MSTN and limb-girdle muscular dystrophy: This is supported by data showing that AAV-mediated delivery of a mutated myostatin propeptide in the muscles of animal models of two limb-girdle muscular dystrophies (LGMD2A caused by mutations in the calpain gene and LGMD2D caused by mutations in the α -sarcoglycan gene) leads to different outcomes: it ameliorates calpain 3 but not α -sarcoglycan deficiency [43].