Genetic and functional analysis of single nucleotide polymorphisms in the beta2-neuronal nicotinic acetylcholine receptor gene (CHRNB2).

The beta2-neuronal nicotinic acetylcholine receptor gene (CHRNB2) is a logical candidate for influencing smoking behavior and nicotine dependence. We discovered six single nucleotide polymorphisms (SNPs) in the CHRNB2 gene by surveying 15.4 kb of genomic sequence including a previously undescribed 3' untranslated region that extends 4.0 kb downstream of the coding region. One of the SNPs causes an amino acid substitution in exon 5, one occurs in the promoter region, one changes an intronic base, and three occur in the 3' untranslated region. The ethnically dependent allele frequencies and the marker-to-marker linkage disequilibrium patterns of five of these polymorphisms were determined. The SNPs were assayed in 743 individuals for whom information on smoking history and lifelong nicotine dependence was available. No significant associations of the individual markers or their haplotypes to smoking behavior or level of nicotine dependence were found.