We find that only the new biomarker based on Pax7 target gene repression is consistently able to discriminate FSHD from control skeletal muscle biopsies in every FSHD biopsy data set, while the discriminatory power of DUX4 target gene expression is limited to just two studies10, 28. This evidence concerns the gene DUX4 and facioscapulohumeral muscular dystrophy.