Evidence of associations between bipolar disorder and the brain-derived neurotrophic factor (BDNF) gene

Brain-derived neurotrophic factor (BDNF) has important roles in neural cell growth and differentiation. Despite multiple lines of evidence suggesting BDNF as a possible contributor to the pathogenesis of bipolar disorder (BD), the results of genetic association studies have been mixed. We hypothesize that BDNF gene polymorphisms may confer increased susceptibility to BD.

Using a cohort of multiplex bipolar families, we performed family-based association testing to look for associations between BD and eight single nucleotide polymorphisms (SNPs) from BDNF.

We found associations (p < 0.05) between BD and six of the eight SNPs analysed, including two SNPs not previously investigated in association studies. We were able to replicate associations previously found between BD and the Val66Met polymorphism of BDNF (rs6265) and the SNPs rs1519480 and rs12273363. We also found evidence of an association between rs11030107 and BD that was not found in a previous study.

Our results support the hypothesis that some BDNF gene polymorphisms may be contributing factors in the pathogenesis of BD. Our study also adds to the body of evidence associating the functional Val66Met polymorphism of BDNF with BD.