1. From the Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania (L.A.G., B.J.S.-J.), the Division of Hematology and the Raymond G. Perelman Center for Cellular and Molecular Therapeutics, Children’s Hospital of Philadelphia (L.A.G., B.J.S.-J.), and Spark Therapeutics (P.E.M., A.M., K.J., R.N., M.C., K.K., F.M., T.C., K.Z.R., X.M.A., K.A.H.), Philadelphia, the Department of Medicine, Division of Hematology and Oncology, Penn State Health Milton S. Hershey Medical Center,...