MYOD1 and facioscapulohumeral muscular dystrophy: However, although forced DUX4 expression inhibits myogenesis and decreases Myogenic Differentiation 1 (MYOD1) transcription [9], [10], only about one in a thousand FSHD myoblasts has detectable DUX4 expression and expression in FSHD myotubes is not much stronger [6], [2].