An exploratory plasma-based functional assay for phenotypic characterization of fibrinolysis in dysfibrinogenemia.

BACKGROUND

Congenital dysfibrinogenemia exhibits heterogeneous clinical phenotypes, ranging from bleeding to thrombosis. However, conventional fibrinogen assays primarily evaluate clot formation alone. Genetic analyses are informative but do not fully explain phenotypic diversity, particularly with respect to clot formation-lysis behavior.

OBJECTIVES

This study developed a novel plasma-based functional assay for exploratory characterization of integrated clot formation-lysis kinetics in congenital dysfibrinogenemia.

METHODS

The Clauss fibrinogen assay was modified by supplementing recombinant tissue-type plasminogen activator and Lys-plasminogen to enable monitoring of the fibrinolysis phase following clot formation, termed the CLySis assay. Clot-fibrinolysis waveform analysis defined the time to fibrinolysis (T lysis) and maximum fibrinolysis velocity. Normal reference intervals were established, and the assay was applied to plasma samples from 22 patients with congenital fibrinogen disorders (19 dysfibrinogenemia and 3 hypofibrinogenemia), including carriers of variants previously reported in patients with thrombosis.

RESULTS

The CLySis assay enabled stable monitoring of clot formation and subsequent fibrinolysis. The T lysis was largely independent of plasma fibrinogen concentration, whereas maximum fibrinolysis velocity was influenced by fibrinogen levels. Among 5 variants previously reported in patients with thrombosis, FGA p.Arg35Cys, FGG p.Arg301Cys, and FGG p.Asp344Gly showed markedly prolonged T lysis compared with the normal reference range, indicating altered clot formation-lysis kinetics. By contrast, FGB p.Arg74Cys and FGG p.Arg301His showed T lysis values within the normal range. Variants without reported thrombotic association also demonstrated normal clot-lysis profiles.

CONCLUSION

The CLySis assay provides a functional, genotype-independent approach for exploratory characterization of clot-lysis behavior in congenital dysfibrinogenemia. This assay may support future phenotypic analyses of dysfibrinogenemia, complementing conventional genetic evaluation.