DUX4 and facioscapulohumeral muscular dystrophy: In addition, D4Z4-2.5 mice present with loss of DNA methylation and H3K9me3 at the D4Z4 repeat array compared to D4Z4-12.5 mice, showing that transgenic FSHD mice have some mechanistic similarities regarding regulating DUX4 repression as described in humans.