FRG1 and Facioscapulohumeral dystrophy: In FSHD cells (Figure 4B), the deletion of D4Z4 repeats and the delocalization of the proximal S/MAR would result in the formation of a giant loop where the subtelomeric 4qA/B sequence is now brought in close proximity not only to DUX4C and FRG1 but also to the proximal ANT1 gene promoter which lies 5 Mbp away on the centromeric side of the region.