Disclosed herein are Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/CRISPR-associated (Cas) 9-based system related compositions and methods of using said CRISPR/Cas9-based system related compositions for altering gene expression and genome engineering. Also disclosed herein are compositions and methods of using said compositions for altering gene expression and genome engineering in muscle, such as skeletal muscle and cardiac muscle.