Congenital Hypofibrinogenemia Research Articles

Prophylaxis and Treatment of Bleeding or Thrombosis with Fibrinogen Concentrate (Fibryga) in Patients with Congenital Hypofibrinogenemia or Dysfibrinogenemia

Congenital fibrinogen disorders (CFDs) are rare and make up approximately 0.6% of all inherited bleeding disorders. Two subtypes include a quantitative deficiency of fibrinogen, congenital afibrinogenemia (CA), congenital hypofibrinogenemia (CH), and qualitative defect of the fibrinogen molecule, congenital dysfibrinogenemia (CD). Patients with CD may have a thrombotic as well as a hemorrhagic disease phenotype. In the past, fresh frozen plasma or cryoprecipitate were the only options available for treatment and prevention of bleeding in patients with CFD. Today in the US, human plasma-derived concentrates (FIBRYGA, Octapharma, Lachlen, Switzerland, and RiaSTAP, CSL, Melbourne, Australia) are available and considered safe and effective treatment options for CD and CH. Guidelines for the treatment and prevention of bleeding is not established for CFDs, and especially for CD. We present eight clinical cases of patients with hypo- or dysfibrinogenemia that were effectively treated with a pooled, plasma-derived fibrinogen concentrate (FIBRYGA) either prophylactically for elective or urgent surgery, or post-traumatic injury. The mean age of patients treated was 34 years (min-max 8-70 years). Three patients were male and five, female. Four patients had CH and four, CD. FIBRYGA was used to prophylactically treat a total of ten surgical procedures and two post-traumatic events in these patients. Dosing of FIBRYGA was based on the goal peak plasma fibrinogen concentration and the manufacturer's prescribing information, but modified to align with local laboratory reference ranges for the functional fibrinogen test. No acute or delayed infusion reactions (nausea, fever, rigors, headache) and no hypersensitivity reactions were noted. One patient developed two adverse events, one thrombotic and one hemorrhagic. This patient underwent left, above the knee amputation (AKA) and had a complicated postoperative period due to her multiple comorbidities including type 2 diabetes, hypertension, and long standing, poorly-controlled, severe peripheral arterial disease. She presented nineteen days after receiving FIBRGYA with a PE and multiple DVTs. Fifty-nine days later she presented with wound dehiscence and underwent an extensive excisional debridement with postoperative bleeding deemed to be secondary to her strap sliding during surgery and acting as a tourniquet for venous blood flow. For the majority (86%) of our patients described here with CH and CD, FIBRYGA was well tolerated and effective in preventing post procedural or post traumatic bleeding complications. The post procedural bleeding noted in one patient may have been due to inadequate fibrinogen concentration or other comorbid conditions. Further clinical studies are needed to determine the role of FIBRGYA and other HFC in the treatment of patients with CFD, especially those with CD.

Placenta percreta management in a patient with a severe congenital hypofibrinogenemia

The obstetrical follow-up of patients with a severe hypofibrinogenemia requires a multidisciplinary collaboration because of potential maternal-fetal complications (recurrent miscarriages, intrauterine fetal demise, post-partum hemorrhage, thrombosis). We report the obstetrical management of a multiparous patient with a severe congenital hypofibrinogenemia associated with a platelet disorder (abnormal phospholipid externalization). A therapeutic strategy based on a biweekly administration of fibrinogen concentrates associated with enoxaparin and aspirin allowed the maintenance of pregnancy. But this last one got complicated by a placenta percreta requiring a salvage hysterectomy with an appropriate hemorrhage prophylaxis.

Analysis of fibrinogen concentrate pharmacokinetics and dosing for bleeds and surgery in adults, adolescents, and children with congenital afibrinogenaemia and hypofibrinogenaemia.

