DRD5 encodes dopamine receptor D5, a G protein-coupled receptor that activates adenylyl cyclase upon dopamine binding 1. The receptor is expressed not only in neural tissue but also in peripheral blood lymphocytes, where all five dopamine receptors (DRD1-DRD5) are present 1. Recent studies reveal that DRD5 signaling can enhance immune responses by activating JAK1-STAT1 signaling in B cells, leading to increased antigen presentation and T cell activation, ultimately suppressing tumor progression 2. Genetic variants in DRD5 show significant associations with psychiatric disorders, with meta-analyses providing evidence for association with childhood ADHD 3, though this association does not extend to adult ADHD 4. Additionally, DRD5 polymorphisms are linked to paranoid schizophrenia in Han Chinese populations 5 and paranoid personality disorder in polydrug users 6. The receptor has also been investigated as a pharmacogenomic target for ADHD treatment response, though findings remain inconsistent 7. These diverse associations highlight DRD5's broad physiological roles beyond traditional dopaminergic neurotransmission, encompassing immune regulation and psychiatric disease susceptibility.