Clinical Implications of Discrepancy between One-Stage Clotting and Chromogenic Factor IX Activity in Hemophilia B.

BACKGROUND: Discrepancy in factor IX activity (FIX:C) between one-stage assay (OSA) and chromogenic substrate assay (CSA) in patients with hemophilia B (PwHB) introduces challenges for clinical management. AIM: To study the differences in FIX:C using OSA and CSA in moderate and mild hemophilia B (HB), their impact on classification of severity, and correlation with genotype. METHODS: Single-center study including 21 genotyped and clinically characterized PwHB. FIX:C by OSA was measured using ActinFSL (Siemens) and CSA by Biophen (Hyphen). In addition, in vitro experiments with wild-type FIX were performed. Reproducibility of CSA was assessed between three European coagulation laboratories. RESULTS: FIX:C by CSA was consistently lower than by OSA, with 10/17 PwHB having a more severe hemophilia type by CSA. OSA displayed a more accurate description of the clinical bleeding severity, compared with CSA. A twofold difference between OSA:CSA FIX:C was present in 12/17 PwHB; all patients had genetic missense variants in the FIX serine protease domain. Discrepancy was also observed with diluted normal plasma, most significant for values below 0.10 IU/mL. Assessment of samples with low FIX:C showed excellent reproducibility of the CSA results between the laboratories. CONCLUSION: FIX:C was consistently higher by OSA compared with the CSA. Assessing FIX:C by CSA alone would have led to diagnosis of a more severe hemophilia type in a significant proportion of patients. Our study suggests using both OSA and CSA FIX:C together with genotyping to classify HB severity and provide essential information for clinical management.

High variability in Factor IX one-stage assay in samples spiked with nonacog beta pegol among different pairs of reagent/detection system.

INTRODUCTION: Haemophilia B (HB) is an X-linked hereditary bleeding disorder characterized by coagulation factor IX (FIX) deficiency. To improve the quality of life of patients and adherence to treatment, recombinant factor concentrates modified to extend their half-life have been developed, called extended half-life factors (EHL: extended half-life). Nonacog beta pegol (N9-GP) is a glycopegylated recombinant human FIX molecule that has a half-life of 93 h with a single dose and has shown a higher recovery percentage than other molecules. To diagnose and monitor the treatment of haemophiliac patients, FIX activity is determined with the one-stage clotting assay (OSA) and/or the chromogenic assay. The objective of this work, carried out in three centres, was to measure the recovery of N9-PG with 10 different activated partial thromboplastin time (APTT) reagents on three platforms, in samples spiked in vitro with N9-GP, at four different concentration levels. METHODS: It was measured the recovery of N9-GP with 10 different APTT reagents (polyphenol, ellagic acid, silice dioxide, colloidal silica as APTT activator on three platforms, in sample spiked in vitro with N9-GP. RESULTS: The results show heterogeneity in the activity of N9-GP measured by OSA with the different APTT reagents when the calibrations were performed with the specific calibrator of each coagulometer. A recovery percentage between 87% and 108% was obtained only with polyphenol and ellagic acid as activator in the three platforms evaluated. The other reagents studied overestimate or underestimate, with no clear profile. When a calibration curve was performed with a calibrator prepared from the N9-GP vial, all APTT reagents met the established recovery requirement. CONCLUSION: APTT reagents with polyphenol or ellagic acid as activator would be the only ones appropriate when using the commercially available OSA with specific calibrator to monitor patients treated with N9-GP.

Knowledge and attitudes toward gene therapy of a cohort of Italian patients with hemophilia.

