[Association between GSK3β polymorphisms and the smoking habits in young Japanese].

Schizophrenia and bipolar disorder show high comorbidity with smoking dependence. Several previous studies reported that glycogen synthase kinase 3β (GSK3β), which is widely expressed in the brain including the dopamine projection areas such as the amygdala, nucleus accumbens and hippocampus, may play a role in neuropsychiatric disorders and dopamine- and serotonin-mediated behavior. In this study, we have analyzed the association of three single nucleotide polymorphisms (SNPs) within GSK3β gene (rs3755557, rs334558, rs6438552) with the smoking habits and age at smoking initiation in a sample of 384 young adult Japanese, which included 172 smokers and 212 non-smokers. As a result, rs334558 was significantly associated with smoking habits in genotype frequency and allelic frequency (P < 0.05). Furthermore, higher haplotype 3 (T-T-T) and haplotype 5 (A-T-C) frequencies were observed in non-smokers than smokers (P < 0.05). Three functional polymorphisms examined in this study reportedly increase transcriptional activity when they have a high-activation allele such as the A allele of -1727A/T (rs3755557), the T allele of -50T/C (rs334558) or T allele of -157T/C (rs6438552). Thus, it was suggested in this study that changes in GSK3β activity may have an impact on smoking habits.