Hemophilia is a rare inherited bleeding disorder in which the blood does not clot normally. Persons with hemophilia may bleed for a longer time than others after an injury or accident. They also may bleed internally, especially in the joints (knees, ankles, and elbows).

Babies born with hemophilia are missing or have a low level of a protein needed for normal blood clotting or blood coagulation. The protein is called a clotting factor.

According to the National Heart, Lung and Blood Institute at the NIH, about 18,000 people in the United States have hemophilia. Each year, about 400 babies are born with the disorder. Hemophilia usually occurs only in males (with very rare exceptions).

A person with hemophilia has a problem with certain proteins in the blood called clotting factors. Hemophilia can be due to:

• A low level of one of the clotting factors
• A clotting factor that is completely missing

When clotting factors are missing, or your body does not have enough of these factors, it can take a long time for your blood to clot after an injury or accident.

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