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Chromosome 22q11.2 deletion syndrome and genetic variations including single-nucleotide polymorphism (SNP) and copy number variation (CNV) in catechol-O-methyltransferase (COMT) situated at 22q11.2 remains controversial. Here, the genetic relationship between COMT and Japanese patients with schizophrenia was investigated by examining whether the SNPs correlated with schizophrenia based on a common disease-common variant hypothesis. Additionally, 22q11.2DS were screened based on a common disease-rare variant hypothesis; low-frequency CNVs situated at two COMT promoters and exons were investigated based on the low-frequency variants with an intermediate effect; and positive findings from the first stage were reconfirmed using a second-stage replication study including a larger sample size. Eight SNPs and 10 CNVs were investigated using Taqman SNP and CNV quantitative real-time polymerase chain reaction method. For the first-stage analysis, 513 unrelated Japanese patients with schizophrenia and 705 healthy controls were examined. For the second-stage replication study, positive findings from the first stage were further investigated using a larger sample size, namely 1,854 patients with schizophrenia and 2,137 controls. The first-stage analysis showed significant associations among schizophrenia, intronic SNP rs165774, CNV6 situated at promoter 1, CNV8 at exon 6, and CNV9 at exon 7. The second-stage study showed that intronic SNP rs165774 (χ(2)  = 8.327, P = 0.0039), CNV6 (χ(2)  = 19.66, P = 0.00005), and CNV8 (χ(2)  = 16.57, P = 0.00025) were significantly associated with schizophrenia. Large and rare CNVs as well as low-frequency CNVs and relatively small CNVs, namely <30 kb in COMT, may be genetic risk factors for schizophrenia., (© 2016 Wiley Periodicals, Inc.)

Recent genome-wide association studies (GWASs) of schizophrenia (SCZ) identified several susceptibility genes and suggested shared genetic components between SCZ and bipolar disorder (BD). We conducted a genetic association study of single nucleotide polymorphisms (SNPs) selected according to previous SCZ GWAS targeting psychotic disorders (SCZ and BD) in the Japanese population. Fifty-one SNPs were analyzed in a two-stage design using first-set screening samples (all SNPs: 1,032 SCZ, 1,012 BD, and 993 controls) and second-set replication samples ("significant" SNPs in the first-set screening analysis: 1,808 SCZ, 821 BD, and 2,321 controls). We assessed allelic associations between the selected SNPs and the three phenotypes (SCZ, BD, and "psychosis" [SCZ + BD]). Nine SNPs revealed nominal association signals for all comparisons (P(uncorrected) < 0.05), of which two SNPs located in the major histocompatibility complex region (rs7759855 in zinc finger and SCAN domain containing 31 [ZSCAN31] and rs1736913 in HLA-F antisense RNA1 [HLA-F-AS1]) were further assessed in the second-set replication samples. The associations were confirmed for rs7759855 (P(corrected) = 0.026 for psychosis; P(corrected) = 0.032 for SCZ), although the direction of effect was opposite to that in the original GWAS of the Chinese population. Finally, a meta-analysis was conducted using our two samples and using our data and data from Psychiatric GWAS Consortium (PGC), which have shown the same direction of effect. SNP in ZSCAN31 (rs7759855) had the strongest association with the phenotypes (best P = 6.8 × 10(-5) for psychosis: present plus PGC results). These data support shared risk SNPs between SCZ and BD in the Japanese population and association between MHC and psychosis., (© 2014 Wiley Periodicals, Inc.)

Several epidemiological and genetic studies have suggested that the risk of type II diabetes (T2D) is likely to overlap with the susceptibility to psychotic disorders such as schizophrenia (SCZ) and bipolar disorder (BD). In this study, we aimed to examine the association of single-nucleotide polymorphisms (SNPs) detected in previous T2D genome-wide association studies (GWAS) with SCZ, BD and psychosis (SCZ plus BD). A total of 37 SNPs were selected from the literature. A two-stage analysis was conducted using a first set of screening samples (total N=3037) and a second set of replication samples (N=4950). None of the SNPs showed a significant association to the screening samples after correction for multiple testing. To avoid type II error, we genotyped the top three SNPs in BCL11A, HMG20A and HNF4A showing associations with any of the phenotypes (Puncorrected <0.01) using independent samples to replicate the nominal associations. However, we were unable to find any significant associations based on the screening results (Puncorrected>0.05). Our findings did not support the shared genetic risk between T2D and psychotic disorders in the Japanese population. However, further replication using a larger sample size is required.

The early growth response gene 2 (EGR2) has been recently reported to be associated with bipolar disorder in the Korean population. However replication studies in independent cohorts of same and different ethnicities are essential for establishing the credibility of a genotype-phenotype association. With this notion, in the present study we have performed a replication study of the reported association of SNPs in EGR2 in a case-control study comprising of 867 unrelated Japanese bipolar disorder patients and 895 age-, sex- and ethnicity-matched controls. Results showed no significant differences in allele and genotype frequencies of EGR2 SNPs between bipolar disorder patients and controls and also in a sex-stratified genetic analysis. The haplotype and meta-analyses also showed no significant association with bipolar disorder. In conclusion, this is the first replication study of the previously reported association of EGR2 with bipolar disorder in a larger sample set and the results showed that the EGR2 gene is unlikely to contribute to the susceptibility of bipolar disorder in a Japanese cohort., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background: Genome-wide association studies have successfully identified several common variants showing robust association with schizophrenia. However, individually, these variants only produce a weak effect. To identify genetic variants with larger effect sizes, increasing attention is now being paid to uncommon and rare variants., Methods: From the 1000 Genomes Project data, we selected 47 candidate single nucleotide variants (SNVs), which were: 1) uncommon (minor allele frequency < 5%); 2) Asian-specific; 3) missense, nonsense, or splice site variants predicted to be damaging; and 4) located in candidate genes for schizophrenia and bipolar disorder. We examined their association with schizophrenia, using a Japanese case-control cohort (2012 cases and 2781 control subjects). Additional meta-analysis was performed using genotyping data from independent Han-Chinese case-control (333 cases and 369 control subjects) and family samples (9 trios and 284 quads)., Results: We identified disease association of a missense variant in GRIN3A (p.R480G, rs149729514, p = .00042, odds ratio [OR] = 1.58), encoding a subunit of the N-methyl-D-aspartate type glutamate receptor, with study-wide significance (threshold p = .0012). This association was supported by meta-analysis (combined p = 3.3 × 10(-5), OR = 1.61). Nominally significant association was observed in missense variants from FAAH, DNMT1, MYO18B, and CFB, with ORs of risk alleles ranging from 1.41 to 2.35., Conclusions: The identified SNVs, particularly the GRIN3A R480G variant, are good candidates for further replication studies and functional evaluation. The results of this study indicate that association analyses focusing on uncommon and rare SNVs are a promising way to discover risk variants with larger effects., (Copyright © 2013 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.)

