Association between polymorphisms in the serotonin transporter gene-linked polymorphic region and risk for irritable bowel syndrome in China: evidence based on a meta-analysis

OBJECTIVE: The association between mutations in the serotonin transporter gene-linked polymorphic region (5-HTTLPR) and irritable bowel syndrome (IBS) differs between populations. This meta-analysis was designed to assess the relationship between 5-HTTLPR polymorphisms and IBS in a Chinese population. METHODS: Relevant published studies from PubMed, Embase, Web of Science, the Cochrane Library, and China National Knowledge Infrastructure databases were accessed prior to May 2018. Odds ratios (ORs) with 95% confidence intervals (CIs) were pooled using STATA software. RESULTS: A total of 754 IBS cases and 578 healthy controls in six studies were included in this meta-analysis. Significant results were obtained between 5-HTTLPR polymorphisms and IBS risk among studies with the genotype distribution of controls in Hardy–Weinberg equilibrium (L vs. S, OR = 1.41, 95% CI: 1.11–1.79; LL vs. SS, OR = 2.17, 95% CI: 1.16–4.08; LL vs. LS + SS, OR = 2.29, 95% CI: 1.25–4.20). In subgroup analyses, 5-HTTLPR polymorphisms were significantly associated with increased IBS-C risk in China; however, no risk was observed for IBS-D and IBS-M. CONCLUSION: This meta-analysis clearly indicates that 5-HTTLPR polymorphisms are associated with an increased risk of IBS in the Chinese population, especially IBS-C.