Background: Many studies have investigated the association between angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism and risk of recurrent miscarriage, but the impact is unclear due to inconsistencies among those studies. This study aimed to quantify the strength of the association between ACE I/D polymorphism and recurrent miscarriage risk by performing a systematic review and meta-analysis.
Design and methods: We searched PubMed, Embase, Web of Science, and Wanfang Medicine databases for eligible articles relating the association between ACE I/D polymorphism and risk of recurrent miscarriage in humans. We estimated the summary odds ratios (ORs) with their 95% confidence intervals (95% CIs) to assess the association.
Results: Eleven studies with a total of 3357 individuals were included in this meta-analysis. Compared to the ACE II genotype, DD and ID were both associated with increased risk of recurrent miscarriage (OR DD versus II=1.81, 95% CI 1.23-2.66, P=0.003; OR ID versus II=1.50, 95% CI 1.25-1.80, P<0.001). Sensitivity analyses further confirmed the association above. No evidence of publication bias was observed.
Conclusion: Meta-analyses of available data show a significant association between ACE I/D polymorphism and recurrent miscarriage risk, and the ACE polymorphic D allele contributes to increased risk of recurrent miscarriage.
Keywords: 95% CI; 95% confidence interval; ACE; ACE I/D; Angiotensin-converting enzyme; Gene polymorphism; HWE; Hardy–Weinberg equilibrium; Meta-analysis; OR; Recurrent miscarriage; odds ratio; skewed X chromosome inactivation.; skewed XCI.
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