Heritage aspects of endometriosis. II. Clinical characteristics of familial endometriosis.

Clinical characteristics of patients with histologically confirmed pelvic endometriosis who had an affected first-degree relative (N = 18) were compared to those who had no such affected relative (N = 105). The only significant difference was that 61% of individuals in the former group had severe endometriosis, compared to only 24% in the latter group. This observation is most consistent with a polygenic/multifactorial etiology, although other genetic mechanisms cannot be excluded. Our observations carry several important practical implications. First, an apparently unaffected patient with an affected first-degree relative should be counseled that her risk of developing endometriosis is 7%. This might influence the choice of contraception, the timing of pregnancy, and the extent to which aggressive diagnostic approaches (e.g., laparoscopy and curettage) would be appropriate.