the AcuStar ADAMTS13 calibration curve and ADAMTS13 concentrations in serially diluted citrated plasma was evaluated after 2 hours incubation at 25°C, 37°C, or 37°C after addition of Ca2+ to preserve the activity of the metalloprotease. Using Bethesda assays based on the 3 incubation procedures and the HemosILR AcuStar ADAMTS13 Activity assay, the inhibitor titers were determined in patients' samples with ADAMTS13 antibodies and compared with those determined using the TechnozymR ADAMTS13 activity ELISA. RESULTS: The criterion of parallelism was respected for the 3 incubation methods over the range of ADAMTS13 concentrations relevant for the detection of ADAMTS13 inhibitor antibodies in a Bethesda assay. In agreement with this observation, all the incubation methods permitted the accurate detection and quantification of inhibitory anti-ADAMTS13 antibodies in the samples from patients with acquired thrombotic thrombocytopenic purpura. CONCLUSION: Incubation of plasma samples with normal plasma at 25°C, 37°C, or 37°C after addition of Ca2+ can be used in a Bethesda assay for quantifying the inhibitory activity of antibodies interfering with ADAMTS13 in the chemiluminescent HemosILR AcuStar ADAMTS13 Activity assay.

Patient perspectives regarding gene therapy in haemophilia: Interviews from the PAVING study.

INTRODUCTION: Exploring patient perceptions regarding gene therapies may provide insights about their acceptability to patients. OBJECTIVE: To investigate opinions of people with haemophilia (PWH) regarding gene therapies. Moreover, this study aimed to identify patient-relevant attributes (treatment features) that influence PWH's treatment choices. METHODS: Semi-structured individual interviews were conducted with Belgian PWH, types A and B. A predefined interview guide included information sections and open, attribute ranking and case questions. Qualitative data were organized using NVivo 12 and analysed following framework analysis. Sum totals of scores obtained in the ranking exercise were calculated per attribute. RESULTS: In total, 20 PWH participated in the interviews. Most participants demonstrated a positive attitude towards gene therapy and were very willing (40%; n = 8) or willing (35%; n = 7) to receive this treatment. The following five attributes were identified as most important to PWH in making their choice: annual bleeding rate, factor level, uncertainty of long-term risks, impact on daily life, and probability that prophylaxis can be stopped. While participants were concerned about the uncertainty regarding long-term safety, most participants were less concerned about uncertainty regarding long-term efficacy. CONCLUSIONS: This qualitative study showed that most PWH have a positive attitude towards gene therapy and that besides efficacy, safety and the related uncertainties, also impact on daily life is important to patients. The identified patient-relevant attributes may be used by regulators, health technology assessment bodies and payers in their evaluation of gene therapies for haemophilia. Moreover, they may inform clinical trial design, pay-for-performance schemes and real-world evidence studies.

The factor VIII treatment history of non-severe hemophilia A.

BACKGROUND: In patients with non-severe hemophilia A, we lack detailed knowledge on the timing of treatment with factor VIII (FVIII) concentrates. This knowledge could provide information about the expected treatment timing in patients with severe hemophilia A treated with non-replacement therapies. OBJECTIVE: To assess the FVIII treatment history in patients with non-severe hemophilia A. METHODS: Patients with non-severe hemophilia (baseline FVIII activity [FVIII:C] 2-40 IU/dL) were included from the INSIGHT study. The primary outcome was median age at first FVIII exposure (ED1). In a subgroup of patients for whom more detailed information was available, we analyzed the secondary outcomes: median age at first 20 EDs, annualized bleeding rate for all bleeds (ABR), joint bleeds (AJBR), and major spontaneous bleeds (ASmBR). RESULTS: In the total cohort (n = 1013), median baseline FVIII activity was 8 IU/dL (interquartile range [IQR] 4-15) and the median age at ED1 was 3.7 years (IQR 1.4-7.7). Median age at ED1 rose from 2.5 years (IQR 1.2-5.7) in patients with FVIII:C 2-5 IU/dL to 9.7 years (IQR 4.8-16.0) in patients with FVIII:C 25-40 IU/dL. In the subgroup (n = 104), median age at ED1, ED5, ED10, and ED20 was 4.0 years (IQR 1.4-7.6), 5.6 years (IQR 2.9-9.3), 7.5 years (IQR 4.4-11.3), and 10.2 years (IQR 6.5-14.2), respectively. Median ABR, AJBR, and ASmBR were 1.1 (IQR 0.5-2.6), 0.3 (IQR 0.1-0.7), and 0 (IQR 0-0), respectively. CONCLUSION: This study demonstrates that in non-severe hemophilia A, the age at first FVIII exposure increases with baseline FVIII:C and that major spontaneous bleeds rarely occur.

