Low-penetrance genes are associated with increased susceptibility to endometriosis.

OBJECTIVE: To investigate whether genetic polymorphisms of CYP1A1, GSTM1, and GSTT1 are associated with endometriosis.
DESIGN: Genetic polymorphism analysis.
SETTING: University department. PATIENT(S): A family with four women in two generations who had endometriosis and one member with suspected endometriosis in the third generation were compared with a group of fertile women. INTERVENTION(S): Laparoscopic examination. MAIN OUTCOME MEASURE(S): Blood specimens were obtained from fertile females and available affected female family members. Multiplex polymerase chain reaction (PCR) and restriction fragment length polymorphism PCR was done to determine each participant's genotype. RESULT(S): All affected family members had genotype CYP1A1 wt/m1 and GSTM1 null deletion. The frequency of this genotype in 54 fertile women was 13%. A 17-year-old family member with suspected endometriosis had the same genotype. One affected member was also a carrier of a GSTT1 null deletion. This combination was not found in any of the fertile participants. The most frequent genotypes in the sample were CYP1A1 wt/wt, with GSTM1 null deletion and at least one functional allele of GSTT1, and CYP1A1 wt/wt, with at least one functional allele of GSTM1 and GSTT1 (33% and 31%, respectively). CONCLUSION(S): The combination of CYP1A1 m1 polymorphism and GSTM1 null deletion is closely associated with penetration of the endometriosis phenotype, whereas GSTT1 null deletion may add to the penetration of this trait.