Evolving Gene Therapy in Primary Immunodeficiency

Genome and Epigenome Editing to Treat Disorders of the Hematopoietic System

The possibility of editing complex genomes in a targeted fashion has revolutionized basic research as well as biomedical and biotechnological applications in the last 5 years. The targeted introduction of genetic changes has allowed researchers to create smart model systems for basic research, bio-engineers to modify crops and farm animals, and translational scientists to develop novel treatment approaches for inherited and acquired disorders for which curative treatment options are not yet available. With the rapid development of genome editing tools, in particular zinc-finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs), and the CRISPR-Cas system, a wide range of therapeutic options have been-and will be-developed at an unprecedented speed, which will change the clinical routine of various disciplines in a revolutionary way. This review summarizes the fundamentals of genome editing and the current state of research. It particularly focuses on the advances made in employing engineered nucleases in hematopoietic stem cells for the treatment of primary immunodeficiencies and hemoglobinopathies, provides a perspective of combining gene editing with the chimeric antigen receptor T cell technology, and concludes by presenting targeted epigenome editing as a novel potential treatment option.