National Center for Advancing and Translational Sciences Genetic and Rare Diseases Information Center, a program of the National Center for Advancing and Translational Sciences

Hemophilia A

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I have severe hemophilia. How often do genetic mutations for severe hemophilia A occur - in caucasians, in women, and in America?  How common is type A versus type B or other types?  How common is the severe form as opposed to the moderate or mild forms?

The following information may help to address your question:


How rare is hemophilia A?

Globally, approximately one in 5,000 males is born with hemophilia A.  Males of every ethnicity are equally affected.  For example, one in 5,000 Hispanic males, one in 5,000 African-American males, and one in 5,000 Caucasian males in the United States have this disorder.[1]
Last updated: 3/11/2013

Can females be affected by hemophilia A?

Yes.  Approximately 10% of women who are carriers for hemophilia A are at risk for abnormal bleeding episodes.[2]  One study found that 5 out of 55 people with mild hemophilia A were female.[4874]
Last updated: 3/12/2013

How common is hemophilia A compared to hemophilia B?

Hemophilia A affects one in 5000 individuals whereas hemophilia B affects one in 20,000.[4874]
Last updated: 3/11/2013

What are the different forms of hemophilia A?

There are three forms of hemophilia A: severe, moderate, and mild. Up to 70% of people with hemophilia A have the severe form, in which symptoms begin before age 1. Symptoms of the moderate form begin between the ages of 1 and 2 years; at least 15% of affected people have the moderate form. About 15% of individuals have the mild form, which begins at age 2 or older.[1]
Last updated: 3/12/2013

We hope this information is helpful. We strongly recommend you discuss this information with your doctor. If you still have questions, please contact us.

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GARD Information Specialist

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  1. Drelich DA. Hemophilia A. Medscape Reference. Sept 10, 2018; http://emedicine.medscape.com/article/779322-overview.
  2. Konkle BA, Huston H, Fletcher SN. Hemophilia A. GeneReviews. June 22, 2017; https://www.ncbi.nlm.nih.gov/books/NBK1404/.