Women with endometriosis display aberrant expression of genes in their eutopic endometrium, many of which (including HOXA10, aromatase, progesterone receptors, matrix metalloproteinases, and ab-integrin) have been implicated in endometrial development and receptivity (reviewed in Macer & Taylor, 2012; Hurst et al, 2014). Here, CYP19A1 is linked to endometriosis.