TATA Box-Binding Proteingene is associated with risk for schizophrenia, age at onset and prefrontal function

Relating enhancer genetic variation across mammals to complex phenotypes using machine learning

Protein-coding differences between species often fail to explain phenotypic diversity, suggesting the involvement of genomic elements that regulate gene expression such as enhancers. Identifying associations between enhancers and phenotypes is challenging because enhancer activity can be tissue-dependent and functionally conserved despite low sequence conservation. We developed the Tissue-Aware Conservation Inference Toolkit (TACIT) to associate candidate enhancers with species' phenotypes using predictions from machine learning models trained on specific tissues. Applying TACIT to associate motor cortex and parvalbumin-positive interneuron enhancers with neurological phenotypes revealed dozens of enhancer-phenotype associations, including brain size-associated enhancers that interact with genes implicated in microcephaly or macrocephaly. TACIT provides a foundation for identifying enhancers associated with the evolution of any convergently evolved phenotype in any large group of species with aligned genomes.

NRN1 Gene as a Potential Marker of Early-Onset Schizophrenia: Evidence from Genetic and Neuroimaging Approaches

Included in the neurotrophins family, the Neuritin 1 gene (NRN1) has emerged as an attractive candidate gene for schizophrenia (SZ) since it has been associated with the risk for the disorder and general cognitive performance. In this work, we aimed to further investigate the association of NRN1 with SZ by exploring its role on age at onset and its brain activity correlates. First, we developed two genetic association analyses using a family-based sample (80 early-onset (EO) trios (offspring onset ≤ 18 years) and 71 adult-onset (AO) trios) and an independent case–control sample (120 healthy subjects (HS), 87 EO and 138 AO patients). Second, we explored the effect of NRN1 on brain activity during a working memory task (N-back task; 39 HS, 39 EO and 39 AO; matched by age, sex and estimated IQ). Different haplotypes encompassing the same three Single Nucleotide Polymorphisms(SNPs, rs3763180–rs10484320–rs4960155) were associated with EO in the two samples (GCT, TCC and GTT). Besides, the GTT haplotype was associated with worse N-back task performance in EO and was linked to an inefficient dorsolateral prefrontal cortex activity in subjects with EO compared to HS. Our results show convergent evidence on the NRN1 association with EO both from genetic and neuroimaging approaches, highlighting the role of neurotrophins in the pathophysiology of SZ.

Investigation of the Influence of TBP CAG/CAA Repeats in Conjunction with HTT CAG Repeats on Huntington's Disease Age at Onset in a Brazilian Sample

Huntington's disease (HD) is a genetic neurodegenerative progressive and fatal disease characterized by motor disorder, cognitive impairment, and behavioral problems, caused by expanded repeats of CAG trinucleotides in the HTT gene. The aim of this study was to investigate the influence of TBP gene CAG/CAA repeats in conjunction with HTT gene CAG repeats, on the age at HD onset in Brazilian individuals. Individuals diagnosed as molecularly negative for HD presented 29-39 TBP CAG/CAA. Their most frequent allele had 36 repeats. In individuals diagnosed as molecularly positive for HD, a range of 25-40 TBP CAG/ CAA was found. The most frequent TBP allele had 38 repeats. We also conducted TBP direct Sanger sequencing of some samples which demonstrated other four TBP structures different from the basic TBP structure and others reported in the literature. The HTT expanded CAG and TBP CAG/CAA repeat sizes jointly explained 66% of the age at onset (AO) in our HD patients. The strongest variable in the model associated with AO was the number of expanded HTT CAG repeats. The difference between the association of HD AO with HTT expanded CAG together with TBP CAG/CAA and the association of HD AO with HTT expanded CAG was 0.001 (∆R²). Therefore, we found a weak association (0.1%) of TBP CAG/CAA repeats on HD AO, if any.

