Given that there is not a diagnostic blood test for endometriosis, there has been interest in identifying biomarkers for the condition [40] and, while there have been over 400 articles with control groups, only four (TNF-a, MMP-9, TIMP-1, and miR-451) are reported to be detected in at least three tissues [40], suggesting that further research on endothelial proteins needs to be explored in endometriosis. This evidence concerns the gene MMP9 and endometriosis.