The first Japanese study reported a significant association of endometriosis with rs10965235 located in CDKN2BAS in 9p21 and with rs16826658m in the linkage disequilibrium block including WNT4 in 1p36 [6]. CDKN2BAS regulates P16, a tumor suppressor genes repressed in endometriosis [7], possibly by promoter hypermethylation [8]. WNT4 has a role in the development of the genitourinary system, steroidogenesis, and folliculogenesis [9, 10]. Here, WNT4 is linked to endometriosis.