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Quantitative leukocyte BDNF promoter methylation analysis in bipolar disorder.

ABSTRACT: BACKGROUND:Bipolar disorder (BD) is a complex psychiatric phenotype with a high heritability and a multifactorial etiology. Multisite collaborative efforts using genome-wide association studies (GWAS) have identified only a portion of DNA sequence-based risk factors in BD. In addition to predisposing DNA sequence variants, epigenetic misregulation may play an etiological role in BD and account for monozygotic twin discordance, parental origin effects, and fluctuating course of BD. In this study, we investigated DNA methylation of the brain-derived neurotrophic factor (BDNF) gene in BD. METHODS:Fifty participants with BD were compared to the same number of age- and sex-matched controls for DNA methylation differences at BDNF promoters 3 and 5. DNA methylation reads were obtained using a mass spectrophotometer for 64 cytosine-guanine (CpG) sites in 36 CpG 'units' across three amplicons of BDNF promoters 3 and 5. RESULTS AND DISCUSSION:Methylation fractions differed between BD participants and controls for 11 of 36 CpG units. Five CpG units, mostly in promoter 5, remained significant after false discovery rate correction (FDR) (p values ? 0.004) with medium to large effect sizes (Cohen's d ? 0.61). Several of the significant CpGs overlapped with or were immediately adjacent to transcription factor binding sites (TFBSs) - including two of the FDR-significant CpG units in promoter 5. For the CpGs in promoter 3, there was a positive and significant correlation between age at sample collection and DNA methylation fraction (rho = 0.56, p = 2.8 ×10(-5)) in BD cases, but not in controls. Statistically significant differences in mean methylation fraction at 5/36 CpG units (after FDR), some at or immediately adjacent to TFBSs, suggest possible relevance for the current findings to BD etiopathogenesis. The positive correlation between age and methylation seen in promoter 3 is consistent with age-related decline in BDNF expression previously reported. Future studies should provide more exhaustive epigenetic study of the BDNF locus to better characterize the relationship between BDNF methylation differences and BD.

SUBMITTER: Strauss JS

PROVIDER: S-EPMC4215812 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Quantitative leukocyte BDNF promoter methylation analysis in bipolar disorder.

Strauss John S JS Khare Tarang T De Luca Vincenzo V Jeremian Richie R Kennedy James L JL Vincent John B JB Petronis Arturas A

International journal of bipolar disorders 20131230

<h4>Background</h4>Bipolar disorder (BD) is a complex psychiatric phenotype with a high heritability and a multifactorial etiology. Multisite collaborative efforts using genome-wide association studies (GWAS) have identified only a portion of DNA sequence-based risk factors in BD. In addition to predisposing DNA sequence variants, epigenetic misregulation may play an etiological role in BD and account for monozygotic twin discordance, parental origin effects, and fluctuating course of BD. In thi ...[more]

PMID: 25505691

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Project description:Major problems of current antidepressant pharmacotherapy are insufficient response rates and difficulties in response prediction. We recently provided preliminary evidence in a small study that patients with major depressive disorder (MDD) with a hypomethylation of the CpG-87 site of the promoter IV region of the brain-derived neurotrophic factor (BDNF) gene are less likely to benefit from antidepressants. Here, we aimed at replicating this finding in a secondary analysis of 561 MDD patients (mean age 40.0 ± 11.9 years, 56% female) included into the Early Medication Change study (EMC). We measured BDNF exon IV promoter and p11 gene methylation at Baseline (BL) as well as BDNF-plasma-levels (pBDNF) at BL and day 14 and related them to treatment outcome. Although we were not able to replicate the predictor function of hypomethylation of the BDNF exon IV promoter, a subgroup of patients with severe depression (Hamilton Depression Rating Scale [HAMD-17] ? 25) (n = 199) and hypermethylation at CpG-87 of the BDNF exon IV promoter had significantly higher remission rates than patients without a methylation (p = 0.032). We also found that 421 (75%) of 561 patients showed an early improvement (? 20% HAMD-17 reduction after 2 weeks), which was associated with a 4.24-fold increased likelihood to remit at study end compared to the 140 patients without early improvement. However, specificity of response prediction of early improvement was low (34%) and false positive rate high (66%). The combination of early improvement with a pBDNF increase between BL and day 14, however, increased the specificity of response prediction from 34 to 76%, and the combination with methylation of the CpG-87 site of the BDNF exon IV promoter from 34 to 62%. Thus, the combined markers reduced false positives rates from 66 to 24% and 38%, respectively. Methylation at other sites or p11 promoter methylation failed to increase specificity of early improvement prediction. In sum, the results add to previous findings that BDNF, BDNF promoter methylation and the combination of clinical and biological markers may be interesting candidates for therapy response prediction which has to be confirmed in further studies. Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT00974155, identifier: NCT00974155.

Dataset Information

Quantitative leukocyte BDNF promoter methylation analysis in bipolar disorder.

Publications

Quantitative leukocyte BDNF promoter methylation analysis in bipolar disorder.

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