Evaluation of risk loci for schizophrenia derived from genome-wide association studies in a German population

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.

Hyperfunctioning of the right posterior superior temporal sulcus in response to neutral facial expressions presents an endophenotype of schizophrenia

Deficits in social cognition have been proposed as a marker of schizophrenia. Growing evidence suggests especially hyperfunctioning of the right posterior superior temporal sulcus (pSTS) in response to neutral social stimuli reflecting the neural correlates of social-cognitive impairments in schizophrenia. We characterized healthy participants according to schizotypy (n = 74) and the single-nucleotide polymorphism rs1344706 in ZNF804A (n = 73), as they represent risk variants for schizophrenia from the perspectives of personality traits and genetics, respectively. A social-cognitive fMRI task was applied to investigate the association of right pSTS hyperfunctioning in response to neutral face stimuli with schizotypy and rs1344706. Higher right pSTS activation in response to neutral facial expressions was found in individuals with increased positive (trend) and disorganization symptoms, as well as in carriers of the risk allele of rs1344706. In addition, a positive association between right-left pSTS connectivity and disorganization symptoms during neutral face processing was revealed. Although these findings warrant replication, we suggest that right pSTS hyperfunctioning in response to neutral facial expressions presents an endophenotype of schizophrenia. We assume that right pSTS hyperfunctioning is a vulnerability to perceive neutral social stimuli as emotionally or intentionally salient, probably contributing to the emergence of symptoms of 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.

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.

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.

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.

Lack of association of the rs1344706 ZNF804A variant with cognitive functions and DTI indices of white matter microstructure in two independent healthy populations

The rs1344706 single nucleotide polymorphism within intron 2 of the ZNF804A gene is strongly associated with schizophrenia and bipolar disorder. This variant has also been associated in some studies with a range of cognitive and neuroimaging phenotypes, but several studies have reported no effect on the same phenotypes in other samples. Here, we genotyped 670 healthy adult Norwegian subjects and 1753 healthy adult Swedish subjects for rs1344706, and tested for associations with cognitive phenotypes including general intellectual abilities, memory functions and cognitive inhibition. We also tested whether rs1344706 is associated with white matter microstructural properties using diffusion tensor imaging (DTI) data from 250 to 340 of the Norwegian and Swedish subjects, respectively. Whole-brain voxel-wise statistical modeling of the effect of the ZNF804A variant on two DTI indices, fractional anisotropy (FA) and radial diffusivity (RD), was performed using tract-based spatial statistics (TBSS), and commonly reported effect sizes were calculated within several large-scale white matter pathways based on neuroanatomical atlases. No significant associations were found between rs1344706 and the cognitive traits or white matter microstructure. We conclude that the rs1344706 SNP has no significant effect on these phenotypes in our two reasonably powered samples.

Variation in psychosis gene ZNF804A is associated with a refined schizotypy phenotype but not neurocognitive performance in a large young male population

Genetic variability within the ZNF804A gene has been recently found to be associated with schizophrenia and bipolar disorder, although the pathways by which this gene may confer risk remain largely unknown. We set out to investigate whether common ZNF804A variants affect psychosis-related intermediate phenotypes such as cognitive performance dependent on prefrontal and frontotemporal brain function, schizotypal traits, and attenuated psychotic experiences in a large young male population. Association analyses were performed using all 4 available self-rated schizotypy questionnaires and cognitive data retrospectively drawn from the Athens Study of Psychosis Proneness and Incidence of Schizophrenia (ASPIS). DNA samples from 1507 healthy young men undergoing induction to military training were genotyped for 4 previously studied polymorphic markers in the ZNF804A gene locus. Single-marker analysis revealed significant associations between 2 recently identified candidate schizophrenia susceptibility variants (rs1344706 and rs7597593) and a refined positive schizotypy phenotype characterized primarily by self-rated paranoia/ideas of reference. Nominal associations were noted with all positive, but not negative, schizotypy related factors. ZNF804A genotype effect on paranoia was confirmed at the haplotype level. No significant associations were noted with central indexes of sustained attention or working memory performance. In this study, ZNF804A variation was associated with a population-based self-rated schizotypy phenotype previously suggested to preferentially reflect genetic liability to psychosis and defined by a tendency to misinterpret otherwise neutral social cues and perceptual experiences in one's immediate environment, as personally relevant and significant information. This suggests a novel route by which schizophrenia-implicated ZNF804A genetic variation may confer risk to clinical psychosis at the general population level.