BACKGROUND: Gene therapy (GT) has recently become a new therapeutic option for hemophilia A and B. However, patient levels of knowledge and attitudes toward it are poorly understood. A general lack of knowledge and education has been highlighted in previous studies. To date, no studies focused on patient attitudes toward GT, priorities, concerns, and information needs, nor how these factors might influence their willingness to accept it. OBJECTIVES: To evaluate knowledge and attitudes toward GT of an Italian cohort of patients with hemophilia. METHODS: A questionnaire was administered to patients with hemophilia A and B to evaluate: (1) clinical data; (2) GT knowledge; (3) willingness to accept GT, perceived benefits and concerns, and information needs. RESULTS: Eighty-five patients participated in the study; 64 with severe hemophilia A and 4 with severe hemophilia B. Participants appeared to know only general information on GT, but little about its detailed functioning. The avoidance of frequent infusions and the reduction of bleeding episodes seem to be the most relevant expected benefits. The possibility of failing or losing effectiveness of GT over time was the main concern. Regarding willingness to undergo GT, 54.4% of respondents gave a negative response, mainly due to fear that treatment will lose effectiveness over time, fear of side effects, and lack of GT knowledge. Greater knowledge increased the acceptability of this disruptive therapy among patients with severe hemophilia. CONCLUSION: Overall, Italian patients with hemophilia showed poor knowledge of GT. However, it seems that greater knowledge was associated with a greater willingness to have GT.

Haemophilia B in Algeria: Realities and therapeutic perspectives.

INTRODUCTION: Haemophilia B is a debilitating hereditary coagulation disorder characterized by prolonged or spontaneous episodes of bleeding caused by a deficiency of endogenous factor IX. In Algeria, even though many studies are being carried out to evaluate the prevalence and management of haemophilia B, there is a paucity of locally published literature that can be used to understand the most recent information on the disease's epidemiology, diagnostic techniques and treatment options. AIMS: The aim of this manuscript is to raise awareness among patients and family clinicians about current practices, recent developments and unmet needs related to haemophilia B in Algeria. METHODS: A comprehensive literature search was conducted through online scientific databases to review publications regarding haemophilia B in Algeria. Exclusions of the review include case studies, interregional comparisons, abstract-only papers and studies outside the range of 2012-2022. RESULTS: The findings discussed relate to the epidemiology of haemophilia B in Algeria, the clinical diagnostic process, disease symptoms, the benefits of molecular and genetic testing, advancements in prophylactic care, as well as unmet needs hindering the progression of optimal haemophilia B management. CONCLUSION: These findings are crucial to encourage the maintenance of national registries with updated epidemiological data, facilitate early and timely detection of disease symptoms, improve the provision of diagnostic facilities and enhance the overall treatment landscape for better patient outcomes.

An updated interactive database for 1692 genetic variants in coagulation factor IX provides detailed insights into hemophilia B.

BACKGROUND: Genetic variants in coagulation factor IX (FIX) are associated with hemophilia B, a rare bleeding disease. F9 variants are widespread across the gene and were summarized in our FIX variant database introduced in 2013. OBJECTIVES: We aimed to rationalize the molecular basis for 598 new F9 variants and 1645 new clinical cases, totaling 1692 F9 variants and 5358 related patient cases. METHODS: New F9 variants were identified from publications and online resources, and compiled into a MySQL database for comparison with the human FIXa protein structure. RESULTS: The new total of 1692 F9 variants correspond to 406 (88%) of the 461 FIX residues and now include 70 additional residues. They comprise 945 unique point variants, 281 deletions, 352 polymorphisms, 63 insertions, and 51 others. Most FIX variants were point variants, although their proportion (56%) has reduced compared to 2013 (73%); at the same time, the proportion of polymorphisms has increased from 5% to 21%. The 764 unique mild severity variants in the mature protein with known phenotypes include 74 (9.7%) quantitative type I variants and 116 (15.2%) predominantly qualitative type II variants. The remaining 574 variants types are unspecified. Inhibitors are associated with 152 hemophilia B cases out of 5358 patients (2.8%), an increase of 93 from the previous database. CONCLUSION: The even distribution of the F9 variants revealed few mutational hotspots, and most variants were associated with small perturbations in the FIX protein structure. The updated database will assist clinicians and researchers in assessing treatments for patients with hemophilia B.

