Objective: To study the reproductive and medical history of monozygotic twin sisters and mothers of patients with endometriosis.
Material and methods: Among 515 patients with endometriosis, eight had a monozygotic twin sister all of whom had had a gynecological laparoscopy or laparotomy. In addition, five of their mothers had had a laparotomy. Details about these 13 relatives were obtained either from medical records (ten cases) or by unmistakable reports from the proband (three cases).
Result: Six of the monozygotic twin sisters (75%) also had symptomatic endometriosis compared with 3.8% among other types of sisters (p < 0.0005). Three of the mothers (38%) had either endometriosis or adenomyosis.
Conclusion: This study gives support to the assumption that endometriosis has a genetic trait.