However in FSHD the FR-MAR is weakened so that the repeat array and its neighbouring genes are brought into a single chromatin loop where the D4Z4 enhancer might up-regulate transcription of any gene ([13], [17]) including the DUX4 (double homeobox) gene that our group mapped inside each D4Z4 element [18]. The gene discussed is DUX4; the disease is facioscapulohumeral muscular dystrophy.