[The association of single-nucleotide polymorphism rs6265 of the brain-derived neurotrophic factor gene with clinical features in Parkinson's disease]. / Assotsiatsiya odnonukleotidnogo polimorfizma rs6265 gena neirotroficheskogo faktora golovnogo mozga s osobennostyami klinicheskoi kartiny bolezni Parkinsona.

OBJECTIVE: To evaluate the frequency and severity of various clinical symptoms of Parkinson's disease (PD) depending on the BDNF rs6265 polymorphism. MATERIAL AND METHODS: The study included 533 patients with PD. The stage of PD was assessed using the Hoehn and Yahr scale (1967), motor symptoms were evaluated with MDS-UPDRS. Assessment of non-motor symptoms (NMS) in PD was conducted using the Beck Depression Inventory II (BDI-II); the Hospital Anxiety and Depression Scale (HADS); the Apathy Scale; the Montreal Cognitive Assessment (MoCA test); the Questionnaire for Impulsive-Compulsive Disorders in PD -Rating Scale (QUIP-RS). Genotyping of the BDNF variant (rs6265) was performed using real-time PCR with TaqMan probes. RESULTS: Most PD patients have a combination of NMS increasing as the disease progresses and is determined by molecular-genetic individual characteristics. There are significant differences in the severity of motor symptoms and NMS: individuals with the AA genotype showed significantly pronounced motor symptoms (p<0.0001); emotional-affective symptoms (p<0.0001); cognitive and impulsive behavioral disorders (p<0.0001). CONCLUSION: The rs6265 BDNF allele A is associated with a wide range of NMS, increasing the risk of their development in patients with PD, thus playing the important role in the etiopathogenesis of this pathology.

[The relationship between the rs6265 polymorphism of the BDNF gene and the level of serum neurotrophic factor in patients with Parkinson's disease]. / Svyaz' polimorfizma rs6265 gena BDNF s urovnem syvorotochnogo neirotroficheskogo faktora u patsientov s bolezn'yu Parkinsona.

OBJECTIVE: To evaluate the clinical features and the level of serum brain-derived neurotrophic factor (BDNF) in groups of patients with Parkinson's disease (PD) differentiated by the genotypes of BDNF polymorphism (rs6265). MATERIAL AND METHODS: The level of serum BDNF in the biomarkers' multiplex panel of neurodegenerative diseases (HNDG3MAG-36K) was assessed in 134 PD patients. Allele discrimination was carried out by real-time PCR using TaqMan probes for the analysis of BDNF rs6265 polymorphism in groups of patients and controls (n=192) matched for sex, age and ethnicity. RESULTS: Comparing the distribution of rs6265 genotypes and alleles between groups of patients and controls no significant differences were found (p>0.05). Serum BDNF levels varied significantly by genotype (rs6265) among PD patients. Minimum mean serum BDNF level (320.1±164.6 pg/ml) was noted for individuals with the AA genotype, which significantly differs from the corresponding indicator among individuals with GA (2944.2±1590.6 pg/ml; p=0.0001) and GG genotypes (2949.4±1620.6 pg/ml; p=3.9×10-5). The concentration of BDNF significantly differed between patients with different forms of PD (p=0.0007) and increased as the stage of the disease progressed according to Hoehn and Yahr staging scale (p=1.0×10-6). CONCLUSION: The BDNF rs6265 polymorphism was not associated with the development of PD in the studied population. The variability of the mean serum BDNF level was established depending on the genotype of the BDNF polymorphism in PD patients and a number of clinical features.

Brain-derived neurotrophic factor G196A (rs6265) gene polymorphism increases Turner syndrome susceptibility.