Liver-related aspects of gene therapy for hemophilia: need for collaborations with hepatologists.

Adeno-associated virus-based gene therapies hemophilia allow long-term transgene expression with reduced annual bleeding rates. Various liver-related aspects are involved in the different phases of gene therapy, such as assessment of liver health in the pretherapy period, patient selection and follow-up, maintenance of liver health after gene therapy, and management of potential short- and long-term adverse events. Increase in alanine aminotransferease is a common adverse event that requires rapid evaluation and an immunosuppressive approach. It is therefore important that hemophilia treaters and hepatologists collaborate at all stages of gene therapy to assess potential safety issues and ensure the long-term success of gene therapy. Special attention should be given to patients with not well-defined conditions, e.g. patients with some degree of liver fibrosis or fatty liver disease, patients with a history of hepatitis C and hepatitis B infection, patients with HIV infection, and patients taking medications that may affect liver function.

Whole F9 gene sequencing identified deep intronic variations in genetically unresolved hemophilia B patients.

BACKGROUND: The disease-causative variant remains unidentified in approximately 0.5% to 2% of hemophilia B patients using conventional genetic investigations, and F9 deep intronic variations could be responsible for these phenotypes. OBJECTIVES: This study aimed to characterize deep intronic variants in hemophilia B patients for whom genetic investigations failed. METHODS: We performed whole F9 sequencing in 17 genetically unsolved hemophilia B patients. The pathogenic impact of the candidate variants identified was studied using both in silico analysis (MaxEntScan and spliceAI) and minigene assay. RESULTS: In total, 9 candidate variants were identified in 15 patients; 7 were deep intronic substitutions and 2 corresponded to insertions of mobile elements. The most frequent variants found were c.278-1806A>C and the association of c.278-1244A>G and c.392-864T>G, identified in 4 and 6 unrelated individuals, respectively. In silico analysis predicted splicing impact for 4 substitutions (c.278-1806A>C, c.392-864T>G, c.724-2385G>T, c.723+4297T>A). Minigene assay showed a deleterious splicing impact for these 4 substitutions and also for the c.278-1786_278-1785insLINE. In the end, 5 variants were classified as likely pathogenic using the American College of Medical Genetics and Genomics guidelines, and 4 as of unknown significance. Thus, the hemophilia B-causing variant was identified in 13/17 (76%) families. CONCLUSION: We elucidated the causing defect in three-quarters of the families included in this study, and we reported new F9 deep intronic variants that can cause hemophilia B.

Little discrepancy between one-stage and chromogenic factor VIII (FVIII)/IX assays in a large international cohort of persons with nonsevere hemophilia A and B.

BACKGROUND: Accurate measurements of coagulation factor activity form an essential part of hemophilia management and are performed by the one-stage or chromogenic assay. Current literature suggests that approximately one-third of persons with nonsevere hemophilia A exhibit assay discrepancy, albeit with a high variability between studies. Such data are scarce in nonsevere hemophilia B. OBJECTIVES: To investigate the extent of factor VIII/IX one-stage and chromogenic assay discrepancy in moderate and mild hemophilia A and B. METHODS: Persons with previously diagnosed nonsevere hemophilia A and B with a factor level of 2 to 35 IU/dL were included from the international DYNAMO cohort study. Central measurements of the factor VIII and IX activity levels were performed by the one-stage and chromogenic assay. Relative and absolute discrepancy definitions were used, with the International Society on Thrombosis and Haemostasis-Scientific and Standardization Committee proposed ratio of >2.0 or <0.5 being the primary outcome. Discrepancy was also evaluated in a subgroup of 13 persons with mutations previously associated with discrepancy (≥3 cases reported in literature). RESULTS: A total of 220 persons were included, of whom 3 (1%) showed assay discrepancy: 2/175 hemophilia A and 1/45 hemophilia B. Six persons (3%) exhibited an absolute difference >10 IU/dL between the assay results. In addition, with more lenient definitions, over 90% of participants (n = 197) had no discrepant results. Only 1 out of 13 persons with a mutation previously associated with discrepancy had significant assay discrepancy. CONCLUSION: Little assay discrepancy was observed despite the presence of mutations previously associated with discrepancy, suggesting that the presence and magnitude of assay discrepancy are largely determined by laboratory variables.

