1. From the Department of Neurology, Boston Children’s Hospital, Harvard Medical School, Boston (B.T.D.); the Developmental Neurology Unit, Fondazione IRCCS Istituto Neurologico Carlo Besta, Milan (R.M., G.B.), and the Center of Translational and Experimental Myology, IRCCS Istituto Giannina Gaslini, Genoa (C.B.) — both in Italy; the Department of Developmental Neurology, Medical University of Gdańsk, Gdańsk, Poland (M.M.-B.); the Paediatric Gait Analysis Service of New South Wales, the Children’s Hospital...