In a study that used longitudinal latent class analysis to identify three classes of differentially progressing early age DMD motor trajectories, boys were grouped into dystrophin isoform groups as follows: Dp427 absent and Dp140/Dp71 present (Group 1); Dp427/Dp140 absent and Dp71 present (Group 2); and Dp427/Dp140/Dp71 absent (Group 3) [34]. Here, DMD is linked to Duchenne muscular dystrophy.