PAX7 and facioscapulohumeral muscular dystrophy: Specifically, DUX4 seems to compete with or suppress the expression of PAX3 and PAX7 (Box 1), and loss of PAX7-target gene expression is a signature of FSHD muscle (Banerji and Zammit, 2019; Banerji et al., 2017; Bosnakovski et al., 2008b, 2017c; Haynes et al., 2017).