Brain-derived neurotrophic factor (BDNF) is a member of the nerve growth factor family. It plays a significant role in the regulation of brain metabolic activity, modification of synaptic efficacy, and enhances neuronal survival. A common naturally occurring allelic variation, i.e. G196A (Val66 Met, rs6265) of the BDNF gene is implicated in neuroplasticity. This study analyzes its expression levels and determines the frequency of BDNF G196A gene polymorphism in women with Turner syndrome (TS) compared to the controls. This case-control study comprised 14 TS patients and 8 healthy individuals. The expression levels of BDNF gene in TS patients were checked by qPCR. For BDNF gene, a dynamic expression range along with the presence of G196A polymorphism was found across all TS patients. The effects of Val66 Met mutation on BDNF protein structure and function were studied by molecular dynamics simulations of wild and mutant (Val66 Met) forms. The analysis of different trajectories generated by simulation showed that there was a significant change in the protein structure due to Val66 Met polymorphism, which might lead to functional impairment. This is first time we are reporting the association of BDNF G196A gene polymorphism with TS risk. Our study suggests that in turner patients, BDNF G196A polymorphism may be an important genetic factor predisposing to neuroplasticity risk and can be exploited as diagnostic/prognostic marker for TS. Further study on a large number of TS samples will prove this point beyond doubts or otherwise enriching the much desired repertoire of personalized medicine.

BDNF Val66Met Genotype Interacts With a History of Simulated Stress Exposure to Regulate Sensorimotor Gating and Startle Reactivity.

Reduced expression of Brain-Derived Neurotrophic Factor (BDNF) has been implicated in the pathophysiology of schizophrenia. The BDNF Val66Met polymorphism, which results in deficient activity-dependent secretion of BDNF, is associated with clinical features of schizophrenia. We investigated the effect of this polymorphism on Prepulse Inhibition (PPI), a translational model of sensorimotor gating which is disrupted in schizophrenia. We utilized humanized BDNFVal66Met (hBDNFVal66Met) mice which have been modified to carry the Val66Met polymorphism, as well as express humanized BDNF in vivo. We also studied the long-term effect of chronic corticosterone (CORT) exposure in these animals as a model of history of stress. PPI was assessed at 30ms and 100ms interstimulus intervals (ISI). Analysis of PPI at the commonly used 100ms ISI identified that, irrespective of CORT treatment, the hBDNFVal/Met genotype was associated with significantly reduced PPI. In contrast, PPI was not different between hBDNFMet/Met and hBDNFVal/Val genotype mice. At the 30ms ISI, CORT treatment selectively disrupted sensorimotor gating of hBDNFVal/Met heterozygote mice but not hBDNFVal/Val or hBDNFMet/Met mice. Analysis of startle reactivity revealed that chronic CORT reduced startle reactivity of hBDNFVal/Val male mice by 51%. However, this was independent of the effect of CORT on PPI. In summary, we provide evidence of a distinct BDNFVal66Met heterozygote-specific phenotype using the sensorimotor gating endophenotype of schizophrenia. These data have important implications for clinical studies where, if possible, the BDNFVal/Met heterozygote genotype should be distinguished from the BDNFMet/Met genotype.

Rare Syndromes and Common Variants of the Brain-Derived Neurotrophic Factor Gene in Human Obesity.

Rare genetic disorders that cause BDNF haploinsufficiency, such as WAGR syndrome, 11p deletion, and 11p inversion, serve as models for understanding the role of BDNF in human energy balance and neurocognition. Patients with BDNF haploinsufficiency or inactivating mutations of the BDNF receptor exhibit hyperphagia, childhood-onset obesity, intellectual disability, and impaired nociception. Prader-Willi, Smith-Magenis, and ROHHAD syndromes are separate genetic disorders that do not directly affect the BDNF locus but share many similar clinical features with BDNF haploinsufficiency, and BDNF insufficiency is believed to possibly contribute to the pathophysiology of each of these conditions. In the general population, common variants of BDNF that affect BDNF gene expression or BDNF protein processing have also been associated with modest alterations in energy balance and cognitive functioning. Thus, variable degrees of BDNF insufficiency appear to contribute to a spectrum of excess weight gain and cognitive impairment that ranges in phenotypic severity. In this modern era of precision medicine, genotype-specific therapies aimed at increasing BDNF signaling in patients with rare and common disorders associated with BDNF insufficiency could serve as useful approaches for treating obesity and neurodevelopmental disorders.

