Familial risk among Japanese patients with endometriosis

OBJECTIVES: This study was designed to examine the prevalence of endometriosis among female siblings of patients with endometriosis in Japan. METHODS: A total of 339 patients with endometriosis were questioned about endometriosis in their sisters. The control group consisted of 284 Japanese healthy fertile women with no history of endometriosis. Similarly, the controls were interviewed about their sisters. RESULTS: We detected sisters with endometriosis in 8.8% of cases and 1.5% of the control population. The relative risk of endometriosis in female siblings was 5.7. However, a significant difference was not seen in age at diagnosis and clinical stage between patients with or without a family history of endometriosis. CONCLUSIONS: These data demonstrate a familial tendency for endometriosis and suggest that endometriosis has a genetic factor in the pathogenesis.