In the subgroup analysis by ethnicity, significant elevated endometriosis risk was associated with CYP1A1Ile462Val polymorphism in Asians but not in Caucasians under all genetic models.
We observed an association between endometriosis and the GSTM1 null deletion, but not with GSTT1 null deletions or the CYP1A1 MspI polymorphism in South Indian women.
RT-PCR with Southern blot analysis, however, showed that HRF overexpression was not always accompanied by CYP1A1 induction in endometriotic implants, suggesting that HRF is inducible in endometriosis without exposure to TCDD.
Our data suggest that CYP19 VNTR (TTTA)(10) allele as well as the combined genotype CYP1A1 m1 polymorphism and GSTM1 null deletion associate with the endometriosis phenotype, whereas the GSTT1 null deletion does not.
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.
However, the combination of the GSTM1 null genotype and the CYP1A1 MspI polymorphism was associated with a small increased risk of endometriosis, and this warrants further investigation.
In fact, the proposed link between dioxin exposure and endometriosis may be explained in part by the up-regulation of the CYP1A1 gene expression in endometriotic tissues.