Thus, an engineered mouse model in which Fat1 functions are specifically ablated in muscles and preserved in the renal system, even though lacking effects of other DUX4 target genes, may represent a more suitable tool to study consequences of the muscle abnormalities in adult, and a better model reflecting the tissue-specific FAT1 depletion that we propose might be occurring in FSHD. This evidence concerns the gene FAT1 and facioscapulohumeral muscular dystrophy.