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About Hemophilia A

Hemophilia A is a rare bleeding disorder caused by a mutation in the gene F8 that provides instructions to make the protein factor VIII (FVIII), which is essential for blood to clot normally. Mutations in the F8 gene lead to reduced or absent levels of FVIII in the blood, making it hard for the body to form blood clots.

People with moderate to severe hemophilia are at risk for spontaneous bleeding, as well as excessive bleeding from minor cuts, falls or normal activities of daily life that would not affect people without hemophilia. The spontaneous and excessive bleeding of hemophilia A can cause many complications, including:

  • bleeding within the skull (intracranial hemorrhage)
  • bleeding in the soft tissue around important organs
  • progressive joint damage

This can result in chronic pain and reduced capabilities to participate in day-to-day activities, as well as depression and anxiety.


Hemophilia A may be diagnosed through screening tests and clotting factor tests. Blood tests are done to measure the time it takes the blood to clot and the amount of clotting factors found in the blood. Genetic testing can also help determine the exact change in the F8 gene and identify other family members at risk for hemophilia A.

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