DUX4 and facioscapulohumeral muscular dystrophy: More importantly, in targeted patient myoblasts, we observed downregulation of not only D4Z4 transcript levels, but also a subset of DUX4 target genes (TRIM43 and ZSCAN4) that are robust biomarkers of the FSHD, validating the significance of the poly-A sequence in DUX4 expression and FSHD pathogenesis.