ADCY2 promoter hypomethylation in adolescents with borderline personality disorder: An RRBS study with targeted BSP replication.
BACKGROUND: Borderline Personality Disorder (BPD) is characterized by emotional dysregulation, impulsivity, and interpersonal instability. Although genetic and environmental contributions to BPD have been investigated, epigenetic correlates in adolescents remain poorly understood. The cyclic adenosine monophosphate (cAMP) signaling pathway is implicated in stress responsivity and emotion regulation, but its epigenetic variation in adolescent BPD remains understudied. METHODS: DNA methylation profiling was performed using Reduced Representation Bisulfite Sequencing (RRBS) in buccal epithelial DNA from adolescents with BPD (n = 15) and healthy controls (HC; n = 15). Differentially methylated regions (DMRs) were identified using metilene, a computational tool for detecting DMRs from bisulfite sequencing data, and subjected to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. Associations between methylation signals and borderline personality features were examined. Adenylate cyclase 2 (ADCY2) promoter methylation was examined using targeted bisulfite sequencing PCR (BSP) in an independent cohort (BPD n = 5; HC n = 5). RESULTS: RRBS identified 7641 DMRs between BPD and HC, with enrichment in pathways related to neuronal signaling and synaptic organization. A hypomethylated DMR was detected in the ADCY2 promoter, a gene implicated in cAMP signaling. Lower ADCY2 promoter methylation was associated with greater clinical severity, including emotional dysregulation, borderline traits, anxiety symptoms, and self-injury behaviors (r=-0.71 to -0.83; all p < 0.0001). Hypomethylation of the ADCY2 promoter was replicated in the independent cohort. CONCLUSIONS: This exploratory two-stage epigenetic study suggests that ADCY2 promoter hypomethylation in peripheral buccal epithelial DNA is associated with core symptom dimensions of adolescent BPD. These findings support a role for cAMP-related epigenetic variation in BPD and warrant replication in longitudinal studies.