Brain-derived Neurotrophic Factor Gene Variants Research Articles

The BDNF protein is associated with glucose homeostasis and food intake in carriers of common BDNF gene variants.

The brain-derived neurotrophic factor (BDNF) concentrations may differ between BDNF gene genotype carriers. These changes occur in individuals with metabolic and mental disorders. The aim of this study was to assess the associations of glucose homeostasis parameters and the frequency of food consumption with BDNF protein concentrations based on the BDNF single-nucleotide polymorphisms (SNPs). Among the 439 participants, some common rs10835211 BDNF gene variants were analyzed. We evaluated BDNF concentration, fasting glucose and insulin concentrations and during oral glucose tolerance tests. Anthropometric measurements, body composition, and body fat distribution were assessed, and 3-day food intake diary and food frequency questionnaire were completed. We noticed significant differences in concentration of BDNF between AA and AG genotype rs10835211 carriers (p=0.018). The group of AA genotype holders were older, and positive correlation was found between age and BDNF in the whole study population (p=0.012) and in the GG genotype carriers (p=0.023). Moreover, BDNF protein correlated with fasting insulin (p=0.015), HOMA-IR (p=0.031), HOMA-B (p=0.010) , and the VAT/SAT ratio (p=0.026) in the GG genotype individuals. Presence of the GG genotype was negatively correlated with nut and seed (p=0.047), lean pork consumption (p=0.015) and the BDNF protein. Moreover, we observed correlations between the frequency of chicken (p=0.028), pasta (p=0.033) and sweet food intake (p=0.040) and BDNF concentration in the general population. Among carriers of the AA genotype, we observed a positive correlation between the consumption of rice (p=0.048) and sweet food (p=0.028) and the BDNF protein level. Peripheral BDNF may be associated with visceral fat content and insulin concentrations in the GG genotype carriers and may depend on variable food intake, which warrants further investigation.

Association of plasma BDNF levels with different stages of Alzheimer’s disease: a cross-sectional study

ABSTRACT Background Growing evidence shows that the expression of brain-derived neurotrophic factor (BDNF) is altered in the peripheral blood of participants with Alzheimer’s disease (AD). It is unclear, however, whether altered BDNF expression is also observed in the early stages of AD. Methods In the present study, 138 normal controls (NC), 57 participants with subjective cognitive decline (SCD), and 37 participants with amnestic mild cognitive impairment (aMCI) and AD were included. Plasma BDNF protein levels were assessed using a commercial multiplex Luminex-based kit. Patient samples were also probed for the presence of BDNF gene variant rs6265. Results Pairwise comparisons between the groups showed that there was not a significant difference in BDNF levels when comparing SCD with NC and when comparing SCD with aMCI/AD, but BDNF levels in aMCI/AD samples were increased when compared with NC samples. For models differentiating clinical groups, discriminant analysis was performed by including education, APOE genotype, and BDNF levels in the model. This approach distinguishes participants with SCD (AUC = 0.630) and aMCI/AD (AUC = 0.665) from NC. Conclusion Our results suggest that expression of BDNF in plasma is altered at the clinical stage of AD.

Prospective cohort study reveals MMP-9, a neuroplasticity regulator, as a prediction marker of cochlear implantation outcome in prelingual deafness treatment

Because of vast variability of cochlear implantation outcomes in prelingual deafness treatment, identification of good and poor performers remains a challenging task. To address this issue, we investigated genetic variants of matrix metalloproteinase 9 (MMP9) and brain-derived neurotrophic factor (BDNF) and plasma levels of MMP-9, BDNF, and pro-BDNF that have all been implicated in neuroplasticity after sensory deprivation in the auditory pathway. We recruited a cohort of prelingually deaf children, all implanted before the age of 2, and carried out a prospective observation (N = 61). Next, we analyzed the association between (i) functional MMP9 (rs20544, rs3918242, rs2234681) and BDNF (rs6265) gene variants (and their respective protein levels) and (ii) the child’s auditory development as measured with the LittlEARS Questionnaire (LEAQ) before cochlear implant (CI) activation and at 8 and 18 months post-CI activation. Statistical analyses revealed that the plasma level of MMP-9 measured at implantation in prelingually deaf children was significantly correlated with the LEAQ score 18 months after CI activation. In the subgroup of DFNB1-related deafness (N = 40), rs3918242 of MMP9 was significantly associated with LEAQ score at 18 months after CI activation; also, according to a multiple regression model, the ratio of plasma levels of pro-BDNF/BDNF measured at implantation was a significant predictor of overall LEAQ score at follow-up. In the subgroup with DFNB1-related deafness, who had CI activation after 1 year old (N = 22), a multiple regression model showed that rs3918242 of MMP9 was a significant predictor of overall LEAQ score at follow-up.

