Polymorphisms in the interleukin 4 promoter -589C/T gene and the risk of asthma: a systematic review and meta-analysis

Background: To identify the association between polymorphisms in the interleukin 4 (IL-4) promoter -589C/T gene and the risk of asthma. Methods: The databases of PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wanfang, Chongqing VIP (CQVIP), and Chinese Biomedical Literature (CBM) were searched and appropriate journal articles on the association between polymorphisms in the IL-4 promoter -589C/T gene and the risk of asthma were retrieved from establishment of the database to April 2021. All relevant randomized controlled trials (RCTs) were included, to the exclusion of duplicate publications, studies with no whole composition, imperfect information or inability to extract data, animal experiments and reviews, and systematic reviews. The software Review manager 5.3 was used to analyze the data. Results: Literature search led to retrieving of 16 publications containing 3181 cases and 3786 controls. The results show that CT, CC, and T gene polymorphisms were risk factors for asthma [odds ratio (OR) =1.05, 95% confidence interval (CI): 0.89-1.24; OR =1.04, 95% CI: 0.85-1.27; OR =1.98, 95% CI: 1.54- 2.53]. Ethnic subgroup analysis showed that genotype CT was associated with the risk of asthma in the Asian population (OR =1.75, 95% CI: 1.01-3.05). Discussion: Through the study of IL-4 (C-590T) gene polymorphism, it was found that CT, TT, and T gene polymorphism were risk factors for asthma, and the results suggested that this locus polymorphism was related to the risk of asthma. The results of subgroup analysis showed that CC and T gene polymorphisms were risk factors for asthma. Thus, IL-4(C-590T) may be the susceptibility gene of asthma.