Alterations in DNA methylation rates of brain-derived neurotrophic factor in patients with schizophrenia

Abstract Background and objectives Schizophrenia (SZ) is one of the most disabling mental illness and the elucidation of diagnostic and therapeutic biomarkers are required. Recent studies investigating the brain morphology, the gene expression profile, and the genetic epidemiology have suggested the involvement of Brain-derived neurotrophic factor (BDNF) and its epigenetic regulation in the pathophysiology of SZ. The current study was conducted to determine the association of DNA methylation of the BDNF gene with the diagnosis or with the characteristics of patients with SZ. Methods We analyzed genomic DNA from peripheral blood of 22 patients with SZ and 22 healthy subjects. The DNA methylation rates (DMRs) of the CpG island at the promoter of exon I of the BDNF gene were measured using EpiTYPER® and the MassARRAY® system (Agena Biosciences). We examined the validity of the methylation profiles as a diagnostic biomarker for SZ by clustering analyses, differences in DMRs between patients and healthy controls, and the relationship between DMRs and patient characteristics. Results The clustering analysis failed to distinguish between healthy controls and patients with SZ, though the DMRs of 4 CpG units were significantly different between these two groups. Whereas the DMR of one CpG (CpG 28) was significantly correlated with the amount of daily antipsychotics, there was no influence of age, severity, or duration of illness on the DMRs of the BDNF gene. Conclusion Despite the small number of subjects, our results suggest the involvement of the changes in DMRs of the BDNF gene in the pathophysiology of SZ.