In people that have hemophilia, blood does not clot normally because it lacks sufficient blood-clotting proteins.


Hemophilia can be inherited, but about 30% of cases of hemophilia are caused by a genetic change. Different types of hemophilia are caused by different clotting factors. Hemophilia A, which is the most common type, is caused by insufficient clotting factor VIII. Hemophilia B, which is the second common type, is caused by insufficient clotting factor IX. Hemophilia C, which is the most mild type, is caused by insufficient clotting factor XI. Hemophilia types A and B are located on the X chromosome and as a result cannot be passed from father to son. Hemophilia C can be passed on easier.

Signs and symptoms include:

  • excessive bleeding from cuts or injuries
  • large, deep bruises
  • unusual bleeding after vaccinations
  • swelling of the joints
  • blood in the urine or stool
  • nosebleeds without a cause

Diagnostic test

In order to test for hemophilia the doctor will take blood tests, and from that he or she will run tests to measure clotting factors VIII and IX in the blood.


Hemophilia A is the most common type, and it occurs once in 4,000-5,000 males worldwide. Hemophilia B occurs once in every 20,000 males worldwide.

How to prevent it

There is no known way to prevent hemophilia, as it is a genetic disorder. Gene therapy clinical trials have been taking place, but they are still considered to be experimental and have not found a known cure yet.


  • joint damage
  • deep bleeding internally
  • an increased risk of developing hepatitis when receiving donor blood


Treatment of hemophilia differs depending on what type. For hemophilia A, it is treated by a prescription hormone injection that stimulates the clotting factors in the blood. Hemophilia B is treated by infusing the person's blood with donor blood clotting factors. Last, Hemophilia C is treated by plasma infusion. However, this is not available in the US and is only used in Europe.  


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