HEY1 (hairy/enhancer-of-split related with YRPW motif 1) inhibits myogenesis by repressing myogenin and Mef2C [40], and its ∼13-fold activation by DUX4 in muscle cells could inhibit muscle differentiation in FSHD. The gene discussed is MYOG; the disease is facioscapulohumeral muscular dystrophy.