Association of angiotensin-converting enzyme gene I/D polymorphism with chronic obstructive pulmonary disease: a meta-analysis

OBJECTIVES: We conducted a meta-analysis of published studies on the angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism associated with the risk of chronic obstructive pulmonary disease, as well as with pulmonary function and circulating angiotensin-converting enzyme changes. METHODS: A literature search, quality assessment and data extraction were completed independently and in duplicate. RESULTS: A total of 16 articles were meta-analysed, including 12 articles (2113 patients and 8786 controls) for chronic obstructive pulmonary disease risk and eight articles (11,664 subjects) for pulmonary and circulating phenotypes. In overall and subgroup analyses, no significance was noted between the I/D polymorphism and chronic obstructive pulmonary disease risk under all genetic models (P>0.05), without heterogeneity or publication bias. Carriers of II, ID and II plus ID genotypes had significantly lower levels of circulating angiotensin-converting enzyme than those with the DD genotype (weighted mean difference −13.35, −8.13 and −10.74 U/L, respectively, P<0.001). For forced expiratory volume in one second (FEV(1))/forced vital capacity, carriers of the DD genotype had marginally lower levels than those with the DD genotype (weighted mean difference –1.66, P=0.034). Furthermore in the case of FEV(1) of 50% or greater of predicted FEV(1), FEV(1) was marginally lower in ID genotype carriers than DD genotype carriers (weighted mean difference −3.50, P=0.056). CONCLUSIONS: Our meta-analytical findings demonstrated that the ACE gene I/D polymorphism was not associated with the risk of chronic obstructive pulmonary disease.