Congenital afibrinogenaemia and hypofibrinogenaemia are rare coagulation disorders where clotting is impaired due to a lack of fibrinogen. Consequent bleeding episodes (BEs) are treated using human fibrinogen concentrate (HFC). This post-hoc analysis compared HFC pharmacokinetics (PK) and dosing between patient age groups and defined the in vivo recovery (IVR) for children with a- and hypofibrinogenaemia. The analysis used data from the FORMA-01 (Phase 2), FORMA-02 and FORMA-04 (Phase 3) multinational, prospective, open-label studies in patients with a- and hypofibrinogenaemia. HFC PK in adults/adolescents (≥12 years; FORMA-01) and children (<12 years; FORMA-04) was examined. Haemostatic efficacy in BE treatment and perioperative prophylaxis was examined in FORMA-02 and FORMA-04 using an objective 4-point scale, with success defined as excellent/good. Median (range) age was 23 years for FORMA-01 (12-53; n=22), 26.5 years for FORMA-02 (12-54; n=25), and 6 years for FORMA-04 (1-10; n=13). Mean PK parameters were lower for children (AUC, Cmax , IVR; p=.02), while clearance was higher. Median (range) total dose of HFC for all BEs was 59.41mg/kg (32.12-273.80) in adults/adolescents and was 24% higher (ns) in children at 73.91mg/kg (47.45-262.50). Treatment was successful in 98.9% of the 89 BEs in adults/adolescents and in 100% of the 10 BEs in children, with comparable results for perioperative prophylaxis. As expected, HFC PK differed between adults/adolescents and children. However, with the higher doses given to children, HFC showed similar efficacy across age groups. Dose adaptation based on age groups appears recommendable.

Heterogeneity of Genotype-Phenotype in Congenital Hypofibrinogenemia-A Review of Case Reports Associated with Bleeding and Thrombosis.

Congenital fibrinogen disorders are diseases associated with a bleeding tendency; however, there are also reports of thrombotic events. Fibrinogen plays a role in the pathogenesis of thrombosis due to altered plasma concentrations or modifications to fibrinogen’s structural properties, which affect clot permeability, resistance to lysis, and its stiffness. Several distinct types of genetic change and pathogenetic mechanism have been described in patients with bleeding and a thrombotic phenotype, including mutations affecting synthesis or processing in three fibrinogen genes. In this paper, we focused on familial hypofibrinogenemia, a rare inherited quantitative fibrinogen disorder characterized by decreased fibrinogen levels with a high phenotypic heterogeneity. To begin, we briefly review the basic information regarding fibrinogen’s structure, its function, and the clinical consequences of low fibrinogen levels. Thereafter, we introduce 15 case reports with various gene mutations derived from the fibrinogen mutation database GFHT (French Study Group on Hemostasis and Thrombosis), which are associated with congenital hypofibrinogenemia with both bleeding and thrombosis. Predicting clinical presentations based on genotype data is difficult. Genotype–phenotype correlations would be of help to better understand the pathologic properties of this rare disease and to provide a valuable tool for the identification of patients who are not only at risk of bleeding, but also at risk of a thrombotic event.

Congenital Afibrinogenemia and Hypofibrinogenemia: Laboratory and Genetic Testing in Rare Bleeding Disorders with Life-Threatening Clinical Manifestations and Challenging Management.

Congenital fibrinogen disorders are rare pathologies of the hemostasis, comprising quantitative (afibrinogenemia, hypofibrinogenemia) and qualitative (dysfibrinogenemia and hypodysfibrinogenemia) disorders. The clinical phenotype is highly heterogeneous, being associated with bleeding, thrombosis, or absence of symptoms. Afibrinogenemia and hypofibrinogenemia are the consequence of mutations in the homozygous, heterozygous, or compound heterozygous state in one of three genes encoding the fibrinogen chains, which can affect the synthesis, assembly, intracellular processing, stability, or secretion of fibrinogen. In addition to standard coagulation tests depending on the formation of fibrin, diagnostics also includes global coagulation assays, which are effective in monitoring the management of replacement therapy. Genetic testing is a key point for confirming the clinical diagnosis. The identification of the precise genetic mutations of congenital fibrinogen disorders is of value to permit early testing of other at risk persons and better understand the correlation between clinical phenotype and genotype. Management of patients with afibrinogenemia is particularly challenging since there are no data from evidence-based medicine studies. Fibrinogen concentrate is used to treat bleeding, whereas for the treatment of thrombotic complications, administered low-molecular-weight heparin is most often. This review deals with updated information about afibrinogenemia and hypofibrinogenemia, contributing to the early diagnosis and effective treatment of these disorders.

