FAT1 and Facioscapulohumeral dystrophy: Finally, no significant quantitative changes were observed in muscle biopsies of twin FSHD foetuses with 7 D4Z4 repeats (Figure 9B), although accumulation of FAT1 protein could be observed in some myofibre nuclei (data not shown), a localization never observed in age matched control biopsies, but reminiscent of adult mouse muscles.