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Received Sep 3, 2017; Revised Nov 2, 2017; Accepted Nov 14, 2017
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1. Introduction
Inflammatory bowel diseases (IBDs) are chronic multifactorial and relapsing inflammatory disorders of the gastrointestinal tract, including Crohn’s disease (CD) and ulcerative colitis (UC). In recent years, the population of patients suffering the IBDs shows an increasing trend. The complex interaction among host immune system, intestinal flora, and environmental factors is considered to be the cause of the IBD pathogenesis [1, 2]. Hence, the identification of genetic factors involved in the development of IBD has attracted attention in the current research area [3].
MicroRNAs (miRNAs) are an abundant class of small, noncoding, and single-stranded RNAs, which play an important role in many biological processes, such as cellular proliferation, differentiation, apoptosis, immune response, and signal transduction by regulating gene expression [4]. It has been reported that many diseases, for example, inflammatory diseases and various cancers, will implicate an miRNA dysregulation [5, 6]. Though the majority of studies are focused on the miRNA expression, a considerable number of publications have reported that the single-nucleotide polymorphisms (SNPs) in miRNA genes could be linked to the genetic susceptibility to disease development.
In the literature, the scholars have reported several miRNA-SNPs, including miRNA-196a2 rs11614913, miRNA-146a rs2910146, and miRNA-499 rs3746444, that are associated with the susceptibility to various diseases such as rheumatoid arthritis (RA) [7, 8], systemic lupus erythematosus (SLE), and various cancers [9, 10]. In addition, some research has been proposed to investigate the association between the SNPs and the risk of IBD [11–15], while the results were inconclusive or even conflicting. Therefore, we performed a meta-analysis to examine how miRNA-196a2 rs11614913, miRNA-146a rs2910146, and miRNA-499 rs3746444 polymorphisms will affect the IBD susceptibility.
2. Methods and Materials
In this work, the meta-analysis was performed according to the statement guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) [16] and the Cochrane handbook was used to lead the analysis.
2.1. Identification of Eligible Studies
The last search was updated on May 1, 2017. Specifically, we carried out a systematic search in...