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 in a Neonate with a Novel Mutation in the FGB Gene

Detection of severe hypofibrinogenemia (<50 mg/dL) in a neonate soon after birth is alarming because of the risk of hemorrhage. A female neonate was noted to be hypofibrinogenemic (<50 mg/dL) on day 0 of birth; she showed no thrombocytopenia/coagulopathy or hemorrhagic symptoms. Considering the possibility of afibrinogenemia, which may cause bleeding, fresh frozen plasma (FFP) was initiated twice a week to maintain her plasma fibrinogen level at 50–100 mg/dL. Thereafter, we found hypofibrinogenemia in her father and elder sister and plasma fibrinogen levels, determined by clot formation and immunological methods, showed similarly reduced values in both the neonate (proband) and her father. Based on a presumed diagnosis of congenital hypofibrinogenemia, sequencing of the fibrinogen genes was performed, revealing a novel heterozygous mutation of FGB (Genbank NG008833); a p.403Try>Stop. The neonate was treated with repeat FFP infusions until two months of age, when treatment was stopped because she remained asymptomatic.

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.

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.