A case of congenital afibrinogenemia with multiple thrombotic and hemorrhagic disorders

This is a case of congenital afibrinogenemia with multiple thrombotic and hemorrhagic events. His fibrinogen concentration was negatively correlated with thrombin time and prothrombin time and abnormally negatively correlated with plasma D-dimer levels. The individualized standard for fibrinogen concentration may help to balance thrombotic and hemorrhagic events for this disease.

One Hundred Years of Congenital Fibrinogen Disorders

Congenital fibrinogen disorders encompass a broad range of fibrinogen defects characterized by a wide molecular and clinical spectrum. From the first clinical description of afibrinogenemia in 1920, many major achievements have contributed to a better understanding of these complex disorders. The finding of causative mutations in all three fibrinogen genes has contributed to reveal the molecular mechanisms involved in biosynthesis of the fibrinogen molecule and to clarify the basic processes of fibrin polymerization and fibrinolysis. The compilation of abundant cases with detailed genetic, biological, and clinical features has enabled the classification of congenital fibrinogen disorders into several types and subtypes. Thus, the recent classification of congenital fibrinogen disorder is based not only on the clottable and antigenic fibrinogen levels but also on the patient's clinical phenotype and genotype. Fibrinogen supplementation is the cornerstone of bleeding management in fibrinogen disorders. Since the discovery of blood fractionation, the method of production of fibrinogen concentrate has been progressively modified to significantly improve purity and safety. Nevertheless, the availability of such products is still limited to a few countries and the optimal threshold of fibrinogen to target is still not established. In this review, we describe the major advances that have characterized 100 years of congenital fibrinogen disorders, focusing on afibrinogenemia and dysfibrinogenemia.

Medical Management of a Mural Thrombus Inducing Repeated Ischemic Strokes in a Patient with Congenital Afibrinogenemia

OBJECTIVES

Congenital afibrinogenemia is an autosomal recessive inherited disorder that can cause thrombotic as well as hemorrhagic events. We describe a case of repeated mild ischemic strokes due to a mural thrombus in the carotid artery and our medical treatment.

CASE DESCRIPTION

A 49-year-old woman with congenital afibrinogenemia developed two minor ischemic strokes in two months. Clinical images revealed scattered fresh infarcts in the right middle cerebral artery region and mild cervical carotid artery stenosis. The risk for surgical treatment was considered to be extraordinarily high. The patient was treated with 100 mg/day of aspirin and 3 g fibrinogen infusion every two weeks. After the one-year course of medication, the mural thrombus gradually decreased, and there were no bleeding or ischemic stroke events.

CONCLUSION

This case report highlights the successful treatment of an ischemic stroke in a patient with a congenital afibrinogenemia with an antiplatelet agent and fibrinogen replacement. There are no guidelines for managing ischemic stroke in patients with congenital afibrinogenemia, and further studies are needed.

The Efficacy of Fibrinogen Concentrates in Relation to Cryoprecipitate in Restoring Clot Integrity and Stability against Lysis

Loss of fibrinogen is a feature of trauma-induced coagulopathy (TIC), and restoring this clotting factor is protective against hemorrhages. We compared the efficacy of cryoprecipitate, and of the fibrinogen concentrates RiaSTAP^® and FibCLOT^® in restoring the clot integrity in models of TIC. Cryoprecipitate and FibCLOT^® produced clots with higher maximal absorbance and enhanced resistance to lysis relative to RiaSTAP^®. The fibrin structure of clots, comprising cryoprecipitate and FibCLOT^®, mirrored those of normal plasma, whereas those with RiaSTAP^® showed stunted fibers and reduced porosity. The hemodilution of whole blood reduced the maximum clot firmness (MCF) as assessed by thromboelastography. MCF could be restored with the inclusion of 1 mg/mL of fibrinogen, but only FibCLOT^® was effective at stabilizing against lysis. The overall clot strength, measured using the Quantra^® hemostasis analyzer, was restored with both fibrinogen concentrates but not cryoprecipitate. α₂antiplasmin and plasminogen activator inhibitor-1 (PAI-1) were constituents of cryoprecipitate but were negligible in RiaSTAP^® and FibCLOT^®. Interestingly, cryoprecipitate and FibCLOT^® contained significantly higher factor XIII (FXIII) levels, approximately three-fold higher than RiaSTAP^®. Our data show that 1 mg/mL fibrinogen, a clinically achievable concentration, can restore adequate clot integrity. However, FibCLOT^®, which contained more FXIII, was superior in normalizing the clot structure and in stabilizing hemodiluted clots against mechanical and fibrinolytic degradation.

