Carrier Status: Obligate vs Possible

A female carrier of hemophilia can pass this gene on to her children, and while she can experience symptoms of the condition, she usually does not. A woman is an obligate carrier (which means she is automatically a carrier of hemophilia) if any of the following apply:

  • She is the biological daughter of a man who has hemophilia
  • She is the biological mother of more than one son with hemophilia
  • She is the biological mother of at least one son with hemophilia and has at least one other blood relative with hemophilia, such as a brother or uncle

It is recommended that women who are carriers or who are at risk of being carriers have their clotting factor VIII level or IX level checked.

Some women who are hemophilia carriers have factor levels below 50%, which can increase their risk of bleeding. Checking a factor level does not confirm whether the woman is also a carrier. It does, however, determine her bleeding risk with injury, surgery, and other procedures.

To determine carrier status, genetic testing of their factor VIII or factor IX gene must also be performed.

We offer this evaluation at the IHTC when a new family diagnosis of hemophilia is made, or if genetic testing has never been performed within a family with a history of hemophilia.