Ex Vivo and In Vivo Evaluation of Fibrinogen Concentrate to Mitigate Post-Surgical Bleeding in Neonates

Introduction: Bleeding is a serious complication among neonates undergoing cardiopulmonary bypass (CPB) and it is linked to significant morbidity and mortality. Current standard of care treatment for bleeding after CPB focuses on the transfusion of adult blood products, including platelets and cryoprecipitate. However, prior work by Nellenbach et al. has demonstrated structural differences between neonatal and adult clotting components. Importantly, neonatal and adult fibrin do not fully integrate during clot formation which may contribute to ineffective clot formation and/or increased thrombotic risk following transfusion of adult cryoprecipitate to neonates. There has been increased interest in using human fibrinogen concentrate (HFC) in treating bleeding in the post-CPB neonate; however, HFC has not been validated in this population through evidence-based means. This study analyzed structural and degradation properties of post-CPB clots +/- the ex vivo addition of HFC and compared structural and degradation properties of post-CPB clots after the in vivo transfusion of HFC versus cryoprecipitate.Methods: Human neonatal plasma samples were collected from patients undergoing CPB at the Children's Hospital of Atlanta. For ex vivo studies, samples were taken at baseline, post-bypass, and post-transfusion of cryoprecipitate (n = 18 patients). Clots were formed for analysis from samples alone as well as post-bypass samples with the addition of 0.5 or 0.9 mg/mL HFC (RiaSTAP, CSL Behring) and structure was examined through confocal microscopy. Clot degradation was assessed through a microfluidic fibrinolysis assay. For in vivo studies, samples were taken at baseline, post-transfusion of cryoprecipitate or HFC, upon ICU arrival, and at 24 hours post-surgery (n = 36 patients). Clots were formed from samples and structure was examined through confocal microscopy. Clot degradation was assessed through a plate-based fibrinolysis assay.Results: In ex vivo studies, clot structural analysis demonstrated no significant differences in fiber density between samples collected at different time points (baseline = 0.541 ± 0.105, post-bypass = 0.431 ± 0.111, post-transfusion = 0.594 ± 0.170). The addition of 0.5 mg/mL or 0.9 mg/mL HFC to post-bypass samples led to a significant increase in fiber density (0.5 mg/mL HFC=0.654 ± 0.158, p=0.02; 0.9 mg/mL HFC= 0.797 ± 0.193, p<0.0001). Functional microfluidic analysis of clot degradation demonstrated significantly faster degradation times among post-bypass samples when compared to baseline samples (baseline degradation rate = 11.061 ± 6.087, post-bypass degradation rate = 25.906 ± 9.990 microns/hour, p=0.04). The addition of 0.5 mg/mL HFC resulted in a slower degradation rate from the original post-CPB degradation rate, but did not reach statistical significance (0.5 mg/mL HFC=14.091 ± 2.241, p=0.14). However, the addition of 0.9 mg/mL HFC resulted in a significantly slower degradation rate (0.9 mg/mL HFC=8.594 ± 6.087, p=0.01). Studies comparing in vivo transfusion of cryoprecipitate and HFC demonstrated no significant difference between treatment groups in clot density or degradation rate for any sample time point.Conclusion: We identify patterns in structural properties of clots formed after the transfusion of HFC that are consistent with successful hemostasis. However, caution is warranted regarding potentially thrombotic risks and should be carefully analyzed in future studies.Figure: Effect of Ex Vivo HFC Addition on Clot Structure and Degradation. (A) Representative confocal imaging of clots formed from different samples and HFC dosages (scale = 50 um). (B) Effect of HFC Addition on Clot Fiber Density. Addition of both 0.5 and 0.9 mg/mL HFC dosages to post-bypass sample result in statistically significant increases in fiber density compared to post-bypass samples. (C) Effect of HFC Addition on Clot Degradation Profiles. Addition of 0.9 mg/mL HFC to post-bypass sample leads to statistically significant slower fibrinolysis. [Display omitted] DisclosuresBrown: Selsym Biotech, Inc.: Other: Co-Founder and CEO. OffLabel Disclosure:RiaSTAP (human fibrinogen concentrate) is FDA approved for the treatment of congenital hypofibrinogenemia.