Brain-derived neurotrophic factor gene variants and obesity in former smokers

ObjectiveFrom genome-wide association studies, brain-derived neurotrophic factor (BDNF) locus on chromosome 11 was the only SNP associated with both smoking and body mass index (BMI) in European, African and Asian population. This study aims to explore the unique genetic predisposition to obesity in former smokers by examining the effects of BDNF on BMI and waist circumference (WC).MethodsThe study design is case-control study with a cohort validation in supplementary. We included 15,072 ethnic Chinese participants in the Guangzhou Biobank Cohort Study (GBCS) with data of four BDNF SNPs related to both BMI and smoking behavior. We used baseline smoke exposure data in 2003–2007 and follow-up outcomes of general obesity (by BMI) and central obesity (WC) in 2008–2012. Odds ratios (ORs) and 95% confidence intervals (CIs) for general obesity and central obesity associated with these SNPs were derived from logistic regression.ResultsOf 15,072 participants (3169 men and 11,903 women), 1664 (11.0%) had general and 7868 (52.2%) had central obesity. In 1233 former smokers, the rs6265 GG, versus AA, genotype was associated with higher risks of general obesity (OR = 1.79, 95% CI = 1.06–3.01) and central obesity (OR = 2.08, 95% CI = 1.47–2.92) after adjustment. These associations were not significant in never or current smokers. In former heavy (≥20 cigarettes/day) smokers, the rs6265 GG genotype showed a higher odds for general obesity (OR = 2.15, 95% CI = 1.05–4.40), while no association was found in former light (1–9 cigarettes/day) smokers. Similar results were found for the association of rs6265 with central obesity and for the associations of other two BDNF SNPs (rs4923457 and rs11030104) with both general and central obesity.ConclusionsWe firstly identified the genetic predisposition (BDNF SNPs) to general and central obesity in former smokers, particularly in former heavy smokers. The different associations of the SNPs for general/central obesity in different smoke exposure groups may be related to the competitive performance of the sites and epigenetic modification, which needs further study.

Targeted sequencing of the BDNF gene in young Chinese Han people with major depressive disorder.

BackgroundAdolescence and young adulthood are considered the peak age for the emergence of many psychiatric disorders, in particular major depressive disorder (MDD). Previous research has shown substantial heritability for MDD. In addition, the brain‐derived neurotrophic factor (BDNF) gene is known to be associated with MDD. However, there has been no study conducting targeted sequencing of the BDNF gene in young MDD patients so far.MethodTo examine whether the BDNF gene is associated with the occurrence of MDD in young patients, we used targeted sequencing to detect the BDNF gene variants in 259 young Chinese Han people (105 MDD patients and 154 healthy subjects).ResultsThe BDNF variant rs4030470 was associated with MDD in young Chinese Han people (uncorrected p = 0.046), but this was no longer significant after applying FDR correction (p = 0.552, after FDR correction). We did not find any significant differences in genotype or haplotype frequencies between the case and control groups, and furthermore discovered no rare mutation variants any of the 259 subjects.ConclusionOur results do not support an association of the BDNF gene variants with MDD in young people in the Chinese Han population.

Association Between BDNF Gene Variant Rs6265 and the Severity of Depression in Antidepressant Treatment-Free Depressed Patients.

