Sejersen et al. [33], in a systematic review of the literature, identified 2199 studies involving protein analysis in tendinopathies and found a trend of increased expression of COL1, COL3, MMP1, MMP9, MMP13, TIMP1 and VEGF and decreased MMP3 [33], demonstrating the importance of cataloging different polymorphisms related to RCT, which may contribute to a better understanding of the lesion. This evidence concerns the gene MMP9 and disease of the tendon.