Gene therapy for hemophilia B

Hemophilia B patients do not produce sufficient amounts of coagulation factor IX and consequently have reduced clotting activity and suffer from acute bleeding episodes. Since hemophilia B results from genetic defects in the gene for factor IX, it is possible to treat the disorder using gene therapy to either correct or replace the defective gene so that active factor IX can be continuously produced in the patient. Conventional gene therapy approaches involve the use of viral or non-viral vectors to deliver the factor IX gene either ex vivo or in vivo. While research in these strategies is providing insight into issues of safety, efficacy and long-term delivery, alternative gene therapy approaches for treating hemophilia B are also being developed. These approaches include homologous replacement, artificial chromosomes, and immuno-isolation. This review will present the advantages and significant results of each approach with particular emphasis on microencapsulation, and an up-date of the current status of gene therapy for hemophilia B.