Dataset Information

Population genetic study of the brain-derived neurotrophic factor (BDNF) gene.

ABSTRACT: Genetic variants in the brain-derived neurotrophic factor (BDNF) gene, predominantly the functional Val66Met polymorphism, have been associated with risk of bipolar disorder and other psychiatric disorders. However, not all studies support these findings, and overall the evidence for the association of BDNF with disease risk is weak. As differences in population genetic structure between patient samples could cause discrepant or spurious association results, we investigated this possibility by carrying out population genetic analyses of the BDNF genomic region. Substantial variation was detected in BDNF coding region single-nucleotide polymorphism (SNP) allele and haplotype frequencies between 58 global populations, with the derived Met allele of Val66Met ranging in frequency from 0 to 72% across populations. F(ST) analyses to assess diversity in the HapMap populations determined that the Val66Met F(ST) value was at the 99.8th percentile among all SNPs in the genome. As the BDNF population genetic differences may be due to local selection, we performed the long-range haplotype test for selection using 68 SNPs spanning the BDNF genomic region in 12 European-derived pedigrees. Evidence for positive selection was found for a high-frequency Val-carrying haplotype, with a relative extended haplotype homozygosity value above the 99 th percentile compared with HapMap data (P=4.6 x 10(-4)). In conclusion, we observed considerable BDNF allele and haplotype diversity among global populations and evidence for positive selection at the BDNF locus. These phenomena can have a profound impact on the detection of disease susceptibility genes and must be considered in gene association studies of BDNF.

SUBMITTER: Petryshen TL

PROVIDER: S-EPMC2888876 | biostudies-literature | 2010 Aug

REPOSITORIES: biostudies-literature

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Population genetic study of the brain-derived neurotrophic factor (BDNF) gene.

Petryshen T L TL Sabeti P C PC Aldinger K A KA Fry B B Fan J B JB Schaffner S F SF Waggoner S G SG Tahl A R AR Sklar P P

Molecular psychiatry 20090303 8

Genetic variants in the brain-derived neurotrophic factor (BDNF) gene, predominantly the functional Val66Met polymorphism, have been associated with risk of bipolar disorder and other psychiatric disorders. However, not all studies support these findings, and overall the evidence for the association of BDNF with disease risk is weak. As differences in population genetic structure between patient samples could cause discrepant or spurious association results, we investigated this possibility by c ...[more]

PMID: 19255578

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Project description:BACKGROUND In a previous study, we reported that pro-brain-derived neurotrophic factor (proBDNF) was involved in the pathology of alcohol dependence, and the single-nucleotide polymorphism (SNP) Val66Met was located at the prodomain of the brain-derived neurotrophic factor gene (BDNF). This polymorphism has been reported to affect intracellular trafficking and activity-dependent secretion of BDNF. Our present research investigated the relationships between the BDNF Val66Met polymorphism and the plasma levels of proBDNF and mature brain-derived neurotrophic factor (mBDNF) in patients with alcohol dependence. MATERIAL AND METHODS The BDNF gene Val66Met polymorphism was genotyped in 59 alcohol-dependent patients and 37 age- and sex-matched controls, and the plasma levels of proBDNF and mBDNF were assessed by enzyme-linked immunosorbent assay in all participants. RESULTS No association was found between the BDNF gene Val66Met polymorphism and alcohol dependence (P>0.05). In comparison with the control group, the level of plasma proBDNF in the alcohol-dependence group was notably increased (Z=-2.228, P=0.026), while the level of mBDNF was remarkedly decreased (Z=-2.014, P=0.044). In the alcohol-dependence group, significant associations were not found between the Val66Met polymorphisms and proBDNF and mBDNF plasma levels (P>0.05). The plasma level of proBDNF was positively correlated with the average daily alcohol consumption in the last month (r=0.344, P=0.008) and drinking history (r=0.317, P=0.014), while the plasma level of mBDNF had negative effects (r=-0.361, P=0.005, with the average daily alcohol consumption; r=-0.427, P=0.001, with drinking history). CONCLUSIONS The BDNF gene Val66Met polymorphism does not appear to affect the secretion of proBDNF and mBDNF in Chinese patients with alcohol dependence. Furthermore, this study reconfirmed that the plasma levels of proBDNF and mBDNF were correlated with the average daily alcohol consumption in the last month and with drinking history.

Project description:The purpose of this study was to examine relationships between genetic markers of central serotonin (5-HT) and dopamine function, and risk for post-treatment relapse, in a sample of alcohol-dependent patients.The study included 154 patients from addiction treatment programs in Poland, who met DSM-IV criteria for alcohol dependence. After assessing demographics, severity of alcohol use, suicidality, impulsivity, depression, hopelessness, and severity of alcohol use at baseline, patients were followed for approximately 1 year to evaluate treatment outcomes. Genetic polymorphisms in several genes (TPH2, SLC6A4, HTR1A, HTR2A, COMT, and BDNF) were tested as predictors of relapse (defined as any drinking during follow-up) while controlling for baseline measures.Of 154 eligible patients, 123 (80%) completed follow-up and 48% (n = 59) of these individuals relapsed. Patients with the Val allele in the Val66Met BDNF polymorphism and the Met allele in the Val158Met COMT polymorphism were more likely to relapse. Only the BDNF Val/Val genotype predicted post-treatment relapse [odds ratio (OR) = 2.62; p = 0.019], and time to relapse (OR = 2.57; p = 0.002), after adjusting for baseline measures and other significant genetic markers. When the analysis was restricted to patients with a family history of alcohol dependence (n = 73), the associations between the BDNF Val/Val genotype and relapse (OR = 5.76, p = 0.0045) and time to relapse (hazard ratio = 4.93, p = 0.001) were even stronger.The Val66Met BDNF gene polymorphism was associated with a higher risk and earlier occurrence of relapse among patients treated for alcohol dependence. The study suggests a relationship between genetic markers and treatment outcomes in alcohol dependence. Because a large number of statistical tests were conducted for this study and the literature on genetics and relapse is so novel, the results should be considered as hypothesis generating and need to be replicated in independent studies.

Dataset Information

Population genetic study of the brain-derived neurotrophic factor (BDNF) gene.

Publications

Population genetic study of the brain-derived neurotrophic factor (BDNF) gene.

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