Transcriptomic meta-analysis in bipolar disorder identifies mitochondrial, synaptic, and inflammatory pathway genes

INTRODUCTION: Bipolar disorder (BD) is a major psychiatric illness with a high global burden, unclear pathophysiology, and limited biological markers, leaving diagnosis reliant on behavioral criteria. While there is an increasing number of individual transcriptomic studies investigating genes involved in BD, comprehensive cross-tissue meta-analyses remain lacking. METHODS: In this study, we conducted eight independent meta-analyses of differentially expressed genes (DEGs) across the whole brain, Brodmann area 9 (BA9), BA9 + BA46, and blood, integrating 19 publicly available postmortem brain datasets with 917 samples (386 BD patients, 531 controls) and six independent peripheral blood cohorts of 638 samples (316 BD, 322 controls). RESULTS: We identified enrichment of genes involved in mitochondrial bioenergetics and oxidative stress, as well as in synaptic structure, signaling, and neuroinflammatory pathways. These findings suggest coordinated disruption of neuronal metabolism and circuit function in BD. Additionally, we found several novel lncRNAs, miRNAs, and snoRNAs, including SNORD62B, SNORA70, and SNORA10, not previously linked to BD. DrugBank annotation highlighted pharmacologically actionable genes, including SST, P2RY12, and C3, underscoring the therapeutic relevance of our findings. CONCLUSION: Together, these results establish an integrated molecular framework of BD pathogenesis involving impaired inhibitory circuitry, mitochondrial dysfunction, neuroimmune dysregulation, and non-coding RNA networks, while providing candidate biomarkers and druggable targets, such as SST, to guide future mechanistic and therapeutic studies.