Paediatric patients with blood-induced ankle joint arthritis demonstrate physiological foot joint mechanics and energetics during walking.

AIM: To compare foot joint kinetics and energetics in male paediatric boys with and without blood-induced ankle joint destruction to these of matched control groups. METHODS: A cross-sectional study was conducted in which 3D gait analysis data were collected from thirty-five male children (6-21 years) with severe or moderate haemophilia and twenty-six typically developing boys. Structural integrity of the tarsal foot joints of all haemophilic patients was assessed using the IPSG-MRI scale. All participants walked barefoot while adopting a physiological gait pattern. Three subgroups were created based on the IPSG-MRI scores: a group with no joint involvement (HealthyHaemo), with uni- or bilaterally involvement (PathoHaemo) and with only unilaterally involvement (Haemo_Unilateral_Patho). RESULTS: The PathoHaemo group presented a significant lower Lisfranc peak dorsiflexion angular velocity (34.7°/s vs 71.4°/s, P = .000, Cohen d = 1.31) and a significantly higher Lisfranc peak plantarflexion angular velocity (-130.5°/s vs -51.8°/s, P = .000, Cohen d = 0.98) compared to the control group. The Haemo_Unilateral_Patho side had a significant higher Chopart peak dorsiflexion angular velocity compared to the Haemo_Unilateral_Healthy side (41.7°/s vs 31.9°/s, P = .002, Cohen d = 1.16). CONCLUSION: No evidence for mild and severe gait deviations could be demonstrated. Internal moments, used as a surrogate measure of joint loading, quantified by the multi-segment foot model were found to be similar within the three subanalyses. We suggest that the ongoing musculoskeletal development in children compensates for structural damage to the ankle joint.

A coagulation defect arising from heterozygous premature termination of tissue factor.

Tissue factor (TF) is the primary initiator of blood coagulation in vivo and the only blood coagulation factor for which a human genetic defect has not been described. As there are no routine clinical assays that capture the contribution of endogenous TF to coagulation initiation, the extent to which reduced TF activity contributes to unexplained bleeding is unknown. Using whole genome sequencing, we identified a heterozygous frameshift variant (p.Ser117HisfsTer10) in F3, the gene encoding TF, causing premature termination of TF (TFshort) in a woman with unexplained bleeding. Routine hematological laboratory evaluation of the proposita was normal. CRISPR-edited human induced pluripotent stem cells recapitulating the variant were differentiated into vascular smooth muscle and endothelial cells that demonstrated haploinsufficiency of TF. The variant F3 transcript is eliminated by nonsense-mediated decay. Neither overexpression nor addition of exogenous recombinant TFshort inhibited factor Xa or thrombin generation, excluding a dominant-negative mechanism. F3+/- mice provide an animal model of TF haploinsufficiency and exhibited prolonged bleeding times, impaired thrombus formation, and reduced survival following major injury. Heterozygous TF deficiency is present in at least 1 in 25,000 individuals and could limit coagulation initiation in undiagnosed individuals with abnormal bleeding but a normal routine laboratory evaluation.

Acquired multi-segment foot kinematics in haemophilic children, adolescents and young adults with or without haemophilic ankle arthropathy.