Genetics of psychiatric disorders in the GWAS era: an update on schizophrenia

The influence of genetic factors in the development of schizophrenia has been convincingly demonstrated by family, twin, and adoption studies. The statistical construct of heritability is generally used for estimating the liability due to genetic factors. Heritability estimates for schizophrenia are reported to be between 60 and 80 %. Due to the technical achievements in whole genome-wide association studies, dissection of the underlying genetic factors was intensified recently, resulting in the conclusion that schizophrenia is essentially a polygenic, complex disorder. Most likely more than 100 genes, each with small effect size, contribute to disease risk. A most recent multi-stage genome-wide association study (Ripke et al. in Nat Genet 2013) identified 22 risk loci and estimated that 8,300 independent single-nucleotide polymorphisms contributed to the risk accounting collectively for 32 % in liability. In addition to this polygenic, complex inheritance, there is also strong indication that in some patients a deletion or insertion of a larger chromosomal region [so-called copy number variation (CNV)] might play a crucial role in pathogenesis. This could be specifically important in sporadic cases with schizophrenia, since a higher frequency of de novo mutations has been associated with these CNVs. Further studies, combining much larger sample sizes as well as application of newer technology, such as deep sequencing technologies will be necessary in order to obtain a more comprehensive understanding of the genetic foundations of schizophrenia.

Association of rs1344706 in the ZNF804A gene with schizophrenia in a case/control sample from Indonesia

BACKGROUND

Association of rs1344706 in the ZNF804A gene (2q32.1) with schizophrenia was first reported in a genome wide scan conducted in a sample of 479 cases and replicated in 6666 cases. Subsequently, evidence by replication was obtained in several samples with European- and Asian ancestral background.

METHODS

We report ascertainment, clinical characterization, quality control, and determination of ancestral background of a case control sample from Indonesia, comprising 1067 cases and 1111 ancestry matched controls. Genotyping was performed using a fluorescence-based allelic discrimination assay (TaqMan SNP genotyping assay) and a newly designed PCR-RFLP assay for confirmation of rs1344706 genotypes.

RESULTS

We confirmed association of the T-allele of rs1344706 with schizophrenia in a newly ascertained sample from Indonesia with Southeast Asian ancestral background (P=0.019, OR=1.155, 95%, CI 1.025-1.301). In addition, we studied several SNPs in the vicinity of rs1344706, for which nominally significant results had been reported. None of the association P values of the additional SNPs exceeded that of rs1344706.

CONCLUSION

We provide additional evidence for association of the ZNF804A gene with schizophrenia. We conclude that rs1344706 or a yet unknown polymorphism in linkage disequilibrium is also involved in conferring susceptibility to schizophrenia in samples with different (Asian) ancestral backgrounds.

The regulation of gene expression involved in TGF-β signaling by ZNF804A, a risk gene for schizophrenia

ZNF804A has been implicated in susceptibility to schizophrenia by several genome-wide association studies (GWAS), follow-up association studies and meta-analyses. However, the biological functions of ZNF804A are not entirely understood. To identify the genes that are affected by ZNF804A, we manipulated the expression of the ZNF804A protein in HEK293 human embryonic kidney cell lines and performed a cDNA microarray analysis followed by qPCR. We found that ZNF804A-overexpression up-regulated four genes (ANKRD1, INHBE, PIK3AP1, and DDIT3) and down-regulated three genes (CLIC2, MGAM, and BIRC3). Furthermore, we confirmed that the expression of ANKRD1, PIK3AP1, INHBE and DDIT3 at the protein level was significantly increased by ZNF804A-overexpression. This is the first report to identify genes whose protein expressions are regulated by ZNF804A. ANKRD1, PIK3AP1, INHBE and DDIT3 are related to transforming growth factor-β (TGF-β) signaling, which plays a crucial role in cell growth and differentiation. On the other hand, recent studies have reported that TGF-β signaling is associated with schizophrenia. These results provide basis for a more progressive investigation of ZNF804A contributions to the susceptibility or pathophysiology of schizophrenia.

Further evidence for the association of genetic variants of ZNF804A with schizophrenia and a meta-analysis for genome-wide significance variant rs1344706

