CHRNA5 and nicotine dependence: The latter three SNPs (evaluated as a haplotype together with the promoter ins/del variation rs3841324) were associated with CHRNA5 expression levels in normal lung tissue27 and were also reported to have a functional role in modulating CHRNA5 promoter transcriptional activity in vitro in neuroblastoma cells25; these findings suggest that these polymorphisms play a functional role in nicotine dependence by influencing CHRNA5 mRNA level in the lungs and possibly in the brain.