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.

Impact of fibrinogen infusion on thrombin generation and fibrin clot structure in patients with inherited afibrinogenemia

INTRODUCTION

Inherited afibrinogenemia is a very rare disease characterized by complete absence of fibrinogen in the circulation and an increased risk in both thrombosis and bleeding. Infusion of fibrinogen concentrate (FC) is the main approach for prevention and management of bleeding; however, it has been reported to carry a thrombotic risk.

METHODS

We investigated the impact of a standard dose (40-100 mg/kg) of FC infusion on the thrombin generation (TG) parameters and the fibrin clot structure formed in plasma samples of patients with afibrinogenemia. Blood samples were collected from 20 patients before (T0) and 1 hour after infusion of FC (T1). TG was studied with Calibrated Automated Thrombography. Fibrin clot structure was assessed with turbidimetry and scanning electron microscopy (SEM).

RESULTS

FC infusions (mean Clauss fibrinogen plasma level 1.21 g/L at T1) led to a statistically significant increase in endogenous thrombin potentials (ETP) (p<0.0001) and thrombin peaks (p=0.02). Nevertheless, when compared to healthy controls, patients' T1 lag times were longer (p=0.002), ETP values were lower (p=0.0003), and thrombin peaks were lower (p<00001). All fibrin polymerization parameters (turbidimetry) obtained at T1 were comparable to those of patients with inherited hypofibrinogenemia matched for fibrinogen plasma levels.

CONCLUSIONS

In summary, fibrinogen infusion with a standard dose of FC increased but did not correct TG and led to formation of fibrin clots similar to those of patients with hypofibrinogenemia. All in all, our results do not support to biological evidence of hypercoagulability induced by FC in patients with afibrinogenemia.

Disorders of Fibrinogen and Fibrinolysis

Fibrinogen plays a fundamental role in coagulation through its support for platelet aggregation and its conversion to fibrin. Fibrin stabilizes clots and serves as a scaffold and immune effector before being broken down by the fibrinolytic system. Given its importance, abnormalities in fibrin(ogen) and fibrinolysis result in a variety of disorders with hemorrhagic and thrombotic manifestations. This review summarizes (i) the basic elements of fibrin(ogen) and its role in coagulation and the fibrinolytic system; (ii) the laboratory evaluation for fibrin(ogen) disorders, including the use of global fibrinolysis assays; and (iii) the management of congenital and acquired disorders of fibrinogen and fibrinolysis.

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.

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

Background

Congenital 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.

Methods

The 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.

Results

A 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.

Conclusions

The mutation induced a structural change at the carboxyl-terminal of the fibrinogen molecule, leading to fibrinogen secretion dysfunction.

Clinical features and genetic defect in six index patients with congenital fibrinogen disorders: Three novel mutations with one common mutation in Taiwan's population

INTRODUCTION

Congenital fibrinogen disorders (CFDs) are caused by mutations in fibrinogen-encoding genes, FGA, FGB, and FGG, which lead to quantitative or qualitative abnormalities of fibrinogen. Although the diagnosis of CFDs is based on antigenic and functional level of fibrinogen, few genotypes are clearly correlated with phenotype.

METHODS

In this study, we investigated all of the referred patients diagnosed as CFDs in Taiwan's population between 1995 and 2020. Clinical features, laboratory data and genetic defects were analysed. Functional fibrinogen level was determined by the Clauss method. Antigenic fibrinogen was measured by an enzyme-linked immunosorbent assay. Fibrinogen genes were assessed for mutations by polymerase chain reaction and sequencing.

RESULTS

A total of 18 patients from six unrelated families with CFDs were identified. One patient from a consanguineous family was diagnosed as afibrinogenemia type 1A with a novel homozygous frameshift mutation in FGB exon 4. The other five (83.3 %) index patients were all diagnosed as dysfibrinogenemia type 3A caused by two novel and one known mutation. Six (33.3 %) patients from three families had a novel mutation in FGB exon 8. The clinical features and laboratory data were highly variable among these patients with the same mutation.

