Association of BDNF G196A Gene Polymorphism with Ischemic Stroke Occurrence and its 6-Month Outcome in an Iranian Population.

Background: Genetic factors like the allele for Brain-Derived Neurotrophic Factor (BDNF) are associated with the outcome of ischemic stroke most likely through affecting neural differentiation and synaptic plasticity. Studies of the association of BDNF G196A gene polymorphism and long-term ischemic stroke outcome in various populations have not been concordant.

Objective: In this research, the association of BDNF G196A gene polymorphism and ischemic stroke occurrence were studied in a northern Iranian population with a glance to its 6-month outcome.

Methods: The genetic variant of BDNF G196A was examined in Ischemic Stroke (IS) patients (n = 206) and control group (n = 200). In IS individuals, outcome variables such as stroke severity, functional disability, and cognitive impairment were examined, respectively, by NIHSS, Barthel Index, and MoCA in an average of 202 days after the stroke occurrence.

Results: The frequency of risk allele G was 12.1% in IS patients and 5.5% in healthy individuals; and the difference was statistically significant (p < 0.0001). The frequency of risk genotype GG, heterozygote and homozygote were 0% and 1%, 24%.3% and 9%, 75.7% and 90%, respectively, for IS and control groups (p < 0.05). After controlling the phenotype confounding factors, logistic regression analysis showed that there was a borderline significant relationship between genotype BDNF GA + GG and IS occurrence (AOR = 1.997,95% CI: 0.252-1.010, p = 0.051). There was no significant difference between the various genotypic groups regarding the severity of the stroke and functional disability. Yet, G allele carriers had more cognitive impairment after IS (p = 0.002).

Conclusion: For the first time in an Iranian population, it was demonstrated that BDNF G196A variant plays a major role in stroke occurrence and consequences. It is suggested that, after IS, G allele carriers should have precedence for medicinal and rehabilitation interventions, in order to reduce their cognitive deficiency.