Association between norepinephrine transporter T-182C polymorphism and major depressive disorder: a meta-analysis

The human norepinephrine transporter (NET) gene is one of the key candidates for genetic studies in major depressive disorder (MDD). The association between NET T-182C gene polymorphisms and MDD risk has been widely reported, but results were controversial and underpowered. The purpose of this study was to derive a more precise estimation of the relationship between NET T-182C polymorphisms and MDD risk through a meta-analysis. Relevant studies were identified from PubMed, Web of Science, Chinese Biomedical Database (CBM), Chinese National Knowledge Infrastructure (CNKI), Ovid and Wan Fang (Chinese) up to March 2013. Finally, seven studies containing 1779 cases and 1584 controls were included. The pooled odds ratio (OR) and 95% confidence interval (CI) were performed. The combined results showed that there was no significant difference between MDD group and control group in all comparison models (T vs. C: OR=1.00, 95% CI=0.83-1.22; TC+TT vs. CC: OR=0.87, 95% CI=0.55-1.36; TT vs. TC+CC: OR=0.96, 95% CI=0.76-1.20; TT vs. CC: OR=1.09, 95% CI=0.66-1.80). When stratifying for the race, there was still no significant difference in genotype distribution between MDD and controls. No publication bias was observed. Conclusively, the present meta-analysis did not suggest a confirmed association between the T-182C polymorphism of the NET gene and MDD.