How is hemophilia inherited?

Hemophilia is an inherited bleeding disorder in which the blood does not clot properly. The mission of CDC’s Division of Blood Disorders is to reduce the morbidity and mortality from blood disorders through comprehensive public health practice. read more

The gene with the instructions for making factor is found only on the sex chromosome labeled X. If the gene is faulty, the result is hemophilia unless there is a dominant, normal gene on a matching X chromosome. read more

Hemophilia is a bleeding disorder that slows the blood clotting process. People with this condition experience prolonged bleeding or oozing following an injury, surgery, or having a tooth pulled. In severe cases of hemophilia, continuous bleeding occurs after minor trauma or even in the absence of injury (spontaneous bleeding). read more

Hemophilia A and hemophilia B are inherited in an X-linked recessive pattern. The genes associated with these conditions are located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. read more

The following examples show how the hemophilia gene can be inherited. It is important to note that in one-third of people with hemophilia, there is no family history of the disorder. In this example, the mother is a carrier of the hemophilia gene, and the father does not have hemophilia. read more