Conflict of interest statement: Declaration of interests SR’s institution has 
received grants from Spark Therapeutics and he has provided presentations on 
behalf of Spark Therapeutics. DC and AD have received grants from Spark 
Therapeutics. JB has received grants from the Foundation Fighting Blindness, the 
National Institutes of Health, and Spark Therapeutics; non-financial support 
from the Center for Advanced Retinal and Ocular Therapeutics, University of 
Pennsylvania, and the FM Kirby Foundation; has a provisional patent pending and 
a US patent licensed to Spark Therapeutics for which she has waived financial 
interest; and is a coauthor on a copyrighted visual function questionnaire used 
in the present study. JAW is an employee of and has equity/options in Spark 
Therapeutics; has received grants from the National Institutes of Health 
(specifically for Clinical and Translational Research Centre services); and has 
a patent pending pertaining to the primary endpoint measure licensed to Spark 
Therapeutics. DCC is an employee of Spark Therapeutics and has a patent pending 
pertaining to the primary endpoint measure licensed to Spark Therapeutics. Z-FY, 
AT, and JWi are employees of Statistics Collaborative, which provides 
statistical and regulatory consulting to Spark Therapeutics. JP is an employee 
of Westat, which was contracted by Spark Therapeutics. SM is a clinical 
coordinator of a study sponsored by Spark Therapeutics, receives salary support 
from the Center for Cellular and Molecular Therapeutics (CCMT) at The Children’s 
Hospital of Philadelphia, and has a patent pending licensed to Spark 
Therapeutics. KAM is a clinical coordinator of a study sponsored by Spark 
Therapeutics and received salary support from CCMT at Children’s Hospital of 
Philadelphia. JWa, TLK, and MD have received salary support from Spark 
Therapeutics and grants from the Carver Center for Macular Degeneration and 
Children’s Hospital of Philadelphia; TLK has received travel support from Spark 
Therapeutics. JAH has received consulting fees from Merck and Kalvista, grants 
from ThromboGenics, and serves on boards for Janssen and Celgene. ES’s 
institution has received grants from Children’s Hospital of Philadelphia and 
Spark Therapeutics. EHS has received grants from Oxford Biomedica. KW is an 
employee of and has equity/options with Spark Therapeutics and has received 
grants from the National Institutes of Health. FS has received grants from 
Regione Campania and serves on boards for Sanofi, Dompe Farmaceutici, and Spark 
Therapeutics. JFW has a patent and a patent pending, both licensed to Spark 
Therapeutics. KAH is an employee of Spark Therapeutics and has a patent pending 
pertaining to the primary endpoint measure. AMM has received grants from Spark 
Therapeutics, the National Institutes of Health, and the Foundation Fighting 
Blindness; non-financial support from the Center for Advanced Retinal and Ocular 
Therapeutics, University of Pennsylvania, and the FM Kirby Foundation; and has a 
provisional patent pending and a US patent licensed to Spark Therapeutics for 
which he has waived financial interest. OE, HR, LR, LAG, FPH, LD, XZ, VBM, WP, 
MW, CJ, DG, and BPL declare no competing interests.