Angiotensin-converting enzyme gene insertion/deletion polymorphism and essential hypertension in the Chinese population: a meta-analysis including 21 058 participants.

Background: The angiotensin-converting enzyme (ACE) gene insertion/deletion (I/D) polymorphism has been suggested to influence susceptibility to essential hypertension (EH), but the results of many individual studies are conflicting. Aim and methods: To explore the relationship between the ACE gene I/D polymorphism and EH in the Chinese population, 67 separated studies were analyzed in a meta-analysis including 21 058 participants. The electronic databases PubMed, Embase, Web of Science, China Biological Medicine Database and China National Knowledge Infrastructure were searched. The pooled odds ratio (ORs) and its corresponding 95% confidence interval were calculated by the random effects model. Results: In this ACE I/D gene polymorphism meta-analysis, the distribution of the D allele frequency was 0.45 for the EH group and 0.40 for the control group. The summary OR for the distribution frequency of D allele was 1.27 (5% confidence interval 1.17-1.37). The heterogeneity among the 67 studies was also significant ( P < 0.00001, I2= 71.4%). There was a significant association between distribution frequency of the D allele and EH risk in Han, Kazakh, Tibetan, Zhuang and unclassified nationalities ( P < 0.05). In contrast, in the national minorities, such as Mongolian, Uigur, Yi, Dongxiang, Yugu, Korean and Gamel, the association between distribution frequency of the D allele and EH risk was not significant ( P > 0.05). Conclusions: In the whole Chinese population, the D allele was significantly linked with EH susceptibility. However, the relation between the I/D polymorphism and EH is still inconclusive in some national minorities and must await larger scale studies. [ABSTRACT FROM AUTHOR]