Decreased white matter FA values in the left inferior frontal gyrus is a possible intermediate phenotype of schizophrenia: evidences from a novel group strategy

Intermediate phenotype could be used to investigate genetic susceptibility. However, genetic and environmental heterogeneity may interfere with identification of intermediate phenotypes. In this study, we minimized these interferences by using a novel group strategy. A total of 22 drug-naive and first-episode schizophrenia (FES) patients, along with 22 of their kin healthy siblings (HS), 22 non-kin healthy siblings (nHS) of other schizophrenia patients and 22 healthy controls (HC), were recruited. Brain imaging was acquired from the participants. Voxel-based analysis was used to investigate differences in white matter integrity derived from diffusion tensor imaging among the four groups. Two cognitive tests related to our findings were selected to confirm the related phenotypic changes. All of the FES, HS, and nHS groups showed decreased fractional anisotropy (FA) values in the left inferior frontal gyrus (IFG) compared with the HC group (p < 0.05, FDR corrected). The scores of Hopkins Verbal learning Test-Revised and Animal Naming in FES patients were significantly lower than in participants belonging to the other three groups (p < 0.05). Significant correlation between Animal Naming scores and FA values in the left IFG was found in FES patients (r = 0.53, p = 0.01). Moreover, FES patients also showed decreased FA values in the left medial frontal gyrus, left inferior temporal gyrus, left parahippocampal gyrus, left posterior cingulate, and right middle temporal gyrus compared with HC (p < 0.05, FDR corrected). Decreased FA values in the left IFG is a possible intermediate phenotype of schizophrenia, and this finding supports the hypothesis that disrupted connectivity of white matter may be the key substrate of schizophrenia.

Capturing schizophrenia-like prodromal symptoms in a spinocerebellar ataxia-17 transgenic rat

RATIONALE

The polyglutamine disease spinocerebellar ataxia type 17 (SCA17) is a neurodegenerative disease leading to severe neurological symptoms during development. Additionally, patients affected by SCA17 display psychosis earlier than their motor disorders.

OBJECTIVE

Here the putative psychotic phenotype and endophenotype of transgenic SCA17 rats was examined.

METHODS

The expression of schizophrenia-like symptoms was evaluated over a longitudinal period before and after the onset of neurological symptoms in SCA17. To this end, transgenic SCA17 rats' monoamine neurotransmission was investigated along with their locomotion at baseline and in response to amphetamine using in-vivo microdialysis in free moving conditions, their sensorimotor gating using pre-pulse inhibition of startle reaction, and their object memory using the novel object recognition test as an index of cognitive impairments.

RESULTS

Presymptomatic SCA17 rats displayed dysregulated monoamine levels at baseline and in response to amphetamine compared with control wild-type (wt) rats. At that stage, neither amphetamine-induced hyperlocomotion nor sensorimotor gating differed from that in wt rats. Symptomatic SCA17 rats developed sensorimotor gating deficits and also showed an impaired object memory, while their monoaminergic responses remained supersensitive to amphetamine.

CONCLUSIONS

The data of the present study demonstrate a neurochemical endophenotype in SCA17 rats resembling that of prodromal schizophrenia. These findings suggest that a sensitization of the monoamine systems arises early in adulthood in SCA17 rats and may predispose them to express schizophrenia-like symptoms later in life.

Glutamate Networks Implicate Cognitive Impairments in Schizophrenia: Genome-Wide Association Studies of 52 Cognitive Phenotypes

Cognitive impairments are a core feature in patients with schizophrenia. These deficits could serve as effective tools for understanding the genetic architecture of schizophrenia. This study investigated whether genetic variants associated with cognitive impairments aggregate in functional gene networks related to the pathogenesis of schizophrenia. Here, genome-wide association studies (GWAS) of a range of cognitive phenotypes relevant to schizophrenia were performed in 411 healthy subjects. We attempted to replicate the GWAS data using 257 patients with schizophrenia and performed a meta-analysis of the GWAS findings and the replicated results. Because gene networks, rather than a single gene or genetic variant, may be strongly associated with the susceptibility to schizophrenia and cognitive impairments, gene-network analysis for genes in close proximity to the replicated variants was performed. We observed nominal associations between 3054 variants and cognitive phenotypes at a threshold of P < 1.0 × 10(-) (4). Of the 3054 variants, the associations of 191 variants were replicated in the replication samples (P < .05). However, no variants achieved genome-wide significance in a meta-analysis (P > 5.0 × 10(-) (8)). Additionally, 115 of 191 replicated single nucleotide polymorphisms (SNPs) have genes located within 10 kb of the SNPs (60.2%). These variants were moderately associated with cognitive phenotypes that ranged from P = 2.50 × 10(-) (5) to P = 9.40 × 10(-) (8). The genes located within 10 kb from the replicated SNPs were significantly grouped in terms of glutamate receptor activity (false discovery rate (FDR) q = 4.49 × 10(-) (17)) and the immune system related to major histocompatibility complex class I (FDR q = 8.76 × 10(-) (11)) networks. Our findings demonstrate that genetic variants related to cognitive trait impairment in schizophrenia are involved in the N-methyl-d-aspartate glutamate network.

