Hemophilia

The congenital hemophilias are uncommon disorders, with a total incidence of 10–20 per 100 000 births. Hemophilia A and hemophilia B are clinically indistinguishable, since both factor VIII (FVIII) and factor IX are essential factors in the intrinsic clotting pathway for activating factor X. The diagnosis of FVIII deficiency should be suspected in males presenting with a characteristic bleeding history, especially if there is a family history of males with abnormal bleeding. The development of an inhibitor, an antibody that inactivates the coagulant function of replacement factor, is one of the most serious complications of hemophilia treatment. Over the last several years, multiple extended half‐life agents for both factor VIII and factor IX deficiencies have been studied and approved. Gene therapy has been studied for decades in hemophilia and remains a long‐term curative opportunity that is continuing to be refined.