ZNF804A and schizophrenia susceptibility in Asian populations

Polymorphism in the ZNF804A Gene and Variation in D1 and D2/D3 Dopamine Receptor Availability in the Healthy Human Brain: A Dual Positron Emission Tomography Study

BACKGROUND

The rs1344706 single nucleotide polymorphism in the ZNF804A gene has been associated with risk for psychosis in multiple genome-wide association studies, yet mechanisms underlying this association are not known. Given preclinical work suggesting an impact of ZNF804A on dopamine receptor gene transcription and clinical studies establishing dopaminergic dysfunction in patients with schizophrenia, we hypothesized that the ZNF804A risk single nucleotide polymorphism would be associated with variation in dopamine receptor availability in the human brain.

METHODS

In this study, 72 healthy individuals genotyped for rs1344706 completed both [18F]fallypride and [11C]NNC-112 positron emission tomography scans to measure D2/D3 and D1 receptor availability, respectively. Genetic effects on estimates of binding potential for each ligand were tested first with canonical subject-specific striatal regions of interest analyses, followed by exploratory whole-brain voxelwise analyses to test for more localized striatal signals and for extrastriatal effects.

RESULTS

Region of interest analyses revealed significantly less D2/D3 receptor availability in risk-allele homozygotes (TT) compared with non-risk allele carriers (G-allele carrier group: TG and GG) in the associative striatum and sensorimotor striatum, but no significant differences in striatal D1 receptor availability.

CONCLUSIONS

These data suggest that ZNF804A genotype may be meaningfully linked to dopaminergic function in the human brain. The results also may provide information to guide future studies of ZNF804A-related mechanisms of schizophrenia risk.

Ethnicity-dependent effects of Zinc finger 804A variant on schizophrenia: a systematic review and meta-analysis

OBJECTIVES

Previous studies and meta-analysis indicated that rs1344706 was associated with schizophrenia in European population, whereas the conclusions in other populations were disputed. To further explore whether the allele A of rs1344706 would increase the risk of schizophrenia in different populations and update the original meta-analysis, we conducted a systematic review and meta-analysis worldwide.

METHODS

A literature search was performed in PubMed, Embase, Cochrane Library, PsycINFO and Web of Science (up to 10 July 2019) according to the inclusion criteria.

RESULTS

A total of 27 articles were included. Our meta-analysis showed an association between rs1344706 and schizophrenia in total populations [P = 0.000; odds ratio (OR) = 1.105; 95% confidence interval (CI), 1.048-1.165], Europe population (P = 0.025; OR = 1.108; 95% CI, 1.013-1.222) and Asian population(P = 0.005; OR = 1.094; 95% CI, 1.027-1.164).

CONCLUSIONS

Our findings suggested that the risk of single nucleotide polymorphism rs1344706 A-allele may increase the risk of schizophrenia worldwide. Also, this ethnicity-dependent effects of ZNF804A variant on schizophrenia may be related to the opposite allele direction. But to elucidate the underlying biological mechanism, further studies with large participant populations are needed.

ZFP804A mutant mice display sex-dependent schizophrenia-like behaviors

Genome-wide association studies uncovered the association of ZNF804A (Zinc-finger protein 804A) with schizophrenia (SZ). In vitro data have indicated that ZNF804A might exert its biological roles by regulating spine and neurite morphogenesis. However, no in vivo data are available for the role of ZNF804A in psychiatric disorders in general, SZ in particular. We generated ZFP804A mutant mice, and they showed deficits in contextual fear and spatial memory. We also observed the sensorimotor gating impairment, as revealed by the prepulse inhibition test, but only in female ZFP804A mutant mice from the age of 6 months. Notably, the PPI difference between the female mutant and control mice was no longer existed with the administration of Clozapine or after the ovariectomy. Hippocampal long-term potentiation was normal in both genders of the mutant mice. Long-term depression was absent in male mutants, but facilitated in the female mutants. Protein levels of hippocampal serotonin-6 receptor and GABAB1 receptor were increased, while those of cortical dopamine 2 receptor were decreased in the female mutants with no obvious changes in the male mutants. Moreover, the spine density was reduced in the cerebral cortex and hippocampus of the mutant mice. Knockdown of ZFP804A impaired the neurite morphogenesis of cortical and hippocampal neurons, while its overexpression enhanced neurite morphogenesis only in the cortical neurons in vitro. Our data collectively support the idea that ZFP804A/ZNF804A plays important roles in the cognitive functions and sensorimotor gating, and its dysfunction may contribute to SZ, particularly in the female patients.