BackgroundBrain-derived neurotrophic factor (BDNF) plays an important role in neuronal plasticity, and its dysregulation has been associated with the pathogenesis of mood and anxiety disorders. Prolactin (PRL) is a pituitary hormone which is also produced as a cytokine by immune cells and could be a neurotrophic factor regulating the functional activity of stress-related mechanisms.AimTo investigate the possible relationship between depressive state and BDNF and PRL genotypes or levels with special reference to severity of depression.MethodsParticipants of 18–70 years with a clinical diagnosis of depressive disorder of at least moderate severity were included. These patients had not been treated with antidepressant drugs before admission to hospital during the preceding period of the last 6 months, and 54.5% had never been treated with antidepressant drugs during their entire life. The DNA was genotyped for rs1341239 within the prolactin and for rs6265, rs7124442, and rs11030104 within the BDNF gene. Rs11030104 violated the Hardy-Weinberg equilibrium distribution and was excluded from further analyses. BDNF and prolactin concentration was measured in serum by MAGPIX multiplex analyzer (Luminex, USA) using MILLIPLEX® MAP kit (Merck, Germany). Genetic associations were determined by sequentially regressing prolactin, BDNF, 17-items Hamilton's Depression (HAMD-17) and Clinical Global Impression scale, Severity (CGI-S) ratings, and depression (absent/present) on the available SNPs. Genetic associations were evaluated assuming an additive model.ResultsA total of 186 depressed patients (of which 169 were women) and 94 healthy controls (67 women) were genotyped. After excluding subjects without genetic information on all three study SNPs, 217 remained of whom 138 suffered from depression. Within depressed patients we observed an association of rs6265 with HAMD-17: mean difference (MD) 2.33 (95%CI 0.49; 4.16; p = 0.014) and CGI-S: MD 0.38 (95%CI 0.09; 0.66; p = 0.011). No significant association was observed between the prolactin SNP rs1341239 and prolactin levels. Similarly the mean differences of BDNF SNPs did not show an association with BDNF: rs6265 −0.042 ln(pg/ml) (95%CI −0.198; 0.113), and rs7124442 0.006 ln(pg/ml) (95%CI −0.117; 0.130). No other association reached statistical significance.ConclusionWe observed a significant association between BDNF gene variant rs6265 and the severity of depression in newly admitted, antidepressant treatment-free, depressed patients. Actual PRL and BDNF levels were not elevated sufficiently in depressed patients to reach statistical significance and were not associated with the studied genotypes.

Brain-Derived Neurotrophic Factor Gene Variants and Obesity in Former Smokers

Brain-Derived Neurotrophic Factor Gene Variants and Obesity in Former Smokers

5-HT2AR and BDNF gene variants in eating disorders susceptibility.

Evidence from family and twin studies points to a genetic contribution to the etiology of eating disorders (EDs), confirmed by the association of several single nucleotide polymorphisms (SNPs) with this group of disorders. Previous reports have suggested that the serotonin receptor (5-HT2AR) and brain-derived neurotrophic factor (BDNF) genes could be both involved in EDs susceptibility. In order to provide further evidence about such association, we focused our attention on two SNPs located in these genes carrying out a genetic association study on a large Italian cohort composed of 556 ED patients and 355 controls (CTRs). Obtained results confirm the presence of an association between 5-HT2AR and BDNF genes and the susceptibility to EDs.

