BDNF Gene

Brain-derived neurotrophic factor (BDNF) is mainly expressed in the central nervous system. It has attracted much attention as a depression candidate gene.

Brain-derived neurotrophic factor (BDNF) is mainly expressed in the central nervous system, particularly in the cortex, hippocampus, and forebrain. Neurotrophic factors promote the survival of neurons by preventing associated signals that initiate programmed cell death. Govindarajan and colleagues (2006) found that transgenic mice who overexpressed BDNF showed anxious behavior and had abnormalities in amygdala neurons that were similar to mice that experienced chronic stress. By contrast, mice who overexpressed BDNF showed decreased depressive-like behavior and healthy hippocampus activity that mimicked the effect of antidepressives. In 2003, a paper by Egan and colleagues identified a single nucleotide polymorphism in humans that causes an amino acid substitution from valine to methionine at codon 66 (V66M). The presence of this polymorphism was associated with depression under stressful circumstances. However, two large-scale studies in 2005 and 2006 failed to replicate this finding. There is some evidence that the V66M polymorphism may be a genetic cause for bipolar disorder.