In orientation to the dbSNP entry for this SNP, rather than as published, the (C;C) genotype averages ~2 PIQ points higher than the (C;T) genotype, which averages 2 PIQ points higher than the (T;T) genotype.[PMID 16801949]
For SNPs rs363039 - rs363043 - rs353016, respectively, the haplotype C-T-T is most associated with higher intelligence in children, whereas the haplotype C-C-T is most associated in adults (SNPs oriented as in dbSNP). [PMID 17908175]
[PMID 20950795] The SNAP25 Gene Is Linked to Working Memory Capacity and Maturation of the Posterior Cingulate Cortex During Childhood
[PMID 22193912] Variants in SNAP25 are targets of natural selection and influence verbal performances in women
[PMID 23593184] DNA variation in the SNAP25 gene confers risk to ADHD and is associated with reduced expression in prefrontal cortex.