CONCLUSIONS

Three novel mutations of CFDs causing afibrinogenemia and dysfibrinogenemia were identified. The point mutation in FGB exon 8 is also a common mutation in Taiwan's population. Considerable phenotypic variability among the patients with an identical mutation was observed.

[Analysis of gene mutation spectrum and pharmacokinetics of fibrinogen infusion in 146 cases of congenital fibrinogen disorders]

Objective: To investigate the clinical type and gene mutations, clinical manifestations, laboratory tests, diagnosis, and fibrinogen replacement therapy of congenital fibrinogen disorders. Methods: Clinical data of 146 patients with congenital fibrinogen disorders diagnosed from April 2000 to November 2020 were retrospectively analyzed. Results: Among the 146 patients, 61 (41.8%) men and 85 (58.2%) women had a median age of 33.5 years at the time of consultation. 34 patients (34.7%) were found to suffer from the disease due to bleeding symptoms, 33 patients (33.7%) due to preoperative examination. 55 patients (56.1%) had at least one bleeding symptom, and 42 patients (42.9%) had no bleeding symptoms. There is a negative correlation between fibrinogen activity concentration and bleeding ISTH-BAT score (rs=-0.412, P=0.001) . A total of 34 gene mutations were detected in 56 patients, of which 84.1% were missense mutations, and 16 new mutations were found. FGA Exon2 and FGG Exon8 mutations accounted for 71.4% of all mutation sites. Patients with afibrinogenemia were younger, with a median age of 2 (1-12) years, an ISTH-BAT score of 4, and patients with dysfibrinogenemia had significantly longer thrombin time (TT) , with a median of 28.5 (19.2-36.6) s. The 1 hour in vivo recovery (IVR) after fibrinogen infusion was (127.19±44.03) %, and the 24 hour IVR was (101.78±43.98) %. In addition to the obvious increase in the concentration of fibrinogen activity, the TT and the prothrombin time (PT) both decreased significantly, and the TT decreased more significantly, with an average decrease of 15.2% compared to the baseline after 24 hours of infusion. Conclusion: Most patients with congenital fibrinogen disorders have mild or no bleeding symptoms. Patients with afibrinogenemia have more severe symptoms. There is a negative correlation between the fibrinogen and the degree of bleeding. Genetic testing is helpful for the diagnosis of disease classification. FIB∶C/FIB∶Ag<0.7 can be used as a basis for clinical diagnosis. The TT can be used as the basis for the diagnosis of dysfibrinogenemia and the effectiveness of fibrinogen infusion.

Clinical phenotype, fibrinogen supplementation, and health-related quality of life in patients with afibrinogenemia

Due to the low prevalence of afibrinogenemia, epidemiologic data on afibrinogenemia are limited, and no data are available on health-related quality of life (HRQoL). We conducted a cross-sectional international study to characterize the clinical features, the fibrinogen supplementation modalities, and their impact on HRQoL in patients with afibrinogenemia. A total of 204 patients (119 adults and 85 children) from 25 countries were included. The bleeding phenotype was severe: 68 (33.3%) patients having at least one bleed per month and 48 (23%) a history of cerebral bleeding. About 35% (n = 72) of patients were treated with fibrinogen concentrates or cryoprecipitates as prophylaxis, 18.1% (n = 37) received ≥1 injection per week, and 16.6% (n = 34) were on home treatment. A thrombotic event was reported in venous and/or arterial territories by 37 (18.1%) patients. Thrombosis occurred even in young patients, and recurrence was frequent (7.4%). The total HRQoL was lower in children than in adults. Discomfort linked to treatment and limitations to sports and leisure were the main concerns. Women and children were particularly affected in family relationships. In multivariate analyses, younger age, residence in Asia or Africa, and a previous thrombotic event were statistically correlated with a worse HRQoL. In summary, our study underlines the severe bleeding and thrombotic phenotype and their impact on HRQoL in afibrinogenemia. The optimal strategy for fibrinogen supplementation needs to be determined. This trial was registered at www.clinicaltrials.gov as #NCT03484065.