Peri‐operative management of multiple tooth extractions in a patient with congenital hypofibrinogenemia receiving anticoagulant therapy

AbstractCongenital fibrinogen disorder is rare and is responsible for the difficulty in achieving hemostasis following surgery. A 75‐year‐old man was referred to our hospital for the management of gingival hemorrhage. He had a medical history of congenital hypofibrinogenemia, right internal carotid stenosis, hypertension, brain infarction, and Alzheimer's disease. A diagnosis of gingival hemorrhage due to periodontitis of the maxillary left second molar and severe periodontitis necessitating extraction in the maxillary second molars bilaterally, mandibular left second molar, and mandibular right first and third molars was made. A pre‐operative hematological examination revealed a fibrinogen level of 53.7 mg/dl. Fibrinogen (3 g) was administered and reached a concentration of 92.8 mg/dl before the surgery. Several episodes of post‐operative hemorrhages in the sockets were managed with local hemostatic treatment and splint adjustment. Fibrinogen levels were maintained at 72.5–92.8 mg/dl, until hemostasis was achieved. This case report illustrates the appropriate management of patients with congenital hypofibrinogenemia requiring extraction of multiple teeth.

A novel fibrinogen γ-chain frameshift mutation, p. Cys365Phefs*41, causing hypofibrinogenemia with bleeding phenotype in a Chinese family.

BackgroundCongenital hypofibrinogenemia is a rare bleeding disease that is classified as the quantitative deficient type. In the present study, investigated the relationship between the genotype and phenotype in a family with hypofibrinogenemia.MethodsThe proband was aware of a predisposition to bleeding. Functional analysis was performed for her all family members, including coagulation function tests, thrombus molecular markers, thromboelastography, scanning electron microscopy, DNA sequencing, and high-performance liquid chromatography-mass spectrometry (HPLC-MS). Pathogenicity analysis and protein modeling of mutant amino acids were also performed.ResultsA novel heterozygous mutation in c.1094delG was detected in FGG exon 8, which resulted in p. Cys365Phefs*41 (containing the signal peptide) in the proband and her mother, who showed a corresponding decrease in fibrinogen function and levels. Thromboelastography indicated that the strength of their blood clots decreased and they had an increased risk of bleeding. The proband fibrin network structure was looser than healthy controls, with large pores in the network, which increased the permeability of lytic enzymes. Results of HPLC-MS showed a lack of mutant peptide chain expression in their plasma, indicating that the family had congenital hypofibrinogenemia, with a clinical phenotype that is related to the degree of fibrinogen deficiency. The mutation truncated the γ-peptide chain and destroyed the functional structure of fibrinogen, including the γ352Cys-γ365Cys disulfide bond. The truncated peptide chains may also lead to nonsense-mediated decay.ConclusionsThe mutation induced a structural change at the carboxyl-terminal of the fibrinogen molecule, leading to fibrinogen secretion dysfunction.

Congenital hypofibrinogenemia: a case report

Fibrinogen disorders are rare bleeding disorders. Fibrinogen is also called factor I which is involved in last step of coagulation cascade. Congenital hypofibrinogenemia is usually caused by mutation of FIB (fibrinogen-binding protein) gene. These disorders should be suspected when Thrombin time is prolonged in well look child with history of bleeding manifestations. We are describing a female child who is having pallor with history of recurrent ecchymosis and minor post traumatic bleeding. Based on coagulation screening profile, we made the diagnosis of hypofibrinogenemia.