ZNF804A Variation May Affect Hippocampal-Prefrontal Resting-State Functional Connectivity in Schizophrenic and Healthy Individuals

The ZNF804A variant rs1344706 has consistently been associated with schizophrenia and plays a role in hippocampal-prefrontal functional connectivity during working memory. Whether the effect exists in the resting state and in patients with schizophrenia remains unclear. In this study, we investigated the ZNF804A polymorphism at rs1344706 in 92 schizophrenic patients and 99 healthy controls of Han Chinese descent, and used resting-state functional magnetic resonance imaging to explore the functional connectivity in the participants. We found a significant main effect of genotype on the resting-state functional connectivity (RSFC) between the hippocampus and the dorsolateral prefrontal cortex (DLPFC) in both schizophrenic patients and healthy controls. The homozygous ZNF804A rs1344706 genotype (AA) conferred a high risk of schizophrenia, and also exhibited significantly decreased resting functional coupling between the left hippocampus and right DLPFC (F(2,165) = 13.43, P < 0.001). The RSFC strength was also correlated with cognitive performance and the severity of psychosis in schizophrenia. The current findings identified the neural impact of the ZNF804A rs1344706 on hippocampal-prefrontal RSFC associated with schizophrenia.

The genome-wide associated candidate gene ZNF804A and psychosis-proneness: Evidence of sex-modulated association

BACKGROUND

The Zinc finger protein 804A (ZNF804A) is a promising candidate gene for schizophrenia and the broader psychosis phenotype that emerged from genome-wide association studies. It is related to neurodevelopment and associated to severe symptoms of schizophrenia and alterations in brain structure, as well as positive schizotypal personality traits in non-clinical samples. Moreover, a female-specific association has been observed between ZNF804A and schizophrenia.

AIM

The present study examined the association of two ZNF804A polymorphisms (rs1344706 and rs7597593) with the positive dimension of schizotypy and psychotic-like experiences in a sample of 808 non-clinical subjects. Additionally, we wanted to explore whether the sexual differences reported in schizophrenia are also present in psychosis-proneness.

RESULTS

Our results showed an association between rs7597593 and both schizotypy and psychotic-like experiences. These associations were driven by females, such those carrying the C allele had higher scores in the positive dimension of both variables compared to TT allele homozygotes.

CONCLUSION

The findings of the present study support the inclusion of ZNF804 variability in studies of the vulnerability for the development of psychopathology in non-clinical samples and consideration of sex as a moderator of this association.

Analyzing a single nucleotide polymorphism in schizophrenia: a meta-analysis approach

BACKGROUND

Schizophrenia is a severe mental disorder affecting >21 million people worldwide. Some genetic studies reported that single nucleotide polymorphism (SNP) involving variant rs1344706 from the ZNF804A gene in human beings is associated with the risk of schizophrenia in several populations. Similar results tend to conflict with other reports in literature, indicating that no true significant association exists between rs1344706 and schizophrenia. We seek to determine the level of association of this SNP with schizophrenia in the Asian population using more recent genome-wide association study (GWAS) datasets.

METHODS

Applying a computational approach with inclusion of more recent GWAS datasets, we conducted a meta-analysis to examine the level of association of SNP rs1344706 and the risk of schizophrenia disorder among the Asian population constituting Chinese, Indonesians, Japanese, Kazakhs and Singaporeans. For a total of 21 genetic studies, including a total of 28,842 cases and 35,630 controls, regression analysis, publication bias, Cochran's Q and I2 tests were performed. The DerSimonian and Laird random-effects model was used to assess the association of the genetic variant to schizophrenia. Leave-one-out sensitivity analysis was also conducted to determine the influence of each study on the final outcome of the association study.

