A link between DNAm and endometriosis has been previously reported in several studies, including hypermethylation of the HOXA10 and progesterone receptor-B (PR-B) promoters in the endometrium of women with endometriosis [18,19,20,21], the latter providing a possible explanation for progesterone resistance and the reduction in the level of PR-B in endometriosis [19,20,21]. Here, RB1 is linked to endometriosis.