Gene therapy for blood diseases.

Genetic diseases affecting proteins and cells composing the blood may be treated by gene therapy using gene addition or gene editing methods. Protein deficiencies (e.g. hemophilia) are being approached using in vivo gene delivery by adeno-associated virus (AAV) vectors for therapeutic gene addition or gene editing. Blood cell diseases (e.g. sickle cell disease) are being approached using ex vivo gene addition or gene editing to treat isolated blood-forming hematopoietic stem cells or T cells that are then re-transplanted. In recent years, there has been much progress, and gene therapy is now routinely providing clinical benefit to patients with a variety of conditions. Several of these gene therapies have been licensed in the U.S. and EU and more for other disorders are being advanced toward licensure. The scope of therapeutic activity for gene therapy is expected to continue to expand as the technical capabilities advance.