The impact of the genome-wide supported variant in the cyclin M2 gene on gray matter morphology in schizophrenia

BACKGROUND

Genome-wide significant associations of schizophrenia with eight SNPs in the CNNM2, MIR137, PCGEM1, TRIM26, CSMD1, MMP16, NT5C2 and CCDC68 genes have been identified in a recent mega-analysis of genome-wide association studies. To date, the role of these SNPs on gray matter (GM) volumes remains unclear.

METHODS

After performing quality control for minor-allele frequency > 5% using a JPT HapMap sample and our sample, a genotyping call rate > 95% and Hardy-Weinberg equilibrium testing (p > 0.01), five of eight SNPs were eligible for analysis. We used a comprehensive voxel-based morphometry (VBM) technique to investigate the effects of these five SNPs on GM volumes between major-allele homozygotes and minor-allele carriers in Japanese patients with schizophrenia (n = 173) and healthy subjects (n = 449).

RESULTS

The rs7914558 risk variant at CNNM2 was associated with voxel-based GM volumes in the bilateral inferior frontal gyri (right T = 4.96, p = 0.0088, left T = 4.66, p = 0.031). These peak voxels, which were affected by the variant, existed in the orbital region of the inferior frontal gyri. Individuals with the risk G/G genotype of rs7914558 had smaller GM volumes in the bilateral inferior frontal gyri than carriers of the non-risk A-allele. Although several effects of the genotype and the genotype-diagnosis interaction of other SNPs on GM volumes were observed in the exploratory VBM analyses, these effects did not remain after the FWE-correction for multiple tests (p > 0.05).

CONCLUSIONS

Our findings suggest that the genetic variant in the CNNM2 gene could be implicated in the pathogenesis of schizophrenia through the GM volumetric vulnerability of the orbital regions in the inferior frontal gyri.

The KCNH2 gene is associated with neurocognition and the risk of schizophrenia

OBJECTIVES

A genetic variant (rs3800779; M30) in the KCNH2 gene has been associated with schizophrenia, a lower intelligence quotient (IQ) and processing speed scores, altered brain functions and increased KCNH2-3.1. mRNA levels in the hippocampus. The aims of this study were to investigate whether the KCNH2 polymorphism is associated with schizophrenia-related neurocognitive deficits and to confirm the association between the variant and schizophrenia.

METHODS

The effects of the risk genotype on IQ and seven neurocognitive batteries were examined by the analysis of covariance in 191 healthy subjects. We performed a meta-analysis of the association between M30 and schizophrenia using five independent ethnic groups (1,720 cases; 2,418 controls).

RESULTS

Consistent with the previous study, we provided evidence that subjects with the risk T carriers had significantly lower IQ scores than those with the G/G genotype (P = 0.048). Of the seven neurocognitive batteries, subjects with the risk genotype demonstrated lower performances on attention/vigilance (P = 0.0079) and working memory (P = 0.0066) relative to subjects with the G/G genotype. Meta-analysis demonstrated evidence for an association between M30 and schizophrenia without showing heterogeneity across studies (odds ratio = 1.18; P = 0.0017).

CONCLUSIONS

These data suggest that the KCNH2 polymorphism could be associated with schizophrenia-related neuropsychological deficits and the risk of developing schizophrenia.

