BRAIN DERIVED NEUROTROPHIC FACTOR (BDNF) GENETIC POLYMORPHISM (VAL66MET) IN SUICIDE: A STUDY OF 512 CASES

The neurotrophin Brain Derived Neurotrophic Factor (BDNF) is a mediator involved in neuronal survival and plasticity of dopaminergic, cholinergic and serotonergic neurons and in various mental illnesses. An altered expression of BDNF has been found in postmortem brain of suicide victims suggesting that the neurotrophin may play a crucial role in the pathophysiology of suicide. In the present study we analysed the BDNF Val66Met polymorphism (A196G, SNP ID: rs6265) in a post-mortem sample of Wernicke area of 512 Slovenian and Caucasian subjects (262 suicide and 250 non suicide control subjects). Frequencies for genotypes GG, GA and AA in total population were 61.5%, 34.4% and 4.1% respectively, with no significant statistical differences between control and case group (2 =.318, p=.853) also after splitting the sample in two groups (AA+GA/GG). In total sample, allelic frequencies were 79% and 21% for G and A allele respectively in concordance with another study on Caucasian populations and in contrast with another study on Asiatic populations. The present study, although limited by the different ethnicity of the studied population, excludes a significant association of BDNF Val66Met polymorphism with suicide, differently from what we observed in a previous study on suicide attempters. Difference in BDNF expression reported in suicide completers may be related to other genetic polymorphisms or to other epigenetic factors such as DNA methylation.