Association of BDNF Gene (rs6265/G196A) Polymorphism with Depression

Abstract

Depression affects an individual’s feelings, thoughts, and behavior. It is known as the most common
mental illness worldwide with complex origin. The risk factors for depression include both genetic as
well as environmental factors. Depression is affecting more than 300 million individuals globally and
is categorized as a major cause of the global burden of disease. Several studies demonstrate the
involvement of the brain-derived neurotrophic factor (BDNF) gene in the etiology of depressive
disorder. This study was designed to assess the association of (rs6265/G196A) polymorphism of the
BDNF gene in the pathogenesis of depression. The cross-sectional study was conducted consisting of
357 samples from Rawalpindi, Pakistan. Depression was determined through questionnaire, using
DSM-Ⅳ (Diagnostic and Statistical Manual for Mental Disorders-Version Ⅳ). DNA was extracted
from the blood samples of study participants. The conventional polymerase chain reaction was
performed to amplify the BDNF gene and to detect the frequency of rs6265/ G196A SNP in the
samples of subjects under study. Statistical analysis was done using Pearson’s Chi-Squared test. It was
observed that the homozygous GG genotype is more prevalent in study subjects than the homozygous
AA or heterozygous AG genotypes. However, depression is likely to be more prevalent in AA
genotype i.e., 37.8%, less prevalent in AG genotype i.e., 34.0%, and least prevalent in GG genotype
i.e., 28.2%. This data shows the A allele of the BDNF gene to be more associated with depression than
the G allele, suggesting this polymorphism to be a somewhat potential target for anti-depressants.