Several subunit genes have been investigated for association with ND and other smoking-related behaviors in human subjects [for reviews, see (Lessov-Schlaggar and others 2008; Li and Burmeister 2009)]. In a recent study, Saccone et al. (2007) reported associations of multiple single nucleotide polymorphisms (SNPs) in the CHRNA5/A3/B4 cluster with ND. However, the significance of these results did not survive correction for multiple testing. More recently, several genome-wide and candidate gene-based association studies provided further evidence for the association of variants of the CHRNA5/A3/B4 gene cluster with various nicotine-related behaviors (Berrettini and others 2008; Bierut and others 2008; Chen and others 2009; Greenbaum and others 2006; Saccone and others 2007; Schlaepfer and others 2008; Sherva and others 2008; Weiss and others 2008). In contrast, other studies have failed to reveal a significant association of this gene cluster with ND or other smoking-related phenotypes (Uhl and others 2008; Vink and others 2009).
