MSTN and Becker muscular dystrophy: Since myostatin was cloned in 1997 [5], many myostatin-blocking agents have gained attention in agriculture applications and in the management of muscle diseases and disorders [6], e.g., injuries, sarcopenia, wasting/cachexia, Duchenne type muscular dystrophy, Becker muscular dystrophy, facioscapulohumeral muscular dystrophy, etc. [7,8].