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

Diversity matters: opportunities in the study of the genetics of psychotic disorders in low- and middle-income countries in Latin America

Lack of diversity regarding genetic and environmental backgrounds weakens the generalization and clinical applicability of research findings on psychotic disorders. Notably, Latin Americans have been generally neglected in genetic studies, comprising less than 2% of genome-wide association study samples. But Latin American populations represent a unique opportunity for research, given the exceptionally high ethnic admixture of this group. Increasing genetic diversity is essential to improve the fine mapping of known regions associated with psychotic disorders, discover novel genetic associations, and replicate studies. Additionally, Latin America is characterized by massive social, political, and economic inequalities, all known risk factors for mental health issues, including psychotic disorders. This article aims to 1) discuss the challenges and advantages of studying Latin America’s particular genetic makeup and environmental context; 2) review previous studies conducted in the region; and 3) describe three Latin American research initiatives in progress: the Neuropsychiatric Genetics of Psychosis in Mexican Populations (NeuroMEX), the Paisa, and the Latin American Network for the Study of Early Psychosis (ANDES) studies.

Spontaneous Regional Brain Activity in Healthy Individuals is Nonlinearly Modulated by the Interaction of ZNF804A rs1344706 and COMT rs4680 Polymorphisms

ZNF804A rs1344706 has been identified as one of the risk genes for schizophrenia. However, the neural mechanisms underlying this association are unknown. Given that ZNF804A upregulates the expression of COMT, we hypothesized that ZNF804A may influence brain activity by interacting with COMT. Here, we genotyped ZNF804A rs1344706 and COMT rs4680 in 218 healthy Chinese participants. Amplitudes of low-frequency fluctuations (ALFFs) were applied to analyze the main and interaction effects of ZNF804A rs1344706 and COMT rs4680. The ALFFs of the bilateral dorsolateral prefrontal cortex showed a significant ZNF804A rs1344706 × COMT rs4680 interaction, manifesting as a U-shaped modulation, presumably by dopamine signaling. Significant main effects were also found. These findings suggest that ZNF804A affects the resting-state functional activation by interacting with COMT, and may improve our understanding of the neurobiological effects of ZNF804A and its association with schizophrenia.

The interaction between the ZNF804A gene and cannabis use on the risk of psychosis in a non-clinical sample

The ZNF804A gene and cannabis use are risk factors for psychosis and both have also been associated with schizotypal traits. This study aimed to investigate: i) the association of lifetime cannabis use (and its dose effect) with schizotypal personality traits, and ii) whether the genetic variability at ZNF804A gene modulates that association. Our sample consisted of 385 Spanish non-clinical subjects (43.1% males, mean age = 21.11(2.19)). Schizotypy was evaluated using the three factors of the Schizotypal Personality Questionnaire-Brief (SPQ-B): Cognitive-Perceptual (SPQ-CP), Interpersonal (SPQ-I) and Disorganized (SPQ-D). Subjects were classified according to their frequency of cannabis consumption, and dichotomized as users or non-users. The effects of a genetic variant of ZNF804A (rs1344706) and cannabis use, as well as their interaction, on each of the three SPQ-B factors were assessed using linear models and permutation tests. Sex, SCL anxiety scores and use of other drugs were included as covariates. Our analysis showed a significant relationship between ZNF804A and SPQ-I: AA genotype was associated with higher scores (β = 0.885 p_FDR = .018). An interaction between the AA genotype and lifetime cannabis use was found in SPQ-CP (β = 1.297 p_FDR = 0.018). This interaction showed a dose-effect pattern among AA subjects: schizotypy scores increased with increasing frequency of cannabis use (sporadic users: β = 0.746 p_FDR = 0.208; monthly users: β = 1.688 p_FDR = 0.091; intense users: β = 1.623 p_FDR = 0.038). These results add evidence on that the ZNF804A gene is associated with schizotypy and suggest that the interaction between cannabis use and ZNF804A genotype could modulate psychosis proneness.

Pleiotropic action of genetic variation in ZNF804A on brain structure: a meta-analysis of magnetic resonance imaging studies

OBJECTIVE

The zinc finger protein 804A (ZNF804A) gene encodes the protein 804A containing the C2H2 zinc finger structure, which plays an important role in embryonic nerve development and repair. Previous studies have shown a significant association between the ZNF804A genetic variation polymorphism rs1344706 and the risk of schizophrenia and brain structure abnormalities. However, the findings are inconsistent.