Recent accumulating evidence has indicated that ZNF804A (zinc finger protein 804A) may be one of the most robustly implicated genes in schizophrenia. In this report, we examined ZNF804A single nucleotide polymorphisms (SNPs) encompassing exon 4 by performing an association study that used a Han Chinese sample comprised of 492 schizophrenia patients and 516 healthy control subjects. A meta-analysis based on previous studies was also performed. For markers rs4667000 and rs1366842, significant differences in allele frequencies were found between cases and controls (Mantel-Haenszel corrected P=0.014 and P=0.025, respectively). Analysis of haplotype rs61739290-rs1366842 showed significant association with schizophrenia (global P=0.0018). Moreover, several other two-, three-, and four-SNP tests of haplotype association were also significant. A meta-analysis comprised of studies that utilized sample sets of either European and/or Han Chinese origin revealed statistically significant associations for two SNPs (rs1366842, P=0.002; and rs3731834, P=0.03) and schizophrenia. In addition, we observed a significant association between marker rsl344706 and schizophrenia (P<1.0×10(-5)) in combined populations. When we separately analyzed the studies by population, consistent and significant differences were found between cases and controls both in the European samples (P<1.0×10(-4)) and in the Chinese samples (P=0.03). In summary, we have added new evidence supporting the association between ZNF804A and schizophrenia in our Han Chinese sample. Further functional exploration of ZNF804A will greatly help us to elucidate the pathogenesis of schizophrenia and find promising new approaches for the treatment of this disorder.

Influence of ZNF804a on brain structure volumes and symptom severity in individuals with schizophrenia

CONTEXT The single-nucleotide polymorphism rs1344706 in the gene ZNF804a has been associated with schizophrenia and with quantitative phenotypic features, including brain structure volume and the core symptoms of schizophrenia. OBJECTIVE To evaluate associations of rs1344706 with brain structure and the core symptoms of schizophrenia. DESIGN Case-control analysis of covariance. SETTING University-based research hospital. PARTICIPANTS Volunteer sample of 335 individuals with schizophrenia spectrum disorders (306 with core schizophrenia) and 198 healthy volunteers. MAIN OUTCOME MEASURES Cerebral cortical gray matter and white matter (WM) volumes (total and frontal, parietal, temporal, and occipital lobes), lateral ventricular cerebrospinal fluid volume, and symptom severity from the Scale for the Assessment of Negative Symptoms and the Scale for the Assessment of Positive Symptoms divided into 3 domains: psychotic, negative, and disorganized. RESULTS The rs1344706 genotype produced significant main effects on total, frontal, and parietal lobe WM volumes (F = 3.98, P = .02; F = 4.95, P = .007; and F = 3.08, P = .05, respectively). In the schizophrenia group, rs1344706 produced significant simple effects on total (F = 3.93, P = .02) and frontal WM volumes (F = 7.16, P < .001) and on psychotic symptom severity (F = 6.07, P = .003); the pattern of effects was concordant with risk allele carriers having larger volumes and more severe symptoms of disease than nonrisk homozygotes. In the healthy volunteer group, risk allele homozygotes had increased total WM volume compared with nonrisk allele carriers (F = 4.61, P = .03), replicating a previously reported association. CONCLUSIONS A growing body of evidence suggests that the risk allele of rs1347706 is associated with a distinctive set of phenotypic features in healthy volunteers and individuals with schizophrenia. Our study supports this assertion by finding that specific genotypes of the polymorphism are associated with brain structure volumes in individuals with schizophrenia and healthy volunteers and with symptom severity in schizophrenia.

ZNF804A rs1344706 variant and schizophrenia in a Romanian population from Cluj Napoca

The ZNF804A rs1344706 variant was the first risk factor to be identified through genome-wide association studies and follow-up studies with meta-analysis for schizophrenia as well as bipolar disorders; we investigated 231 schizophrenia and 222 controls to see whether this particular variant was associated with schizophrenia in a Romanian population from Cluj Napoca. Clearly, there was no association between the ZNF804A rs1344706 variant and schizophrenia. Our study provides evidence for those that found no association with schizophrenia. A surprising result of our study was that the T allele frequency is the highest, thus far among the ethnic groups studied. We used a PCR-RFLP method that had been recently developed in our laboratory to the genotype ZNF804A rs1344706 variant. In conclusion, the ZNF804A rs1344706 variant was not associated with schizophrenia in the Romanian population from Cluj Napoca (χ(2)=0.734, p=0.693).

Clinical applications of schizophrenia genetics: genetic diagnosis, risk, and counseling in the molecular era

Schizophrenia is a complex neuropsychiatric disease with documented clinical and genetic heterogeneity, and evidence for neurodevelopmental origins. Driven by new genetic technologies and advances in molecular medicine, there has recently been concrete progress in understanding some of the specific genetic causes of this serious psychiatric illness. In particular, several large rare structural variants have been convincingly associated with schizophrenia, in targeted studies over two decades with respect to 22q11.2 microdeletions, and more recently in large-scale, genome-wide case-control studies. These advances promise to help many families afflicted with this disease. In this review, we critically appraise recent developments in the field of schizophrenia genetics through the lens of immediate clinical applicability. Much work remains in translating the recent surge of genetic research discoveries into the clinic. The epidemiology and basic genetic parameters (such as penetrance and expression) of most genomic disorders associated with schizophrenia are not yet well characterized. To date, 22q11.2 deletion syndrome is the only established genetic subtype of schizophrenia of proven clinical relevance. We use this well-established association as a model to chart the pathway for translating emerging genetic discoveries into clinical practice. We also propose new directions for research involving general genetic risk prediction and counseling in schizophrenia.

