We then tested the cis-acting effect in frontal cortex from individuals of African ancestry. All 10 subjects who were AEI-positive are heterozygous for 10 variants in a ∼9 kb region (−22.3 kb to −13.2 kb relative to the AUG of CHRNA5), defined by an intronic SNP (rs11858230) of PSMA4 and rs7164030 located upstream of CHRNA5 (Figures 4b and 5). Five subjects who were AEI-negative are homozygous for these 10 variants. This analysis suggests that the potential functional variants altering CHRNA5 mRNA expression levels are likely located in this region.
