It has been demonstrated that GDF-9, a growth factor released by oocytes, is decreased in the follicular fluid of infertile endometriosis patients.4This is caused by inflammatory factors in the female pelvic area, where there is an increase in the concentration of inflammatory cytokines such as TNF-α which leads to impaired function or quality of oocytes indirectly through cumulus cells.3This is confirmed by a study by Nakahara et al.,5which discovered that cumulus cells of endometrioma patients experienced a much higher rate of apoptosis than in patients without endometrioma. The gene discussed is GDF9; the disease is endometriosis.