Aberrant expression of DUX4-FL in FSHD is associated with a decreased number D4Z4 repeats, DNA hypomethylation, and a telomeric sequence that is used as a poly-adenylation signal for the DUX4-FL mRNA (Daxinger et al., 2015; Gatica and Rosa, 2016; Hewitt, 2015; Himeda et al., 2015; Tawil et al., 2014; Wang and Tawil, 2016). Here, DUX4 is linked to facioscapulohumeral muscular dystrophy.