MATERIALS AND METHODS

Seventeen studies on structural magnetic resonance imaging (sMRI), with 1,031 schizophrenia patients and 3,416 healthy controls, were included in the meta-analysis. These analyses were performed using Anisotropic Effect-Size Signed Differential Mapping (AES-SDM) software and Comprehensive Meta-Analysis (CMA) software.

RESULTS

rs1344706 risk allele carriers of schizophrenia had increased gray matter in the brain regions including frontal lobe, temporal lobe, and other brain regions, but the carriers of healthy individuals had decreased gray matter and white matter integrity in the frontal lobe, central network, and other brain regions. The results of sensitivity analysis are stable, but publication bias exists in a few analyses of indexes.

CONCLUSION

Abnormalities of brain structure have a strong relationship with ZNF804A gene rs1344706 polymorphism, but the association may be different in healthy individuals and those with mental disorders.

Control of CNS functions by RNA-binding proteins in neurological diseases

Purpose of Review

This review summarizes recent studies on the molecular mechanisms of RNA binding proteins (RBPs) that control neurological functions and pathogenesis in various neurodevelopmental and neurodegenerative diseases, including autism spectrum disorders, schizophrenia, Alzheimer's disease, amyotrophic lateral sclerosis, frontotemporal dementia, and spinocerebellar ataxia.

Recent Findings

RBPs are critical players in gene expression that regulate every step of posttranscriptional modifications. Recent genome-wide approaches revealed that many proteins associate with RNA, but do not contain any known RNA binding motifs. Additionally, many causal and risk genes of neurodevelopmental and neurodegenerative diseases are RBPs. Development of high-throughput sequencing methods has mapped out the fingerprints of RBPs on transcripts and provides unprecedented potential to discover new mechanisms of neurological diseases. Insights into how RBPs modulate neural development are important for designing effective therapies for numerous neurodevelopmental and neurodegenerative diseases.

Summary

RBPs have diverse mechanisms for modulating RNA processing and, thereby, controlling neurogenesis. Understanding the role of disease-associated RBPs in neurogenesis is vital for developing novel treatments for neurological diseases.

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 schizophrenia susceptibility gene ZNF804A confers risk of major mood disorders

OBJECTIVES

Genome-wide association studies (GWAS) followed by independent replications suggest that ZNF804A is a risk gene for schizophrenia (SCZ), considering the substantial genetic overlap between SCZ and major mood disorders (e.g., bipolar disorder (BPD) and major depressive disorder (MDD)).

METHODS

We collected the data of two ZNF804A single-nucleotide polymorphisms (SNPs rs1344706 and rs7597593) from European and Asian populations to perform systematic meta-analyses with major mood disorders in a total of 65,240 subjects.

RESULTS

Meta-analysis showed that rs1344706 and rs7597593 were both associated with major mood disorders as well as diagnosis of either BPD or MDD, although neither of the analyses achieved a genome-wide level of statistical significance.

CONCLUSIONS

Our data provide evidence for the genetic involvement of ZNF804A SNPs in the susceptibility of major mood disorders, but further replication analyses in larger samples are necessary.

[Genetic aspects of schizophrenia]

Schizophrenia is a disease with a complex non-Mendelian inheritance mechanism in most cases involving the combined action of a large number of genes. Identifying of genomic variations associated with schizophrenia endophenotypes has a great potential. This review describes genetic markers of the disease, current methods of their analysis, including genome-wide association study (GWAS). Certain genes with mutations that increase the risk of schizophrenia are described. Functional polymorphisms with phenotypic expression, which are significantly associated with clinical manifestation of schizophrenia, can serve as useful genetic markers. The authors highlight that currently there are no certain susceptibility genes. Further global research and search for markers in different population groups are needed.

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.

Molecular mechanisms underlying noncoding risk variations in psychiatric genetic studies

Recent large-scale genetic approaches such as genome-wide association studies have allowed the identification of common genetic variations that contribute to risk architectures of psychiatric disorders. However, most of these susceptibility variants are located in noncoding genomic regions that usually span multiple genes. As a result, pinpointing the precise variant(s) and biological mechanisms accounting for the risk remains challenging. By reviewing recent progresses in genetics, functional genomics and neurobiology of psychiatric disorders, as well as gene expression analyses of brain tissues, here we propose a roadmap to characterize the roles of noncoding risk loci in the pathogenesis of psychiatric illnesses (that is, identifying the underlying molecular mechanisms explaining the genetic risk conferred by those genomic loci, and recognizing putative functional causative variants). This roadmap involves integration of transcriptomic data, epidemiological and bioinformatic methods, as well as in vitro and in vivo experimental approaches. These tools will promote the translation of genetic discoveries to physiological mechanisms, and ultimately guide the development of preventive, therapeutic and prognostic measures for psychiatric disorders.

