In the Korean and Japanese populations, advanced stage endometriosis was seen mostly in patients who had the TNF-α -1031T/C polymorphism (13,30) but there were no significant differences in frequencies between endometriosis cases and controls for TNF-α -238G/A, -308G/A, -857C/T, and -863C/A polymorphisms (13). This evidence concerns the gene TNF and endometriosis.