1. From Bluebird Bio, Cambridge, MA (S.G., D.W., H.B., P.D.G., G.P., M.F., A.Y., M.G., S.B.V., A.M., J.L., R.A.C., M.B.); the Cellular and Molecular Therapeutics Branch, National Heart, Lung, and Blood Institute–National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD (J.T.); GeneWerk, Heidelberg, Germany (M.S.); the University of Alabama at Birmingham, Birmingham (J.K.); and the Division of Pediatric Hematology–Oncology, Medical University of South...