SNPs in the SNAP25 gene were initially [PMID 17160701] linked to intelligence but have failed to replicate [PMID 19418213].
While now suspect, the original work can be found in [PMID 17160701] and [PMID 17081262] or this pdf poster show association between the CHRM2 gene and intelligence . In this study of ~300 Caucasians, the (G;G) genotype appeared to typically have a 4 point higher IQ than the (A;G) genotype, which had a 4 point higher IQ (on average) than the (A;A) genotype. A nearby SNP, rs324650, showed similar results to rs324640, and was in linkage disequilibrium (r2 = 0.90) with it. [PMID 17081262]
[PMID 18979273] Acetylcholine receptor M2 gene variants, heart rate recovery, and risk of cardiac death after an acute myocardial infarction
[PMID 16501017] Heart rate recovery after maximal exercise is associated with acetylcholine receptor M2 (CHRM2) gene polymorphism.
[PMID 17996044] Exploring the functional role of the CHRM2 gene in human cognition: results from a dense genotyping and brain expression study.
[PMID 18634760] Uncovering genes for cognitive (dys)function and predisposition for alcoholism spectrum disorders: a review of human brain oscillations as effective endophenotypes.