To date, only a few genes, such as those coding for peroxisome proliferator-activated receptors gamma (PPARγ), CCAAT-enhancer-binding proteins alpha (CEBPα), myogenin, myostatin, and matrix metallopeptidases (MMPs), have been identified in relation to muscle changes after rotator cuff tears [20, 21, 24, 27]. Here, MSTN is linked to rotator cuff syndrome.