The relationship between nicotine metabolism of CYP2A6 and the smoking behavior in a Japanese population was investigated. The CYP2A6 genotypes were determined by the PCR method. There was a significant difference in the frequency of the CYP2A6*4C allele, which is a whole deleted allele for the human CYP2A6 gene, between smokers and nonsmokers. The frequency of the CYP2A6*4C allele was higher in nonsmokers than in smokers, whereas the frequency of CYP2A6*1A/*1B heterozygotes with a higher activity of nicotine metabolism was lower. In this study it was suggested that the CYP2A6*4C allele may prevent the carrier from smoking and the CYP2A6*1A/*1B heterozygote may be at risk for developing smoking behavior.

Panic disorder (PD) is the repeated sudden occurrence of panic attacks, episodes characterized by psychological symptoms. Peripheral benzodiazepine receptor (PBR) is closely associated with personality traits for anxiety tolerance, and that it holds promise as a biological marker of stressful conditions. We have performed association analyses using the polymorphism to determine the PBR in PD. We screened the subjects for sequence variations within the 5' region, the coding region (exons 2-4), and the 3' noncoding region. One novel missense variant in exon 4, derived from the nucleotide transition in codon 162 (CGT --> CAT:485G > A) resulting in an arginine-to-histidine (Arg --> His) change, was detected in these subjects. The 485G > polymorphism of the PBR gene was analyzed in 91 PD patients and 178 controls. The genotypic and allelic analyses of the 485G > A revealed significant differences between the panic patients and the comparison subjects (P = 0.021 and 0.014, respectively). The present study provides new and important evidence that variation in the PBR gene influences susceptibility to PD.

In the past, there have been many epidemiological and genetic studies of mood disorders, schizophrenia, and alcohol dependence, and in this study, the human serotonin 2A receptor (5-HTR2A) polymorphism was examined in 80 patients with mood disorders, 50 patients with schizophrenia and 41 patients with alcohol dependence. 5-HTR is related to affectivity, regulation, and pharmacologic effects of antidepressant, anti-anxiety and antipsychotic medications. The polymorphism in 5-HTR2A (102T/C, -1438 A/G) was identified by the polymerase chain reaction (PCR), followed by restriction fragment length polymorphism (RFLP). The results suggest that 5-HTR2A (102T/C, -1438G/A) polymorphism might not be associated with susceptibility to schizophrenia or mood disorders, and it might not be a risk factor contributing to alcohol dependency. We found that the 102T/C polymorphism was in linkage disequilibrium with the -1438G/A polymorphism in psychosis (mood disorder, schizophrenia, and alcohol dependence) and in health controls. Further studies are needed to determine whether or not the novel serotonin receptor (5-HTR) polymorphism reflects the pathogenesis of schizophrenia, mood disorders, and alcohol dependence.

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