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Updated: Oct 18, 2025

Author Spotlight: High-Sensitivity Tissue Factor Activity Assay for Plasma Diagnosis
Published on: December 29, 2023
Mechanism, Functions, and Diagnostic Relevance of FXII Activation by Foreign Surfaces
Sandra Konrath1, Reiner K Mailer1, Thomas Renné1
1Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
Abstract:
Factor XII (FXII) is a serine protease zymogen produced by hepatocytes and secreted into plasma. The highly glycosylated coagulation protein consists of six domains and a proline-rich region that regulate activation and function. Activation of FXII results from a conformational change induced by binding ("contact") with negatively charged surfaces. The activated serine protease FXIIa drives both the proinflammatory kallikrein-kinin pathway and the procoagulant intrinsic coagulation cascade, respectively. Deficiency in FXII is associated with a prolonged activated partial thromboplastin time (aPTT) but not with an increased bleeding tendency. However, genetic or pharmacological deficiency impairs both arterial and venous thrombosis in experimental models. This review summarizes current knowledge of FXII structure, mechanisms of FXII contact activation, and the importance of FXII for diagnostic coagulation testing and thrombosis.
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