Jerry Mendell, MD, FAAN, Nationwide Children’s Hospital & Ohio State University, Columbus, OH, discusses the results from a trial of SRP-9001 gene transfer therapy in Duchenne muscular dystrophy (DMD) presented at the American Academy of Neurology (AAN) 2021 Annual Meeting. Prof. Mendell explains the difference observed between younger and older patients regarding clinical effects and correlates the results with muscular loss in these patients. The need to change the age randomization criteria in future studies is highlighted. This interview took place during the AAN 2021 Annual Meeting.