Background: Tetrahydrobiopterin (BH4) plays an important role in the biosynthesis of serotonin, melatonin and catecholamines, all of which are implicated in the pathophysiology of mood disorders (MDs), including major depressive disorder (MDD) and bipolar disorder (BP). Production of BH4 is regulated by GTP cyclohydrolase transcription and activity. Thus, we considered the GTP cyclohydrolase gene (GCH1) to be a good candidate gene in the pathophysiology of MDs and of the serotonin selective reuptake inhibitors (SSRIs) response in MDD, and conducted a case-control study utilizing three SNPs (rs8007267, rs3783641 and rs841) and moderate sample sizes (405 MDD patients, including 262 patients treated by SSRIs, 1022 BP patients and 1805 controls)., Method: A multiple logistic regression analysis was carried out to compare the frequencies of each SNP genotype for the target phenotype across patients and controls in several genetic models, while adjusting for possible confounding factors. A clinical response was defined as a decrease of more than 50% from the baseline score on the Structured Interview Guide for Hamilton Rating Scale for Depression (SIGH-D) within 8 weeks, and clinical remission as a SIGH-D score of less than 7 at 8 weeks., Result: No associations between three SNPs in GCH1 and MDD or BP were observed; however, GCH1 was associated with SSRI therapeutic response in MDD in all the marker's haplotype analysis (Global P value=0.0379)., Conclusions: Results suggest that GCH1 may predict response to SSRI in MDD in the Japanese population. Nevertheless, a replication study using larger samples may be required for conclusive results, since our sample size was small., (Copyright © 2012 Elsevier B.V. All rights reserved.)

Recent GWAS demonstrated an association between candidate genes located at region 6p22.1 and schizophrenia. This region has been reported to house certain candidate SNPs, which may be associated with schizophrenia at HIST1H2BJ, PRSS16, and PGBD1. These genes may presumably be associated with pathophysiology in schizophrenia, namely epigenetics and psychoneuroimmunology. A three-step study was undertaken to focus on these genes with the following aims: (1) whether these genes may be associated in Japanese patients with schizophrenia by performing a 1st stage case-control study (514 cases and 706 controls) using Japanese tagging SNPs; (2) if the genetic regions of interest for the disease from the 1st stage of analyses were found, re-sequencing was performed to search for new mutations; (3) finally, a replication study was undertaken to confirm positive findings from the 1st stage were reconfirmed using a larger number of subjects (2,583 cases and 2,903 controls) during a 2nd stage multicenter replication study in Japan. Genotyping was performed using TaqMan PCR method for the selected nine tagging SNPs. Although three SNPs situated at the 3' side of PGBD1; rs3800324, rs3800327, and rs2142730, and two-window haplotypes between rs3800327 and rs2142730 showed positive associations with schizophrenia, these associations did not have enough power to sustain significance during the 2nd stage replication study. In addition, re-sequencing for exons 5 and 6 situated at this region did not express any new mutations for schizophrenia. Taken together these results indicate that the genes HIST1H2BJ, PRSS16, and PGBD1 were not associated with Japanese patients with schizophrenia., (Copyright © 2012 Wiley Periodicals, Inc.)

This study aimed to estimate the prevalence of sexual dysfunction, evaluated by the Nagoya Sexual Function Questionnaire (NSFQ), and hyperprolactinemia in patients with schizophrenia and examine a relationship between sexual dysfunction and serum prolactin levels. This cross-sectional, comparative study was performed using a sample comprising 195 Japanese schizophrenic in- and outpatients treated with antipsychotics (117 males and 78 females). Data were collected from October 2009 to January 2010 using single, cross-sectional ratings of sexual function assessed by the NSFQ and concurrent measurement of serum prolactin levels. The prevalence of sexual dysfunction in patients with schizophrenia was high (males 66.7%; females 79.5%). Hyperprolactinemia (>25ng/ml) was highly prevalent among schizophrenia patients, affecting 53.8% of females and 51.3% of males. Among female patients, 16.7% had prolactin levels>100ng/ml. There was no relationship between sexual dysfunction and serum prolactin levels. The present study demonstrated a higher prevalence of sexual dysfunction and hyperprolactinemia in Japanese schizophrenia patients. Clinicians should keep these problems in mind and discuss potential solutions with patients to improve patients' quality of life and adherence to therapy., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Methamphetamine (MAP) dependence is a highly heritable and aberrant dopaminergic signaling that has been implicated in the disease. Glial cell line-derived neurotrophic factor (GDNF), which plays an important role in the survival of dopaminergic neurons, may be involved in this disorder. In this study, we examined the association between GDNF and MAP dependence using a Japanese population-based sample. We selected eight single nucleotide polymorphisms (SNPs) in the GDNF locus for the association analysis. When patients with MAP dependence were divided into two subgroups consisting of multi-substance and MAP-only users, we detected a significant association between these two groups and the tagging SNP, rs2910704 (after Bonferroni's correction; allele P=0.034). Thus, GDNF is likely to be related to the severity of MAP use in the Japanese population., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Alterations in centrosomal function have been suggested in the pathology of schizophrenia. The molecule pericentriolar material 1 (PCM1) is involved in maintaining centrosome integrity and in the regulation of the microtubule cytoskeleton. PCM1 forms a complex at the centrosome with the disrupted-in-schizophrenia 1 (DISC1) protein, which is a major susceptibility factor for schizophrenia. The association between genetic variants in the PCM1 gene and schizophrenia has been reported by several case-control studies, linkage studies and a meta-analysis. The aims of this study are to replicate the association between four single-nucleotide polymorphisms (SNPs) in the PCM1 gene and schizophrenia in a Japanese population (1496 cases and 1845 controls) and to perform a meta-analysis of the combined sample groups (3289 cases and 3567 controls). We failed to find a significant association between SNPs or haplotypes of the PCM1 gene and schizophrenia in the Japanese population (P>0.28). The meta-analysis did not reveal an association between the four examined SNPs and schizophrenia. Our data did not support genetic variants in the PCM1 gene as a susceptibility locus for schizophrenia., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Background: Using a knock-out mouse model, it was shown that NETO1 is a critical component of the NMDAR complex, and that loss of Neto1 leads to impaired hippocampal long term potentiation and hippocampal-dependent learning and memory. Moreover, hemizygosity of NETO1 was shown to be associated with autistic-like behavior in humans., Purpose of the Research: We examined the association between schizophrenia and the neuropilin and tolloid-like 1 gene (NETO1). First, we selected eight single nucleotide polymorphisms (SNPs) within the NETO1 locus, based on the Japanese schizophrenia genome wide association study (JGWAS) results and previously conducted association studies. These SNPs were genotyped in the replication sample comprised of 963 schizophrenic patients and 919 healthy controls. We also examined the effect of associated SNPs on scores in the Continuous Performance Test and the Wisconsin Card Sorting Test Keio version (schizophrenic patients 107, healthy controls 104)., Results: There were no significant allele-wise and haplotype-wise associations in the replication analysis after Bonferroni correction. However, in meta-analysis (JGWAS and replication dataset) three association signals were observed (rs17795324: p = 0.028, rs8098760: p = 0.017, rs17086492: p = 0.003). These SNPs were followed up but we could not detect the allele-specific effect on cognitive performance measured by the Continuous performance test (CPT) and Wisconsin Card Sorting test (WCST)., Major Conclusions: We did not detect evidence for the association of NETO1 with schizophrenia in the Japanese population. Common variants within the NETO1 locus may not increase the genetic risk for schizophrenia in the Japanese population. Additionally, common variants investigated in the current study did not affect cognitive performance, as measured by the CPT and WCST.

