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Genome-wide association studies (GWASs) have identified >100 susceptibility loci for schizophrenia (SCZ) and demonstrated that SCZ is a polygenic disorder determined by numerous genetic variants but with small effect size. We conducted a GWAS in the Japanese (JPN) population (a) to detect novel SCZ-susceptibility genes and (b) to examine the shared genetic risk of SCZ across (East Asian [EAS] and European [EUR]) populations and/or that of trans-diseases (SCZ, bipolar disorder [BD], and major depressive disorder [MDD]) within EAS and between EAS and EUR (trans-diseases/populations). Among the discovery GWAS subjects (JPN-SCZ GWAS: 1940 SCZ cases and 7408 controls) and replication dataset (4071 SCZ cases and 54479 controls), both comprising JPN populations, 3 novel susceptibility loci for SCZ were identified: SPHKAP (Pbest = 4.1 × 10-10), SLC38A3 (Pbest = 5.7 × 10-10), and CABP1-ACADS (Pbest = 9.8 × 10-9). Subsequent meta-analysis between our samples and those of the Psychiatric GWAS Consortium (PGC; EUR samples) and another study detected 12 additional susceptibility loci. Polygenic risk score (PRS) prediction revealed a shared genetic risk of SCZ across populations (Pbest = 4.0 × 10-11) and between SCZ and BD in the JPN population (P ~ 10-40); however, a lower variance-explained was noted between JPN-SCZ GWAS and PGC-BD or MDD within/across populations. Genetic correlation analysis supported the PRS results; the genetic correlation between JPN-SCZ and PGC-SCZ was ρ = 0.58, whereas a similar/lower correlation was observed between the trans-diseases (JPN-SCZ vs JPN-BD/EAS-MDD, rg = 0.56/0.29) or trans-diseases/populations (JPN-SCZ vs PGC-BD/MDD, ρ = 0.38/0.12). In conclusion, (a) Fifteen novel loci are possible susceptibility genes for SCZ and (b) SCZ "risk" effect is shared with other psychiatric disorders even across populations., (© The Author(s) 2018. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objective: Worldwide use of the Hamilton Rating Scale for Depression (HRSD) presupposes that depression symptomatology can be measured the same way across countries but no empirical study has yet examined this issue. We therefore examined cross-cultural consistency of factor structure of HRSD., Method: A 17-item HRSD data were sought for 5,185 individuals diagnosed with major depression in Japan, Europe and North America. Candidate factor structures were obtained with simultaneous component analysis (SCA) across the three cultures. They were then submitted to multiple-group confirmatory factor analysis (CFA)., Results: According to SCA, 3-, 4- or 5-factor solutions were found to optimally and adequately summarize the variables for all the three populations. When submitted to CFA, the 5-factor solution was the best fitting and the most parsimonious: they were 'anhedonia/retardation,''guilt/agitation,''bodily symptoms,''insomnia' and 'appetite.', Conclusion: Common underlying factors exist for HRSD among Japanese, European and American patients with major depression.

Objective: Most prevalence studies of seasonal changes in mood and behavior have come from Western countries. The authors' goal was to determine the prevalence of seasonal changes in mood and behavior in a randomly selected group of Japanese workers., Method: They administered a Japanese translation of the Seasonal Pattern Assessment Questionnaire to 1,276 civil servants in Nagoya, Japan., Results: The estimated prevalence of winter seasonal affective disorder was 0.86%, the estimated prevalence of winter subsyndromal seasonal affective disorder was 0.86%, the estimated prevalence of summer seasonal affective disorder was 0.94%, and the estimated prevalence of summer subsyndromal seasonal affective disorder was 2.12%., Conclusions: The authors conclude that seasonal changes in mood and behavior occur in Japan, but at a lower frequency and with a different profile than in the United States or Europe.