Blood-clotting factor XII, a β-globulin (615 aa), that is activated by contact with surfaces, forming factor XIIa, which then activates factor XI. Factor XIIa also generates plasmin from plasminogen and kallikrein from prekallikrein. Both plasmin and kallikrein activate the complement cascade. Hageman factor is important both in clotting and activation of the inflammatory process. Named after John Hageman, who was the first person to be identified with a deficiency in the factor. Mutations in the factor XII gene are the cause of hereditary angioedema (HAE) type III.
Subjects: Medicine and Health.