Table 2. Meta-analysis of associations between GSTM1, GSTT1, and GSTM1-GSTT1 polymorphisms and endometriosis.
| Genes | Comparisons | Sample size Case Control | No.ofstudies | Test of association OR (95% CI) p Model | Test of heterogeneity χ2 p I2 | ||||||
| GSTM1 | |||||||||||
| Overall | GSTM1(−) vs. GSTM1(+) | 3330 | 3959 | 25 | 1.54 | 1.30–1.83 | <0.001 | R | 0.115 | <0.001 | 64.7 |
| BS | GSTM1(−) vs. GSTM1(+) | 3037 | 3577 | 22 | 1.45 | 1.23–1.71 | <0.001 | R | 0.080 | <0.001 | 57.3 |
| Ethnicity | |||||||||||
| European | GSTM1(−) vs. GSTM1(+) | 1407 | 1773 | 10 | 1.58 | 1.19–2.09 | 0.002 | R | 0.130 | 0.001 | 68.5 |
| Asian | GSTM1(−) vs. GSTM1(+) | 1923 | 2186 | 15 | 1.52 | 1.21–1.91 | <0.001 | R | 0.121 | <0.001 | 64.5 |
| Source of Controls | |||||||||||
| PB | GSTM1(−) vs. GSTM1(+) | 948 | 1340 | 6 | 1.52 | 1.08–2.16 | 0.005 | R | 0.124 | 0.018 | 70.1 |
| HB | GSTM1(−) vs. GSTM1(+) | 2382 | 2619 | 19 | 1.55 | 1.26–1.91 | <0.001 | R | 0.125 | <0.001 | 64.8 |
| GSTT1 | |||||||||||
| Overall | GSTT1(−)vs. GSTT1(+) | 2263 | 2380 | 16 | 1.41 | 1.10–1.82 | 0.007 | R | 0.163 | <0.001 | 67.0 |
| Ethnicity | |||||||||||
| European | GSTT1(−) vs. GSTT1(+) | 877 | 821 | 6 | 1.21 | 0.74–1.99 | 0.450 | R | 0.253 | 0.007 | 68.4 |
| Asian | GSTT1(−) vs. GSTT1(+) | 1386 | 1559 | 10 | 1.53 | 1.14–2.06 | 0.005 | R | 0.143 | 0.001 | 67.5 |
| GSTM1-GSTT1 | GSTM1-GSTT1(−) vs.other genotypes | 1008 | 1164 | 5 | 1.33 | 1.03–1.72 | 0.027 | F | 0.037 | 0.236 | 27.8 |
Abbreviations: OR, odds ratio; CI, confidence interval; BS, based on score (studies with quality scores <7 were excluded); PB, population-based; HB, hospital-based; F, fixed-effects model; R, random-effects model.