Methylenetetrahydrofolate reductase (MTHFR) is a critical molecule for single-carbon transfer reactions. Recent evidence suggests that polymorphisms of MTHFR are related to neural tube deficits and the pathogenesis of schizophrenia. While several studies have demonstrated associations between the gene encoding the MTHFR (MTHFR) polymorphisms and schizophrenia, these studies lack consistency. Therefore, we conducted a gene-wide association study (patients with schizophrenia = 696, control subjects = 747) and performed imputation analysis. Additionally, we performed meta-analysis on currently available data from 18 studies for two common functional polymorphisms (rs1801131 and rs1801133). There were no significant associations with schizophrenia in the single marker analysis for the seven tagging SNPs of MTHFR. In the haplotypic analysis, a nominally significant association was observed between the haplotypes, which included four SNPs (rs1801133, rs17421511, rs17037396, and rs9651118) and the schizophrenic patients. Additionally, the imputation analysis demonstrated there were several associated markers on the MTHFR chromosomal region. However, confirmatory analyses of three tagging SNPs (rs1801133, rs17037396, and rs9651118) and the top SNP (rs17421511) for the imputation results (patients with schizophrenia = 797, control subjects = 1025) failed to replicate the haplotypic analysis and the imputation results. These findings suggest that MTHFR polymorphisms are unlikely to be related to the development of schizophrenia in the Japanese population. However, since our meta-analysis results demonstrated strong support for association of rs1801133 with schizophrenia, further replication studies based on a gene-wide approach need to be considered., (Copyright © 2010 Elsevier B.V. All rights reserved.)

Several investigations have reported that abnormalities in circadian rhythms might be related with the pathophysiology of psychiatric disorders, since many psychiatric patients have insomnia and sleep-awake disturbance. A recent animal study reported that Magel2, which encodes a member of the MAGE/necdin family of proteins, might be associated in the pathophysiology of psychiatric disorders. Magel2 gene knockout mice showed altered concentrations of both dopamine and serotonin in several parts of the brain compared with controls. In addition, the authors of that study detected a bilateral reduction in cortical volume in distinct regions of the Magel2 gene knockout mice brain, including focused regions in the parieto-temporal lobe of the cerebral cortex, the amygdala, the hippocampus, and the nucleus accumbens. These mice were also found to have hypoactivity and abnormalities in circadian rhythms. From this evidence, we considered Magel2 gene (MAGEL2) to be a good candidate gene for the pathophysiology of schizophrenia and mood disorder, and we conducted a case-control study among Japanese (731 schizophrenia patients, 465 MDD patients, 156 BP patients and 758 controls) using three tagging SNPs in MAGEL2 (rs850815, rs8920 and rs4480754), selected using the HapMap database. We did not find any association between MAGEL2 and schizophrenia, BP or MDD in allele/genotype-wise analysis or haplotype-wise analysis. Our results suggest that MAGEL2 may not play a role in the pathophysiology of schizophrenia and mood disorders in the Japanese population. A replication study using larger samples may be required for conclusive results, since our sample size was small and our study analyzed only three SNPs in MAGEL2.

Several recent investigations reported that the serotonin 2A receptor gene (HTR2A) was associated with selective serotonin reuptake inhibitors (SSRIs) in major depressive disorder. There have also been two reported association analyses of HTR2A with SSRI response in Japanese MDD patients, but the results were rather inconsistent and both studies had the problem of small sample sizes. Therefore, we conducted a replication association study using a sample larger than those in the two original Japanese studies (265 MDD patients), and found that four SNPs, two functional SNPs (-A1438G: rs6311 and T102C: rs6313) and two SNPs (rs7997012 and rs1928040) in HTR2A, were associated with the therapeutic response to SSRIs. HTR2A was associated with the therapeutic response SSRIs in Japanese MDD patients in a haplotype-wise analysis (P(all markers) = 0.0136), and a significant association between rs1928040 in HTR2A and SSRI response was detected in MDD (P(allele-wise analysis) = 0.0252). However, this significance disappeared after Bonferroni correction (P(allele-wise analysis) = 0.101). In conclusion, we suggest that HTR2A may play an important role in the pathophysiology of the therapeutic response to SSRIs in Japanese MDD patients. However, it will be important to replicate and confirm these findings in other independent studies using large samples.