Brain-Derived Neurotrophic Factor Gene Variants and Obesity in Former Smokers

Objective: From genome-wide association studies, brain-derived neurotrophic factor (BDNF) locus on chromosome 11 was the only SNP associated with both smoking and body mass index (BMI). This study aims to explore the unique genetic predisposition to obesity in former smokers by examining the effects of BDNF on BMI and waist circumference (WC). Methods: We included 15,072 ethnic Chinese participants in the Guangzhou Biobank Cohort Study (GBCS) with data of four BDNF SNPs related to both body mass index (BMI) and smoking behavior. We used baseline smoke exposure data in 2003-2007 and follow-up outcomes of general obesity (by BMI) and central obesity (waist circumference) in 2008-2012. Odds ratios (ORs) and 95% confidence intervals (CIs) for general obesity and central obesity associated with these SNPs were derived from logistic regression. Results: Of 15,072 participants (3,169 men and 11,903 women), 1,664 (11.0%) had general and 7,868 (52.2%) had central obesity. We replicated the associations of the four BDNF SNPs with obesity and smoking status in the GBCS. In 1,233 former smokers, the rs6265 GG, versus AA, genotype was associated with higher risks of general obesity (OR=1.79, 95% CI=1.06-3.01) and central obesity (OR=2.08, 95% CI=1.47-2.92) after adjustment. These associations were not significant in never or current smokers. In former heavy (≥20 cigarettes/day) smokers, the rs6265 GG genotype showed a higher odds for general obesity (OR=2.15, 95% CI=1.05-4.40), while no association was found in former light (1-9 cigarettes/day) smokers. Similar results were found for the association of rs6265 with central obesity and for the associations of other two BDNF SNPs (rs4923457 and rs11030104) with both general and central obesity. Conclusions: We firstly identified the genetic predisposition (BDNF SNPs) to general and central obesity in former smokers, particularly in former heavy smokers. Funding Statement: This study was supported by research grants from the Guangdong Natural Science Foundation of China, Guangdong, China (Grant number: 9451062001003477); the Guangzhou Science and Information Bureau, Guangzhou, China (2012J5100041); the National Natural Science Foundation of China (81773502 and 81703308). The study is funded by The University of Hong Kong Foundation for Educational Development and Research, Hong Kong; the Guangzhou Public Health Bureau and the Guangzhou Science and Technology Bureau, Guangzhou, China; and The University of Birmingham, UK. Declaration of Interests: None declared. Ethics Approval Statement: The GBCS was approved by the Medical Ethics Committee of the Guangzhou Medical Association. All participants provided written informed consent before participating.

Suicide attempt, clinical correlates, and BDNF Val66Met polymorphism in chronic patients with schizophrenia.

Recent evidence suggests the role of brain-derived neurotrophic factor (BDNF) in the pathophysiology of suicidal behavior. Because schizophrenia patients usually have high suicide rates and numerous studies have suggested that BDNF may contribute to the psychopathology of schizophrenia, we hypothesized that the functional polymorphism of BDNF (Val66Met) was associated with suicide attempts in patients with schizophrenia in a Chinese Han population. This polymorphism was genotyped in 825 chronic schizophrenia patients with (n = 123) and without (n = 702) suicide attempts and 445 healthy controls without a history of suicide attempts using a case-control design. The schizophrenia symptoms were assessed by the Positive and Negative Syndrome Scale. There were no significant differences in BDNF Val66Met genotype and allele distributions between the patients and healthy controls. However, we found the Val allele (p = .023) and the Val/Val genotypes (p = .058) to be associated with a history of suicide attempts. Moreover, some clinical characteristics, including age and cigarettes smoked each day, interacted with the BDNF gene variant and appeared to play an important role in suicide attempts among schizophrenia patients. The BDNF Val66Met polymorphism itself and its interaction with some clinical variables may influence suicide attempts among schizophrenia patients. (PsycINFO Database Record

COMT and BDNF Gene Variants Help to Predict Alcohol Consumption in Alcohol-dependent Patients.

The neurobiology of alcohol dependence (AD) involves alterations in neurotransmitters and the stress response. We hypothesized that an interaction between functional variants of dopaminergic and neurotrophic genes may influence drinking in AD. The relationship between alcohol consumption and single-nucleotide polymorphisms, Val66Met in the brain-derived neurotrophic factor (BDNF), and Val158Met in the catechol-O-methyltransferase (COMT), was analyzed among 281 alcohol-dependent individuals. Individuals carrying both the COMT Met158Met genotype and the BDNF Val66Val genotype drank more than those with other variants of these genes (P = 0.039). Those who had a family history of AD also drank more than those without a family history (P = 0.048). Patients with both Met/Met genotype in the COMT Val158Met polymorphism and Val/Val genotype in the BDNF Val66Met polymorphism suffered from more health problems than those carrying other variants (P = 0.030) and had lower motivation to change drinking patterns (P = 0.031). Patients carrying both the BDNF Val66Val and COMT Met158Met variants had higher alcohol consumption. These effects may be influenced by the effects of BDNF and COMT on dopamine responses to alcohol. Motivation-enhancing strategies might benefit the group of patients identified by genotyping in this study, and also treatment aimed at reducing alcohol consumption.

BDNF Polymorphisms Are Associated With Cognitive Performance in Schizophrenia Patients Versus Healthy Controls.

