hematology and oncology
Hemophilia
Etiology of Hemophilia
Hemophilia is an inherited disorder that results from mutations, deletions, or inversions affecting the factor VIII orfactor IXgene. Because these genes are located on the X chromosome, hemophilia affects males almost exclusively. Female children of males with hemophilia are obligate carriers, but male children are normal. Each male child of a carrier has a 50% chance of having hemophilia, and each female child has a 50% chance of being a carrier. Some female carriers of hemophilia A or B become symptomatic during invasive procedures or childbirth. In these instances, the unaffected or normal X chromosome (with the normal factor VIII or IX gene) is preferentially inactivated. These females typically have factor levels in the same range as males with mild hemophilia (factor VIII or IX > 5% but<50%). In patients undergoing surgery, the factor VIII or IX levels can be too low for normal hemostasis. 