Objective: Endometriosis is inherited as a complex trait, which means that multiple susceptibility genes interact with each other and with environmental factors to produce the phenotype. We investigated the frequency of glutathione S-transferase M1 and T1 (GSTM1 and GSTT1) null mutations in women with endometriosis in a Japanese population.
Methods: One hundred fourteen unrelated women with endometriosis were enrolled. Samples of umbilical cord blood obtained from 179 female newborn infants were used as population controls. Genomic DNA isolated from endometriosis patients and controls were subjected to multiple polymerase chain reactions to determine the GSTM1 and GSTT1 genotypes.
Results: There were no significant differences in the frequencies of the GSTM1 (P = .83, odds ratio 0.95) and GSTT1 (P = .24, odds ratio 0.75) null mutations between endometriosis patients and controls. The endometriosis group was divided into a subgroup of stage IV disease only, but no statistically significant differences were observed in the frequency of the GSTM1 null mutation (P = .88, odds ratio 0.96, 95% confidence interval 0.57-1.63) and the GSTT1 null mutation (P = .33, odds ratio 0.77, 95% confidence interval 0.45-1.30) between any of these groups and the controls.
Conclusion: These findings suggest that the GSTM1 and GSTT1 null mutations are not likely to be associated with an increased risk of endometriosis in a Japanese population.