Background: Several lines of evidence suggest that the dopaminergic nervous system contributes to methamphetamine (METH) dependence, and there is increasing evidence of antagonistic interactions between dopamine and adenosine receptors. We therefore hypothesized that variations in the A2A adenosine receptor (ADORA2A) gene modify genetic susceptibility to METH dependence/psychosis., Methods: We first analyzed variations in the exons and exon-intron boundaries of the ADORA2A gene in METH dependent/psychotic patients. Then an association analysis between these single nucleotide polymorphisms and METH dependence/psychosis was performed using a total of 171 METH dependent/psychotic patients and 229 controls., Results: We found 6 variations, of which one single nucleotide polymorphism (SNP) was novel. Significant associations were observed between the allelic and genotypic frequencies of the Exon2+751 (rs5751876) SNP and METH dependence/psychosis. These associations were observed especially in females. In the clinical feature analyses, significant associations were observed between the SNP and the patient subgroup using METH alone (i.e., without concomitant use of other substances of abuse)., Conclusions: These results suggest that the ADORA2A gene could be a vulnerability factor for METH dependence/psychosis, especially in females and/or in patients using only METH.

We examined the association of schizophrenia (SCZ) and dihydropyrimidinase-like 2 (DPYSL2), also known as collapsin response mediator protein 2, which regulates axonal growth and branching. We genotyped 20 tag single nucleotide polymorphisms (SNPs) in 1464 patients and 1310 controls. There were two potential associations in a screening population of 384 patients and 384 controls (rs2585458: P=0.046, rs4733048: P=0.014). However, we could not replicate these associations in a confirmatory population of 1080 patients and 926 controls (rs2585458: P=0.39, rs4733048: P=0.70) or a joint analysis (rs2585458: P=0.72, rs4733048: P=0.10). We conclude that DPYSL2 does not have a major function in SCZ in Japanese subjects.

Chromosome 22q13 region has been implicated in schizophrenia in several linkage studies. Genes within this locus are therefore promising genetic and biologic candidate genes for schizophrenia if they are expressed in the brain or predicted to have some role in brain development. A recent study reported that bromodomain-containing 1 gene (BRD1), located in 22q13, showed an association with schizophrenia in a Scottish population. Except for being a putative regulator of transcription, the precise function of BRD1 is not clear; however, expression analysis of BRD1 mRNA revealed widespread expression in mammalian brains. In our study, we explored the association of BRD1 with schizophrenia in a Japanese population (626 cases and 770 controls). In this association analysis, we first examined 10 directly genotyped single-nucleotide polymorphisms (SNPs) and 20 imputed SNPs. Second, we compared the BRD1 mRNA levels between cases and controls using lymphoblastoid cell lines (LCLs) derived from 29 cases and 30 controls. Although the SNP (rs138880) that previously has been associated with schizophrenia showed the same trend in the Japanese population, no significant association was detected between BRD1 and schizophrenia in our study. Similarly, no significant differences in BRD1 mRNA levels in LCLs were detected. Taken together, we could not strongly show that common SNPs in the BRD1 gene account for a substantial proportion of the genetic risk for schizophrenia in the Japanese population.

Several investigations have reported that the translin-associated factor X gene (TSNAX)/disrupted-in-schizophrenia-1 gene (DISC1) was associated with major psychiatric disorders including schizophrenia, bipolar disorder (BP), and major depressive disorder (MDD). TSNAX is located immediately upstream of DISC1, and has been shown to undergo intergenic splicing with DISC1. It thus may also be influenced by translocation. To our knowledge, there are no reported gene-based association analyses between TSNAX and mood disorders in the Japanese population. We conducted a case-control study of Japanese samples (158 bipolar patients, 314 major depressive disorder patients, and 811 controls) with three tagging SNPs in TSNAX, selected using HapMap database. In addition, we performed an association analysis between TSNAX and the efficacy of fluvoxamine treatment in 120 Japanese patients with MDD. The MDD patients in this study had scores of 12 or higher on the 17 items of the Structured Interview Guide for Hamilton Rating Scale for Depression (SIGH-D). We defined a clinical response as a decrease of more than 50% in baseline SIGH-D within 8 weeks, and clinical remission as an SIGH-D score of less than 7 at 8 weeks. We found an association between rs766288 in TSNAX and female MDD in the allele/genotype analysis. However, we did not find any association between TSNAX and BP or the fluvoxamine therapeutic response in MDD in the allele/genotype analysis or haplotype analysis. Our results suggest that rs766288 in TSNAX may play a role in the pathophysiology of female MDD in the Japanese population. A replication study using larger samples may be required for conclusive results, since our sample size was small.

Recently, ubiquitin-specific peptidase 46 (Usp46) has been identified as a quantitative trait gene responsible for immobility in the tail suspension test and forced swimming test in mice. Mice with 3-bp deletion in Usp46 exhibited loss of 'behavioral despair' under inescapable stresses in addition to abnormalities in circadian behavioral rhythms and the GABAergic system. Considering the face and construct validity as an animal model for bipolar disorder, we explored an association of USP46 and bipolar disorder in a Japanese population. We also examined an association of USP46 and schizophrenia. We found nominal evidence for an association of rs12646800 and schizophrenia. This association was not significant after correction for multiple testing. No significant association was detected for bipolar disorder. In conclusion, our data argue against the presence of any strong genetic susceptibility factors for bipolar disorder or schizophrenia in the region USP46.

To test the hypothesis that mitochondrial DNA (mtDNA) variants contribute to the susceptibility to schizophrenia, we sequenced the entire mtDNAs from 93 Japanese schizophrenic patients. Three non-synonymous homoplasmic variants in subunit six of the ATP synthase (MT-ATP6) gene that were detected only in patients but not in controls were suggested to be slightly deleterious, because (1) their original amino acid residues (AA) were highly conserved and (2) the physicochemical differences between the original and altered AA were relatively high. In addition, we detected three novel heteroplasmic variants that were potentially pathogenic. Although functional analysis is needed, rare variants in the mtDNA may convey susceptibility to schizophrenia.

