Analysis of common genetic variants identifies RELN as a risk gene for schizophrenia in Chinese population.

UNLABELLED: Abstract Objectives. Several lines of evidence have shown that both RELN mRNA and protein are possibly down-regulated in the brain of schizophrenia patients. Recent association studies in European populations suggested RELN as a risk gene for schizophrenia. In this study, we test if RELN contributes to the risk of schizophrenia in Chinese population. Methods. We conducted case-control association analysis of 19 representative single nucleotide polymorphisms (SNPs) spanning the entire region of RELN in two independent Han Chinese samples from southwestern China (the Kunming sample and the Yuxi sample). Results. We identified six SNPs significantly associated with schizophrenia in the Kunming sample and four of them remained significant in the combined samples (the P values range from 0.006 to 4.0 × 10(-5)). Haplotype analysis also suggested significant associations for the haplotypes incorporating the six significant SNPs (global P < 1.0 × 10(-5)). Additionally, we also observed several other haplotypes (defined by a different set of SNPs) significantly associated with schizophrenia in the Kunming sample. However, the reported association of rs7341475 in Ashkenazi Jews was not significant in Han Chinese. CONCLUSIONS: Our findings demonstrate that RELN is a susceptibility gene for schizophrenia in Chinese population, and it is likely a common risk gene for schizophrenia in major populations worldwide.

ZNF804A and schizophrenia susceptibility in Asian populations.

ZNF804A, a recently identified risk gene for schizophrenia, has been extensively investigated and the principle finding for this locus has been the association with SNP rs1344706 in populations of European ancestries. However, in Asian populations, only a few studies have been conducted for rs1344706 and the results were inconsistent. Here, we studied rs1344706 and schizophrenia susceptibility in multiple Asian case-control samples (10 Chinese and 2 Japanese samples; N = 21,062), and the meta-analyses indicated non-significant association of rs1344706 with schizophrenia (P = 0.26), suggesting the same SNP identified in European samples is not predisposing risk in Asians. Further genotyping and association analyses of a set of SNPs spanning the entire genomic region of ZNF804A (520 kb) identified no association except for SNP rs359895 (P = 7.8 x 10(-5) , N = 5,172), a newly reported risk SNP located in the ZNF804A promoter region with functional implications. This suggests that ZNF804A may also contribute to schizophrenia susceptibility in Asians although the risk SNP is different from that in Europeans, and it was supported by the detected up-regulation of ZNF804A mRNA expression in the blood cells of Chinese schizophrenia patients compared with normal controls (P = 0.004). Additionally, the linkage disequilibrium (LD) structure analyses using data from HapMap indicated distinct LD blocks across ZNF804A between Chinese and Europeans, which may explain the different association patterns between them, and also highlight the compounding difficulty of genetic studies of complex diseases like schizophrenia when studying multiple ethnic populations.

Association of RELN promoter SNPs with schizophrenia in the Chinese population.

Previous research on gene expression analysis and association tests have suggested that RELN is a risk gene for schizophrenia in world populations. Based on the reported down-regulation of RELN in schizophrenia patients compared with normal subjects, we speculated that variants in the RELN promoter region may confer risk for schizophrenia. In this study, we investigated the associations of three SNPs in the promoter region of RELN with schizophrenia in a case-control sample from southwestern China (940 cases and 1 369 controls). The results suggested that none of the SNPs showed significant associations in our sample, indicating the risk variants for schizophrenia in RELN may not be located in the promoter region. We also performed meta-analysis by combining our data with previously reported data on the Chinese population with a total sample size of 2 843 individuals, and the result remained non-significant. Collectively, our results suggested variants in the RELN promoter may not harbor risk SNPs associated with schizophrenia in the Chinese population.

Genetic association and identification of a functional SNP at GSK3ß for schizophrenia susceptibility.

OBJECTIVE: GSK3ß is a key gene in neurodevelopment, and also an important target of antipsychotics. Several lines of evidence including association and gene expression studies have suggested GSK3ß as a susceptibility gene for schizophrenia, but the underlying genetic mechanism is still unknown. In this study, we test whether the genetic variants in GSK3ß contribute to the risk of schizophrenia in Chinese population. METHODS: We first conducted an association analysis of 9 representative SNPs spanning the entire genomic region of GSK3ß in two independent Han Chinese case-control samples from southwestern China (the Kunming sample and the Yuxi sample, a total of 2550 subjects).Then using EMSA and reporter gene assays, we tested the functional impact of the identified risk SNP on transcriptional factor binding affinity and promoter activity. RESULTS: We observed weak allelic associations of three GSK3ß SNPs (rs3755557, rs7431209 and rs13320980) with schizophrenia in the combined Han Chinese samples. Further analysis using genotypes (under recessive genetic model) supported the association of rs3755557 (p = 0.01, corrected), which is located in the GSK3ß promoter region. The functional assays demonstrated that the risk SNP (rs3755557) could influence the transcription factor binding affinities, resulting in a higher promoter activity of the risk allele. CONCLUSION: Our findings suggest that GSK3ß is likely a risk gene for schizophrenia, and its expression alteration caused by the risk SNP in the promoter region may contribute to the etiology of schizophrenia.

Allelic differences between Han Chinese and Europeans for functional variants in ZNF804A and their association with schizophrenia.

OBJECTIVE: ZNF804A is a schizophrenia risk gene that was recently identified by genome-wide association studies as well as subsequent replications. Although the results are consistent among studies in European populations, there have been conflicting reports in Chinese populations. The authors conducted both association and functional analyses to test whether ZNF804A is a risk gene for schizophrenia in Chinese populations. METHOD: The authors recruited two case-control samples of independent Han Chinese (a total of 2,207 participants) from southwestern China. A total of six single-nucleotide polymorphisms (SNPs), including the key SNP (rs1344706) that showed significant association with schizophrenia in European populations and the other five promoter SNPs of ZNF804A, were tested. Based on the results of the association analysis, the authors performed two functional assays to test the impact of the risk SNP on transcriptional factor binding affinity and promoter activity. RESULTS: The SNP rs1344706 was not associated with schizophrenia in either of the two Han Chinese groups, and this result was confirmed by meta-analyses in five Han Chinese samples. However, the authors identified two ZNF804A promoter SNPs that were significantly associated with schizophrenia in both samples, and the significance was strengthened in the combined samples and further supported by haplotype analysis. The functional assays demonstrated that the risk SNP (rs359895) can influence Sp1 binding affinity, resulting in a higher promoter activity of the risk allele. CONCLUSIONS: Our results suggest that ZNF804A is a common risk gene for schizophrenia in world populations and that the newly identified functional SNP (rs359895) is likely a risk SNP for schizophrenia.