Skip to Content
Home > Wellness > Health Library > Hemophilia: Understanding Genetic Risk
The genetic factors that cause
hemophilia are passed down through the X
chromosome. Every male has one X chromosome and one Y
chromosome. Every female has two X chromosomes. Males inherit a Y chromosome
from their father and an X chromosome from their mother; females inherit an X
chromosome from each parent.
The chance that a child will inherit hemophilia depends upon whether
he or she inherits an affected gene from one or both parents. Hemophilia
affects men almost exclusively. Females may be a
carrier of the gene that causes hemophilia but will
not usually have any signs or symptoms of the disease. A female who is a
carrier usually has one defective gene on the X chromosome and one normal gene
on the X chromosome. When she has a normal working chromosome, she won't have
symptoms. She has a 50% chance of passing on the defective gene to her
children. If a woman who is a carrier is affected by hemophilia, the symptoms
are usually very mild. In rare cases, a woman gets a defective gene from both
her mother and her father and is born with hemophilia.
Hemophilia can also develop when the gene that is responsible for
producing clotting factors changes (mutates). In this case, hemophilia is not
inherited; the person in whom the gene changes will be the first person in a
family to have hemophilia or will be a carrier. The person may pass this gene
down to any children that he or she has.
Here are some examples of the genetics of hemophilia. The chance of having hemophilia depends on whether the parents have hemophilia or are carriers.
August 3, 2011
E. Gregory Thompson, MD - Internal Medicine & Brian Leber, MDCM, FRCPC - Hematology
How this information was developed to help you make better health decisions.
To learn more visit Healthwise.org
© 1995-2013 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated.
Our interactive Decision Points guide you through making key health decisions by combining medical information with your personal information.
You'll find Decision Points to help you answer questions about:
Get started learning more about your health!
Our Interactive Tools can help you make smart decisions for a healthier life. You'll find personal calculators and tools for health and fitness, lifestyle checkups, and pregnancy.
Feeling under the weather?
Use our interactive symptom checker to evaluate your symptoms and determine appropriate action or treatment.
Genesis HealthCare System | 1-800-322-4762