WFDC3 and facioscapulohumeral muscular dystrophy: In addition, mRNA levels of two DUX4 target genes (Wfdc3, Zscan4c), commonly used as biomarkers of DUX4 transcriptional activity78–80, were quantified along with the mRNA level of Myog a myogenic marker known to be downregulated in FSHD, contrary to Wfdc3 and Zscan4c84–86.