DUX4 and facioscapulohumeral muscular dystrophy: In FSHD, the aberrant expression of DUX4 in the muscle causes the expression of germline DUX4 transcriptional targets [26]; the repression of oxidative stress response genes [34,35,36,37]; disruptions in cell cycle and migration [35,38]; disruption of RNA metabolism, splicing, surveillance, and transport [38,39]; and a reduction in myogenic capacity due to the misregulation of MYOD1 and its downstream targets, including structural and contractile components [28,29,33,36,37,40,41,42,43].