DUX4 and facioscapulohumeral muscular dystrophy: Another gene in the region, DUX4c (Box 1), has an identical N-terminus and homeodomains (Box 1) to DUX4, but a divergent C-terminus, and is upregulated in FSHD myoblasts and biopsies (Ansseau et al., 2006, 2009).