Congenital Hypofibrinogenemia: Presentation of a Rare Coagulation Disorder

Fibrinogen is a precursor of fibrin, which acts as a procoagulant plasma soluble protein. It is involved in blood viscosity and clot stability to help in the recovery of damaged blood vessels. We describe the case of a preterm newborn who presented with abdominal distension and manifestations of bleeding in venipuncture sites. In the initial laboratories, prolonged coagulation times were observed with a decreased concentration of fibrinogen. This newborn had transfusion support, with recovery in factor levels and a subsequent decrease in them. Based on this trend and ruling out other possible causes of hypofibrinogenemia, such as liver disease, sepsis, or disseminated intravascular coagulation, the diagnosis of congenital hypofibrinogenemia was made. This case report includes the diagnostic and therapeutic approach of an unusual hemorrhagic presentation in the newborn, highlighting the need for transfusion and dynamic fibrinogen replacement to prevent complications and seek rapid improvement in symptoms.

Successful Conservative Treatment of Ovulation-Related Hemoperitoneum in a Patient With Congenital Hypofibrinogenemia: A Case Report and Review of Literature

Intraperitoneal bleeding provoked by rupture of an ovarian follicle at ovulation or a corpus-luteum-cyst is not uncommon among women of reproductive-age. Usually, this is minimal and passes unnoticed. Massive hemoperitoneum is rare and is commonly associated with an underlying pathology. Patients with coagulation disorders or receiving anticoagulation therapy are exceptionally prone to develop massive hemoperitoneum that could at times be life-threatening if not identified and treated early. Very few cases of ovulation-related massive hemoperitoneum among afibrinogenemic/hypofibrinogenemic patients were reported to the literature. We present a case of congenital hypofibrinogenemia who presented with acute abdominal pain due to massive hemoperitoneum identified on ultrasonography. As the patient continued to be hemodynamically stable, on close monitoring of vital signs and serial hematologic parameters, conservative management with fresh frozen plasma (FFP) was started. This treatment modality was successful in inhibiting bleeding and ameliorating the clinical condition. The possibility of coagulation defects should be entertained in the differential diagnosis of acute abdomen with massive hemoperitoneum especially when no identifiable direct cause could be elicited. Conservative treatment aiming at conserving ovarian integrity and function has been successful in the management of cases with afibrinogenemic/hypofibrinogenemic and other bleeding disorders, thereby averting the need for surgical intervention. It should be the modality of choice in hemodynamically stable patients. Optimal management can be attained through careful clinical assessment and close follow-up by a multidisciplinary team including gynecologists, hematologists, surgeons and intensive care specialists. Ways to prevent recurrence should be accurately introduced to patients. J Clin Gynecol Obstet. 2020;9(4):112-118 doi: https://doi.org/10.14740/jcgo628

A Novel Nonsense Mutation in FGB (c.1421G>A; p.Trp474Ter) in the Beta Chain of Fibrinogen Causing Hypofibrinogenemia with Bleeding Phenotype.

Congenital hypofibrinogenemia is a rare bleeding disorder characterized by a proportional decrease of functional and antigenic fibrinogen levels. Hypofibrinogenemia can be considered the phenotypic expression of heterozygous loss of function mutations occurring within one of the three fibrinogen genes (FGA, FGB, and FGG). Clinical manifestations are highly variable; most patients are usually asymptomatic, but may appear with mild to severe bleeding or thrombotic complications. We have sequenced all exons of the FGA, FGB, and FGG genes using the DNA isolated from the peripheral blood in two unrelated probands with mild hypofibrinogenemia. Coagulation screening, global hemostasis, and functional analysis tests were performed. Molecular modeling was used to predict the defect of synthesis and structural changes of the identified mutation. DNA sequencing revealed a novel heterozygous variant c.1421G>A in exon 8 of the FGB gene encoding a Bβ chain (p.Trp474Ter) in both patients. Clinical data from patients showed bleeding episodes. Protein modelling confirmed changes in the secondary structure of the molecule, with the loss of three β sheet arrangements. As expected by the low fibrinogen levels, turbidity analyses showed a reduced fibrin polymerisation and imaging difference in thickness fibrin fibers. We have to emphasize that our patients have a quantitative fibrinogen disorder; therefore, the reduced function is due to the reduced concentration of fibrinogen, since the Bβ chains carrying the mutation predicted to be retained inside the cell. The study of fibrinogen molecules using protein modelling may help us to understand causality and effect of novel genetic mutations.