The schizophrenia risk gene MIR137 acts as a hippocampal gene network node orchestrating the expression of genes relevant to nervous system development and function

MicroRNAs (miRs) are small regulatory molecules, which orchestrate neuronal development and plasticity through modulation of complex gene networks. MicroRNA-137 (miR-137) is a brain-enriched RNA with a critical role in regulating brain development and in mediating synaptic plasticity. Importantly, mutations in this miR are associated with the pathoetiology of schizophrenia (SZ), and there is a widespread assumption that disruptions in miR-137 expression lead to aberrant expression of gene regulatory networks associated with SZ. To systematically identify the mRNA targets for this miR, we performed miR-137 gain- and loss-of-function experiments in primary rat hippocampal neurons and profiled differentially expressed mRNAs through next-generation sequencing. We identified 500 genes that were bidirectionally activated or repressed in their expression by the modulation of miR-137 levels. Gene ontology analysis using two independent software resources suggested functions for these miR-137-regulated genes in neurodevelopmental processes, neuronal maturation processes and cell maintenance, all of which known to be critical for proper brain circuitry formation. Since many of the putative miR-137 targets identified here also have been previously shown to be associated with SZ, we propose that this miR acts as a critical gene network hub contributing to the pathophysiology of this neurodevelopmental disorder.

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.

Nonverbal auditory working memory: Can music indicate the capacity?

Different working memory (WM) mechanisms that underlie words, tones, and timbres have been proposed in previous studies. In this regard, the present study developed a WM test with nonverbal sounds and compared it to the conventional verbal WM test. A total of twenty-five, non-music major, right-handed college students were presented with four different types of sounds (words, syllables, pitches, timbres) that varied from two to eight digits in length. Both accuracy and oxygenated hemoglobin (oxyHb) were measured. The results showed significant effects of number of targets on accuracy and sound type on oxyHb. A further analysis showed prefrontal asymmetry with pitch being processed by the right hemisphere (RH) and timbre by the left hemisphere (LH). These findings suggest a potential for employing musical sounds (i.e., pitch and timbre) as a complementary stimuli for conventional nonverbal WM tests, which can additionally examine its asymmetrical roles in the prefrontal regions.

Overlapping 16p13.11 deletion and gain of copies variations associated with childhood onset psychosis include genes with mechanistic implications for autism associated pathways: Two case reports

Copy number variability at 16p13.11 has been associated with intellectual disability, autism, schizophrenia, epilepsy, and attention-deficit hyperactivity disorder. Adolescent/adult- onset psychosis has been reported in a subset of these cases. Here, we report on two children with CNVs in 16p13.11 that developed psychosis before the age of 7. The genotype and neuropsychiatric abnormalities of these patients highlight several overlapping genes that have possible mechanistic relevance to pathways previously implicated in Autism Spectrum Disorders, including the mTOR signaling and the ubiquitin-proteasome cascades. A careful screening of the 16p13.11 region is warranted in patients with childhood onset psychosis.

Overview of genetic research in anorexia nervosa: The past, the present and the future

BACKGROUND

Even though the evidence supporting the presence of a heritable component in the aetiology of anorexia nervosa (AN) is strong, the underlying genetic mechanisms remain poorly understood. The recent publication of a genome-wide association study (GWAS) of AN (Boraska, Mol Psychiatry, 2014) was an important step in genetic research in AN.

OBJECTIVE

To briefly sum up strengths and weaknesses of candidate-gene and genome-wide approaches, to discuss the genome-wide association studies of AN and to make predictions about the genetic architecture of AN by comparing it to that of schizophrenia (since the diseases share some similarities and genetic research in schizophrenia is more advanced).

METHOD

Descriptive literature review.

RESULTS

Despite remarkable efforts, the gene-association studies in AN did not advance our knowledge as much as had been hoped, although some results still await replication.

DISCUSSION

Continuous effort of participants, clinicians and researchers remains necessary to ensure that genetic research in AN follows a similarly successful path as in schizophrenia. Identification of genetic susceptibility loci provides a basis for follow-up studies.

