Heritable aspects of endometriosis. I. Genetic studies.

Systematic genetic studies in endometriosis apparently have not been conducted; therefore, we studied 123 patients with histologically proved endometriosis. Nine of 153 (5.8%) female sibs (over age 18) of patients with histologically proved endometriosis were considered similarly affected; 10 of 123 mothers (8.1%) were affected; 19 of 276 (6.9%) of all first-degree relatives were affected. By contrast, only one of 104 (1.0%) female sibs of their husbands and only one of 107 (0.9%) mothers of their husbands were affected, significantly (p less than 0.05) less for both sibs and mothers. Several genetic etiologies can be postulated, but polygenic/multifactorial inheritance seems most likely because of (1) the 6.9% recurrence risk for all first-degree relatives and (2) observations that the 18 patients with an affected first-degree relative were more likely to have severe endometriosis than those without an affected first-degree relative.