INTRODUCTION AND AIM: The ankle joint remains vulnerable in children with haemophilia and is the primary joint affected. The purpose of this study was to dynamically characterize the segmental foot and ankle kinematics of male children, adolescents and young adults with or without ankle arthropathy. METHODS: The barefoot multi-segment foot kinematics of 70 ankles from 35 haemophilia subjects between 6 and 20 years old were captured with the Rizzoli Multi-Segment Foot Model. Joint damage of the tibiotalar and subtalar joints was scored using the IPSG-MRI score. The feet of patients with or without evidence of ankle arthropathy were compared with those of matched typically developing boys via a nonpaired comparison. The differences between the affected and nonaffected sides of patients with unilateral ankle arthropathy were assessed using a paired comparison. RESULTS: Subjects without arthropathy demonstrated a nonsignificant trend towards a higher frontal plane range of motion (RoM) at the midfoot upon loading response and a lower sagittal plane RoM at the midfoot during midstance. No differences were observed between the affected side group and their matched control group. The affected side of unilaterally affected subjects exhibited a nonsignificant tendency towards a higher frontal plane RoM at the ankle joint upon loading response and terminal stance compared to the healthy side. CONCLUSION: Most patients maintained physiological rocker function of the ankle and had no (mal)adaptive motion patterns in the more distal joints of the foot. Therefore, established structural lesions may remain subclinical with respect to moderate functional activities like walking.

The biomechanical behaviour of ankle and foot joints during walking with shoes in patients with haemophilia.

INTRODUCTION: Patients with haemophilia (PwH) often prefer shod walking over barefoot walking as footwear offers ankle joint stability and comfort during gait. Yet, the biomechanical mechanisms contributing to the latter remain poorly understood. AIM: To explore the effect of shoes on the biomechanical functioning of the ankle and foot complex in PwH with and without haemophilic ankle arthropathy and to determine the amount of ankle joint loading during shod walking. METHODS: We analysed data of PwH without haemophilic ankle arthropathy (n = 5) and PwH with severe haemophilic ankle arthropathy (n = 17) and a control group (n = 17). During 3D gait analysis, a four-segment kinetic foot model was used to calculate kinematic and kinetic parameters of the ankle, Chopart, Lisfranc and first metatarsophalangeal (MTP 1) joints during both barefoot and shod walking. RESULTS: We found a significantly greater ankle joint power generation during shod walking compared to barefoot walking in PwH with severe haemophilic ankle arthropathy (P < .001). Chopart joint biomechanics were significantly lowered in all three groups during shod walking compared to barefoot walking. During shod walking, the ankle joint load was significantly lowered in both PwH groups (P = .039 and P = .002), but not in the control group (P = .952). CONCLUSION: Explorations in this study uncover a tendency that shoes alter the biomechanical functioning of the ankle and foot complex in PwH and simultaneously lower the ankle joint load during walking.

Blood-induced cartilage damage alters the ankle joint load during walking.

Ankle cartilage damage due to repeated joint bleeds often leads to altered gait in adult patients with hemophilia. It is therefore of clinical importance to develop an understanding of the biomechanical gait features in hemophilia patients with and without blood-induced cartilage damage and age-matched control subjects. We recruited a control group (n = 17), patients with hemophilia (PwH) without blood-induced ankle cartilage damage (PwH_NoCartDam , n = 5) and PwH with severe blood-induced ankle cartilage damage (PwH_CartDam , n = 19). We collected three-dimensional gait analysis data with following outcome variables in the ankle, Chopart and the first metatarsophalangeal (MTP 1) joints: range of motion (ROM) during stance phase, peak joint moment and powers. Biomechanical loading (BW) was quantified as the joint reaction forces using inverse dynamic analysis. Loading rate (BW/s) and impulse (BW*s) were calculated between 50% and 70% of stance phase. All biomechanical variables of the ankle joint were significantly lowered in the PwH_CartDam group compared with both the control subjects and the PwH_NoCartDam group. No compensatory biomechanical function was observed in other foot joints. An ankle loading rate of 2.64 ± 0.83 BW/s was observed in the control group, which was significantly higher than 1.75 ± 0.43 BW/s (P = .049) and 1.22 ± 0.59 BW/s (P < .001) in respectively the PwH_NoCartDam group and PwH_CartDam group. Patients with severe blood-induced cartilage damage demonstrated a (mal)adaptive gait strategy as they experience difficulties to properly unload the ankle cartilage during walking.