Treatment for Hemophilia: Gene Therapy vs Transplantation

To the Editor. —Drs Lozier and Brinkhous 1 summarized gene therapy approaches that could be used for patients with hemophilia. They discussed in vivo and ex vivo approaches with and without vectors. They stated, "The introduction of the genetic material for factor VIII or factor IX into appropriate target cells is the only foreseeable approach to 'cure' either disorder." Another option that might be considered is transplantation of human yolk sac tissue. Fetal rat yolk sac tissue secretes many of the proteins secreted by fetal rat liver including fibrinogen. 2 Orthotopic transplantation of adult liver in patients with hemophilia P resulted in normal postoperative levels of factor VIII. 3 Most patients with hemophilia would not be candidates for orthotopic liver transplantation because of the associated risks and need for lifelong immunosuppression. Heterotopic transplantation of fetal liver or yolk sac could be alternatives to orthotopic liver transplantation. Since the yolk sac