Factor IX (activated) and von Willebrand factor (FIXa and VWF)

Factor IX (activated, FIXa) is a serine protease essential for the activation of Factor X during the intrinsic phase of the coagulation cascade. Deficiency in Factor IX leads to Hemophilia B, treated with FIX concentrates. Von Willebrand factor is a large, multimeric glycoprotein synthesized in endothelial cells and megakaryocytes, with primary functions in mediating platelet adhesion to damaged endothelium and serving as a carrier for Factor VIII, protecting it from proteolytic degradation. VWF is stored in Weibel-Palade bodies and released in response to vascular injury. Deficiency or dysfunction of VWF causes von Willebrand disease, the most common inherited bleeding disorder, and dysregulation can also result in thrombotic pathologies. VWF also interacts with various drugs, and its role as both an adhesive and carrier protein makes it a complex therapeutic target.

Other names

Factor IXaCoagulation factor IXavWFvWf

For Factor IX: Replaces deficient FIXa for coagulation; inhibitors (heparin, warfarin) reduce activity. For Von Willebrand Factor: Enhances platelet adhesion; DDAVP increases endogenous VWF release; caplacizumab inhibits VWF-platelet interaction.