Accumulating evidence has shown that brain-derived neurotrophic factor (BDNF) may be involved in the pathogenesis of schizophrenia. Moreover, BDNF genetic variants, especially the Val66Met polymorphism, may influence specific aspects of human cognition. This study aimed to investigate the potential association of BDNF gene polymorphisms with susceptibility to schizophrenia and cognitive impairments in patients with schizophrenia in a Han Chinese population. Four polymorphisms (rs6265, rs12273539, rs10835210, and rs2030324) of the BDNF gene were analyzed in a case-control study of 1,887 Han Chinese individuals (844 patients meeting DSM-IV diagnosis of schizophrenia and 1,043 healthy controls). Cognitive function was measured using the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) in 598 patients and 434 controls. The current study was conducted from 2008 to 2011. Significant differences in the genotype and allele frequencies between patients and controls were observed only for rs10835210 (both P < .05). Further, we found that the rs10835210 polymorphism had a significant effect on language performance only in schizophrenia (P < .05). However, BDNF rs12273539 played a stronger role in cognitive performance among both patients and healthy controls, especially on attention (P < .001) and the RBANS total score (P < .01). These findings suggest the role of these BDNF gene variants in susceptibility to schizophrenia and in some aspects of cognitive function.

P.3.038 The brain-derived neurotrophic factor gene variant Val66Met and personality predict stressful life events

Psychedelic drugs such as lysergic acid diethylamide (LSD) were used extensively in psychiatry in the past and their therapeutic potential is beginning to be re-examined today. Psychedelic psychotherapy typically involves a patient lying with their eyes-closed during peak drug effects, while listening to music and being supervised by trained psychotherapists. In this context, music is considered to be a key element in the therapeutic model; working in synergy with the drug to evoke therapeutically meaningful thoughts, emotions and imagery. The underlying mechanisms involved in this process have, however, never been formally investigated. Here we studied the interaction between LSD and music-listening on eyes-closed imagery by means of a placebo-controlled, functional magnetic resonance imaging (fMRI) study. Twelve healthy volunteers received intravenously administered LSD (75 µg) and, on a separate occasion, placebo, before being scanned under eyes-closed resting conditions with and without music-listening. The parahippocampal cortex (PHC) has previously been linked with (1) music-evoked emotion, (2) the action of psychedelics, and (3) mental imagery. Imaging analyses therefore focused on changes in the connectivity profile of this particular structure. Results revealed increased PHC–visual cortex (VC) functional connectivity and PHC to VC information flow in the interaction between music and LSD. This latter result correlated positively with ratings of enhanced eyes-closed visual imagery, including imagery of an autobiographical nature. These findings suggest a plausible mechanism by which LSD works in combination with music listening to enhance certain subjective experiences that may be useful in a therapeutic context.

BDNF gene polymorphisms and haplotypes in relation to cognitive performance in Polish healthy subjects.

The brain derived neurotrophic factor (BDNF) is a neurotrophin that plays an important role in the cell survival, axonal and dendritic growth, and synaptic plasticity. BDNF gene polymorphisms, 'functional Val66Met mainly, were shown to influence human brain structure and cognition. The aim of the study was to assess the relationship between twelve BDNF gene variants and their haplotypes and cognitive performance measured using the Wisconsin Card Sorting Test (WCST), the Trail Making Test (TMT), the Stroop Test which are to a large extent connected with prefrontal cortex activity. Our sample consisted of 460 healthy participants from Polish population. We detected possible association between five BDNF polymorphisms (rs11030101, rs10835210, rs2049046, rs2030324, rs2883187) and TMT_A. Additionally, one haplotype block made from eleven BDNF variants (rs2883187, rs1401635, rs2049046, rs2030324, rs11030101, rs10835210, rs1013402, rs1401635, rs1013402), as significant linkage disequilibrium appeared. We discovered possible relationships of CACCGCGTACG and CACCGCGTACG haplotypes with TMT_A and TMT_B performance respectively. Our results confirmed the involvement of BDNF in the regulation of psychomotor speed, working memory and executive function in healthy subjects measured by a task engaging visuoperceptual abilities.