RESULTS

Our summarized analysis for Asian population revealed a pooled odds ratio of 1.06, 95% confidence interval of 1.01-1.11 and two-tailed P-value of 0.0228. Our test for heterogeneity showed the presence of large heterogeneity (I2=53.44%, P =0.00207) and Egger's regression test (P =0.8763) and Begg's test (P =0.8347), indicating no presence of publication bias among our selected studies. In our sensitivity analysis, 10 different studies comprising of ~50% of the entire study had an impact on our final results as each leave-one-out test became insignificant. Our result suggests that genetic variant rs1344706 might be associated with the development of schizophrenia in Asians.

Progress in genome-wide association studies of schizophrenia in Han Chinese populations

Since 2006, genome-wide association studies of schizophrenia have led to the identification of numerous novel risk loci for this disease. However, there remains a geographical imbalance in genome-wide association studies, which to date have primarily focused on Western populations. During the last 6 years, genome-wide association studies in Han Chinese populations have identified both the sharing of susceptible loci across ethnicities and genes unique to Han Chinese populations. Here, we review recent progress in genome-wide association studies of schizophrenia in Han Chinese populations. Researchers have identified and replicated the sharing of susceptible genes, such as within the major histocompatibility complex, microRNA 137 (MIR137), zinc finger protein 804A (ZNF804A), vaccinia related kinase 2 (VRK2), and arsenite methyltransferase (AS3MT), across both European and East Asian populations. Several copy number variations identified in European populations have also been validated in the Han Chinese, including duplications at 16p11.2, 15q11.2-13.1, 7q11.23, and VIPR2 and deletions at 22q11.2, 1q21.1-q21.2, and NRXN1. However, these studies have identified some potential confounding factors, such as genetic heterogeneity and the effects of natural selection on tetraspanin 18 (TSPAN18) or zinc finger protein 323 (ZNF323), which may explain the population differences in genome-wide association studies. In the future, genome-wide association studies in Han Chinese populations should include meta-analyzes or mega-analyses with enlarged sample sizes across populations, deep sequencing, precision medicine treatment, and functional exploration of the risk genes for schizophrenia.

The schizophrenia risk gene ZNF804A: clinical associations, biological mechanisms and neuronal functions

ZNF804A (zinc-finger protein 804A) has been recognized as a schizophrenia risk gene across multiple world populations. Its intronic single-nucleotide polymorphism (SNP) rs1344706 is among one of the strongest susceptibility variants that have achieved genome-wide significance in genome-wide association studies (GWAS) for schizophrenia and has been widely and intensively studied. To elucidate the biological mechanisms underlying the genetic risk conferred by rs1344706, we retrospectively analyzed the progresses in brain gene expression quantitative trait loci (eQTL) analyses, ZNF804A-induced pathway alterations in neural cells and changes in synaptic phenotypes associated with ZNF804A expression. Based on these data, we hypothesize a potential biological mechanism for a genetic risk allele of ZNF804A in schizophrenia pathogenesis. We also review the efforts being made to characterize the affected intermediate phenotypes using neuroimaging and neuropsychological approaches. We then discuss additional common and rare ZNF804A variants in schizophrenia susceptibility and the potential genetic heterogeneity of these genomic loci between Europeans and Asians. This review for we believe the first time systematically presents the evidence for ZNF804A, describing its discovery and likely roles in brain development and schizophrenia pathogenesis. We believe that this work has summarized this information with a systemic and broad assessment of recent findings.

Association between the zinc finger protein 804A (ZNF804A) gene and the risk of schizophrenia and bipolar I disorder across diagnostic boundaries

OBJECTIVES

In this study, we aimed to determine the role of genetic variations within the zinc finger protein 804A (ZNF804A) gene, a candidate for a psychosis risk-conferring gene, in the development of schizophrenia (SZ) and bipolar disorder (BP) in the Korean population.

METHODS

A total of 921 patients with SZ, bipolar I (BP-I) and II (BP-II) disorder, and 502 control subjects participated in the study. Twenty-one tag single nucleotide polymorphisms (SNPs) across the genomic region of ZNF804A and seven reference SNPs based on previous reports were genotyped. We applied logistic regression analyses under additive, dominant and recessive models.

RESULTS

Fifteen of the 28 SNPs showed a nominally significant association with at least one diagnostic group. However, none of these associations remained significant after false discovery rate (FDR) correction. As the trend of association was observed mostly in SZ and BP-I with similar patterns, we performed a post hoc analysis for the combined SZ and BP-I group. Five SNPs (rs2369595, rs6755404, rs10931156, rs12476147 and rs1366842) showed a significant association with an FDR-corrected P of <.05.

