CHR7 encodes the muscarinic acetylcholine receptor 2, a G protein-coupled receptor expressed in the brain, neuromuscular junctions, and autonomic ganglia 1. Upon acetylcholine binding, CHR7 undergoes conformational change and couples to G(i)/G(o) proteins to inhibit adenylate cyclase activity, modulating downstream signaling cascades 1. The receptor plays critical roles in neuronal excitability, synaptic plasticity, and acetylcholine feedback regulation 2. Genetic variation in CHR7 associates with multiple neuropsychiatric phenotypes. Polymorphisms in the 5' untranslated region predispose to alcohol dependence, drug dependence, and major depressive disorder 34. CHR7 variants also correlate with cognitive performance, particularly performance IQ, suggesting involvement in higher cognitive processing 52. Gene-environment interactions are evident, with CHR7 genotypes influencing externalizing behavior more strongly under conditions of lower parental monitoring 6. Additionally, CHR7 polymorphisms associate with tardive dyskinesia severity and cognitive impairment in schizophrenia patients, with potential gene-gene interactions with GRIN2A 7. These findings establish CHR7 as a functionally important locus influencing risk for psychiatric and cognitive disorders.