BDNF polymorphisms are associated with schizophrenia onset and positive symptoms

Numerous studies have showed that brain-derived neurotrophic factor (BDNF) may be involved in the pathogenesis and pathophysiology of schizophrenia. The purposes of this study were to investigate the potential association of BDNF gene polymorphisms with susceptibility to schizophrenia and the psychopathological symptoms in patients with schizophrenia in a Han Chinese population. Four polymorphisms (rs6265, rs12273539, rs10835210 and rs2030324) of the BDNF gene were analyzed in a case–control study of 1887 Han Chinese individuals (844 patients and 1043 controls). We assessed 825 patients for psychopathology using the Positive and Negative Syndrome Scale. In single marker analyses the BDNF rs10835210 mutant A allele was significantly associated with schizophrenia. Haplotype analyses revealed higher frequencies of haplotypes containing the mutant A allele of the rs10835210 in schizophrenia than controls. We also found that this polymorphism rs10835210 was associated with positive symptoms, and the patients carrying the mutational allele A showed more positive symptoms. These findings suggest the role of these BDNF gene variants in both susceptibility to schizophrenia and in clinical symptom severity.

Interactive effects of BDNF Val66Met genotype and trauma on limbic brain anatomy in childhood.

Childhood trauma is a major precipitating factor in psychiatric disease. Emerging data suggest that stress susceptibility is genetically determined, and that risk is mediated by changes in limbic brain circuitry. There is a need to identify markers of disease vulnerability, and it is critical that these markers be investigated in childhood and adolescence, a time when neural networks are particularly malleable and when psychiatric disorders frequently emerge. In this preliminary study, we evaluated whether a common variant in the brain-derived neurotrophic factor (BDNF) gene (Val66Met; rs6265) interacts with childhood trauma to predict limbic gray matter volume in a sample of 55 youth high in sociodemographic risk. We found trauma-by-BDNF interactions in the right subcallosal area and right hippocampus, wherein BDNF-related gray matter changes were evident in youth without histories of trauma. In youth without trauma exposure, lower hippocampal volume was related to higher symptoms of anxiety. These data provide preliminary evidence for a contribution of a common BDNF gene variant to the neural correlates of childhood trauma among high-risk urban youth. Altered limbic structure in early life may lay the foundation for longer term patterns of neural dysfunction, and hold implications for understanding the psychiatric and psychobiological consequences of traumatic stress on the developing brain.

Effects of the Interaction Between the Level of Anxiety and the Val66Met Polymorphism of the Brain-Derived Neurotrophic Factor Gene on Attention in Patients with Schizophrenia Spectrum Disorders

The effects of the Val66Met polymorphism of the brain-derived neurotrophic factor (BDNF) gene and levels of trait anxiety (negative emotionality) on attention were studied in 90 patients with schizophrenia and schizoaffective psychosis. Attention was evaluated using auditory event-related potentials (ERP) and neuropsychological testing. Genotype was found to have a significant effect (anxiety was not) on the efficiency of performing the neuropsychological test on attention and the amplitude of the ERP P300 wave in the frontal and temporal leads. Carriers of the Met allele has poorer performance of the attention task than subjects with the ValVal genotype, and also showed a lower P300 wave amplitude. Genotype combined with the level of anxiety was found to affect the N100 wave in response to the non-significant stimulus, significant differences being seen only in the group with a low level of anxiety: the Met allele was associated with lower N100 amplitudes. Among patients with high levels of anxiety, N100 wave amplitude was independent of the BDNF gene variant present. It is suggested that people with high levels of anxiety expend more effort to solve the task correctly at the early stages of signal recognition, the amplitudedecreasing effect of the “risk allele” being eliminated.

A functional brain-derived neurotrophic factor (BDNF) gene variant increases the risk of moderate-to-severe allergic rhinitis

