| a blood constituent necessary for clotting, the absence of which is characterized by a hemophilialike condition. |
| factor IX n. A protein substance in blood plasma that participates in and is essential for the blood-clotting process. A deficiency of this factor is the cause of Christmas disease. |
Christmas factor n.
See factor IX.
factor IX n.
A factor in the clotting of blood necessary for the formation of intrinsic blood thromboplastin; a deficiency of it causes hemophilia B. Also called antihemophilic globulin B, Christmas factor.