Coagulation factor X

Coagulation Factor X, also known as Stuart-Prower factor, is a crucial enzyme in the coagulation cascade, playing a pivotal role in the process of blood clotting. This enzyme is synthesized in the liver and requires vitamin K for its activation. Factor X is part of both the intrinsic and extrinsic coagulation pathways, leading to the conversion of prothrombin to thrombin, which is essential for the formation of a blood clot.

Structure and Function

Coagulation Factor X is a serine protease that is activated to Factor Xa through cleavage by either the intrinsic or extrinsic pathways. The intrinsic pathway involves the activation of Factor X by Factor IXa in the presence of Factor VIIIa, calcium ions, and phospholipids. The extrinsic pathway, on the other hand, activates Factor X through the complex of tissue factor (TF) and Factor VIIa. Once activated, Factor Xa forms a complex with Factor Va, calcium ions, and phospholipids to convert prothrombin to thrombin.

Genetic and Clinical Aspects

The gene for Factor X is located on chromosome 13 (13q34) and mutations in this gene can lead to Factor X deficiency, a rare bleeding disorder characterized by a propensity to bleed due to the impaired coagulation cascade. This condition can be inherited in an autosomal recessive manner, leading to varying degrees of bleeding symptoms depending on the level of Factor X activity.

Therapeutic Use and Anticoagulation

Factor Xa is a target for new anticoagulant drugs, which are used to prevent and treat thromboembolic disorders. These drugs, known as direct Factor Xa inhibitors, include rivaroxaban, apixaban, and edoxaban. They work by selectively inhibiting Factor Xa, thus preventing thrombin formation and reducing the risk of clot formation.

Research and Development

Research into Factor X and its activated form, Factor Xa, continues to be a significant area of interest, particularly in the development of new anticoagulant therapies. Understanding the precise mechanisms of action and the potential for adverse effects is crucial in the ongoing development of safer, more effective anticoagulant drugs.