CONCLUSIONS

This study supports a possible role of ZNF804A in the common susceptibility of major psychoses, and identified additional candidate variants of the gene in the Korean population.

Metabolic pathways in the periphery and brain: Contribution to mental disorders?

The association between mental disorders and diabetes has a long history. Recent large-scale, well-controlled epidemiological studies confirmed a link between diabetes and psychiatric illnesses. The scope of this review is to summarize our current understanding of this relationship from a molecular perspective. We first discuss the potential contribution of diabetes-associated metabolic impairments to the etiology of mental conditions. Then, we focus on possible shared molecular risk factors and mechanisms. Simple comorbidity, shared susceptibility loci, and common pathophysiological processes in diabetes and mental illnesses have changed our traditional way of thinking about mental illness. We conclude that schizophrenia and affective disorders are not limited to an imbalance in dopaminergic and serotoninergic neurotransmission in the brain. They are also systemic disorders that can be considered, to some extent, as metabolic disorders.

A comprehensive meta-analysis of ZNF804A SNPs in the risk of schizophrenia among Asian populations

Common variants in ZNF804A increased the risk of schizophrenia (and bipolar disorder), with low effect sizes in Europeans, which is in line with the polygenic nature of the illnesses, and implies that genetic analyses in small samples may not be sufficient to detect stable results. This notion is supported by the inconsistent replications of ZNF804A variations among individual small Asian samples, indicating the absence of definitive conclusions in this population. We collected psychiatric phenotypic and genetic data from Asian genome-wide association (GWA) and individual replication studies, which include up to 13,452 cases, 17,826 healthy controls, and 680 families, that is, the largest-scale study on ZNF804A in Asian populations to date. The European GWAS risk single nucleotide polymorphism (SNP) rs1344706 was nominally associated with schizophrenia in these Asian samples (one-tailed P = 4.26 × 10(-2) , odds ratio [OR] = 1.048), and the association was further strengthened when bipolar disorder data was also included (one-tailed P = 1.85 × 10(-2) , OR = 1.057). Besides, a non-synonymous SNP rs1366842 in the exon 4 of ZNF804A was also associated with schizophrenia (P = 9.96 × 10(-3) , OR = 1.095). We additionally analyzed other 163 SNPs covering ZNF804A region, but none of them showed any evidence of association. Though the two SNPs did not remain significant if we applied multiple corrections, our analysis should be interpreted as a primary replication study with in prior hypothesis, and rs1344706 and rs1366842 might confer a small but detectable risk of schizophrenia (and bipolar disorder) in Asians. Moreover, the current data suggest the necessity of replication analyses in a large enough scale samples.

Meta-analysis indicates that SNP rs9939609 within FTO is not associated with major depressive disorder (MDD) in Asian population

BACKGROUND

Major depressive disorder (MDD) is one of the most prevalent psychiatric illnesses with heritability of up to 38%. The fat mass- and obesity-associated (FTO) gene, in particular the single nucleotide polymorphism (SNP) rs9939609, has been identified as a genetic risk loci associated with MDD. However, most prior studies have involved European and American populations. Whether rs9939609 is an true risk SNP for MDD in Asian populations remains inconclusive.

METHODS

In the present study, we conducted a meta-analysis of the association between rs9939609 and MDD in Asian populations by combining 5 available case-control samples totaling 6531 cases and 12,359 controls.

RESULTS

Our meta-analysis suggests that rs9939609 is not a risk SNP for MDD in Asian populations by fixed effect model (Z=1.04, P=0.30, OR=0.96, 95% CI=0.90-1.03).

LIMITATIONS

The age distribution and gender ratios were not matched well in the combined samples of cases and controls. Publication bias might be also considered with only a relatively small number of association studies of FTO rs9939609 with MDD in Asian populations.

CONCLUSIONS

The absence of association of rs9939609 with MDD in our Asian populations suggests a potential genetic heterogeneity in the susceptibility of MDD on this locus.

