CYP19A1 and endometriosis: In addition, other studies have found that the abnormal expression of Cytochrome P450 Family 19 Subfamily A Member 1 (CYP19A1), Epidermal Growth Factor Receptor (EGFR), Estrogen Receptor 2 (ESR2), Fos Proto-Oncogene, AP- 1 Transcription Factor Subunit (FOS), and Insulin-like growth factor 1 (IGF1) related to the steroid pathway may also be related to the ovarian dysfunction of endometriosis (Roy et al., 2015) It is noteworthy that the genetic changes in ovaries are at least partly due to steroid biosynthesis.