When analyzing the nine paired (VL–TA) FSHD muscle biopsy sets we observed a trend of increased DUX4 signature expression and reduced PAX7 score in the TA muscle, which corresponds with the TA muscle being often more affected than the VL muscle, though this trend did not reach statistical significance (Supplementary Fig. S5). Here, DUX4 is linked to Facioscapulohumeral dystrophy.