Association of vitamin D receptor gene polymorphisms with susceptibility to childhood asthma: A meta‐analysis

Summary Background As for the association of vitamin D receptor (VDR) gene polymorphisms with susceptibility to pediatric asthma, results of published studies yielded conflicts. A systematic review was conducted on the relationship between childhood asthma and VDR gene polymorphisms, including Apa I (rs7975232), Bsm I (rs1544410), Fok I (rs2228570), and Taq I (rs731236). Methods PubMed, Web of Science, CBM (Chinese Biomedical Database), CNKI (China National Knowledge Infrastructure), and Wanfang (Chinese) database were searched for relevant studies. Pooled odds ratios (OR) with 95% confidence interval (CI) were calculated. Results Overall results suggested that there was a statistically significant association between Apa I polymorphism and childhood asthma in homozygote model (OR = 1.674, 95%CI = 1.269–2.208, P  < 0.001) and allele model (OR = 1.221, 95%CI = 1.084–1.375, P  = 0.001). Stratification by ethnicity revealed a statistical association in Asians (OR = 1.389, 95%CI = 1.178–1.638, P  < 0.001). There was some evidence of an association between Bsm I polymorphism and childhood asthma in the homozygote (OR = 1.462, 95%CI = 1.016–2.105, P  = 0.041) and allele models (OR = 1.181, 95%CI = 1.006–1.386, P  = 0.042). This association reached significance only in the Caucasian group (OR = 1.236, 95%CI = 1.029–1.485, P  = 0.023). For Fok I, a statistical association was detected in dominant model (OR = 1.281, 95%CI = 1.055–1.555, P  = 0.012); this association was significant in allele model (OR = 1.591, 95%CI = 1.052–2.405, P  = 0.028) in Caucasian. Conclusion Apa I polymorphism plays a particular role in childhood asthma in Asians. Fok I polymorphism may be connected with pediatric asthma in Caucasian population. And Bsm I polymorphism marginally contributes to childhood asthma susceptibility, while there might be no association between Taq I polymorphism and childhood asthma risk. Pediatr Pulmonol. 2017;52:423–429. © 2016 Wiley Periodicals, Inc.