No association between schizophrenia susceptibility variants and macroscopic structural brain volume variation in healthy subjects

Previous studies have suggested that genetic variants for schizophrenia susceptibility might contribute to structural brain volume variations in schizophrenia patients, including total brain volume, hippocampal volume, and amygdalar volume. However, whether these schizophrenia susceptibility variants are associated with macroscopic structural brain volume (i.e., intracranial volume, total brain volume, and hippocampal volume) in healthy subjects is still unclear. In this study, we investigated the associations between 47 schizophrenia susceptibility variants (from 25 well-characterized schizophrenia susceptibility genes) and cranial volume variation in a healthy Chinese sample (N = 1,013). We also extracted the association between these 47 schizophrenia risk variants and the macroscopic structural brain volume (intracranial volume, total brain volume and hippocampal volume) in a large healthy sample of European ancestry (ENIGMA sample, N = 5,775). We identified several single-nucleotide polymorphisms (SNPs) nominally associated with intracranial volume, total brain volume, and hippocampal volume at P < 0.05 (uncorrected). However, after Bonferroni corrections for multiple testing, no SNP showed significant association. Hence, our results do not support previous observations that schizophrenia susceptibility variants are associated with brain structure (e.g., hippocampal volume) in healthy individuals, and indicate that single schizophrenia risk variant may not contribute significantly to macroscopic brain structure (e.g., intracranial volume or hippocampal volume) variation in healthy subjects.

Psychiatric genetics in China: achievements and challenges

To coordinate research efforts in psychiatric genetics in China, a group of Chinese and foreign investigators have established an annual “Summit on Chinese Psychiatric Genetics” to present their latest research and discuss the current state and future directions of this field. To date, two Summits have been held, the first in Changsha in April, 2014, and the second in Kunming in April, 2015. The consensus of roundtable discussions held at these meetings is that psychiatric genetics in China is in need of new policies to promote collaborations aimed at creating a framework for genetic research appropriate for the Chinese population: relying solely on Caucasian population-based studies may result in missed opportunities to diagnose and treat psychiatric disorders. In addition, participants agree on the importance of promoting collaborations and data sharing in areas where China has especially strong resources, such as advanced facilities for non-human primate studies and traditional Chinese medicine: areas that may also provide overseas investigators with unique research opportunities. In this paper, we present an overview of the current state of psychiatric genetics research in China, with emphasis on genome-level studies, and describe challenges and opportunities for future advances, particularly at the dawn of “precision medicine.” Together, we call on administrative bodies, funding agencies, the research community, and the public at large for increased support for research on the genetic basis of psychiatric disorders in the Chinese population. In our opinion, increased public awareness and effective collaborative research hold the keys to the future of psychiatric genetics in China.

ZNF804A rs1344706 is associated with cortical thickness, surface area, and cortical volume of the unmedicated first episode schizophrenia and healthy controls

The effects of ZNF804A rs1344706, a prominent susceptibility gene for schizophrenia, on gray matter (GM) structure in unmedicated schizophrenia (SZ) patients are still unknown, although several previous studies investigated the effects in medicated SZ patients and healthy controls (HC). Analyzing cortical thickness, surface area, and GM volume simultaneously may provide a more precise and complete picture of the effects. We genotyped 59 unmedicated first episode SZ patients and 60 healthy controls for the ZNF804A single nucleotide polymorphism (SNP) rs1344706, and examined between-group differences in cortical thickness, surface area, and cortical volume using a full-factorial 2 × 2 analysis of variance (ANOVA). We found the risk allele (T) in ZNF804A rs1344706, compared to the non-risk allele (G), was associated with thinner cortex in the bilateral precuneus, left precentral gyrus, and several other regions, associated with a smaller cortical surface area in the left superior parietal, precuneus cortex and left superior frontal, and associated with a lower cortical volume in the left superior frontal, left precentral, and right precuneus in SZ patients. In contrast, in the controls, the T allele was associated with the increased cortical measurements compared to the G allele in the same regions as those mentioned above. ZNF804A rs1344706 has significant, but different, effects on cortical thickness, surface area, and cortical volume in multiple regions of the brain cortex. Our findings suggest that ZNF804A rs1344706 may aggravate the risk for schizophrenia by exerting its effects on cortical thickness, surface area, and cortical volume in these brain regions.