Differences in wild-type- and R338L-tenase complex formation are at the root of R338L-factor IX assay discrepancies.

Adeno-associated virus (AAV) gene therapy has the potential to functionally cure hemophilia B by restoring factor (F)IX concentrations into the normal range. Next-generation AAV therapies express a naturally occurring gain-of-function FIX variant, FIX-Padua (R338L-FIX), that increases FIX activity (FIX:C) by approximately eightfold compared with wild-type FIX (FIX-WT). Previous studies have shown that R338L-FIX activity varies dramatically across different clinical FIX:C assays, which complicates the monitoring and management of patients. To better understand mechanisms that contribute to R338L-FIX assay discrepancies, we characterized the performance of R338L-FIX in 13 1-stage clotting assays (OSAs) and 2 chromogenic substrate assays (CSAs) in a global field study. This study produced the largest R338L-FIX assay dataset to date and confirmed that clinical FIX:C assay results vary over threefold. Both phospholipid and activating reagents play a role in OSA discrepancies. CSA generated the most divergent FIX:C results. Manipulation of FIX:C CSA kits demonstrated that specific activity gains for R338L-FIX were most profound at lower FIX:C concentrations and that these effects were enhanced during the early phases of FXa generation. Supplementing FX into CSA had the effect of dampening FIX-WT activity relative to R338L-FIX activity, suggesting that FX impairs WT tenase formation to a greater extent than R338L-FIX tenase. Our data describe the scale of R338L-FIX assay discrepancies and provide insights into the causative mechanisms that will help establish best practices for the measurement of R338L-FIX activity in patients after gene therapy.

Factor IX inhibitors in haemophilia B: A report of National Haemophilia Registry in China.

INTRODUCTION: The development of inhibitors against factor FIX (FIX) is the most serious complication of FIX replacement therapy in haemophilia B (HB) patients. Currently, only few cohorts of HB inhibitor patients have been reported worldwide. AIM: This Chinese nationwide study of HB inhibitor patients explored their risk factors for FIX inhibitor development and experience on their management. METHODS: We retrospectively analysed patient characteristics, F9 genotypes, treatment strategies and outcomes of HB inhibitor patients registered to the Chinese National Registry and Patient Organization Registry. RESULTS: Forty-four unique HB inhibitor patients were identified in 4485 unique HB patients registered by year 2021 to the two Registries. Inhibitor diagnosis were usually delayed and the low prevalence (.98%) may suggest some inhibitor patients were not identified. Their median age at inhibitor diagnosis was 7.5 (IQR, 3.0-14.8) years. Most patients (95.5%) had high-titre inhibitors. Allergic/Anaphylactic reactions occurred in 59.1% patients. Large deletions and nonsense mutations were the most common F9 mutation types in our FIX inhibitor patients. Patients with large F9 gene deletions were more likely to develop inhibitors (p = .0002), while those with missense mutations had a low risk (p < .0001). Thirteen (29.5%) patients received immune tolerance induction (ITI) therapy using low-dose prothrombin complex concentrate regimens. Twelve completed ITI with three (25.0%) achieving success. Nephrotic syndrome developed in two (16.7%) patients during ITI. CONCLUSION: This study reports the largest Chinese cohort of HB inhibitor patients. Large deletions were most significantly associated with inhibitor development. Low-dose ITI might be feasible for FIX inhibitor eradication.

The activated partial thromboplastin time-clot waveform analysis in hemophilia: Does it help in differentiation?