Serotonin 6 receptor gene and schizophrenia: case-control study and meta-analysis

OBJECTIVES

Several lines of evidence suggest that genetic alterations in serotonin 6 (5-HT6) receptors might be associated with the pathophysiology of schizophrenia. We sought to assess the relationship between genotype alterations in 5-HT6 receptors and schizophrenia both in a case-control study and a meta-analysis.

METHODS

We conducted an association study of the 5-HT6 receptor gene (HTR6) in Japanese patients with schizophrenia (n = 836) and controls (n = 857). Five tagging single-nucleotide polymorphisms (SNPs), including rs1805054 (C267T) in HTR6, were selected. In addition, we carried out a meta-analysis between rs1805054, which has been examined in other studies, and schizophrenia, searching PubMed through August 2011.

RESULTS

There were no significant associations between the tagging SNPs in HTR6 and schizophrenia in any of the genotype models in both the simple and the multiple logistic regression analyses correcting for potential confounds. Similarly, no significant association was found in the all-marker haplotype multiple logistic regression analysis (p = 0.491). Moreover, in the meta-analysis of rs1805054, drawing data from five studies, including our own (schizophrenia patients = 1366, controls = 1376), rs1805054 was also not associated with schizophrenia.

CONCLUSIONS

Our results indicate that tagging SNPs in HTR6 may not play a role in the pathophysiology of schizophrenia.

Is the conserved mammalian region of ZNF804A locus associated with schizophrenia? A population-based genetics analysis

Recently, several genome-wide association studies (GWASs) have reproduced the significant association of the single nucleotide polymorphism (SNP) rs1344706 (located in intron 2 of the zinc finger protein 804A (ZNF804A) on chromosome 2q32.1) with schizophrenia. Bioinformatic analysis of the chromosome segment around rs1344706 suggests that a short conserved mammalian region exists approximately 3kb downstream of rs1344706. In the present work, we studied all SNPs in this conserved mammalian region and performed genetic analyses on samples from Chinese schizophrenia patients (n = 516) and compared control subjects (n = 520). Significant association between an allele of rs13423388 and schizophrenia was found (P = 0.0012). Haplotype analysis of the three SNPs rs4666998, rs13423388, and rs56280129 showed significant associations with schizophrenia (global P = 0.00001). Furthermore, we performed a four-SNP haplotype analysis which included the SNPs from the three-SNP haplotype analysis and rs1344706 (global P = 0.0005), and found that haplotype GCCG was associated with schizophrenia (P = 0.003). In summary, the present study adds new evidence for an association between the conserved mammalian region of the ZNF804A gene and schizophrenia. Further research is needed to clarify the transcriptional regulation of ZNF804A gene and to relate this to the pathophysiology of schizophrenia.

[Systematic review of the Genomewide Association Studies (GWAS) in schizophrenia]

INTRODUCTION

Heritability in schizophrenia can reach up to 80% and the risk in families is 5-10 times higher than in the general population. The large contribution of genetics in this disorder has led to a growing interest in its study.

OBJECTIVES

To review the findings of genetic studies known as Genomewide Association Studies (GWAS) on schizophrenia.

METHOD

Systematic search using Pubmed with the key words GWAS and (psychosis) or (schizophrenia). The following web pages have been reviewed: http://www.szgene.org/largescale.asp and www.genome.gov/gwastudies/.

RESULTS

The GWAS have focused on causal biological aspects, such as the histocompatibility complex, glutamate metabolism, apoptosis and inflammatory processes, and the immune system (TNF-β, TNFR1). Also focused in the search were the genes that modulate the appearance of secondary metabolic and cardiac effects and secondary effects in subjects with schizophrenia and on anti-psychotic treatment. In neurorecognition, over-expression of the MET proto-oncogene (MET) has been associated with a low susceptibility for schizophrenia and a better cognitive performance, as well as a lower susceptibility for the incidence of cancer. Mention is also made of the different genes that mediate in cognitive functioning depending on the anti-psychotic treatment received.

CONCLUSIONS

The main interests of the GWAS during the last few years have been the neurobiological pathways involved in schizophrenia. The discoveries arising from these studies have been limited. This has led to an innovative approach on the aetiological study of the disorder by studying gene-environment interactions.