Three biomarkers are based on DUX4 target gene expression: our Choi et al., a set of 212 ‘early’ DUX4 target genes18,37; Geng et al., a set of 165 ‘late’ DUX4 target genes18,38; and the Yao et al., a set of 114 ‘late’ DUX4 target genes.39,49 The fourth FSHD biomarker is based on PAX7 target gene repression that we derived from 311 upregulated and 290 downregulated PAX7 target genes.18 The final biomarker was our Lymphoblast score, derived from 237 genes found to be upregulated in FSHD lymphoblastoid cell lines compared to controls.19 Here, DUX4 is linked to facioscapulohumeral muscular dystrophy.