INTRODUCTION: The clot waveform analysis (CWA) provide valuable information beyond clotting time. The present study was planned to assess whether the activated partial thromboplastin time (aPTT)-CWA can differentiate between hemophilia A (HA), hemophilia B (HB), or hemophilia A with inhibitors (HAWI). METHODS: The aPTT-CWA was generated by an optical detection system (ACL-TOP™ 500 coagulation analyzer) and the other tests were performed as per instructions from the manufacturer in the kit. RESULTS: A total of 75 samples (47-HA, 16-HAWI, and 12-HB) with prolonged aPTT were recruited. On analyzing the quantitative aPTT-CWA data of HA (non-inhibitors) and HB samples, the width of acceleration 1 [+] peak was the differentiating finding. Among the significant parameters, the second derivative [+] peak was lower in both mild and moderate HA, equating to HB. The time for the height of 1/2 fibrin formation and width of velocity was significantly higher in mild, moderate and severe HA. The study did not show any significant differentiating finding while comparing HAWI and hemophilia A non-inhibitors (HANI). In the subgroups of HAWI and HANI with aPTT <70 s and 70-100 s, the second derivative [+] peak (2A) was higher and the time for the height of 1/2 fibrin formation (1C) was lesser in HAWI. CONCLUSION: The aPTT-CWA parameters may be supportive for the differentiation of hemophilia including its severity and the existence of inhibitors.

Insights into the Molecular Genetic of Hemophilia A and Hemophilia B: The Relevance of Genetic Testing in Routine Clinical Practice.

Hemophilia A and hemophilia B are rare congenital, recessive X-linked disorders caused by lack or deficiency of clotting factor VIII (FVIII) or IX (FIX), respectively. The severity of the disease depends on the reduction of coagulation FVIII or FIX activity levels, which is determined by the type of the pathogenic variants in the genes encoding the two factors (F8 and F9, respectively). Molecular genetic analysis is widely applied in inherited bleeding disorders. The outcome of genetic analysis allows genetic counseling of affected families and helps find a link between the genotype and the phenotype. Genetic analysis in hemophilia has tremendously improved in the last decades. Many new techniques and modifications as well as analysis softwares became available, which made the genetic analysis and interpretation of the data faster and more accurate. Advances in genetic variant detection strategies facilitate identification of the causal variants in up to 97% of patients. In this review, we discuss the milestones in genetic analysis of hemophilia and highlight the importance of identification of the causative genetic variants for genetic counseling and particularly for the interpretation of the clinical presentation of hemophilia patients.

The profile of patients with haemophilia managed at a haemophilia treatment centre in Pretoria, Gauteng.

BACKGROUND: Haemophilia A and B are X-linked recessive bleeding disorders resulting from a deficiency of factors VIII and IX, respectively. Early diagnosis and a comprehensive approach to management is mandatory. This study aimed to describe the profile of patients with haemophilia (PWH) managed at Dr George Mukhari Academic Hospital (DGMAH) with the view to identify potential areas to improve haemophilia care. METHODS: A cross-sectional, descriptive study that retrospectively reviewed clinical and laboratory records of PWH managed at DGMAH haemophilia treatment centre from 01 January 2003 to 31 December 2017. RESULTS: Forty-four males were identified, with the majority being adults (~61%). Haemophilia A patients (~82%) outnumbered those with haemophilia B (~18%). Spontaneous mucocutaneous bleeding was the most frequent presenting feature followed by haemarthrosis. Disease-related complications included joint complications and life-threatening bleeds. There was a delay in diagnosis in 11% PWH. Management included episodic plasma-derived factor replacement and bypassing agents for patients with inhibitors. Only 13% of PWH were on home therapy. Prevalence of inhibitor development was 18%. There was a paucity of recorded data regarding prophylaxis, genetic counselling, psychological and physiotherapy support. CONCLUSION: The majority of PWH were adults, and haemophilia A was more prevalent than haemophilia B. A delay in haemophilia diagnosis could be addressed by increasing the awareness of haemophilia in health facilities. Expanding home therapy and introducing prophylaxis will likely improve the quality of life in PWH. Study outputs have included compilation of diagnostic and management algorithms to optimise haemophilia care at DGMAH.