The neuregulin 1 gene (NRG1) has been identified as a candidate gene for schizophrenia in a linkage study in the Icelandic population. Recent evidence also suggested that it might be related to the neurodevelopmental hypothesis and glutamate hypothesis for schizophrenia. Because the symptomatology of methamphetamine (METH) use disorder with accompanying psychosis is similar to that of patients with schizophrenia, NRG1 is an appropriate candidate gene for METH-induced psychosis. We conducted a case-control association study between NRG1 and METH-induced psychosis in a Japanese population (184 subjects with METH-induced psychosis and 534 controls). Written informed consent was obtained from each subject. We selected four SNPs (SNP8NRG221533, SNP8NRG241930, SNP8NRG243177, and rs3924999) in NRG1 from previous reports. No significant association was found between NRG1 and METH-induced psychosis in the allele/genotype-wise or haplotype-wise analyses. In conclusion, NRG1 might not contribute to the risk of METH-induced psychosis in the Japanese population.

Recently the clock genes have been reported to play some roles in neural transmitter systems, including the dopamine system, as well as to regulate circadian rhythms. Abnormalities in both of these mechanisms are thought to be involved in the pathophysiology of major mental illness such as schizophrenia and mood disorders including bipolar disorder (BP) and major depressive disorder (MDD). Recent genetic studies have reported that CLOCK, one of the clock genes, is associated with these psychiatric disorders. Therefore, we investigated the association between the six tagging SNPs in CLOCK and the risk of these psychiatric disorders in Japanese patients diagnosed with schizophrenia (733 patients), BP (149) and MDD (324), plus 795 Japanese controls. Only one association, with schizophrenia in females, was detected in the haplotype analysis (P = 0.0362). However, this significance did not remain after Bonferroni correction (P = 0.0724). No significant association was found with BP and MDD. In conclusion, we suggest that CLOCK may not play a major role in the pathophysiology of Japanese schizophrenia, BP and MDD patients. However, it will be important to replicate and confirm these findings in other independent studies using large samples.

Background: A recent study reported an association between rs2234693, which influences enhancer activity levels in estrogen receptor alpha gene (ESR1), and schizophrenia. This study reported that schizophrenic patients with the CC genotype have significantly lower ESR1 mRNA levels in the prefrontal cortex than patients with other genotypes. The symptoms of methamphetamine induced psychosis are similar to those of paranoid type schizophrenia. Therefore, we conducted an association analysis of rs2234693 with Japanese methamphetamine induced psychosis patients., Method: Using rs2234693, we conducted a genetic association analysis of case-control samples (197 methamphetamine induced psychosis patients and 197 healthy controls). The age and sex of the control subjects did not differ from those of the methamphetamine induced psychosis patients., Results: We detected a significant association between ESR1 and methamphetamine induced psychosis patients in allele/genotype-wise analysis. For further interpretation of these associations, we performed single marker analysis of subjects divided by sex. Rs2234693 was associated with male methamphetamine induced psychosis., Discussion: Our results suggest that rs2234693 in ESR1 may play a role in the pathophysiology of Japanese methamphetamine induced psychosis patients.

Background: Several lines of evidence implicate abnormalities in glutamate neural transmission in the pathophysiology of mood disorders, including major depressive disorder (MDD) and bipolar disorder (BP). Preclinical antidepressant effects were also reported for group II metabotropic glutamate receptor (Group II mGluRs) antagonists show dose-dependent antidepressant-like effects in murine models of depression. Also, it has been suggested that abnormalities in the hypothalamic-pituitary-adrenal axis and serotonergic neural transmission are important mechanisms in the pathophysiology of mood disorders. Group II mGluRs play an important role in regulating the function of these mechanisms. From these results, it has been suggested that abnormalities in Group II mGluRs might be involved in the pathophysiology of mood disorders, including MDD) and BP, and may influence the clinical response to treatment with SSRIs in MDD. Therefore, we studied the association between Group II mGluR genes (GRM2 and GRM3) and mood disorders and the efficacy of fluvoxamine treatment in Japanese MDD patients., Materials and Methods: Using three tagging SNPs in GRM2 and an SNP (rs6465084) reported functional variant in GRM3, we conducted a genetic association analysis of case-control samples (325 MDD patients, 155 BP patients and 802 controls) in the Japanese population. In addition, we performed an association analysis of GRM2 and GRM3 and the efficacy of fluvoxamine treatment in 117 Japanese patients with MDD. The MDD patients in this study had scores of 12 or higher on the 17 items of the Structured Interview Guide for Hamilton Rating Scale for Depression (SIGH-D). We defined a clinical response as a decrease of more than 50% in baseline SIGH-D within 8 weeks, and clinical remission as an SIGH-D score of less than 7 at 8 weeks., Results: We found an association between rs6465084 in GRM3 and MDD in the allele-wise analysis after Bonferroni's correction (P-value=0.0371). However, we did not find any association between GRM3 and BP or the fluvoxamine therapeutic response in MDD in the allele/genotype-wise analysis. We also did not detect any association between GRM2 and MDD, BP or the fluvoxamine therapeutic response in MDD in the allele/genotype-wise or haplotype-wise analysis., Discussion: We detected an association between only one marker (rs6465084) in GRM3 and Japanese MDD patients. However, because we did not perform an association analysis based on LD and a mutation scan of GRM3, a replication study using a larger sample and based on LD may be required for conclusive results.

Because several investigations, including genetic studies, have reported associations between serotonin (5-HT) 2A receptor gene and mood disorders, 5-HT 2A receptor gene (HTR2A) is a good candidate gene for the pathophysiology of mood disorders such as major depressive disorder (MDD) and bipolar disorder (BP). Using two functional SNPs (T102C and -A1438G) and two SNPs (rs7997012 and rs1928040) in HTR2A, which reported an association with therapeutic response to the SSRI, we conducted a genetic association analysis of case-control samples (325 MDD patients, 155 BP patients and 802 controls) in the Japanese population. We did not detect significant an association of HTR2A with MDD and BP in allele/genotype-wise or haplotype-wise analysis. In this study, we could detect no evidence of genetic association between 4 markers near HTR2A and mood disorders in the Japanese population, but sample sizes, especially BP, were probably too small to allow a meaningful test.

