In addition, while subclinical/undiagnosed endometriosis as an underlying factor responsible for unexplained infertility is not a novel observation per se, the unexpected combination of VCAM-1, VEGF, sICAM-3, angiopoietin-1, and sTie-2, which are all proteins that have been associated with endometriosis, is novel and compelling; however, a causal association between these proteins, endometriosis, and UI requires more study, and the exclusion of other mechanisms that are out of the scope of this study. This evidence concerns the gene VEGFA and endometriosis.