BACKGROUND: Previous studies have implicated norepinephrine transporter (NET) gene polymorphisms in the etiology of major depressive disorder (MDD). Recently, two single nucleotide NET polymorphisms, T-182C (rs2242446) in the promoter region and G1287A (rs5569) in exon 9, were found to be associated with MDD in different populations. However, inconsistent and inconclusive results have also been obtained. METHODS: In this study, we examined whether rs2242446 and rs5569 genetic variants are related to the etiology of MDD using a meta-analysis. Relevant case-control studies were retrieved by database searching and selected according to established inclusion criteria. RESULTS: Eight articles were identified that tested the relationship between the NET T-182C and/or G1287A polymorphism and MDD. Statistical analyses revealed no significant association between these polymorphisms and MDD (OR=1.23, 95% CI=0.77-1.97, P=0.38 for T-182C; OR=1.00, 95% CI=0.78-1.29, P=0.99 for G1287A). LIMITATIONS: The results must be treated with caution because of the small sample sizes of several included studies. CONCLUSIONS: Our findings suggest that the NET T-182C and G1287A polymorphisms are not susceptibility factors for MDD.
BACKGROUND: Previous studies have implicated norepinephrine transporter (NET) gene polymorphisms in the etiology of major depressive disorder (MDD). Recently, two single nucleotide NET polymorphisms, T-182C (rs2242446) in the promoter region and G1287A (rs5569) in exon 9, were found to be associated with MDD in different populations. However, inconsistent and inconclusive results have also been obtained. METHODS: In this study, we examined whether rs2242446 and rs5569 genetic variants are related to the etiology of MDD using a meta-analysis. Relevant case-control studies were retrieved by database searching and selected according to established inclusion criteria. RESULTS: Eight articles were identified that tested the relationship between the NETT-182C and/or G1287A polymorphism and MDD. Statistical analyses revealed no significant association between these polymorphisms and MDD (OR=1.23, 95% CI=0.77-1.97, P=0.38 for T-182C; OR=1.00, 95% CI=0.78-1.29, P=0.99 for G1287A). LIMITATIONS: The results must be treated with caution because of the small sample sizes of several included studies. CONCLUSIONS: Our findings suggest that the NETT-182C and G1287A polymorphisms are not susceptibility factors for MDD.