DUX4 and facioscapulohumeral muscular dystrophy: Further, our observations suggest that a slightly elevated HR in FSHD may be indicative of physical inactivity or deconditioning, which may put this group at risk for future CVD or cardiac events, but this could be secondary to FSHD or overexpression of the DUX4 gene mutation, as we did not observe alterations in autonomic function in this group.