Genetic Variants in the FGB and FGG Genes Mapping in the Beta and Gamma Nodules of the Fibrinogen Molecule in Congenital Quantitative Fibrinogen Disorders Associated with a Thrombotic Phenotype

Fibrinogen is a hexameric plasmatic glycoprotein composed of pairs of three chains (Aα, Bβ, and γ), which play an essential role in hemostasis. Conversion of fibrinogen to insoluble polymer fibrin gives structural stability, strength, and adhesive surfaces for growing blood clots. Equally important, the exposure of its non-substrate thrombin-binding sites after fibrin clot formation promotes antithrombotic properties. Fibrinogen and fibrin have a major role in multiple biological processes in addition to hemostasis and thrombosis, i.e., fibrinolysis (during which the fibrin clot is broken down), matrix physiology (by interacting with factor XIII, plasminogen, vitronectin, and fibronectin), wound healing, inflammation, infection, cell interaction, angiogenesis, tumour growth, and metastasis. Congenital fibrinogen deficiencies are rare bleeding disorders, characterized by extensive genetic heterogeneity in all the three genes: FGA, FGB, and FGG (enconding the Aα, Bβ, and γ chain, respectively). Depending on the type and site of mutations, congenital defects of fibrinogen can result in variable clinical manifestations, which range from asymptomatic conditions to the life-threatening bleeds or even thromboembolic events. In this manuscript, we will briefly review the main pathogenic mechanisms and risk factors leading to thrombosis, and we will specifically focus on molecular mechanisms associated with mutations in the C-terminal end of the beta and gamma chains, which are often responsible for cases of congenital afibrinogenemia and hypofibrinogenemia associated with thrombotic manifestations.

Successful Conservative Treatment of Ovulation-Related Hemoperitoneum in a Patient With Congenital Hypofibrinogenemia: A Case Report and Review of Literature

Successful Conservative Treatment of Ovulation-Related Hemoperitoneum in a Patient With Congenital Hypofibrinogenemia: A Case Report and Review of Literature

Safety and Efficacy of Fibrinogen Concentrate in Congenital Fibrinogen Deficiency: A Post-Marketing Observational Study