G72 is one of the most widely tested genes for association with schizophrenia. As G72 activates the D-amino acid oxidase (DAO), G72 is termed D-amino acid oxidase activator (DAOA). The aim of this study is to investigate the association between G72 and schizophrenia in a Japanese population, using the largest sample size to date (1774 patients with schizophrenia and 2092 healthy controls). We examined eight single nucleotide polymorphisms (SNPs), which had been associated with schizophrenia in previous studies. We found nominal evidence for association of alleles, M22/rs778293, M23/rs3918342 and M24/rs1421292, and the genotype of M22/rs778293 with schizophrenia, although there was no association of allele or genotype in the other five SNPs. We also found nominal haplotypic association, including M15/rs2391191 and M19/rs778294 with schizophrenia. However, these associations were no longer positive after correction for multiple testing. We conclude that G72 might not play a major role in the risk for schizophrenia in the Japanese population.

Accumulating evidence suggests that phosphatidylinositol (PI) pathways have been involved in the secretion of dopamine (DA) and the regulation of DA transporter, which is a target of methamphetamine (METH). A recent large-scale gene-association study in a Dutch population demonstrated that the PIK4CA gene was closely linked to schizophrenia [Jungerius et al. (2007); Mol Psychiatry]. Here, we conducted a case (N = 232)-control (N = 233) study of the PIK4CA gene on Japanese METH abusers, which can manifest severe psychosis similar to schizophrenia. The genotype and allelic distributions of all four single nucleotide polymorphisms (SNPs) did not differ significantly between the METH abusers and the controls. The comparisons based on the classification of the psychosis as transient or prolonged and on the presence or absence of spontaneous relapse revealed no significant distribution of the four SNPs compared to the controls. Furthermore, haplotype analyses showed almost the same frequencies between the METH abusers and the controls. The present study suggests that the PIK4CA gene does not play a significant role in the vulnerability to METH use disorder in the Japanese population., (2008 Wiley-Liss, Inc.)

The neuronal nitric oxide synthase gene (NOS1) is located on 12q24, in a susceptibility region for schizophrenia, and produces nitric oxide (NO) in the brain. NO plays a role in neurotransmitter release and is the second messenger of the N-methyl-D-aspartate (NMDA) receptor. Furthermore, it is connected to the dopaminergic and serotonergic neural transmission systems. Therefore, abnormalities in the NO pathway are thought to be involved in the pathophysiology of schizophrenia. Several genetic studies showed an association of NOS1 with schizophrenia. However, results of replication studies have been inconsistent. Therefore, we conducted a replication study of NOS1 with schizophrenia in a Japanese sample. We selected seven SNPs (rs41279104, rs3782221, rs3782219, rs561712, rs3782206, rs2682826, and rs6490121) in NOS1 that were positively associated with schizophrenia in previous studies. Two SNPs showed an association with Japanese schizophrenic patients (542 cases and 519 controls, rs3782219: P allele = 0.0291 and rs3782206: P allele = 0.0124, P genotype = 0.0490), and almost these significances remained with an increased sample size (1154 cases and 1260 controls, rs3782219: P allele = 0.0197 and rs3782206: P allele = 0.0480). However, these associations also might have resulted from type I error on account of multiple testing (rs3782219: P allele = 0.133 and rs3782206: P allele = 0.168). In conclusion, we could not replicate the association between seven SNPs in NOS1 and schizophrenia found in several earlier studies, using larger Japanese schizophrenia and control samples.

Recent studies have shown that selective serotonin reuptake inhibitors (SSRIs) have circadian properties, suggesting that the antidepressive action of SSRIs may also be attributable to circadian mechanisms. Another study reported an association between clock gene (CLOCK) and improvements in insomnia symptoms from SSRIs treatment. Therefore, we examined the association between CLOCK and the efficacy of fluvoxamine treatment in 121 patients with Japanese major depressive disorder (MDD). The MDD patients in this study had scores of 12 or higher on the 17 items of the Structured Interview Guide for Hamilton Rating Scale for Depression (SIGH-D). We defined a therapeutic response as a decrease of more than a 50% in baseline SIGH-D within 8 weeks, and clinical remission as a SIGH-D score of less than seven at 8 weeks. We selected three tagging SNPs in CLOCK for the subsequent statistical association analysis. We detected a significant association between rs3736544, a synonymous polymorphism in exon 20, and the fluvoxamine therapeutic response in MDD in the allele/genotype-wise analyses. In addition, remission with fluvoxamine was also significantly associated with rs3736544. These associations remained significant after Bonferroni correction. Moreover, haplotype analysis findings supported these significant associations, which appeared to be due mainly to rs3736544, in the fluvoxamine therapeutic remission. Our results indicate that CLOCK genotype may be a predictor of fluvoxamine treatment response in Japanese MDD. However, our sample size was small, and a replication study using larger samples may be required for conclusive results.

Several investigations have suggested that disruption of circadian rhythms may provide the foundation for the development of mood disorders such as bipolar disorder (BP) and major depressive disorder (MDD). Recent animal studies reported that prokineticin 2 or prokineticin 2 receptor gene deficient mice showed disruptions in circadian and homeostatic regulation of sleep. This evidence indicates that prokineticin 2 gene (PROK2) and prokineticin 2 receptor gene (PROKR2) are good candidate genes for the pathogenesis of mood disorders. To evaluate the association between PROK2, PROKR2, and mood disorders, we conducted a case-control study of Japanese samples (151 bipolar patients, 319 major depressive disorder patients, and 340 controls) with four and five tagging SNPs in PROK2 or PROKR2, respectively, selected by HapMap database. We detected a significant association between PROKR2 and major depressive disorder and bipolar disorder in the Japanese population. In conclusion, our findings suggest that PROKR2 may play a role in the pathophysiology of mood disorders in the Japanese population. However, because our samples were small, it will be important to replicate and confirm these findings in other independent studies using larger samples.

