TRANK1 (tetratricopeptide repeat and ankyrin repeat containing 1) is a susceptibility gene for bipolar disorder (BD) with emerging roles in other neuropsychiatric conditions. The leading BD risk locus at chromosome 3 involves SNP rs9834970 near TRANK1, showing genome-wide significant association in both European and East Asian populations 1. Lower TRANK1 mRNA expression constitutes a principal BD risk factor, as demonstrated through expression quantitative trait loci (eQTL) and Mendelian randomization analyses in human brain tissue 1. Fine-mapping studies identify TRANK1 among genes involved in neurotransmission and neurodevelopment contributing to BD pathogenesis 23. TRANK1 encodes a motor adapter protein involved in mitochondrial transport along axons; its dysregulation impairs colocalization of mitochondria with transport machinery 4. TRANK1 expression is modulated by microbiota-dependent type 1 interferon signaling, with overexpression associated with blood-brain barrier impairment and neuroinflammation in BD 5. Beyond BD, TRANK1 variants associate with Kleine-Levin syndrome, particularly in cases with birth difficulties, suggesting gene-environment interactions in sleep and circadian disorders 67. Circulating anti-TRANK1 IgG antibodies may serve as a biomarker for a schizophrenia subgroup 8. Despite these associations, TRANK1's precise neuronal function remains incompletely understood, necessitating further mechanistic investigation.