Background: Congenital fibrinogen deficiencies (CFD), including afibrinogenemia and hypofibrinogenemia, are associated with severe and/or frequent bleeding episodes (BEs) that can occur spontaneously or following trauma. Human fibrinogen concentrate (HFC) has been shown to rapidly restore hemostasis in the event of such bleeding. The safety and efficacy of a new highly purified HFC have been demonstrated in interventional clinical studies; however, real-world evidence collected from routine clinical practice is needed to corroborate these data. Aims: The FORMA-07 study will collect real-world evidence from clinical practice concerning the safety and efficacy of a new HFC in the treatment of CFD. This highly purified, plasma-derived, lyophilized HFC undergoes two dedicated virus inactivation/removal steps during production. Methods: The FORMA-07 study is a post-marketing, multicenter observational study in adults and adolescents (≥12 years) with congenital afibrinogenemia or hypofibrinogenemia who are expected to require on-demand treatment with HFC for BEs. The study will examine treatment with a highly purified, plasma-derived, double virus inactivated/eliminated, lyophilized HFC (Octapharma). This Octapharma-sponsored study will seek approval from independent ethics committees prior to study start. Informed consent will be obtained from all subjects. Exclusion criteria include: other bleeding disorders, including acquired fibrinogen deficiency and dysfibrinogenemia; anti-fibrinogen inhibitors; participation in concurrent clinical studies. The study outline is shown in Figure 1. The primary endpoint is the incidence of thromboembolic adverse drug reactions (ADRs) in patients receiving HFC for on-demand treatment of BEs. Secondary endpoints include the hemostatic efficacy of HFC for treatment of all BEs recorded in the study (with focus on major BEs), assessed by the investigator using a 4-point objective scale within 2-24 hours following treatment. Safety endpoints include ADRs, serious ADRs, and ADRs of special interest (i.e., thromboembolic events and allergic reactions, including anaphylaxis). The planned study duration is up to 6 years and the study aims to enroll a minimum of 25 patients treated with HFC, to describe 105 BEs, including a minimum of 10 major BEs in 10 patients. During the observation period, enrolled patients may be treated for any BEs. Results: Results will be monitored on an ongoing basis and the study is expected to end Q2 2025. Conclusions: This study will collect real-world evidence for the safety and efficacy of HFC during routine clinical use in the treatment of bleeding in patients with congenital fibrinogen deficiency. Figure 1 Disclosures Schwartz: Octapharma: Employment. Peyvandi:Alnylam: Honoraria; Bioverativ: Membership on an entity's Board of Directors or advisory committees; Grifols: Honoraria; Kedrion: Honoraria; Octapharma: Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees. Solomon:Octapharma: Employment. Knaub:Octapharma: Employment. Toth:Octapharma: Employment.

Spontaneous vulvar hematoma as a rare manifestation of congenital hypofibrinogenemia. Case report

Introduction: Congenital fibrinogen disorders are rare conditions in which there are quantitative and qualitative alterations of factor I; the vast majority of patients are asymptomatic.Case presentation: A 19-year-old female patient with a history of congenital hypofibrinogenemia presented with spontaneous vulvar hematoma along with hypotension, tachycardia, stupor and hematoma of 20cm in the right labium majus. On admission, the young woman had hemoglobin 6.6 g/dL, fibrinogen 74 mg/dL and prolonged clotting times. She received red blood cells transfusion and cryoprecipitates, followed by surgical drainage and intravenous fibrinogen replacement, adjusting the dose according to fibrinogen levels in plasma. The patient presented progressive improvement without hemorrhagic recurrence and fibrinogen levels within the target values until hospital discharge.Discussion: Afibrinogenemia and hypofibrin­ogenemia are part of the quantitative factor I disorders; in the first case, there is total absence of circulating fibrinogen, and in the second case the levels are below 150 mg/dL. Sponta­neous vulvar hematoma as a severe hemorrhagic manifestation is not frequent in symptomatic patients; its treatment is based on fibrinogen replacement in an individualized manner and surgical management when required.Conclusion: Hypofibrinogenemia is a rare dis­ease, and fibrinogen replacement is one of the mainstays of treatment.

Congenital hypofibrinogenemia – A cause for neck swelling

Congenital hypofibrinogenemia is a rare condition which can present as spontaneous hemorrhage. We present a case of a 7-year-old male who presented with complaints of sudden swelling over the cheek and neck after an episode of fever and upper respiratory tract infection. The diagnosis was delayed as the initial diagnosis of deep neck space infection was suspected, and the patient was treated in that line. The diagnosis was suspected when the child developed swelling in the knee joint and workup was done for hypofibrinogenemia. The child was transfused with cryoprecipitate and he has complete recovery by day 7.