The mesolimbic system is thought to be involved in the reinforcing action of many addictive drugs and the release of dopamine modulated by neuronal nicotine cholinergic receptors (nAChRs). Several investigations suggested that nAChRs on dopaminergic terminals play an important role in the development of some long-lasting adaptations associated with drug abuse. A majority of high-affinity nicotine binding sites in the brain have been showed in heteropentameric alpha4 (alpha4) and beta2 subunit (beta2) of nAChRs. Therefore, we conducted a genetic association analysis of the alpha4 gene (CHRNA4) and beta2 gene (CHRNB2) with methamphetamine (METH)-use disorder (191 cases and 753 controls). We first evaluated the linkage disequilibrium (LD) structure of these genes and selected 7 and 5 tagging SNPs (tag SNPs) on CHRNA4 and CHRNB2, respectively. Some tag SNPs were significantly associated with total METH-use disorder and METH-induced psychosis; however, these associations were no longer statistically significant after Bonferroni's correction for multiple testing. In conclusion, our results suggest that neither CHRNA4 nor CHRNB2 plays a major role in Japanese METH-use disorder.

Abnormal intracellular signaling molecules in dopamine signal transduction are thought to be associated with the pathophysiology of methamphetamine (METH)-use disorder. A recent study reported that a new intracellular protein, prostate apoptosis response 4 (Par-4), plays a critical role in dopamine 2 receptor signaling. We therefore analyzed the association between the Par-4 gene (PAWR) and METH-use disorder in a Japanese population (191 patients with METH-use disorder and 466 healthy controls). Using the recommended "gene-based" association analysis, we selected five tagging SNPs in PAWR from the HapMap database. No significant allele/genotype-wise or haplotype-wise association was found between PAWR and METH-use disorder. These results suggest that PAWR does not play a major role in METH-use disorders in the Japanese population.

A recent study showed a significant association between schizophrenia in European samples and the glutamate cysteine ligase modifier (GCLM) subunit gene, which is the key glutathione (GSH)-synthesizing enzyme. Since the symptoms of methamphetamine (METH)-induced psychosis are similar to those of schizophrenia, the GCLM gene is thought to be a good candidate gene for METH-use disorder or related disorders. To evaluate the association between the GCLM gene and METH-use disorder and schizophrenia, we conducted a case-control study of Japanese subjects (METH-use disorder, 185 cases; schizophrenia, 742 cases; and controls, 819). Four SNPs (2 SNPs from an original report and JSNP database, and 2 "tagging SNPs" from HapMap database) in the GCLM gene were examined in this association analysis; one SNP showed an association with both METH-use disorder and METH-induced psychosis. After Bonferroni's correction for multiple testing, however, this significance disappeared. No significant association was found with schizophrenia. Our findings suggest that a common genetic variation in the GCLM gene might not contribute to the risk of METH-use disorder and schizophrenia in the Japanese population.

Several lines of evidence from animal and genetic analyses showed that the calcineurin A gamma subunit gene (PPP3CC) plays an important role in the pathogenesis of schizophrenia. Moreover, a recent large Japanese case-control study confirmed the genetic association of PPP3CC with schizophrenia. The symptoms of methamphetamine (MAP)-induced psychosis are similar to those of schizophrenia, suggesting that PPP3CC is an attractive candidate gene not only for schizophrenia, but also for METH-related disorders. In this study, we carried out a genetic association study of PPP3CC with MAP-use disorder in a Japanese population. We selected five haplotype-tagging SNPs from the aforementioned replication study and genotyped 393 samples (MAP abuse, 128; control, 265). We could not detect a significant association of all tagging SNPs with each condition. In conclusion, our data suggest that PPP3CC does not elevate the risk of MAP-use disorder in the Japanese population.

Genetic factors are thought to be involved in the development of treatment-resistant schizophrenia (TRS). Since several antipsychotic drugs inhibit the release of neurotransmitters via the serotonin receptors 3 (5-HT3), a dysfunction of this kind of receptor might be associated with the development of TRS. Thus, single-marker and haplotype analyses of the tag-single nucleotide polymorphisms (SNPs) of the 5-HT3B subunit gene (HTR3B) were performed in TRS (n = 101) and non-TRS (n = 244) patients. The deletion allele at the 3 bp-insertion/deletion polymorphism site (-100&#95;-102delAAG) located in the putative HTR3B promoter region is significantly more frequent in the TRS group than the insertion allele by a single-marker comparison (p = 0.031). In addition, luciferase promoter assays showed that the deletion allele exhibited significantly higher transcriptional activity than the insertion allele in COS7 cells (p < 0.05). These results suggest that HTR3B is involved in the development of TRS in the Japanese population.

Several lines of evidence, including genome-wide linkage scans and postmortem brain studies of patients with schizophrenia or bipolar disorder, have suggested that DARPP-32 (dopamine- and cAMP-regulated phosphoprotein, 32 kDa), a key regulatory molecule in the dopaminergic signaling pathway, is involved in these disorders. After evaluating the linkage disequilibrium pattern of the gene encoding DARPP-32 (PPP1R1B; located on 17q12), we conducted association analyses of this gene with schizophrenia and bipolar disorder. Single-marker and haplotypic analyses of four single nucleotide polymorphisms (SNPs; rs879606, rs12601930, rs907094, and rs3764352) in a sample set (subjects with schizophrenia=384, subjects with bipolar disorder=318, control subjects=384) showed that PPP1R1B polymorphisms were not significantly associated with schizophrenia, whereas, even after Bonferroni corrections, significant associations with bipolar disorder were observed for rs12601930 (corrected genotypic p=0.00059) and rs907094 (corrected allelic p=0.040). We, however, could not confirm these results in a second independent sample set (subjects with bipolar disorder=366, control subjects=370). We now believe that the significant association observed with the first sample set was a result of copy number aberrations in the region surrounding these SNPs. Our findings suggest that PPP1R1B SNPs are unlikely to be related to the development of schizophrenia and bipolar disorder in the Japanese population.