Near-infrared spectroscopy in schizophrenia: a possible biomarker for predicting clinical outcome and treatment response

Functional near-infrared spectroscopy (fNIRS) is a relatively new technique that can measure hemoglobin changes in brain tissues, and its use in psychiatry has been progressing rapidly. Although it has several disadvantages (e.g., relatively low spatial resolution and the possibility of shallow coverage in the depth of brain regions) compared with other functional neuroimaging techniques (e.g., functional magnetic resonance imaging and positron emission tomography), fNIRS may be a candidate instrument for clinical use in psychiatry, as it can measure brain activity in naturalistic position easily and non-invasively. fNIRS instruments are also small and work silently, and can be moved almost everywhere including schools and care units. Previous fNIRS studies have shown that patients with schizophrenia have impaired activity and characteristic waveform patterns in the prefrontal cortex during the letter version of the verbal fluency task, and part of these results have been approved as one of the Advanced Medical Technologies as an aid for the differential diagnosis of depressive symptoms by the Ministry of Health, Labor and Welfare of Japan in 2009, which was the first such approval in the field of psychiatry. Moreover, previous studies suggest that the activity in the frontopolar prefrontal cortex is associated with their functions in chronic schizophrenia and is its next candidate biomarker. Future studies aimed at exploring fNIRS differences in various clinical stages, longitudinal changes, drug effects, and variations during different task paradigms will be needed to develop more accurate biomarkers that can be used to aid differential diagnosis, the comprehension of the present condition, the prediction of outcome, and the decision regarding treatment options in schizophrenia. Future fNIRS researches will require standardized measurement procedures, probe settings, analytical methods and tools, manuscript description, and database systems in an fNIRS community.

Impact of the genome wide supported NRGN gene on anterior cingulate morphology in schizophrenia

Background

The rs12807809 single-nucleotide polymorphism in NRGN is a genetic risk variant with genome-wide significance for schizophrenia. The frequency of the T allele of rs12807809 is higher in individuals with schizophrenia than in those without the disorder. Reduced immunoreactivity of NRGN, which is expressed exclusively in the brain, has been observed in Brodmann areas (BA) 9 and 32 of the prefrontal cortex in postmortem brains from patients with schizophrenia compared with those in controls.

Methods

Genotype effects of rs12807809 were investigated on gray matter (GM) and white matter (WM) volumes using magnetic resonance imaging (MRI) with a voxel-based morphometry (VBM) technique in a sample of 99 Japanese patients with schizophrenia and 263 healthy controls.

Results

Although significant genotype-diagnosis interaction either on GM or WM volume was not observed, there was a trend of genotype-diagnosis interaction on GM volume in the left anterior cingulate cortex (ACC). Thus, the effects of NRGN genotype on GM volume of patients with schizophrenia and healthy controls were separately investigated. In patients with schizophrenia, carriers of the risk T allele had a smaller GM volume in the left ACC (BA32) than did carriers of the non-risk C allele. Significant genotype effect on other regions of the GM or WM was not observed for either the patients or controls.

Conclusions

Our findings suggest that the genome-wide associated genetic risk variant in the NRGN gene may be related to a small GM volume in the ACC in the left hemisphere in patients with schizophrenia.

Genomics and pharmacogenomics of schizophrenia

Schizophrenia (SCZ) is among the most disabling of mental disorders. Several neurobiological hypotheses have been postulated as responsible for SCZ pathogenesis: polygenic/multifactorial genomic defects, intrauterine and perinatal environment-genome interactions, neurodevelopmental defects, dopaminergic, cholinergic, serotonergic, gamma-aminobutiric acid (GABAergic), neuropeptidergic and glutamatergic/N-Methyl-D-Aspartate (NMDA) dysfunctions, seasonal infection, neuroimmune dysfunction, and epigenetic dysregulation. SCZ has a heritability estimated at 60-90%. Genetic studies in SCZ have revealed the presence of chromosome anomalies, copy number variants, multiple single-nucleotide polymorphisms of susceptibility distributed across the human genome, aberrant single nucleotide polymorphisms (SNPs) in microRNA genes, mitochondrial DNA mutations, and epigenetic phenomena. Pharmacogenetic studies of psychotropic drug response have focused on determining the relationship between variation in specific candidate genes and the positive and adverse effects of drug treatment. Approximately, 18% of neuroleptics are major substrates of CYP1A2 enzymes, 40% of CYP2D6, and 23% of CYP3A4; 24% of antidepressants are major substrates of CYP1A2 enzymes, 5% of CYP2B6, 38% of CYP2C19, 85% of CYP2D6, and 38% of CYP3A4; 7% of benzodiazepines are major substrates of CYP2C19 enzymes, 20% of CYP2D6, and 95% of CYP3A4. About 10-20% of Western populations are defective in genes of the CYP superfamily. Only 26% of Southern Europeans are pure extensive metabolizers for the trigenic cluster integrated by the CYP2D6+CYP2C19+CYP2C9 genes. The pharmacogenomic response of SCZ patients to conventional psychotropic drugs also depends on genetic variants associated with SCZ-related genes. Consequently, the incorporation of pharmacogenomic procedures both to drugs in development and drugs on the market would help to optimize therapeutics in SCZ and other central nervous system (CNS) disorders.

