Abstract
BackgroundIn view of previous conflicting findings, this meta-analysis was performed to comprehensively determine the overall strength of associations between brain-derived neurotrophic factor (BDNF) genetic polymorphism Val66Met and susceptibility to bipolar disorders (BPD).MethodsLiteratures published and cited in Pubmed and Wanfang Data was searched with terms of ‘Val66Met’, ‘G196A’, ‘rs6265’, ‘BDNF’, ‘association’, and ‘bipolar disorder’ up to March 2014. All original case–control association studies were meta-analyzed with a pooled OR to estimate the risk and 95% confidence interval (CI) to reflect the magnitude of variance.ResultsTwenty-one case–control association studies met our criteria for the meta-analysis. Overall, there was no significant difference in allelic distribution of Val66Met polymorphism between patients and controls with a pooled OR = 1.03 (95% CI 0.98, 1.08) although there was a trend towards association between Val66Met polymorphism and BPD in Caucasians with an OR of 1.08 (95% CI 1.00, 1.16). However, subgroup analyses showed that there was a significant association of Val allele with decreased disease susceptibility for bipolar disorder type II with a pooled OR of 0.88 (95% CI 0.78, 0.99).ConclusionsThere is no compelling evidence to supportVal66Met polymorphism in BDNF gene playing an important role in the susceptibility to BPD across different ethnicities.Electronic supplementary materialThe online version of this article (doi:10.1186/s12888-014-0366-9) contains supplementary material, which is available to authorized users.
Highlights
In view of previous conflicting findings, this meta-analysis was performed to comprehensively determine the overall strength of associations between brain-derived neurotrophic factor (BDNF) genetic polymorphism Val66Met and susceptibility to bipolar disorders (BPD)
Twenty-one case–control association studies met our criteria for the meta-analysis (Table 1)
The case–control sample from a genome-wide association study was excluded from current meta-analysis [37]
Summary
In view of previous conflicting findings, this meta-analysis was performed to comprehensively determine the overall strength of associations between brain-derived neurotrophic factor (BDNF) genetic polymorphism Val66Met and susceptibility to bipolar disorders (BPD). Bipolar disorders (BPD) are chronic, recurrent, debilitating disorders with high lifetime prevalence and significant disease burden across different populations [1,2,3]. Recent advances in pharmacological treatment for BPD remained quite modest. The treatment of bipolar depression is still a major challenge [4,5]. BPD is frequently unrecognized and misdiagnosed, in patients presenting with their first-episode of depression. These patients are often treated with inappropriate and costly regimens [6,7,8,9]. There is an urgent need to understand the pathophysiology of BPD in order to develop earlier diagnoses and more effective treatments [10]
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