Background: We investigated differentially methylated and expressed genes between panic disorder (PD) and healthy controls (HCs) to determine whether DNA methylation and expression level of candidate genes can be used as biomarkers for diagnosis and early response.
Methods: Illumina infiniun Methylation EPIC (850 k) Beadchip for genome-wide methylation screening and mRNA sequencing was conducted in a discovery set (30 patients with PD and 30 matched HCs). The candidate gene loci methylation and expression were verified in an independent validation sample (101 PD patients and 107 HCs).
Results: In the discovery set, there were 3613 differentially methylated cytosine phosphate guanosine sites and these differential methylation positions were located within 1938 unique genes, including 1758 hypermethylated genes, 150 hypomethylated genes, and the coexistence of hypermethylation and hypomethylation sites were found in 30 genes. There were 1111 differential transcripts in PD compared to normal controls (850 down-regulated and 261 up-regulated). Further, 212 differentially expressed genes were screened (40 up-regulated and 172 down-regulated). In the validation set, compared with HCs, there was no significant difference in DNA methylation level of Casitas B-lineage lymphoma (CBL) gene loci (cg07123846). The expression level of CBL gene in PD patients was lower (vs. HCs). After four weeks' treatment, the baseline expression level of CBL gene in the responders was higher than nonresponders.
Limitations: The sample size was limited. We only chose CBL as a candidate gene. Follow-up periods were short.
Conclusions: There are differences in genome-wide DNA methylation and mRNA expression between PD patients and HCs. The changes in expression level of CBL gene may be an important molecular marker for PD diagnosis and early response.
Keywords: DNA methylation; Epigenetic; Escitalopram; Expression profiling; Panic disorder.
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