Although altered expression of non-coding RNAs (Cabianca et al., 2012) and neighbouring 4q genes – e.g. FRG1 (Gabellini et al., 2006) and mutations in FAT1 (Caruso et al., 2013) – have also been implicated in FSHD, there is growing consensus that aberrant expression of DUX4 underlies pathogenesis in both FSHD1 and FSHD2, acting with a gain-of-function mechanism (Tawil et al., 2014). The gene discussed is DUX4; the disease is facioscapulohumeral muscular dystrophy.