Competing interests: Y Erbas: YE has received personal compensation from Roche and Novartis for advisory board participation and is the parent of a child with SMA and tracheostomy. R Finkel: Richard S Finkel declares personal compensation for advisory board participation from Astellas, Biogen, Dyne, Genentech, Ionis, Italfarmaco, Novartis, ReveraGen, Roche, Sarepta and Scholar Rock; data safety monitoring board participation for an Ionis-sponsored study on Angelman syndrome, University of Texas Southwestern sponsored study on Lafora body disease, and more remotely for a Sarepta-sponsored study on Duchenne and Nationwide Children’s Hospital study on SMA; research funding from Biogen, Dyne, Genentech, Genethon, Italfarmaco, Roche, and Sarepta, Scholar Rock; editorial fees from Elsevier for co-editing a neurology textbook; and license fees from the Children’s Hospital of Philadelphia. Ethics: The mother of patient 2 has given permission for videos of her daughter, born in 2014, be used in conjunction with this article and made available publicly though a hyperlink.