Genome-wide association analysis of age at onset in schizophrenia in a European-American sample

We performed a genome-wide association analysis to identify genetic variants influencing age at onset (AAO) and examine gene × gender interactions for AAO in schizophrenia (SCZ) using a European-American sample (1,162 cases). Linear regression model in PLINK was used to test for associations with AAO while the GxE option was chosen to test for the influence of gene × gender interactions. The most significant association with AAO was observed with SNP rs7819815 (P = 3.10×10(-7)) at 8q24.22. The next best signal was at 4q25 in COL25A1 gene (rs17039583, P = 4.30×10(-6)) and the third region was at 4p16.1 (rs17407555, P = 4.56×10(-6) , near RAF1P1, and rs4697924, P = 1.23×10(-5) within WDR1 gene). Conditional analysis on chromosome 4 indicated that 4p16.1 and 4q25 loci were independent. Furthermore, 2 SNPs (rs16834822 and rs16834824) at 1q43 in RYR2 showed strong associations in the female sample (P = 2.10×10(-6) and 2.33×10(-6) , respectively) and strong gene × gender interactions in influencing AAO (P = 9.23×10(-7) and 1.15×10(-6) , respectively) while the second best region showing gene × gender interaction was at 7q22.3 (rs179863, P = 2.33×10(-6) ). Using an independent sample of 1,068 cases, we could not replicate the associations for above top SNPs; however, we found nominal significance associations for their flanking SNPs (P < 0.05). These findings provide evidence of several genetic variants influencing AAO of SCZ.

The SIGMAR1 gene is associated with a risk of schizophrenia and activation of the prefrontal cortex

Several studies have identified the possible involvement of sigma non-opioid intracellular receptor 1 (SIGMAR1) in the pathogenesis of schizophrenia. The Gln2Pro polymorphism in the SIGMAR1 gene has been extensively examined for an association with schizophrenia. However, findings across multiple studies have been inconsistent. We performed a meta-analysis of the association between the functional Gln2Pro polymorphism and schizophrenia using combined samples (1254 patients with schizophrenia and 1574 healthy controls) from previously published studies and our own additional samples (478 patients and 631 controls). We then used near-infrared spectroscopy to analyze the effects of the Gln2Pro genotype, a schizophrenia diagnosis and the interaction between genotype and diagnosis on activation of the prefrontal cortex (PFC) during a verbal fluency task (127 patients and 216 controls). The meta-analysis provided evidence of an association between Gln2Pro and schizophrenia without heterogeneity across studies (odds ratio=1.12, p=0.047). Consistent with previous studies, patients with schizophrenia showed lower bilateral activation of the PFC when compared to controls (p<0.05). We provide evidence that Pro carriers, who are more common among patients with schizophrenia, have significantly lower activation of the right PFC compared to subjects with the Gln/Gln genotype (p=0.013). These data suggest that the SIGMAR1 polymorphism is associated with an increased risk of schizophrenia and differential activation of the PFC.

Unstable genes unstable mind: beyond the central dogma of molecular biology

Schizophrenia has a polygenic mode of inheritance and an estimated heritability of over 80%, but success in understanding its genetic underpinnings to date has been modest. Unlike in trinucleotide neurodegenerative disorders, the phenomenon of genetic anticipation observed in schizophrenia or bipolar disorder has not been explained. For the first time, we provide a plausible molecular explanation of genetic anticipation and pathophysiology of schizophrenia, at least in part, with supporting evidence. We postulate that abnormally increased numbers of CAG repeats in many genes being expressed in the brain, coding for glutamine, cumulatively press for higher demand of glutamine in the respective brain cells, resulting in a metabolic crisis and dysregulation of the glutamate-glutamine cycle. This can adversely affect the functioning of both glutamate and GABA receptors, which are known to be involved in psychosis, and may also affect glutathione levels, increasing oxidative stress. The resulting psychosis (gain in function), originating from unstable genes, is described as an effect "beyond the central dogma of molecular biology". The hypothesis explains genetic anticipation, as further expansions in subsequent generations may result in increased severity and earlier occurrence. Many other well described findings provide proof of concept. This is a testable hypothesis, does not deny any known facts and opens up new avenues of research.