Replication of ZNF804A gene variant associations with risk of heroin addiction

Heroin addiction is heritable, but few specific genetic variants have been reproducibly associated with this disease. The zinc finger protein 804A (ZNF804A) gene is a biologically plausible susceptibility gene for heroin addiction, given its function as a transcription factor in human brain. Novel associations of two common ZNF804A single nucleotide polymorphisms (SNPs), rs7597593 and rs1344706, with heroin addiction have been reported in Han Chinese. Both SNPs have also been implicated for regulating ZNF804A expression in human brain, including the addiction-relevant dorsolateral prefrontal cortex. In this independent replication study, we tested the rs7597593 and rs1344706 SNP genotypes and their corresponding haplotypes for association with heroin addiction using cases drawn from the Urban Health Study and population controls: total N = 10 757 [7095 European Americans (EAs) and 3662 African Americans (AAs)]. We independently replicated both ZNF804A SNP associations in EAs: the rs7597593-T (P = 0.016) and rs1344706-A (P = 0.029) alleles both being associated with increased risk of heroin addiction, consistent with the prior report. Neither SNP was associated in AAs alone, but meta-analysis across both ancestry groups resulted in significant associations for rs1344706-A [P = 0.016, odds ratio (95% confidence interval) = 1.13 (1.02-1.25)] and its haplotype with rs7597593-T [P = 0.0067, odds ratio (95% confidence interval) = 1.16 (1.04-1.29)]. By showing consistent associations across independent studies and diverse ancestry groups, our study provides evidence that these two ZNF804A SNPs and their risk haplotype are among the few replicable genetic associations with heroin addiction.

Postnatal neurodevelopmental expression and glutamate-dependent regulation of the ZNF804A rodent homologue

The zinc finger protein ZNF804A rs1344706 variant is a replicated genome-wide significant risk variant for schizophrenia and bipolar disorder. While its association with altered brain structure and cognition in patients and healthy risk allele carriers is well documented, the characteristics and function of the gene in the brain remains poorly understood. Here, we used in situ hybridization to determine mRNA expression levels of the ZNF804A rodent homologue, Zfp804a, across multiple postnatal neurodevelopmental time points in the rat brain. We found changes in Zfp804a expression in the rat hippocampus, frontal cortex, and thalamus across postnatal neurodevelopment. Zfp804a mRNA peaked at postnatal day (P) 21 in hippocampal CA1 and DG regions and was highest in the lower cortical layers of frontal cortex at P1, possibly highlighting a role in developmental migration. Using immunofluorescence, we found that Zfp804a mRNA and ZFP804A co-localized with neurons and not astrocytes. In primary cultured cortical neurons, we found that Zfp804a expression was significantly increased when neurons were exposed to glutamate [20μM], but this increase was blocked by the N-methyl-d-aspartate receptor (NMDAR) antagonist MK-801. Expression of Comt, Pde4b, and Drd2, genes previously shown to be regulated by ZNF804A overexpression, was also significantly changed in an NMDA-dependent manner. Our results describe, for the first time, the unique postnatal neurodevelopmental expression of Zfp804a in the rodent brain and demonstrate that glutamate potentially plays an important role in the regulation of this psychiatric susceptibility gene. These are critical steps toward understanding the biological function of ZNF804A in the mammalian brain.

The Multifarious Hippocampal Functions of MicroRNA-137

MicroRNAs (miRs) have emerged as a powerful class of endogenous noncoding RNAs involved in posttranscriptional gene expression regulation. miR-137 has repeatedly been associated with schizophrenia and intellectual disability. Recent studies describe the mechanisms of miR-137 in mediating basic synaptic transmission and plasticity in the hippocampus. A picture is emerging in which miR-137 acts as a potent player in regulating glutamatergic synaptic transmission in the hippocampus by controlling the translation of functionally critical genes at spatially opposite ends of the synapse, contributing to the pathogenesis of cognitive impairments as seen in neurodevelopmental disorders.

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.

Recent genetic findings in schizophrenia and their therapeutic relevance

Over 100 loci are now associated with schizophrenia risk as identified by single nucleotide polymorphisms (SNPs) in genome-wide association studies. These findings mean that 'genes for schizophrenia' have unquestionably been found. However, many questions remain unanswered, including several which affect their therapeutic significance. The SNPs individually have minor effects, and even cumulatively explain only a modest fraction of the genetic predisposition. The remainder likely results from many more loci, from rare variants, and from gene-gene and gene-environment interactions. The risk SNPs are almost all non-coding, meaning that their biological significance is unclear; probably their effects are mediated via an influence on gene regulation, and emerging evidence suggests that some key molecular events occur during early brain development. The loci include novel genes of unknown function as well as genes and pathways previously implicated in the pathophysiology of schizophrenia, e.g. NMDA receptor signalling. Genes in the latter category have the clearer therapeutic potential, although even this will be a challenging process because of the many complexities concerning the genetic architecture and mediating mechanisms. This review summarises recent schizophrenia genetic findings and some key issues they raise, particularly with regard to their implications for identifying and validating novel drug targets.

