A novel mutation in the fibrinogen Aα chain (Gly13Arg, fibrinogen Nanning) causes congenital dysfibrinogenemia associated with defective peptide A release

Guideline for diagnosis and management of congenital dysfibrinogenemia

INTRODUCTION

Congenital dysfibrinogenemia (CD) is characterized by dysfunction induced by an abnormal fibrinogen molecule structure that results in blood coagulation dysfunction. The clinical manifestations of CD patients are asymptomatic, bleeding and thrombosis. The majority of patient are asymptomatic. However, the single fibrinogen detection method is easy to cause missed diagnosis or misdiagnosis of CD patients. The treatment strategies of CD patients with different clinical manifestations are also different.

METHODS

Combing the existing experimental diagnosis technology, literature and our research results, a simple and practical CD diagnostic criteria was proposed. And based on the relevant literature and existing treatment guidelines, more comprehensive treatment recommendations are summarized.

RESULTS

In this new criteria, combination Clauss method and PT derived method was proposed to detect fibrinogen and its ratio was used to diagnose for CD. Diagnosis also needs to be combined the clinical manifestations, family investigation and genetic testing. According to different clinical manifestation (bleeding, thrombosis or asymptomatic), treatment methods and strategies are different. The treatment of CD patients should consider the patient's personal and family history of bleeding or thrombosis. Treatment of thrombosis and pregnancy may be more challenging. The risk of bleeding and thrombosis should be evaluated and balanced at all times during clinical treatment. These detailed treatment recommendations can provide reference for patients with different clinical manifestations of CD.

CONCLUSIONS

The new CD diagnosis criteria and comprehensive treatment recommendations can effectively improve the diagnosis and treatment of CD.

Mutations Accounting for Congenital Fibrinogen Disorders: An Update

Fibrinogen is a complex protein that plays a key role in the blood clotting process. It is a hexamer composed of two copies of three distinct chains: Aα, Bβ, and γ encoded by three genes, FGA, FGB, and FGG, clustered on the long arm of chromosome 4. Congenital fibrinogen disorders (CFDs) are divided into qualitative deficiencies (dysfibrinogenemia, hypodysfibrinogenemia) in which the mutant fibrinogen molecule is present in the circulation and quantitative deficiencies (afibrinogenemia, hypofibrinogenemia) with no mutant molecule present in the bloodstream. Phenotypic manifestations are variable, patients may be asymptomatic, or suffer from bleeding or thrombosis. Causative mutations can occur in any of the three fibrinogen genes and can affect one or both alleles. Given the large number of studies reporting on novel causative mutations for CFDs since the review on the same topic published in 2016, we performed an extensive search of the literature and list here 120 additional mutations described in both quantitative and qualitative disorders. The visualization of causative single nucleotide variations placed on the coding sequences of FGA, FGB, and FGG reveals important structure function insight for several domains of the fibrinogen molecule.

A novel heterozygous mutation (γIIe367Thr) causes congenital dysfibrinogenemia in a Chinese family

: The aim of this study was to elucidate the molecular defects in a Chinese family with dysfibrinogenemia. The fibrinogen activity was measured by the one-stage clotting method. The fibrinogen antigen was measured with immunoturbidimetry. The fibrinogen gene was amplified by PCR with direct sequencing. Suspected mutation was confirmed by reverse sequencing. Bioinformatics and model analysis were used to study the conservatism and harm of the mutation. The proband had a history of menorrhagia. Study showed fibrinogen activity at 0.35 g/l and fibrinogen antigen at 2.05 g/l. Sequencing analysis detected a heterozygous c.1178T>C missense mutation in exon 9 of FGG gene resulting in p.IIe367Thr. The bioinformatics and model analysis indicated that the IIe367Thr mutation may disrupt the activation of the fibrinogen. We detected a novel IIe367Thr missense mutation in the FGG. To our knowledge this is causative mutation has not been reported so far.

Comparison of clinical phenotype with genetic and laboratory results in 31 patients with congenital dysfibrinogenemia in northern Slovakia

Congenital dysfibrinogenemia (CD) is a rare disorder of hemostasis. The majority of cases are caused by heterozygous missense mutations in one of the three fibrinogen genes. Patients with CD may experience bleeding and thrombosis, but many are asymptomatic. To better describe the clinical, laboratory, and genotypic picture of CD, we evaluated 31 patients from seven unrelated families using standard coagulation tests and genetic analysis. The clinical phenotype consisted of bleeding in 13/31 (42%) patients; other patients (18/31; 58%) were asymptomatic. Among patients with bleeding, symptoms were mostly in single anatomical sites, with variable intensity of bleeding. Compared to results from a previous large systematic survey, our results showed a similar mean bleeding score, but a higher incidence of bleeding episodes without thrombotic complications. In the present study, we identified three known pathogenic point mutations in the FGA (c.95G > A, c.104G > A) and FGB (c.586C > T) genes. The variants of CD identified in this cross-sectional study were either asymptomatic or had bleeding manifestations and showed similar laboratory features, irrespective of genotype. Results from genetic and clinical studies will continue to yield valuable information on the structure and function of the fibrinogen molecule.

Combined use of Clauss and prothrombin time-derived methods for determining fibrinogen concentrations: Screening for congenital dysfibrinogenemia

BACKGROUND

In this study, the significance of fibrinogen concentration assessed by a combination of Clauss and prothrombin time (PT)-derived methods for screening for congenital dysfibrinogenemia were investigated, and the screening efficiency of fibrinogen PT-derived/Clauss ratio on congenital dysfibrinogenemia was analyzed.

METHODS

We compared fibrinogen concentrations determined by the Clauss, PT-derived, and enzyme-linked immunosorbent assay (ELISA) methods in 73 patients with congenital dysfibrinogenemia and 81 normal controls. Receiver operating characteristic (ROC) curves were utilized to evaluate the efficacy of fibrinogen PT-derived/Clauss ratio in screening for congenital dysfibrinogenemia.

RESULTS

Fibrinogen concentrations determined by the Clauss method were dramatically lower than by the PT-derived method and ELISA, and correlated poorly with the latter two methods in patients with congenital dysfibrinogenemia. Fibrinogen concentrations in normal controls were slightly lower according to the Clauss method than to the PT-derived method and ELISA; however, each method yielded results within the normal range and the correlation was good. The area under the ROC curve of fibrinogen PT-derived/Clauss ratio for diagnosis of congenital dysfibrinogenemia was 1 with a standard error of 0, 95% confidence interval of 0.976-1.00, and optimal critical diagnosis point of 1.43. When fibrinogen PT-derived/Clauss ratio was >1.43, the sensitivity and specificity for diagnosis of congenital dysfibrinogenemia were both 100%.

CONCLUSIONS

The combined use of Clauss and PT-derived methods for determining fibrinogen concentrations improves the efficiency of screening for congenital dysfibrinogenemia, as the fibrinogen PT-derived/Clauss ratio has high sensitivity and specificity in diagnosis of congenital dysfibrinogenemia. This ratio could serve an important screening tool for this disease.