The -116C/G polymorphism in XBP1 gene is associated with psychiatric illness in Asian population: A meta-analysis

X-box binding protein 1 (XBP1) is a pivotal transcription factor and plays an important role in the pathogenesis of psychiatric illness. The association between XBP1-116C/G polymorphism and risk of psychiatric illness has been investigated in different populations. However, the results of these studies remain conflicting. Therefore, we performed a systematic meta-analysis to evaluate the association between XBP1-116C/G polymorphism and the overall psychiatric illness risk. Pubmed, Embase, and Chinese Biomedical Literature Database (CBM) were searched for case-control studies on the association between XBP1-116C/G polymorphism and psychiatric illness risk published up to July 31, 2014. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to access the strength of this association. Fourteen case-control studies including 3,512 cases and 4,889 controls were included. Overall, no significant association was found between XBP1-116C/G polymorphism and the risk of psychiatric illness (C/G vs. C/C: OR = 1.04, 95%CI = 0.92-1.17, P = 0.54). However, there was a significant association between this polymorphism and the psychiatric illness in Asian population (C/G vs. C/C: OR = 1.27, 95%CI = 1.00-1.61, P = 0.05; G/G + C/G vs. C/C: OR = 1.32, 95%CI = 1.05-1.65, P = 0.02). Furthermore, we found a significant association between XBP1-116C/G polymorphism and the risk of bipolar disorder in Asian population (C/G vs. C/C: OR = 1.81, 95%CI = 1.15-2.86, P = 0.01). The XBP1-116C/G polymorphism is associated with an increased risk of bipolar disorder in Asian population.