Hemophilia B (also called “Christmas disease”) is a deficiency in clotting factor IX. Hemophilia A is 7 times more common than Hemophilia B. The incidence of Hemophilia B is 1 out of 34,500 men. The outcome is good with proper treatment and specialized management. Most people with Hemophilia B are able to lead successful and relatively normal lives. (see Hemophilia A information above to learn about how hemophilia affects.
Inheritance Pattern – Women and Hemophilia . Hemophilia A is caused by an inherited sex-linked recessive trait with the defective gene located on the X chromosome. Females are carriers of this trait. Fifty percent of the male offspring of female carriers have the disease and 50% of their female offspring are carriers. All female children of a male with hemophilia are carriers of the trait, and are called obligate carriers. One third of all cases of hemophilia A occur when there is no family history of the disorder. Called a spontaneous mutation, these cases of hemophilia develop as the result of a new or spontaneous gene mutation. Genetic counseling may be advised for carriers. Female carriers can be identified by a testing procedure called DNA Carrier Testing. The only way a female could have hemophilia is if her father has it and her mother carries the gene, or if she developed Acquired Hemophilia which is very rare. Women who are carriers can also be asymptomatic carriers, whereby they do experience factor deficiencies.