In control biopsies, the highest detected cumulative normalized read count for DUX4 signature was 13.7 (average 6.44, range 1.2–13.7), whereas the FSHD biopsies showed a wide range of DUX4 signature expression levels, with 19/39 (48.7%) biopsies showing a cumulative normalized read count > 20 (labeled DUX4-positive (DUX4POS); average 169.5, range 20.3–807.8). This evidence concerns the gene DUX4 and facioscapulohumeral muscular dystrophy.