Bioinformatic analyses and conceptual synthesis of evidence linking ZNF804A to risk for schizophrenia and bipolar disorder

Advances in molecular genetics, fueled by the results of large-scale genome-wide association studies, meta-analyses, and mega-analyses, have provided the means of identifying genetic risk factors for human disease, thereby enriching our understanding of the functionality of the genome in the post-genomic era. In the past half-decade, research on neuropsychiatric disorders has reached an important milestone: the identification of susceptibility genes reliably associated with complex psychiatric disorders at genome-wide levels of significance. This age of discovery provides the groundwork for follow-up studies designed to elucidate the mechanism(s) by which genetic variants confer susceptibility to these disorders. The gene encoding zinc-finger protein 804 A (ZNF804A) is among these candidate genes, recently being found to be strongly associated with schizophrenia and bipolar disorder via one of its non-coding mutations, rs1344706. Neurobiological, molecular, and bioinformatic analyses have improved our understanding of ZNF804A in general and this variant in particular; however, more work is needed to establish the mechanism(s) by which ZNF804A variants impinge on the biological substrates of the two disorders. Here, we review literature recently published on ZNF804A, and analyze critical concepts related to the biology of ZNF804A and the role of rs1344706 in schizophrenia and bipolar disorder. We synthesize the results of new bioinformatic analyses of ZNF804A with key elements of the existing literature and knowledge base. Furthermore, we suggest some potentially fruitful short- and long-term research goals in the assessment of ZNF804A.

Expression of ZNF804A in human brain and alterations in schizophrenia, bipolar disorder, and major depressive disorder: a novel transcript fetally regulated by the psychosis risk variant rs1344706

IMPORTANCE

The single-nucleotide polymorphism rs1344706 in the zinc finger protein 804A gene (ZNF804A) shows genome-wide association with schizophrenia and bipolar disorder. Little is known regarding the expression of ZNF804A and the functionality of rs1344706.

OBJECTIVES

To characterize ZNF804A expression in human brain and to investigate how it changes across the life span and how it is affected by rs1344706, schizophrenia, bipolar disorder, and major depressive disorder.

DESIGN, SETTING, AND PARTICIPANTS

Molecular and immunochemical methods were used to study ZNF804A messenger RNA (mRNA) and ZNF804A protein, respectively. ZNF804A transcripts were investigated using next-generation sequencing and polymerase chain reaction-based methods, and ZNF804A protein was investigated using Western blots and immunohistochemistry. Samples of dorsolateral prefrontal cortex and inferior parietal lobe tissue were interrogated from 697 participants between 14 weeks' gestational age and age 85 years, including patients with schizophrenia, bipolar disorder, or major depressive disorder.

MAIN OUTCOMES AND MEASURES

Quantitative measurements of ZNF804A mRNA and immunoreactivity, and the effect of diagnosis and rs1344706 genotype.

RESULTS

ZNF804A was expressed across the life span, with highest expression prenatally. An abundant and developmentally regulated truncated ZNF804A transcript was identified, missing exons 1 and 2 (ZNF804AE3E4) and predicted to encode a protein lacking the zinc finger domain. rs1344706 influenced expression of ZNF804AE3E4 mRNA in fetal brain (P = .02). In contrast, full-length ZNF804A showed no association with genotype (P > .05). ZNF804AE3E4 mRNA expression was decreased in patients with schizophrenia (P = .006) and increased in those with major depressive disorder (P < .001), and there was a genotype-by-diagnosis interaction in bipolar disorder (P = .002). ZNF804A immunoreactivity was detected in fetal and adult human cerebral cortex. It was localized primarily to pyramidal neurons, with cytoplasmic as well as dendritic and nuclear staining. No differences in ZNF804A-immunoreactive neurons were seen in schizophrenia or related to rs1344706 (P > .05).

CONCLUSIONS AND RELEVANCE

rs1344706 influences the expression of ZNF804AE3E4, a novel splice variant. The effect is limited to fetal brain and to this isoform. It may be part of the mechanism by which allelic variation in ZNF804A affects risk of psychosis. ZNF804A is translated in human brain, where its functions may extend beyond its predicted role as a transcription factor.