Association between variants of zinc finger genes and psychiatric disorders: systematic review and meta-analysis

Psychiatric disorders have a negative impact on society and human lives. Genetic factors are involved in the occurrence and development of psychiatric diseases. ZNF804A has been identified as one of the most compelling risk genes associated with broad phenotypes related to psychosis. We conducted a systematic meta-analysis and reviewed ZNF804A variants in psychosis-related disorders, including schizophrenia, bipolar disorder, and attention-deficit hyperactivity disorder. We also summarized the association between other zinc finger protein genes (ZNFs) and psychiatric diseases. The meta-analysis included a total of six variants of ZNF804A and three variants of other ZNFs (ZDHHC8 and ZKSCAN4), and the effects of ZNF variants on neurocognition and neuroimaging phenotypes were reviewed. The biological functions of these variants are also presented. We verified that ZNF804A was significantly related to psychiatric diseases, and the association between ZNF804A rs1344706 and psychosis (schizophrenia and bipolar disorder) did not vary with disease or ethnicity. The main brain area regulated by ZNF804A rs1344706 was the dorsolateral prefrontal cortex. The effect of ZNF804A variants on cognition did not display consistency with different diseases or methodologies. These findings suggest that ZNF804A might play an important role in common pathogenesis of psychiatric diseases, and its variants are likely involved in regulating the expression of psychosis-related genes, especially the dopamine pathway genes. Further research should focus on the molecular mechanisms by which ZNF804A variants act in psychiatric diseases and related phenotypes.

ZNF804A genetic variation (rs1344706) affects brain grey but not white matter in schizophrenia and healthy subjects

BACKGROUND

Genetic variation in the gene encoding ZNF804A, a risk gene for schizophrenia, has been shown to affect brain functional endophenotypes of the disorder, while studies of white matter structure have been inconclusive.

METHOD

We analysed effects of ZNF804A single nucleotide polymorphism rs1344706 on grey and white matter using voxel-based morphometry (VBM) in high-resolution T1-weighted magnetic resonance imaging scans of 62 schizophrenia patients and 54 matched healthy controls.

RESULTS

We found a significant (p < 0.05, family-wise error corrected for multiple comparisons) interaction effect of diagnostic group x genotype for local grey matter in the left orbitofrontal and right and left lateral temporal cortices, where patients and controls showed diverging effects of genotype. Analysing the groups separately (at p < 0.001, uncorrected), variation in rs1344706 showed effects on brain structure within the schizophrenia patients in several areas including the left and right inferior temporal, right supramarginal/superior temporal, right and left inferior frontal, left frontopolar, right and left dorsolateral/ventrolateral prefrontal cortices, and the right thalamus, as well as effects within the healthy controls in left lateral temporal, right anterior insula and left orbitofrontal cortical areas. We did not find effects of genotype of regional white matter in either of the two cohorts.

CONCLUSIONS

Our findings demonstrate effects of ZNF804A genetic variation on brain structure, with diverging regional effects in schizophrenia patients and healthy controls in frontal and temporal brain areas. These effects, however, might be dependent on the impact of other (genetic or non-genetic) disease factors.

Association between rs1344706 of ZNF804A and schizophrenia: a meta-analysis

Schizophrenia is one of the most serious mental diseases found in humans. Previous studies indicated that the single nucleotide polymorphism (SNP) rs1344706 in the gene ZNF804A encoding zinc finger protein 804A was associated with schizophrenia in Caucasian population but not in Chinese Han population. However, current results are conflicting in Asian population. In the present study, a meta-analysis was performed to revisit the association between rs1344706 and the risk of schizophrenia in Asian, Caucasian and other populations. Electronic search of PubMed database identified 25 case–control studies with available genotype frequencies of rs1344706 for the meta-analysis, involving a total of 15,788 cases and 22,654 controls. A pooled odds ratio (OR) with 95% confidence interval (CI) was used to assess the association. The current meta-analysis showed an association between rs1344706 and schizophrenia in Caucasian populations (P = 0.028, OR = 1.138, 95% CI: 1.014–1.278; P = 0.004 for heterogeneity) and Asian populations (P = 0.008, OR = 1.092, 95% CI: 1.023–1.165; P = 0.001 for heterogeneity), but not in other populations (P = 0.286, OR = 1.209, 95% CI: 0.853–1.714, P = 0.120 for heterogeneity). Egger’s test (P > 0.05) and Begg’s test (P > 0.05) are both suggestive of the lack of publication bias for the included studies. Thus, the absence of association in other populations suggests a genetic heterogeneity in the susceptibility of schizophrenia and demonstrates the difficulties in replicating genome-wide association study findings regarding schizophrenia across different ethnic populations. To validate the association between rs1344706 and schizophrenia, further studies with larger participant populations worldwide are needed.

