FRG1 expression is moderately induced by the DUX4-FL transcription factor in human myocytes due to a human specific DUX4-FL responsive intronic enhancer [92], and overexpression of FRG1 in muscle results in an FSHD-like myopathy in mice and impaired muscle development, function, and movement in Xenopus and C. elegans [36–38, 93]. This evidence concerns the gene DUX4 and facioscapulohumeral muscular dystrophy.