Although all placental organisms have a DUXC ortholog, human DUX4 is primate-specific, rendering it difficult to study developmentally in traditional model organisms, and all FSHD animal models are engineered transgenics (Bosnakovski et al., 2017; Bosnakovski et al., 2022; Jones and Jones, 2018; Jones et al., 2016; Pakula et al., 2019; Wuebbles et al., 2010). Here, DUX4 is linked to facioscapulohumeral muscular dystrophy.