Investigation of the Bleeding Tendency in Sudanese Female Carriers of Hemophilia B.

Background: Hemophilia (HB) is an X-linked, recessive bleeding disorder characterized by the deficiency or absence of the coagulation factor IX. Usually, females are carriers of the trait, while males are affected. FIX deficiency leads to uncontrollable bleeding events, and the severity is dependent on the levels of the clotting factor. The objective of this research was to measure the prevalence of bleeding tendency in Sudanese carriers of HB. Materials and Methods: In this cross-sectional study, 88 Sudanese carriers of HB participated. The activated partial thromboplastin time test (APTT) and FIX test were performed for each carrier. The frequencies of DNA polymorphism and FIX-linked restriction fragments BamHI, HhaI, and MnII were also assessed. The study was conducted in Khartoum, Sudan, during the period from 2015 to 2017. Results: The study showed that 55 (62.5%) HB carriers were from the Laban village in the White Nile State, and all of them were members of the Shinkheb tribe. The mean age of the study population was 26.3 years. Among the carriers, 57 (64.7%) had abnormal coagulation profiles. The mean value of the APTT level among carriers was significantly increased (P value: 0.000), while the mean concentration of the FIX levels among the carriers was significantly decreased (P value: 0.000). The study also showed a negative correlation between PTT and F assay with P value of 0.000 and R value of 0.578. Conclusion: The APTT is high in most carriers and the FIX assay level is low in most carriers. Most carriers had no symptoms and were not bleeding. The Shinkheb tribe is the most ethnic tribe carrying HB (62.5%). HhaII is more informative for carrier detection than others, but it is of significant value if both (MnII and HhaII) were performed in parallel. In Sudanese, BamHI was informative but MnII and HhaII were best in the mutation detection and for prenatal diagnosis.

Results of genetic analysis of 11 341 participants enrolled in the My Life, Our Future hemophilia genotyping initiative in the United States.

BACKGROUND: Hemophilia A (HA) and hemophilia B (HB) are rare inherited bleeding disorders. Although causative genetic variants are clinically relevant, in 2012 only 20% of US patients had been genotyped. OBJECTIVES: My Life, Our Future (MLOF) was a multisector cross-sectional US initiative to improve our understanding of hemophilia through widespread genotyping. METHODS: Subjects and potential genetic carriers were enrolled at US hemophilia treatment centers (HTCs). Bloodworks performed genotyping and returned results to providers. Clinical data were abstracted from the American Thrombosis and Hemostasis Network dataset. Community education was provided by the National Hemophilia Foundation. RESULTS: From 2013 to 2017, 107 HTCs enrolled 11 341 subjects (68.8% male, 31.2% female) for testing for HA (n = 8976), HB (n = 2358), HA/HB (n = 3), and hemophilia not otherwise specified (n = 4). Variants were detected in most male patients (98.2%% HA, 98.1% HB). 1914 unique variants were found (1482 F8, 431 F9); 744 were novel (610 F8, 134 F9). Inhibitor data were available for 6986 subjects (5583 HA; 1403 HB). In severe HA, genotypes with the highest inhibitor rates were large deletions (77/80), complex intron 22 inversions (9/17), and no variant found (7/14). In severe HB, the highest rates were large deletions (24/42). Inhibitors were reported in 27.3% of Black versus 16.2% of White patients. CONCLUSIONS: The findings of MLOF are reported, the largest hemophilia genotyping project performed to date. The results support the need for comprehensive genetic approaches in hemophilia. This effort has contributed significantly towards better understanding variation in the F8 and F9 genes in hemophilia and risks of inhibitor formation.

Recurrent bleeding after rubber band ligation diagnosed as mild hemophilia B: a case report and literature review.

