Among the 139 subjects (92 smokers and 47 nonsmokers) who participated in the [123I]5-IA SPECT imaging study, one nonsmoker and two smokers carried different nonsynonymous rare variants in the exon 5 cytoplasmic loop region. The nonsmoker, who was a 30-year-old EA female, carried a p.Arg336Cys rare variant. Compared to a group of four age-matched control nonsmokers, the regional α4β2 nAChR availability in the brain of this rare variant carrier was 69.3%, 63.0% and 76.7% higher in the cortical areas, striatum, and cerebellum, respectively (Figure 3A, subject 1 (S1), and Figure 3B). The α4β2 nAChR availabilities among the two smokers who carried nonsynonymous rare variants (p.Pro452Ser and p.Arg487Gln) and their age-matched control smokers were similar.