A novel fibrinogen gamma-chain mutation, p.Cys165Arg, causes disruption of the γ165Cys–Bβ227Cys disulfide bond and ultimately leads to hypofibrinogenemia

BackgroundCongenital hypofibrinogenemia is a type of hereditary disease characterized by impaired fibrinogen synthesis and/or secretion induced by mutations in the fibrinogen gene. ObjectivesWe investigated the phenotypes, genotypes, and pathogenesis of congenital hypofibrinogenemia in an affected family. Patients/methodsThe proband had a risk of bleeding; therefore, conventional coagulation screening was performed for the proband and her family members. Mutation sites in all exons and flanking sequences of FGA, FGB, and FGG were identified, with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) performed to indicate the expression of abnormal chains. The effect of the mutation sites on fibrinogen structure and function was predicted by molecular modeling, and purified plasma fibrinogen from the proband was analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and scanning electron microscopy. Thromboelastography was applied to assess the risk of bleeding and clotting in the proband. ResultsFibrinogen levels in the proband were 1.21 g/L, 1.31 g/L, and 1.38 g/L according to Clauss assay, the prothrombin time method, and enzyme-linked immunosorbent assay, respectively. A novel heterozygous mutation (γCys165Arg), a heterozygous mutation (AαIle6Val), and two genetic polymorphisms (AαThr331Ala and BβArg478Lys) in fibrinogen were found in the proband, and MALDI-TOF MS indicated absence of the mutated chain in patient plasma. Additionally, the heterozygous mutation (γCys165Arg) displayed substitution of a nonpolar γ165Cys (low mass) with a positively charged Arg (high mass) along with a small fiber diameter and loose network structure. ConclusionsFibrinogen γCys165Arg mutations cause damage to the interchain disulfide bonds of fibrinogen and hinder fibrinogen secretion, possibly explaining the pathological mechanism associated with congenital hypofibrinogenemia.

Congenital hypofibrinogenemia associated with γK232T

SummaryWe have previously reported a case of congenital hypofibrinogenemia caused by a novel heterozygous A→C transition at nucleotide 5864 of FGG, leading to the K232T substitution in the fibrinogen γ-chain. However, the pathogenic mechanism is still unclear. To further reveal its molecular basis, we examined the effects of γK232T substitution on fibrinogen synthesis, stability, and secretion through in vitro expression of mutant γ232T in Chinese hamster ovary (CHO) cells. Quantitative RT-PCR of the variant γ-chain mRNA showed that the γ232T transcribed the variant cDNA. Enzyme-linked immunosorbent assay and Western blot analysis of the cell lysates and culture media showed that the CHO cells transfected with successfully synthesized the variant fibrinogen, but failed to secrete it into the culture medium. Furthermore, fibrinogen purified from the plasma of patient showed a normal thrombin-catalyzed fibrin polymerization, also indicating the impeding secretion of variant γ232T fibrinogen. In conclusion, our data reveal that the γK232T is responsible for the congenital hypofibrinogenaemia through interfering with the correct secretion of fibrinogen.

A Novel Mutation in the Fibrinogen Bβ Chain (c.490G>A; End of Exon 3) Causes a Splicing Abnormality and Ultimately Leads to Congenital Hypofibrinogenemia.

We found a novel heterozygous mutation in the fibrinogen Bβ chain (c.490G>A) of a 3-year-old girl with congenital hypofibrinogenemia. To clarify the complex genetic mechanism, we made a mini-gene including a FGB c.490G>A mutation region, transfected it into a Chinese Hamster Ovary (CHO) cell line, and analyzed reverse transcription (RT) products. The assembly process and secretion were examined using recombinant mutant fibrinogen. Direct sequencing demonstrated that the mutant RT product was 99 bp longer than the wild-type product, and an extra 99 bases were derived from intron 3. In recombinant expression, a mutant Bβ-chain was weakly detected in the transfected CHO cell line, and aberrant fibrinogen was secreted into culture media; however, an aberrant Bβ-chain was not detected in plasma. Since the aberrant Bβ-chain was catabolized faster in cells, the aberrant Bβ-chain in a small amount of secreted fibrinogen may catabolize in the bloodstream. FGB c.490G>A indicated the activation of a cryptic splice site causing the insertion of 99 bp in intron 3. This splicing abnormality led to the production of a Bβ-chain possessing 33 aberrant amino acids, including two Cys residues in the coiled-coil domain. Therefore, a splicing abnormality may cause impaired fibrinogen assembly and secretion.