A total of eight predictors were included in the multivariate logistic regression model: CA125, BDNF, a record of previous surgery for endometriosis, painful periods leading to referral for endometriosis, age at first intercourse pain, age at first painkillers use, age at first ovarian cyst symptom and severity of menstrual pain during last cycle. The gene discussed is BDNF; the disease is Ovarian cyst.