Hemophilia

Hemophilia is a family of rare bleeding disorders characterized by deficiency of clotting factors. Hemophilia A is an inherited deficiency of factor VIII, whereas hemophilia B (Christmas disease) represents a deficiency of factor IX. Both hemophilia A and B are X-linked diseases, with hemophilia A accounting for 80 to 85% of cases and hemophilia B 15 to 20%. Although hemophilia has historically referred to deficiencies of factors VIII and IX, it is important to recognize that similar bleeding disorders can occur with other missing clotting factors, although this is far more rare. This review covers the definition, history, epidemiology, biology/genetics, clinical manifestations, diagnosis, differential diagnosis, treatment, complications, measures of quality of care, and prognosis of hemophilia, as well as future directions. Figures show the clotting cascade, the genetic makeup of severe hemophilia A, an algorithm for diagnosing hemophilia, and hemophilic arthropathy in a patient’s knees. Tables list severity in hemophilia A and B, treatment of acute bleeding in hemophilia A and B, frequency of dosing in acute bleeding, and treatment of acute bleeding with inhibitors. This review conta