Investigating Peripheral SIAH3 DNA Methylation in Adult Mental Disorders in Relation to Adverse Childhood Events

Adult mental disorders (aMD), including borderline personality disorder (BPD), major depressive disorder (MDD), and social anxiety disorder (SAD), share adverse childhood experiences (ACEs) as an environmental risk factor. Epigenetic mechanisms, including DNA methylation (DNAm), may mediate the biological link between early adversity and psychiatric risk. SIAH3, implicated in stress-related and mitochondrial pathways, has been previously associated with both ACE and aMD. This study examined SIAH3 DNAm in adults with BPD, MDD, or SAD, relative to healthy control participants (HC), testing effects of diagnosis, ACE exposure, and their interaction across the pooled sample and within each diagnostic group. Both aMD diagnosis and high ACE exposure showed trends toward SIAH3 hypomethylation, and a significant diagnosis × ACE interaction emerged, with inconclusive post-hoc tests. Disorder-specific analyses revealed heterogeneous patterns: in BPD, high ACE showed a trend toward hypermethylation in unadjusted models; in MDD, interaction effects were marginal and not robust to covariate adjustment; in SAD, significant main effects and a diagnosis × ACE interaction were observed, with high ACE associated with lower DNAm exclusively in HC. These findings suggest disorder-specific epigenetic responses to ACE, positioning SIAH3 as a potential molecular link between early life stress, mitochondrial function, and aMD.