Table 3 reports the comparison of MTHFR polymorphism distribution according to the presence of ovarian endometriosis, regardless of the presence of concomitant peritoneal endometriosis (n = 81) or DIE endometriosis and regardless of the presence of concomitant ovarian or peritoneal endometriosis (n = 25). This evidence concerns the gene MTHFR and endometriosis.