A meta-analysis of 25 studies with 2645 participants showed that leptin levels (weighted mean difference (WMD) = 4.45 mg/mL, 95% CI = 2.42–6.49, p < 0.01) and leptin/BMI ratio (WMD = 0.32 mg/mL, 95% CI = 0.23–0.42, p < 0.001) were significantly higher in women with endometriosis [36]. This evidence concerns the gene LEP and endometriosis.