Rs6265

Rs6265, also called Val66Met or G196A, is a gene variation, a single nucleotide polymorphism (SNP) in the BDNF gene that codes for the so-called brain-derived neurotrophic factor.

Well over hundred research studies have examined the polymorphism.

Association with neuropsychiatric disorders
A number of studies has examined the polymorphism in relation to neuropsychiatric disorders, such as depression. It is generally thought that some variants of the polymorphism lead to memory impairment and susceptibility to neuropsychiatric disorders, and a 2007 meta-analysis of case-control studies found a relationship between the SNP and substance-related disorders, eating disorders, and schizophrenia. Another 2007 meta-analysis could, however, find no association between the SNP and schizophrenia or bipolar disorder. Meta-analyses of Alzheimer's disease and Parkinson's disease also indicate that the SNP has little or no association with these diseases. Also inconsistencies in association studies with depression have been noted.

In treatment response studies val/val homozygotes may respond better than met allele carriers with drug resistant depression treated with repetitive transcranial magnetic stimulation.

Subject variables in healthy humans
One study has reported that met/met carriers tends to have lower body mass index compared to the two other genotypes. Another study showed that subjects with the val/val genotype had higher mean intelligence. The same study found no association with personality traits as measured with the Tridimensional Personality Questionnaire. Also a Polish 2007 study observed no significant relationship between the polymorphism and personality in healthy females. A German 2005 study could though find an association with personality traits measured with NEO-Five Factor Inventory, with Val/Val subjects scoring higher on anxiety and neuroticism dimensions.

Other studies
A study in transgenic mice has found that met/met mice exhibits increased anxiety-related behaviors.