Meta-analysis of the association of brain-derived neurotrophic factor Val66Met polymorphism with obsessive-compulsive disorder

Objective: Brain-derived neurotrophic factor (BDNF) plays an important role in neural survival and was proposed to be related to psychiatric disorders. Val66Met (also known as rs6265 or G196A), the only known functional polymorphism of the BDNF gene, has been widely studied and considered to be associated with risk of some psychiatric disorders such as bipolar disorder and schizophrenia. However, studies evaluating its association with obsessive-compulsive disorder (OCD) obtained inconsistent results. The purpose of this study was to derive a more precise estimation of the association between BDNF Val66Met polymorphism and OCD susceptibility by a meta-analysis. Method: We carried a structured literature search in PubMed, Embase, PsycINFO and Chinese Biomedical Database up to December 2014; and retrieved all eligible case-control studies according to the including criteria. Meta-analysis was performed for four genetic models: allelic model: Met versus Val; additive model: Met/Met versus Val/Val; recessive model: Met/Met versus Val/Val + Val/Met; and dominant model: Val/Met + Met/Met versus Val/Val. Stratified analyses were performed by ethnicity and gender where appropriate. Results: A total of eight articles with nine studies including 1632 OCD cases and 2417 controls were identified. No significant association was detected in any comparison when the whole data were pooled together or stratified by ethnicity or gender in all four genetic models (p>0.05 for each comparison). Conclusion: Despite some limitations, our meta-analysis suggests that no significant association exists between the BDNF Val66Met polymorphism and OCD susceptibility.