CHRNA4 and CHRNB2 in affecting ND, concluding that CHRNB2 has a significant effect on ND when analyzed in interaction with CHRNA4. A smaller study in schizophrenic smokers suggested that CHRNA7 may be associated with smoking status (De Luca and others 2004), although the relevance of this finding to the general population of smokers is unknown. Variants in CHRNB1, CHRNB3, and CHRM1 (the second type of acetylcholine receptor found in both the brain and the periphery) also are associated with ND (Bierut and others 2007; Lou and others 2006). Greenbaum et al. (2006) reported a nominally significant association of ND and related behaviors with CHRNA7 and CHRNB2 in a relatively small sample.
