DUX4 and facioscapulohumeral muscular dystrophy: The majority of current laboratory animal models of FSHD try to mimic DUX4 misexpression via the transgenic insertion or injection of DUX4. An example of this would be FLExDUX4—which is a line of conditional floxed DUX4-FL transgenic mice—that was developed by Jones and Jones (2018) in order to overcome “developmental toxicity of low DUX4 expression from leaky transgenes” and create the conditions for DUX4 animal experiments on mice that are viable and fertile (see: “Therapeutic approaches: AOs”) [120].