BACKGROUND: Hemophilia is a recessive hemorrhagic disease relevant to X chromosome. In mild hemophilia cases, spontaneous bleeding is rare and the blood clotting function is normal, but severe bleeding may occur after trauma or surgery. Therefore, missed diagnosis of hemophilia before operation may contribute to bleeding after hemorrhoid operation. CASE PRESENTATION: A 21-year-old male was hospitalized in the anorectal department because of repeated bleeding after hemorrhoid surgery. Despite several suture hemostasis procedures, the patient still suffered from recurrent bleeding. He had no family history of hemophilia or bleeding tendency, and had not been diagnosed with hemophilia before this admission. The diagnosis of mild hemophilia B was made after further examination of coagulation indexes. By using frozen plasma and coagulation factor complex to supplement coagulation factors, the patient's bleeding was stopped and he was discharged after 23 days in hospital. During the follow-up, lower-than-normal coagulation factors were still found in him, but no bleeding occurred again. CONCLUSIONS: The undiagnosed patient with mild hemophilia B has an increased risk of bleeding after hemorrhoid surgery because of the consumption of coagulation factors. This case report aims to address the importance of hemophilia screening before operation and reduce the risk of postoperative bleeding. For patients with recurrent bleeding after hemorrhoid surgery, hemophilia should be further excluded. Wound bleeding may recur in hemophilia patients after suture hemostasis. Therefore, prompt supplementation of coagulation factors is needed to help stop bleeding once the diagnosis of hemophilia is made.

High risk and low prevalence diseases: Hemophilia emergencies.

INTRODUCTION: Hemophilia is a bleeding disorder due to coagulation pathway factor deficiency that is associated with significant morbidity and mortality. OBJECTIVE: This review highlights the pearls and pitfalls of the emergency department (ED) evaluation of hemophilia, including diagnostic procedures, imaging, and management based on current evidence. DISCUSSION: Hemophilia is marked by deficiency in factor VIII (in hemophilia A) or IX (in hemophilia B), which may result in severe bleeding. The severity of the disease depends upon factor levels. Patients with severe deficiency most commonly present in the first two years of life. Severe bleeding may include intracranial hemorrhage, retroperitoneal bleeding, large hematomas, bleeding within the chest or abdomen/pelvis, and subacute or delayed postpartum bleeding. ED management is the immediate replacement of clotting factors based on the suspicion of bleed rather than the confirmation of one. The doses for factor concentrate replacement to achieve factor levels of 100% are 50 U/kg for FVIII and 100 U/kg for FIX. The development of inhibitors can complicate the clinical picture and treatment possibilities. Consultation with the hematology specialist is recommended to assist with evaluation and management. CONCLUSION: Emergency physician knowledge of hemophilia, including the presentation, evaluation, and management, can improve the care of these patients.

Hemofilia B, un sangrado atípicamente abundante durante una prueba rutinaria de un neonato / Hemophilia B, an atypically heavy bleeding during a routine test of a newborn

La hemofilia B es un trastorno hematológico producido por el déficit del factor IX. Aunque generalmente se diagnostica cuando el lactante inicia el gateo o deambulación en forma de hemartros o hemorragias musculares, en este caso el debut es a los 3 días de vida, con un sangrado abundante atípico durante una prueba de rutina. La exploración y pruebas complementarias (hemograma, coagulación, ecografías de partes blandas y grandes articulaciones) no revelaron datos de gravedad. El factor IX, que determina la gravedad, pasó del 1% a un 3% en 24 horas por lo que no precisó de tratamiento (AU)

Hemophilia B is a blood disorder caused by a deficiency of factor IX. Although it is usually diagnosed when the infant starts crawling or walking through the detection of hemarthrosis or muscle bleeds, in this case the onset occurred at 3 days of age with detection of heavy atypical bleeding during a routine test. The examination and additional testing (blood count, coagulation, ultrasound of soft tissue and large joints) did not evince severe disease. Factor IX, which determines the severity, increased from 1% to 3% in 24 hours, so treatment was not required. (AU)