Results showed that eight out of 16 differentially methylated genes found in patients with endometriosis overlapped with the menstrual cycle-related genes: seven genes (PI3, SLC43A3, MGAT5B, MUC4, HIVEP3, FGG and CANT1) from comparison between MS and LS phases and one gene (LTK) from M to P comparison. The gene discussed is PI3; the disease is endometriosis.