COAGULATION FACTORS AND RELATED SUBSTANCES

Number and/or name	Function	Associated genetic disorders
I (Fibrinogen)	Forms clot (fibrin)	Congenital afibrinogenemia, Familial renal amyloidosis
II (Prothrombin)	Its active form (IIa) activates I, V, VII, VIII, XI, XIII, protein C, platelets	Hypoprothrombinemia, Thrombophilia
III Tissue factor	Co-factor of VIIa (formerly known as factor III)
IV Calcium	Required for coagulation factors to bind to phospholipid (formerly known as factor IV)
V (Proaccelerin, labile factor)	Co-factor of X with which it forms the prothrombinase complex	Activated protein C resistance
VI	Unassigned – old name of Factor Va
VII (Stable factor, proconvertin)	Activates IX, X	congenital proconvertin/factor VII deficiency
VIII (Antihemophilic factor A)	Co-factor of IX with which it forms the tenase complex	Haemophilia A
IX (Antihemophilic factor B or Christmas factor)	Activates X: forms tenase complex with factor VIII	Haemophilia B
X (Stuart-Power factor)	Activates II: forms prothrombinase complex with factor V	Congenital Factor X deficiency
XI (plasma thromboplastin antecedent)	Activates IX	Haemophilia C
XII (Hageman factor)	Activates factor XI, VII and prekallikrein	Hereditary angioedema type III
XIII (fibrin-stabilizing factor)	Congenital Factor XIIIa/b deficiency
von Willebrand factor	Binds to VIII, mediates platelet adhesion	von Willebrand disease
Prekallikrein (Fletcher factor)	Activates XII and prekallikrein; cleaves HMWK	Prekallikrein/Fletcher Factor deficiency
High-molecular-weight kininogen (HMWK) (Fitzgerald factor)	Supports reciprocal activation of XII, XI, and prekallikrein	Kininogen deficiency
Fibronectin	Mediates cell adhesion	Glomerulopathy with fibronectin deposits
Antithrombin III	Inhibits IIa, Xa, and other proteases	Antithrombin III deficiency
Heparin cofactor II	Inhibits IIa, cofactor for heparin and dermatan sulfate ("minor antithrombin")	Heparin cofactor II deficiency
Protein C	Inactivates Va and VIIIa	Protein C deficiency
Protein S	Cofactor for activated protein C (APC, inactive when bound to C4b-binding protein)	Protein S deficiency
Protein Z	Mediates thrombin adhesion to phospholipids and stimulates degradation of factor X by ZPI	Protein Z deficiency
Protein Z-related protease inhibitor (ZPI)	Degrades factors X (in presence of protein Z) and XI (independently)
Plasminogen	Converts to plasmin, lyses fibrin and other proteins	Plasminogen deficiency, type I (ligneous conjunctivitis)
Alpha 2-antiplasmin	Inhibits plasmin	Antiplasmin deficiency
Tissue plasminogen activator (tpa)	Activates plasminogen	Familial hyperfibrinolysis and thrombophilia
Urokinase	Activates plasminogen	Quebec platelet disorder
Plasminogen activator inhibitor-1 (PAI1)	Inactivates tPA & urokinase (endothelial PAI)	Plasminogen activator inhibitor-1 deficiency
Plasminogen activator inhibitor-2 (PAI2)	Inactivates tPA & urokinase (placental PAI)
Cancer procoagulant	Pathological factor X activator linked to thrombosis in cancer