The significant association between the dizziness item and CHRNA4 (rs3787140) is a novel finding, and somewhat difficult to interpret in the context of previous studies. The α4 subunit commonly combines with the β2 subunit to form some of the most widely distributed and common nAChR subtypes in the brain (Gotti et al., 2007). In case-control analysis of the NICSNP sample, nominal significance was reported for other SNPs in CHRNA4, but not rs3787140 (Saccone et al., in press). In other samples, Feng et al. (2004) reported an association between the CHRNA4 gene and nicotine dependence (as measured by the Fagerstrom Test for Nicotine Dependence – FTND (Heatherton et al., 1991)), but no association with CHRNB2. Also using the FTND, Li et al (2005) found an association with CHRNA4, but not CHRNB2. Another study by Hutchison et al (2007) showed an association between CHRNA4, nicotine dependence, a “rush” or “high” following a cigarette, and the expression of α4β2 nAChRs in the nucleus accumbens. This study also presented functional data for two SNPs in the 5′UTR and promoter region of CHRNA4. Two other
