DTNBP1 (dystrobrevin binding protein 1) is a component of the BLOC-1 complex essential for biogenesis of lysosome-related organelles and synaptic function 1. The protein regulates synaptic vesicle trafficking, neurotransmitter release, and dopaminergic signaling in the prefrontal cortex and striatum 2. DTNBP1 facilitates activity-dependent BDNF secretion to maintain GABAergic inhibitory neurotransmission, and modulates dopamine D2 receptor surface expression and prefrontal cortical activity 1. Clinically, DTNBP1 variants are associated with schizophrenia susceptibility, though genetic evidence remains mixed 34. Schizophrenia patients exhibit significantly reduced dysbindin mRNA levels in the dorsolateral prefrontal cortex, and genetic variation in DTNBP1 affects cortical mRNA expression levels 5. In healthy subjects, DTNBP1 polymorphisms influence cognitive functions including memory and intelligence 6. DTNBP1 mutations also cause Hermansky-Pudlak syndrome type 7, and rare variants have been identified in intellectual disability cases 7. Epistatic interactions between DTNBP1 and COMT genes modulate dopaminergic signaling non-additively, suggesting complex genetic mechanisms in behavioral and cognitive phenotypes 2.