Congenital factor X deficiency is a very rare blood-clotting disorder present at birth that results in excessive or prolonged bleeding after an injury or surgery. Factor X is one of 13 proteins involved in proper formation of blood clots. Blood clots are needed to heal wounds, form scabs, and stop bleeding. When factor X levels are low or absent, the blood does not clot correctly, leading to excessive bleeding. Congenital factor X deficiency runs in families and is an autosomal recessive disorder, which means an individual must have two copies of the changed gene that causes the condition. A person with one changed gene would be a carrier of the condition but not have any symptoms. If both parents are carriers, their children have a one in four chance of having the disease. The main symptom of congenital factor X deficiency is excessive and abnormal bleeding. This may occur after childbirth, surgery, trauma, and with menstruation (periods). Bleeding can also occur in the muscles, joints, the mouth, the gut, or, infrequently, the brain. Easy bruising and nosebleeds are also common. Congenital factor X deficiency can be diagnosed by a physician using blood tests. Treatment for congenital factor X deficiency is largely based on controlling bleeding and treating any underlying conditions that contribute to excessive bleeding. When necessary, excessive bleeding can be stopped with infusions of clotting factors into the blood.