Spontaneous splenic rupture in a patient with congenital afibrinogenemia

Clinical, Laboratory, and Molecular Aspects of Congenital Fibrinogen Disorders

Congenital fibrinogen disorders (CFDs) include afibrinogenemia, hypofibrinogenemia, dysfibrinogenemia, and hypodysfibrinogenemia. The fibrinogen levels, the clinical features, and the genotype define several sub-types, each with specific biological and clinical issues. The diagnosis of CFDs is based on the measurement of activity and antigen fibrinogen levels as well as on the genotype. While relatively easy in quantitative fibrinogen disorders, the diagnosis can be more challenging in qualitative fibrinogen disorders depending on the reagents and methods used, and the underlying fibrinogen variants. Overall, quantitative and qualitative fibrinogen defects lead to a decrease in clottability, and usually in a bleeding tendency. The severity of the bleeding phenotype is moreover related to the concentration of fibrinogen. Paradoxically, patients with CFDs are also at risk of thrombotic events. The impact of the causative mutation on the structure and the fibrinogen level is one of the determinants of the thrombotic profile. Given the major role of fibrinogen in pregnancy, women with CFDs are particularly at risk of obstetrical adverse outcomes. The study of the fibrin clot properties can help to define the impact of fibrinogen disorders on the fibrin network. The development of next generation sequencing now allows the identification of genetic modifiers able to influence the global hemostasis balance in CFDs. Their integration in the assessment of the patient risk on an individual scale is an important step toward precision medicine in patients with such a heterogeneous clinical course.

A Case Report of Congenital Afibrinogenemia and Literature Review of Management of Post-circumcision Bleeding

We present a case of bleeding from circumcision in a full-term newborn male resulting from a rare coagulopathy, congenital afibrinogenemia, and a review of the literature regarding the management of bleeding after circumcision. Bleeding was managed with silver nitrate, suturing, thrombin powder, Arista^TM AH (absorbable hemostatic particles; Becton, Dickinson and Company, Franklin Lakes, USA), FFP (fresh frozen plasma), and cryoprecipitate. The Fibrinogen level was less than 30 mg/dl (ref 150-430 mg/dl). The diagnosis of congenital afibrinogenemia was confirmed by a gene test. The baby was found to have a heterozygous pathogenic variant (c.510+1G>T) and a heterozygous likely pathogenic variant (c.1037del) in the FGA gene.

Extension of the Human Fibrinogen Database with Detailed Clinical Information—The αC-Connector Segment

Fibrinogen, an abundant plasma glycoprotein, is involved in the final stage of blood coagulation. Decreased fibrinogen levels, which may be caused by mutations, are manifested mainly in bleeding and thrombotic disorders. Clinically relevant mutations of fibrinogen are listed in the Human Fibrinogen Database. For the αC-connector (amino acids Aα240–410, nascent chain numbering), we have extended this database, with detailed descriptions of the clinical manifestations among members of reported families. This includes the specification of bleeding and thrombotic events and results of coagulation assays. Where available, the impact of a mutation on clotting and fibrinolysis is reported. The collected data show that the Human Fibrinogen Database reports considerably fewer missense and synonymous mutations than the general COSMIC and dbSNP databases. Homozygous nonsense or frameshift mutations in the αC-connector are responsible for most clinically relevant symptoms, while heterozygous mutations are often asymptomatic. Symptomatic subjects suffer from bleeding and, less frequently, from thrombotic events. Miscarriages within the first trimester and prolonged wound healing were reported in a few subjects. All mutations inducing thrombotic phenotypes are located at the identical positions within the consensus sequence of the tandem repeats.

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.

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.

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.

A Novel Frameshift Mutation in the FGA Gene (c.196 delT) Leading to Congenital Afibrinogenemia

BACKGROUND

Congenital afibrinogenemia is characterized by the absence of fibrinogen. Congenital fibrinogen disorders result from several mutations in FGA, FGB, or FGG. Their epidemiology is not well known.

OBSERVATION

The present study reports on 2 children with congenital afibrinogenemia. The first child, a male who is now 9 years old, was diagnosed with afibrinogenemia after spontaneous intracranial bleeding at the age of 3 years. The second child is a 2-year-old female cousin of the first patient, who was diagnosed with afibrinogenemia after coagulation tests were carried out due to frequent epistaxis and mucocutaneous bleeding. At follow-up, blood samples of the patients and their parents were sent to the Department of Genetic Medicine and Development, University Medical Center, Switzerland, for polymerase chain reaction analysis. In both patients, the novel homozygous frameshift mutation in the FGA exon 3: c.196 delT was detected. The parents of the patients were both heterozygous for the same mutation.

CONCLUSIONS

Congenital afibrinogenemia is a rare coagulation disease. The molecular epidemiology of congenital fibrinogen disorders is complex, and the identification of new mutations will help shed light on this complex molecular structure. Therefore, a genetic analysis that includes more centers is needed.

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.

Clinical Consequences and Molecular Bases of Low Fibrinogen Levels

The study of inherited fibrinogen disorders, characterized by extensive allelic heterogeneity, allows the association of defined mutations with specific defects providing significant insight into the location of functionally important sites in fibrinogen and fibrin. Since the identification of the first causative mutation for congenital afibrinogenemia, studies have elucidated the underlying molecular pathophysiology of numerous causative mutations leading to fibrinogen deficiency, developed cell-based and animal models to study human fibrinogen disorders, and further explored the clinical consequences of absent, low, or dysfunctional fibrinogen. Since qualitative disorders are addressed by another review in this special issue, this review will focus on quantitative disorders and will discuss their diagnosis, clinical features, molecular bases, and introduce new models to study the phenotypic consequences of fibrinogen deficiency.

Congenital afibrinogenemia: a case report of a spontaneous hepatic hematoma

INTRODUCTION

Afibrinogenemia is a rare coagulation disorder. Clinical features of spontaneous bleeding, bleeding after minor trauma, or after surgery have been described as well as thrombo-embolic complications. In this article, we presented the case of a 19-year old female with congenital afibrinogenemia who was admitted with a spontaneous intrahepatic hematoma.

CONCLUSIONS

Supportive treatment including transfusion and fibrinogen administration, associated with repeated packing surgeries and selective embolization, were successfully performed.

Can the phenotype of inherited fibrinogen disorders be predicted?

Congenital fibrinogen disorders are rare diseases affecting either the quantity (afibrinogenaemia and hypofibrinogenaemia) or the quality (dysfibrinogenaemia) or both (hypodysfibrinogenaemia) of fibrinogen. In addition to bleeding, unexpected thrombosis, spontaneous spleen ruptures, painful bone cysts and intrahepatic inclusions can complicate the clinical course of patients with quantitative fibrinogen disorders. Clinical manifestations of dysfibrinogenaemia include absence of symptoms, major bleeding or thrombosis as well as systemic amyloidosis. Although the diagnosis of any type of congenital fibrinogen disorders is usually not too difficult with the help of conventional laboratory tests completed by genetic studies, the correlation between all available tests and the clinical manifestations is more problematic in many cases. Improving accuracy of diagnosis, performing genotype, analysing function of fibrinogen variants and carefully investigating the personal and familial histories may lead to a better assessment of patients' phenotype and therefore help in identifying patients at increased risk of adverse clinical outcomes. This review provides an update of various tests (conventional and global assays, molecular testing, fibrin clot analysis) and clinical features, which may help to better predict the phenotype of the different types of congenital fibrinogen disorders.