Postmortem studies regarding schizophrenia revealed altered expression of genes related to gamma-amino butyric acid neurotransmission system. One of the most consistent findings is the reduced level of 67 kDa glutamic acid decarboxylase isoform (GAD(67)). Moreover, several studies reported positive associations between the GAD(67) gene (GAD1) and schizophrenia. These reasons, motivated us to carry out replication study regarding association between GAD1 (fourteen tagging SNPs) and schizophrenia in Japanese population (562 schizophrenic patients and 470 controls). However we couldn't confirm significant association that had been previously reported. Considering size of our sample and strategy that corresponds well with the approaches used in gene-based association analysis, our conclusion is that GAD1 does not play a major role in schizophrenia in Japanese population.

The regulator of the G-protein signaling 4 (RGS4) has been implicated in the susceptibility to schizophrenia. RGS4 interacts with ErbB3 that acts as receptors for neuregulin 1 and these proteins may play a role in the pathogenesis of schizophrenia via glutamatergic dysfunction. Recently, two meta-analysis studies provided different interpretations for the genetic association between RGS4 and schizophrenia. We attempted to confirm this association in a case-control study of 1918 Japanese patients with schizophrenia and 1909 Japanese control subjects. Four widely studied single nucleotide polymorphisms (SNPs) were genotyped, and none showed association with schizophrenia. SNP 1 (rs10917670), p=0.92; SNP 4 (rs951436), p=0.91; SNP 7 (rs951439), p=0.27; and SNP 18 (rs2661319), p=0.43. A haplotype block constructed by these SNPs spans the 5' flanking region to the 5' mid-region of the RGS4 gene. Previous meta-analysis showed that both two major haplotypes of this block were risk haplotypes. The two common haplotypes were observed in the Japanese population. However, neither haplotype was significantly associated with schizophrenia. We conclude that the common haplotypes and SNPs of the RGS4 gene identified thus far are unlikely to contribute to the genetic susceptibility to schizophrenia in the Japanese population.

Several lines of evidence suggest that disturbance of myelin-related genes is associated with the etiology of schizophrenia. Recently, the 2',3'-cyclic nucleotide 3'-phosphodiesterase (CNP) gene and the oligodendrocyte lineage transcription factor 2 (OLIG2) gene were reported to be related to the development of schizophrenia, based on the results of genetic association and microarray studies. In the present study, no significant association with schizophrenia was observed by single-marker or haplotype analysis for 6 tag SNPs of these genes (759 cases, 757 controls). These findings suggest that CNP and OLIG2 are unlikely to be related to the development of schizophrenia in the Japanese population.

Several investigations suggest that complexin may be a schizophrenia-susceptibility factor. We conducted a genetic association analysis between complexin genes (CPLX1 and CPLX2) and schizophrenia in Japanese patients (377 cases and 341 controls). Ten and eleven haplotype-tagging (ht)SNPs in CPLX1 and CPLX2, respectively, were selected. Only one htSNP (rs930047 in CPLX2) in allele-wise analysis showed significance, and even this disappeared with an increased sample size (563 cases and 519 controls: P = .757). Haplotype-wise analysis showed a weak association with a combination of htSNPs in CPLX2 (P = .0424), but this may be a result of type I error due to multiple testing. Our results suggest that complexin genes do not play a major role in schizophrenia in Japanese patients.

Recent study of linkage disequilibrium mapping showed one of the trace amine receptor (TRAR) genes, TRAR4, was associated with schizophrenia. We conducted a replication study of TRAR4 with schizophrenia in Japanese patients. We used two large independent sets of samples in a first-set analysis (cases=405, controls=401) and second-set analysis (cases=503, controls=440). In the first-set analysis, one Marker (Marker5) showed a significant association, but this significance was not seen in the second-set analysis. Our results indicate that TRAR4 may not play a major role in Japanese schizophrenia patients, and that it is important to examine the possibility of false positives in genetic association analysis.

Background: Abnormality of the V-akt murine thymoma viral oncogene homologue 1 (AKT1) may be a predisposing factor in schizophrenia. Recent evidence supporting this hypothesis showed decreased AKT1 protein levels in patients with schizophrenia and significant association of AKT1 haplotypes according to the transmission disequilibrium test., Methods: We provide the first replication of this evidence using a relatively large case-control sample (507 Japanese schizophrenia and 437 control subjects). We genotyped five single nucleotide polymorphisms (SNPs) from the original study and one additional SNP., Results: We found a positive association with an SNP (SNP5) different from the original study's findings (SNP3) and also significance in the haplotypes constructed from the combination of SNP5. Linkage disequilibrium around SNP5 was complex and may produce this positive association., Conclusions: Our study provides support for the theory that AKT1 is a susceptibility gene for Japanese schizophrenia. Fine linkage disequilibrium mapping is required for a conclusive result.

It has been suggested that individual genetic factors are involved in susceptibility to drug dependence and the manifestation of drug-induced psychosis. The aim of this study was to examine the relation between methamphetamine abusers/psychosis and the type 1 sigma receptor gene polymorphisms. Subjects comprised 143 MAP abusers and 181 healthy controls. Two polymorphisms in the type 1 sigma receptor gene, GC-241-240TT and A61C (Gln2Pro), were examined in the present study. No significant differences were observed in either polymorphism between healthy controls and MAP abusers/psychosis. In the subgroup analyses, the rate of CC genotype of A61C tended to be higher in MAP patients who had experienced spontaneous relapse without MAP use than in those who had not (P = .06, OR = 3.02 95%CI = 0.92-9.92). However, the level of this significant trend did not remain after the Bonferroni's multiple correction. This study suggests that type 1 sigma receptor gene is unlikely to play a major role in substance abuse liability and/or the development of MAP psychosis.

In the central nervous system, tissue-plasminogen activator (t-PA)/plasmin system is involved in long-term synaptic plasticity and remodeling, and participates in rewarding effects of methamphetamine (MAP), by acutely regulating MAP-induced dopamine release in the nucleus accumbens. The aim of this study was to examine the relationships between the patients with MAP abusers/psychosis and the t-PA/plasminogen system genes. Subjects comprised 185 MAP abusers and 288 healthy controls. Four polymorphisms in the t-PA, plasminogen activator inhibitor, and plasminogen genes were examined in the present study. No significant differences were observed in each polymorphism between healthy controls and MAP abusers/psychosis. This study suggests that t-PA/plasminogen system is unlikely to be a major contributor to the substance abuse liability and/or the development of MAP psychosis.