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Hemophilia is an inherited disease, most commonly affecting males, that is characterized by a deficiency in blood clotting. The responsible gene is located on the X chromosome, and since males inherit only one copy of the X chromosome, if that chromosome carries the mutated gene then they will have the disease. Females have a second, usually normal, copy of the gene on their other X chromosome, so they are capable of passing on the disease without experiencing its symptoms.

Images and animations are courtesy of the National Human Genome Research Institute's Talking Glossary (

Materials for Hemophilia



Description: An overview on hemophilia


Description: Questions answered by GARD Information Specialists, links to resources, information about research, conferences, genetic testing, and genetic services

History of Bleeding Disorders

Description: Information on the history of bleeding disorders

Learning About Hemophilia

Description: An overview on hemophilia

Teen Health: Hemophilia

Description: Hemophilia information written for teens and links to information on related topics

What Are Hemophilia A & B?

Description: Hemophilia A and B are two disorders characterized by slow and inefficient formation of blood clots leading to prolonged bleeding and spontaneous internal bleeding.

What is Hemophilia?

Description: An overview on hemophilia



Description: HemoAction Games teach players how to prevent bleeds and manage hemophilia while learning about the clotting process, types of bleeds, factor infusions, and suitable physical activities.

Interactive Tutorials

Your Genes Your Health - Hemophilia

Description: An interactive Web site exploring Hemophilia disease.


Playing it Safe With Hemophilia

Description: A video about hemophilia and playing sports