Strikingly, increased DUX4 activity was also shown in DPED patient-derived fibroblasts transdifferentiated into the myogenic lineage (Lemmers et al., 2021), further strengthening the hypothesis that DUX4c buffers DUX4 function in FSHD. This evidence concerns the gene DUX4 and facioscapulohumeral muscular dystrophy.