Nouri et al. Reproductive Biology and Endocrinology 2010, 8:85 http://www.rbej.com/content/8/1/85 Open Access RESEARCH © 2010 Nouri et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Research Family incidence of endometriosis in first-, second-, and third-degree relatives: case-control study Kazem Nouri* 1 , Johannes Ott 1 , Birgitt Krupitz 2 , Johannes C Huber 1 and Rene Wenzl 3 Abstract Background: Initial publications examining the hereditary aspects of endometriosis appeared in the early seventies and demonstrated an up to seven-fold risk for endometriosis in first-degree relatives of endometriosis patients. The aim was to evaluate the influence of hereditary aspects on the endometriosis risk in our patient collective. Methods: In a retrospective cohort study we evaluated the incidence of endometriosis among first-, second-, and third-degree relatives of endometriosis patients and compare it with its incidence among first-, second-, and third- degree relatives of patients without endometriosis. Result(s): Eighty patients in whom endometriosis had been confirmed laparoscopically and histologically by biopsy and 60 patients in whom no endometriosis had been found during laparoscopy were given a questionnaire about the presence of symptoms associated with endometriosis and its family incidence. Patients of both the endometriosis and the control group were 37.7 ± 6.2 and 45.9 ± 12.0 years of age at the time of the interview, respectively (p < 0.05). Information about the presence of endometriosis was more readily available for relatives of those in the endometriosis group than for those in the control group (325/749 [43.4%] vs. 239/425 [56.2%], p < 0.05). In 5/136 (3.7%) and 8/134 (6.0%) first-degree relatives of endometriosis patients and the control group, respectively, information about the presence of endometriosis was not available (p = 0.554). Endometriosis was found in 8/136 (5.9%) first-degree relatives of patients and in 4/134 (3.0%) first-degree relatives of controls in the real-case analysis (p = 0.248). When comparing endometriosis characteristics between endometriosis patients with and without a history of familial endometriosis, no significant differences were found. Conclusion(s): There is a trend toward an increased familial incidence of endometriosis. In contrast to the literature, we found a less dramatic increase in familial risk for the development of endometriosis. Background Endometriosis is one of the most common gynecological diseases, and occurs in 2-10% of women of reproductive age [1]. Symptoms include severe pelvic pain, dysmenor- rhoea, bladder and bowel discomfort, and infertility. To date, very little is known about its etiology and pathogen- esis. Because a number of studies have demonstrated an increased risk for developing the disease in mothers and/ or sisters of patients, endometriosis likely has a genetic basis [2-6]. Initial publications examining the hereditary aspects of endometriosis appeared in the early seventies [3]. In 1981, Simpson et al. were able to demonstrate that the risk for endometriosis in first-degree relatives of endo- metriosis patients is seven-fold compared to the normal population [4]. Five years later, only a four-fold increased risk for developing the disease was estimated for mothers and sisters of an endometriosis patient. [5]. A study con- ducted in twins demonstrated that the incidence of endo- metriosis in monozygotic twins was twice that in dizygotic twins [6]. In addition, it has been shown that the severity of endometriosis is higher among patients with a positive family history [7]. Accordingly, one could conclude that if a woman has endometriosis, the risk that her first-degree relatives will also have endometriosis could be anywhere from 4-7 times higher than that of the general population [4,5]. For practical reasons, only a few studies have dealt with the endometriosis incidence in second- and third-degree relatives of endometriosis patients [8]. The purpose of * Correspondence: kazem.nouri@meduniwien.ac.at 1 Department of Gynecologic Endocrinology and Reproductive Medicine, Medical University of Vienna, Vienna, Austria Full list of author information is available at the end of the article