Brain-derived neurotrophic factor (BDNF) is a secretory protein that has been implicated in the pathogenesis of allergic rhinitis (AR), atopic asthma, and eczema, but it is currently unknown whether BDNF polymorphisms influence susceptibility to moderate-to-severe AR. We sought to identify disease associations and the functional effect of BDNF genetic variants in patients with moderate-to-severe AR. Tagging single nucleotide polymorphisms (SNPs) spanning the BDNF gene were selected from the human HapMap Han Chinese from Beijing (CHB) data set, and associations with moderate-to-severe AR were assessed in 2 independent cohorts of Chinese patients (2216 from Shandong province and 1239 living in Singapore). The functional effects of the BDNF genetic variants were determined by using both invitro and exvivo assays. The tagging SNP rs10767664 was significantly associated with the risk of moderate-to-severe AR in both Singapore Chinese (P= .0017; odds ratio, 1.324) and ShandongChinese populations (P= .039; odds ratio, 1.180). The coding nonsynonymous SNP rs6265 was in perfect linkage with rs10767664 and conferred increased BDNF protein secretion by a human cell line invitro. Subjects bearing the AA genotype of rs10767664 exhibited increased risk of moderate-to-severe AR and displayed increased BDNF protein and total IgE levels in plasma. Using a large-scale expression quantitative trait locus study, we demonstrated that BDNF SNPs are significantly associated with altered BDNF concentrations in peripheral blood. A common genetic variant of the BDNF gene is associated with increased risk of moderate-to-severe AR, andthe AA genotype is associated with increased BDNF mRNAlevels in peripheral blood. Together, these data indicate that functional BDNF gene variants increase the risk of moderate-to-severe AR.

Brain-Derived Neurotrophic Factor Gene Variants and Alzheimer Disease: An Association Study in an Alzheimer Disease Italian Population

Brain-derived neurotrophic factor (BDNF) promotes neuronal survival during development and protects neurons from insults of various kinds. Changes in production of BDNF have been reported in differing neurodegenerative pathologies and, in particular, in Alzheimer disease (AD). We studied 200 AD patients and 408 healthy controls for BDNF Val66Met(G196A) polymorphism, 200AD and 384 healthy controls for BDNF 270 C/T polymorphism, and 200AD and 393 healthy controls for BDNF 11757 G/C polymorphism by restriction fragment length polymorphism (RFLP) and real-time PCR. Our results indicated that the 11757 G/C BDNF polymorphism was significantly associated with AD. A statistically significant increase of GG genotype frequency in AD versus healthy subjects (p=0.0331) was observed, whereas the CG genotype demonstrates a statistically significant decrease of frequency in AD patients versus controls (p=0.0194). We focused our attention on haplotype reconstruction: A statistically significant decrease of the TAC haplotype frequency in AD patients versus healthy controls group (p=0.005) and a statistically significant increase of the CAC haplotype frequency in patients versus control (p=0.019) was demonstrated. We then studied the haplotype frequencies dividing patients according to gender. A statistically significant increase of the CAC haplotype in the male AD group compared with male healthy controls (p=0.041) was found, whereas a statistically significant decrease of TAC haplotype frequency in AD females versus healthy females (p=0.005) and a statistically significant increase of CAC haplotype frequency in female patients versus healthy females (p=0.019) was noticed. We propose that these haplotypes could be a further effective marker for AD.

Interaction of the DRD3 and BDNF gene variants in subtyped bipolar disorder

Bipolar disorder is a severe mental disorder with prominent genetic etiologic factors. Dopaminergic dysfunction has been implicated in the pathogenesis of bipolar disorder, which suggests that the dopamine D3 receptor gene (DRD3) is a strong candidate gene. The brain-derived neurotrophic factor (BDNF) gene has been implicated in the etiology of bipolar disorder. We examined the association between the BDNF Val66Met and DRD3 Ser9Gly polymorphisms with two subtypes of bipolar disorder: bipolar-I and -II. Because BDNF regulates DRD3 expression (1), we also examined possible interactions between these genes. We recruited 964 participants: 268 with bipolar-I, 436 with bipolar-II, and 260 healthy controls. The genotypes of the BDNF Val66Met and DRD3 Ser9Gly polymorphisms were determined using polymerase chain reactions plus restriction fragment length polymorphism analysis. Logistic regression analysis showed a significant main effect for the Val/Val genotype of the BDNF Val66Met polymorphism (P=0.020), which predicted bipolar-II patients. Significant interaction effects for the BDNF Val66Met Val/Val genotype and both DRD3 Ser9Gly Ser/Ser and Ser/Gly genotypes were found only in bipolar-II patients (P=0.027 and 0.006, respectively). We provide initial evidence that the BDNF Val66Met and DRD3 Ser9Gly genotypes interact only in bipolar-II disorder and that bipolar-I and bipolar-II may be genetically distinct.