Coagulation factor II, Coagulation factor VII, Coagulation factor IX, Coagulation factor X (FII (or II), FVII (or VII), FIX (or IX), FX (or X))

The four factors—Coagulation factor II (Prothrombin), Coagulation factor VII, Coagulation factor IX, and Coagulation factor X—are serine protease enzymes that are essential for the normal process of blood coagulation[3][5]. They are synthesized in the liver as vitamin K–dependent zymogens, each with a characteristic domain structure (Gla domain, EGF-like domains, serine protease domain)[3][6]. Upon activation, they function sequentially in the coagulation cascade to generate thrombin and fibrin, which are necessary for the formation of a stable blood clot. Deficiency or dysfunction of any leads to bleeding disorders, while their over-activation is a key contributor to pathologic thrombosis[3][5][6]. Each factor is a validated drug target for anticoagulant therapy and for replacement in congenital or acquired bleeding disorders.

Other names

FIIProthrombinFVIIFIXChristmas factorFXStuart–Prower factor

Inhibition: small molecule or biologic drugs inhibit enzymatic activity to prevent thrombin generation and fibrin clot formation (e.g., FXa inhibitors) Replacement: recombinant or plasma-derived factor replacement for treating deficiencies (e.g., FIX concentrates for hemophilia B)