Abnormal fibrinogen with an Aα 16Arg → Cys substitution is associated with multiple cerebral infarctions

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.

Congenital (hypo-)dysfibrinogenemia and bleeding: A systematic literature review

Ranging from bleeding to thrombosis, the clinical features of congenital fibrinogen qualitative disorders, including dysfibrinogenemia and hypodysfibrinogenemia, are highly heterogeneous. Although the associations between some specific fibrinogen mutations and the thrombotic phenotypes have been well elucidated, the underlying mechanism between fibrinogen variants and bleeding events remains underestimated. After systematically reviewing the literature of (hypo-)dysfibrinogenemia patients with bleeding phenotypes, we identified several well-characterized bleeding-related fibrinogen variants in those patients. Several possible pathomechanisms are proposed to explain the genotype-phenotype associations: 1, mutations in the NH₂-terminal portion of the Aα chain hamper fibrinogen fitting into the active site cleft of thrombin and drastically slow the conversion of fibrinogen into monomeric fibrin; 2, mutations adding new N-linked glycosylation sites introduce bulky and negatively charged carbohydrate side chains and undermine the alignment of fibrin monomers during polymerization; 3, mutations generating unpaired cysteine form extra disulfide bonds between the abnormal fibrinogen chains and produce highly branched and fragile fibrin networks; 4, truncation mutations in the fibrinogen αC regions impair the lateral fibril aggregation, as well as factor XIII crosslinking, endothelial cell and platelet binding. These established relationships between specific variants and the bleeding tendency will help manage (hypo-)dysfibrinogenemia patients to avoid adverse bleeding outcomes.

Congenital dysfibrinogenemia caused by γAla327Val mutation: structural abnormality of D region

BACKGROUND

: Congenital dysfibrinogenemia (CD) is a coagulation disorder caused by mutations in the fibrinogen genes, which result in abnormal fibrinogen function. However, the precise pathogenesis underlying it remains unclear.

METHODS

: In this study, we identified a novel heterozygous mutation in an asymptomatic patient with CD caused by γ Ala327Val mutation. Aimed to investigate the pathogenesis, functional studies of fibrinogen isolated from the proband and her family members were performed, such as coagulation function, fibrinogen aggregation test, and fibrin clot lysis test. Coagulation was monitored using a thromboelastometer, and the fibrin clot network structure was observed by scanning electron microscopy. The effect of the mutation on fibrinogen structure and function was predicted by molecular modeling.

RESULTS

: The fibrinogen activity concentration in patients with CD was significantly lower than that in healthy individuals, indicating that fibrinogen activity was low. Proband's fibrinogen activity concentration was 0.75 g/L(Clauss method) and antigen concentration (immune turbidimetry method) was 1.59 g/L(normal reference range for both parameters: 2.0-4.0 g/L). Thromboelastography showed that the K value of patients with CD was higher than that of healthy individuals and Angle values were decreased, indicating that mutation impaired fibrinogen function. Compared to fibrinogen from healthy individuals, fiber network structure of the proband was loose, pore size was increased, and fiber branch nodes were increased.

CONCLUSIONS

: Ala327Val heterozygous missense mutation leads to changes in the structure of fibrinogen D region and impairs the aggregation function of fibrinogen. This mutation is reported here for the first time.

Novel peripheral blood cell ratios: Effective 3-month post-mechanical thrombectomy prognostic biomarkers for acute ischemic stroke patients

BACKGROUND

Red blood cell distribution width to platelet ratio (RPR), Monocyte to high-density lipoprotein ratio (MHR), and Neutrophil to lymphocyte ratio (NLR) are novel inflammatory biomarkers in laboratory tests, which are associated with clinical outcomes in malignancy, cardiovascular and cerebrovascular diseases. This study aimed to determine their predictive value for the prognosis of acute ischemic stroke after mechanical thrombectomy (MT).

METHODS

A total of 286 patients with acute ischemic stroke (AIS) admitted to a tertiary stroke center in China between January 2018 and February 2020 were treated by MT. Demographic characteristics, risk factors, clinical data, laboratory parameters, and clinical outcomes were recorded. The clinical outcome was disability or death at discharge or 90 days (defined as a modified Rankin Scale score of 3-6). The relationship between RPR, MHR, and NLR and functional outcomes was investigated by binary Logistic regression analysis, and further assessed by receiver operating characteristic curve (ROC). The Kaplan-Meier method was used to analyze the survival rate of prognosis factors.

RESULTS

A total of 286 patients with AIS underwent MT (median age, 70.00; Interquartile range [IQR], 63.00-77.00; 41.6% female). Patients with unfavorable outcome showed higher RPR, MHR, and NLR than those with favorable outcome (RPR, [8.63; IQR, 6.30-10.78] vs [6.17; IQR, 5.11-7.35], P < 0.001; MHR, [0.40; IQR, 0.31-0.53] vs [0.34; IQR, 0.27-0.47], P = 0.005; NLR, [5.28; IQR, 3.63-8.02] vs [3.44; IQR, 2.63-4.63], P < 0.001). In multivariate and ROC curve analysis, higher RPR (>8.565) (odds ratio [OR], 1.671; 95% confidence interval [CI], 1.127-2.479; P = 0.011) and higher MHR (>0.368) (OR, 9.374; 95% CI, 1.160-75.767; P = 0.036), higher NLR (>4.030) (OR, 1.957; 95% CI, 1.382-2.770; P < 0.001) were independently associated with unfavorable outcome. The combined predictive value of the three indexes was higher than that of a single index. Kaplan-Meier survival curve analysis showed that the 90-day survival rate (82.1% vs 66.2%) was significantly different between the low RPR group and the high RPR group (χ² = 4.960, P = 0.026).

CONCLUSION

Higher RPR, MHR, and NLR might be independent risk factors for predicting 3-month poor prognosis in patients with AIS who underwent MT.