How might ZNF804A variants influence risk for schizophrenia and bipolar disorder? A literature review, synthesis, and bioinformatic analysis

The gene that encodes zinc finger protein 804A (ZNF804A) became a candidate risk gene for schizophrenia (SZ) after surpassing genome-wide significance thresholds in replicated genome-wide association scans and meta-analyses. Much remains unknown about this reported gene expression regulator; however, preliminary work has yielded insights into functional and biological effects of ZNF804A by targeting its regulatory activities in vitro and by characterizing allele-specific interactions with its risk-conferring single nucleotide polymorphisms (SNPs). There is now strong epidemiologic evidence for a role of ZNF804A polymorphisms in both SZ and bipolar disorder (BD); however, functional links between implicated variants and susceptible biological states have not been solidified. Here we briefly review the genetic evidence implicating ZNF804A polymorphisms as genetic risk factors for both SZ and BD, and discuss the potential functional consequences of these variants on the regulation of ZNF804A and its downstream targets. Empirical work and predictive bioinformatic analyses of the alternate alleles of the two most strongly implicated ZNF804A polymorphisms suggest they might alter the affinity of the gene sequence for DNA- and/or RNA-binding proteins, which might in turn alter expression levels of the gene or particular ZNF804A isoforms. Future work should focus on clarifying the critical periods and cofactors regulating these genetic influences on ZNF804A expression, as well as the downstream biological consequences of an imbalance in the expression of ZNF804A and its various mRNA isoforms.

Evidence of allelic imbalance in the schizophrenia susceptibility gene ZNF804A in human dorsolateral prefrontal cortex

The rs1344706, an intronic SNP within the zinc-finger protein 804A gene (ZNF804A), was identified as one of the most compelling risk SNPs for schizophrenia (SZ) and bipolar disorder (BD). It is however not clear by which molecular mechanisms ZNF804A increases disease risk. We evaluated the role of ZNF804A in SZ and BD by genotyping the originally associated rs1344706 SNP and an exonic SNP (rs12476147) located in exon four of ZNF804A in a sample of 422 SZ, 382 BD, and 507 controls from the isolated population of the Costa Rica Central Valley. We also investigated the rs1344706 SNP for allelic specific expression (ASE) imbalance in the dorsolateral prefrontal cortex (DLPFC) of 46 heterozygous postmortem brains. While no significant association between rs1344706 and SZ or BD was observed in the Costa Rica sample, we observed an increased risk of SZ for the minor allele (A) of the exonic rs12476147 SNP (p=0.026). Our ASE assay detected a significant over-expression of the rs12476147 A allele in DLPFC of rs1344706 heterozygous subjects. Interestingly, cDNA allele ratios were significantly different according to the intronic rs1344706 genotypes (p-value=0.03), with the rs1344706 A allele associated with increased ZNF804A rs12476147 A allele expression (average 1.06, p-value=0.02, for heterozygous subjects vs. genomic DNA). In conclusion, we have demonstrated a significant association of rs12476147 with SZ, and using a powerful within-subject design, an allelic expression imbalance of ZNF804A exonic SNP rs12476147 in the DLPFC. Although this data does not preclude the possibility of other functional variants in ZNF804A, it provides evidence that the rs1344706 SZ risk allele is the cis-regulatory variant directly responsible for this allelic expression imbalance in adult cortex.

An evaluation of association between a novel hippocampal biology related SNP (rs7294919) and schizophrenia

Recent genetic analyses have implicated several candidate susceptibility variants for schizophrenia. The single nucleotide polymorphism (SNP) rs7294919 is likely a schizophrenia-susceptibility variant according to its significant association with hippocampal volume, hippocampus function, and cognitive performance as well as the nominal association with schizophrenia. However, all previous analyses were conducted only in Europeans, and whether rs7294919 is associated with schizophrenia in other populations are yet to be tested. Here, we conducted a case-control analysis of rs7294919 with schizophrenia in six independent Chinese (N = 3) and Japanese (N = 3) samples, including a total of 7,352 cases and 10,824 controls. The results of our association analysis were not able to confirm the association of rs7294919 with schizophrenia (p = 0.51 in total samples, odds ratio = 1.02 for allele[C]). The absence of rs7294919's association in Chinese and Japanese suggest a potential genetic heterogeneity in the susceptibility of schizophrenia on this locus and also demonstrate the difficulties in replicating associations of schizophrenia across different ethnic populations.

