Factor X deficiency is a disorder caused by too little of a protein called factor X in the blood. It leads to problems with blood clotting (coagulation).

When you bleed, the body launches a series of activities that help the blood clot. This is called the coagulation cascade. The process involves special proteins called coagulation factors. (Factor X is a coagulation factor.) Each factor's reaction triggers the next reaction. The final product of the coagulation cascade is the blood clot.

When certain coagulation factors are missing, the chain reaction does not take place normally. Factor X deficiency is often caused by a defect of the factor X gene that is passed through families (inherited). Bleeding ranges from mild to severe. Another cause of factor X deficiency is amyloidosis (a disorder in which protein fibers that can't dissolve deposit in tissues and organs and affect their function).

Women with this condition may have very heavy menstrual bleeding and bleeding after delivery. Newborn boys with the condition may have longer-than-normal bleeding after circumcision.

Factor X deficiency affects 1 out of every 500,000 people.

• Nose bleeds
• The loss of blood into joints
• Muscle bleeding
• Mucous membrane bleeding

• Prolonged prothrombin time
• Prolonged partial thromboplastin time
• Low factor X activity
• Normal thrombin time