Nucleotide sequences including a micro-dystrophin gene are provided. The micro-dystrophin genes may be operatively linked to a regulatory cassette. Methods of treating a subject having, or at risk of developing, muscular dystrophy, sarcopenia, heart disease, or cachexia are also provided. The methods may include administering a pharmaceutical composition including the micro-dystrophin gene and a delivery vehicle to a subject. Further, the methods may include administering the pharmaceutical composition a subject having Duchenne muscular dystrophy or Becker muscular dystrophy.