Evaluation of the relationship between the ZNF804A single nucleotide polymorphism rs1344706 A/C variant and schizophrenia subtype in Han Chinese patients

OBJECTIVE

Recent genome wide association studies (GWASs) assessing the relationship between schizophrenia (SZ) and the ZNF804A gene, particularly the single nucleotide polymorphism (SNP) rs1344706, have yielded conflicting results. Schizophrenia is a heterogeneous disorder, so it is possible that an association may be restricted to specific SZ subtypes and that population heterogeneity may obscure a contribution of ZNF804A allelic variation to SZ risk. We thus evaluated the association between rs1344706 and different clinical SZ subtypes in a large Han Chinese patient population.

METHOD

The rs1344706 genotype was determined in 1,025 SZ patients and 977 healthy controls using polymerase chain reaction restriction fragment length polymorphisms (PCR-RFLPs). The clinical SZ subtypes included paranoid, catatonic, disintegrated, and undifferentiated, diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition IV (DSM-IV).

RESULTS

No significant differences in genotype and allele frequencies were found between controls and either the total SZ population (A > C, chi2 = 4.339, 2.994; p = 0.227, 0.087, respectively) or paranoid SZ patients (chi2 = 2.053, 0.002; p = 0.562, 0.973, respectively). However, there was a significant association between genotype frequency and SZ subtype (chi2 = 12.632, p = 0.049).

CONCLUSIONS

We found no evidence that the ZNF804A SNP rs1344706 is a susceptibility locus for SZ. However, conflicting results from previous association studies may be due to genetic heterogeneity between different patient SZ subtypes.

Meta-analysis indicates that the European GWAS-identified risk SNP rs1344706 within ZNF804A is not associated with schizophrenia in Han Chinese population

Recent genetic association studies have implicated several candidate susceptibility variants for schizophrenia among general populations. Rs1344706, an intronic SNP within ZNF804A, was identified as one of the most compelling candidate risk SNPs for schizophrenia in Europeans through genome-wide association studies (GWASs) and replications as well as large-scale meta-analyses. However, in Han Chinese, the results for rs1344706 are inconsistent, and whether rs1344706 is an authentic risk SNP for schizophrenia in Han Chinese is inconclusive. Here, we conducted a systematic meta-analysis of rs1344706 with schizophrenia in Chinese population by combining all available case-control samples (N = 12), including a total of 8,982 cases and 12,342 controls. The results of our meta-analysis were not able to confirm an association of rs1344706 A-allele with schizophrenia (p = 0.10, odds ratio = 1.06, 95% confidence interval = 0.99-1.13). Such absence of association was further confirmed by the non-superiority test (p = 0.0003), suggesting that rs1344706 is not a risk SNP for schizophrenia in Han Chinese. Detailed examinations of individual samples revealed potential sampling bias in previous replication studies in Han Chinese. The absence of rs1344706 association in Han Chinese suggest a potential genetic heterogeneity in the susceptibility of schizophrenia on this locus and also demonstrate the difficulties in replicating genome-wide association findings of schizophrenia across different ethnic populations.

Meta-analysis and brain imaging data support the involvement of VRK2 (rs2312147) in schizophrenia susceptibility

Recent genome-wide association studies have reported a set of schizophrenia susceptibility genes, but many of them await further replications in additional samples. Here we analyzed 5 genome-wide supported variants in a Han Chinese sample, and the variant rs2312147 at VRK2 showed significant association, which was confirmed in the meta-analysis combining multiple Asian and European samples (P=3.17×10(-4), N=7498). Rs2312147 is also associated with brain structure in healthy subjects, including the total brain volume and the white matter volume. Gene expression analyses indicated an up-regulation of VRK2 in schizophrenia patients. Our data provide further evidence for the contribution of VRK2 to schizophrenia.