Classic hemophilia is the result of a deficiency of which coagulation factor?

Classic hemophilia, also known as hemophilia A, arises from a deficiency in Factor VIII, which is crucial for the blood coagulation process. Factor VIII is a cofactor for Factor IX in the intrinsic pathway of the coagulation cascade, aiding in the conversion of prothrombin to thrombin, which is essential for fibrin formation and proper clotting.

The deficiency of Factor VIII leads to impaired clot formation, resulting in prolonged bleeding episodes, especially after injuries or surgeries. Individuals with this condition often experience spontaneous bleeding, particularly into joints and muscles, which can lead to pain and long-term joint damage if not appropriately managed.

This understanding of the specific role of Factor VIII in the clotting process helps clarify why it is the factor associated with classic hemophilia. The other factors mentioned, such as Factor VII, Factor IX, and Factor XI, are involved in different clotting pathways or types of hemophilia, but they do not relate to classic hemophilia specifically. Factor IX is associated with hemophilia B, while Factor XI is linked to a different bleeding disorder known as hemophilia C.