SMCHD1 and facioscapulohumeral muscular dystrophy: Given that SMCHD1 has been reported to collaborate with the Polycomb Repressive Complex 1 (PRC1) in X-chromosome inactivation [178,179] and that PRC1 is involved in silencing of the FSHD locus [46,180], it is tempting to speculate that SMCHD1 gene correction acts together with PRC1 to reinstate epigenetic silencing of the FSHD locus.