PAX7 and facioscapulohumeral muscular dystrophy: However, DUX4 and PAX7 have non-overlapping expression profiles during in vitro myogenesis of FSHD-derived stem cells [86], single-cell RNA-seq show DUX4-negative cells have a PAX7 repression signature [87], and there are no published reports of PAX7/DUX4 double-positive cells being found in FSHD biopsies or cell culture, all suggesting the PAX7-related mis-regulation is likely downstream of DUX4 expression in FSHD.