How I treat dysfibrinogenemia

Congenital dysfibrinogenemia (CD) is caused by structural changes in fibrinogen that modify its function. Diagnosis is based on discrepancy between decreased fibrinogen activity and normal fibrinogen antigen levels and is confirmed by genetic testing. CD results from monoallelic mutations in fibrinogen genes leading to clinically heterogenous disorders. Most patients with CD are asymptomatic at time of diagnosis but the clinical course may be complicated by a tendency to bleeding and/or thrombosis. Patients with a thrombotic-related fibrinogen variant are particularly at risk and in such patients long-term anticoagulation should be considered. Management of surgery and pregnancy raise important and difficult issues. The mainstay of CD treatment remains fibrinogen supplementation. Antifibrinolytic agents are part of the treatment in some specific clinical settings. In this article, we discuss five clinical scenarios to highlight common clinical challenges. We detail our approach to establish a diagnosis of CD and discuss strategies for the management of bleeding, thrombosis, surgery and pregnancy.

Blood, Sweat, and Fears: A Novel Mutation Associated With Anaphylaxis and Nonresponse in a Patient With Afibrinogenemia

Congenital afibrinogenemia is a rare disorder characterized by a lack of detectable fibrinogen. The mainstay of treatment for acute bleeding episodes or perioperative management is replacement with fibrinogen concentrate or fibrinogen-containing blood products. The development of neutralizing antibodies and severe allergic reactions to fibrinogen replacement is rarely reported in afibrinogenemia patients. Here the treatment regimen is described for a 6-year-old girl with a severe allergic reaction to multiple fibrinogen-containing products who became refractory to treatment because of a presumed inhibitor to fibrinogen.

Heterogeneity of congenital afibrinogenemia, from epidemiology to clinical consequences and management

Fibrinogen is a complex protein playing a major role in coagulation. Congenital afibrinogenemia, characterized by the complete absence of fibrinogen, is associated with major hemostatic defects. Even though the clinical course is unpredictable and can be completely different among patients, severe bleeding is the prominent symptom. Patients are also at increased risk of thrombosis and sometimes suffer from spontaneous spleen rupture, bone cysts and defective wound healing. Due to the relative rarity of afibrinogenemia, there are no evidence-based strategies for helping physicians in care of these patients. Fibrinogen supplementation is the keystone to prevent or treat bleeding events. In addition, fibrinogen, a pleiotropic protein with numerous physiological roles in immunity, angiogenesis and tissue repair, is involved in many diseases. Indeed, depletion of fibrinogen in animal models of infections, tumors and neurological diseases has an effect on the clinical course. The consequences for patients with afibrinogenemia still need to be investigated.

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.

Afibrinogenemia caused by a novel homozygous missense mutation, FGB p.Cys241Tyr, in a male patient with recurrent intracranial bleeding: case report and review of literature

INTRODUCTION

Congenital afibrinogenemia is a severe bleeding disorder, sometimes manifesting as thrombosis and/or pregnancy complications. Intracranial haemorrhage (ICH) constitutes the major cause of death in this disease.

METHODS

We present the case of a male patient with congenital afibrinogenemia, who presented with recurrent intracranial hemorrhages, despite prophylactic fibrinogen substitution. We also review the literature for the risk of intracranial hemorrhages in afibrinogenemia.

RESULT

Molecular analysis revealed a novel homozygous missense mutation in FGB exon 5, p.Cys241 Tyr, that was named "Fibrinogen Krakow V".

DISCUSSION AND CONCLUSION

Intracranial hemorrhage is a severe manifestation of afibrinogenemia, also in children. The clinical presentation of afibrinogenemia is variable. Fibrinogen substitution carries a risk of thrombotic complications.

Women With Congenital Hypofibrinogenemia/Afibrinogenemia: From Birth to Death

Congenital fibrinogen disorders are a group of most frequent rare coagulation disorder, characterized by deficiency and/or defects in the fibrinogen molecule. Quantitative disorders include hypofibrinogenemia and afibrinogenemia. Due to their specific physiological characteristics, female patients tend to have congenital hypofibrinogenemia/afibrinogenemia, such as spontaneous recurrent abortion, menorrhagia, infertility, antepartum and postpartum hemorrhage, and so on. Current studies of congenital hypofibrinogenemia/afibrinogenemia mainly focus on different types of fibrinogen mutations, etiology/pathogenesis, and some rare case reports of the diseases. So far, there is no study available to systematically review the specific features of female patients with congenital bleeding disorders. This review aims to deal with hematological, gynecologic and obstetric issues, and relevant clinical management of congenital hypofibrinogenemia/afibrinogenemia at different life stages of female patients. We believe this review provides valuable reference for clinicians in the field of hematology, obstetrics, as well as gynecology.