However, individuals meeting the genetic, epigenetic, and clinical criteria for FSHD express stable DUX4-fl mRNA and DUX4-FL target genes in their skeletal muscles, initiating a detrimental cascade of events which culminate in muscle pathology and disease [4–6, 9, 10, 20, 21]. This evidence concerns the gene DUX4 and facioscapulohumeral muscular dystrophy.