A role for the BDNF gene Val66Met polymorphism in schizophrenia? A comprehensive review.

Schizophrenia is believed to arise from complex gene-environment interactions. Brain-derived neurotrophic factor (BDNF) is involved in neuronal development, differentiation and plasticity. A functional single nucleotide polymorphism that results in a valine (Val) to methionine (Met) substitution at codon 66 (Val66Met) results in the aberrant sorting and release of mature BDNF through the activity-dependent secretion pathway. The Val66Met polymorphism has been linked to impaired neurocognitive function in healthy adults, and identified as a locus of risk for a range of neuropsychiatric disorders including schizophrenia. Here we provide a comprehensive review of the relationship between the BDNF Val66Met polymorphism and schizophrenia, integrating evidence from the fields of genetic epidemiology, clinical psychiatry, behavioral neuroscience and neuroimaging. We argue that while the Val66Met polymorphism may not be a major risk-conferring agent for the development of schizophrenia per se, there is mounting evidence that the polymorphism modulates a range of clinical features of the illness, including age of onset, symptoms, therapeutic responsiveness, neurocognitive function and brain morphology.

Val66Met polymorphism of brain-derived neurotrophic factor is associated with idiopathic dystonia.

The Val66Met (G196A; rs6265) single nucleotide polymorphism of brain-derived neurotrophic factor (BDNF) affects morphology and neuronal activity, and is expected to be associated with central nervous system disorders. However, it remains controversial whether Val66Met polymorphism is a risk factor for idiopathic dystonia. We aimed to clarify the impact of BDNF polymorphism on idiopathic dystonia. A literature search of PubMed was carried out. A random-effects model was employed for the meta-analysis. A pooled odds ratio (OR) was calculated along with 95% confidence intervals (CI) to reflect the risk of idiopathic dystonia in each genotype (GG, AG, AA) or minor allele. The proportion of variation due to heterogeneity was computed and expressed as I(2). Five case-control studies, comprising a total sample size of 1804 subjects (784 idiopathic dystonia patients, 1020 normal controls), were included in this meta-analysis. AA genotype was significantly more frequent in patients with idiopathic dystonia (OR=1.47, 95% CI 1.09-1.99, p=0.01, four studies, n=1716). This finding was derived from homogeneous studies (p=0.97, I(2)=0%). Our meta-analysis has revealed a significant overall effect of the AA genotype on the development of idiopathic dystonia.

Association of the brain-derived neurotrophic factor gene G196A rs6265 polymorphisms and the cognitive function and clinical symptoms of schizophrenia.

UNLABELLED: This study aimed to explore the association between BDNF G196A gene rs6265 polymorphisms and the cognitive function and clinical symptoms of schizophrenia. METHODS: BDNF G196A rs6265 genotype and allele frequency were measured using Polymerase Chain Reaction (PCR) methods in 224 drug-free patients with schizophrenia and 220 controls. Psychotic symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS), and cognitive functioning was assessed using the Wisconsin Card Sorting Test (WCST) and the Trail Making Test (TMT). In the patient group, differences in severity of symptoms across the three genotypes (i.e., G/G, G/A and A/A) of G196A were assessed using one-way analysis of variance. RESULTS: G/A genotype had higher frequencies than GG or AA genotype in both patients and controls. There was no significant difference in G/G, G/A, A/A genotype frequency between patients and controls (P > 0.05). The allele G had higher frequencies than allele A in both patients and controls. There was no significant difference in G or A allele frequency between patients and controls (P > 0.05). There was significant difference in A/A genotype frequency between positive group patients and negative group patients. There was no significant difference in cognitive performance between patients with G/G, G/A and A/A genotype (all P > 0.05). CONCLUSION: BDNF G196A gene rs6265 polymorphism is not associated with the cognitive function but with the clinical symptoms of schizophrenia.