DUX4 and facioscapulohumeral muscular dystrophy: Interrogation of the 67‐gene DUX4 biomarker panel (DUX4‐67)10 revealed a minor DUX4‐affected subpopulation (six cells) exclusively within myotube D3 (FF2 sample) of the female FSHD, with no comparable signal detected in male FSHD or HCs (Figure 4A,B).