Human brain weight is correlated with expression of the 'housekeeping genes' beta-2-microglobulin (β2M) and TATA-binding protein (TBP)

AIMS

Many variables affect mRNA measurements in post mortem human brain tissue. Brain weight has not hitherto been considered to be such a factor. This study examined whether there is any relationship between brain weight and mRNA abundance.

METHODS

We investigated quantitative real-time RT-PCR data for five 'housekeeping genes' using the 104 adult brains of the Stanley Microarray Consortium series. Eleven data sets were analysed, from cerebellum, hippocampus, and anterior cingulate cortex. We used a specified sequence of correlations, partial correlations and multiple regression analyses.

RESULTS

Brain weight correlated with the 'raw' (i.e. non-normalized) data for two mRNAs, β2-microglobulin and TATA-binding protein, measured in cerebellum and hippocampus, respectively. In hippocampus, the geometric mean of three housekeeping gene transcripts also correlated with brain weight. The correlations were significant after adjusting for age, sex and other confounders, and the effect of brain weight was confirmed using multiple regression. No correlations with brain weight were seen in the anterior cingulate cortex, nor for the other mRNAs examined.

CONCLUSIONS

The findings were not anticipated; they need replication in another brain series, and a more systematic survey is indicated. In the interim, we suggest that quantitative gene expression studies in human brain should inspect for a potential influence of brain weight, especially as the affected transcripts are commonly used as reference genes for normalization purposes in studies of neurological and psychiatric disorders. The relationship of brain weight with β2-microglobulin mRNA may reflect the roles of major histocompatibility complex class I genes in synapse formation and plasticity.

The impact of a genome-wide supported psychosis variant in the ZNF804A gene on memory function in schizophrenia

A recent genome-wide association study showed that a variant (rs1344706) in the ZNF804A gene was associated with schizophrenia and bipolar disorder. Replication studies supported the evidence for association between this variant in the ZNF804A gene and schizophrenia and that this variant is the most likely susceptibility variant. Subsequent functional magnetic resonance imaging studies in healthy subjects demonstrated the association of the high-risk ZNF804A variant with neural activation during a memory task and a theory of mind task. As these cognitive performances are disturbed in patients with schizophrenia, this gene may play a role in cognitive dysfunction in schizophrenia. The aim of the current study was to investigate the potential relationship between this ZNF804A polymorphism and memory function. The effects of the high-risk ZNF804A genotype, diagnosis, and genotype-diagnosis interaction on verbal memory, visual memory (VisM), attention/concentration, and delayed recall (measured by the Wechsler Memory Scale-Revised) were analyzed by two-way analysis of covariance in 113 patients with schizophrenia and 184 healthy subjects. Consistent with previous studies, patients with schizophrenia exhibited poorer performance on all indices as compared to healthy control subjects (P < 0.001). A significant ZNF804A genotype-diagnosis interaction was found for VisM performance (P = 0.0012). Patients with the high-risk T/T genotype scored significantly lower on VisM than G carriers did (P = 0.018). In contrast, there was no genotype effect for any index in the healthy control subjects (P > 0.05). Our data suggest that rs1344706 may be related to memory dysfunction in schizophrenia. © 2010 Wiley-Liss, Inc.

Positive symptoms of psychosis correlate with expression of ubiquitin proteasome genes in peripheral blood

Several brain- and blood-based gene expression studies in patients with psychotic disorders (e.g., schizophrenia) have identified genes in the ubiquitin proteasome system (UPS) pathway as putative biomarkers. However, to date an examination of the UPS pathway in the broader context of symptom severity in psychosis has not been conducted. The purpose of this study was to investigate the correlation between clinical scores on the Scales for the Assessment of Positive and Negative Symptoms (SAPS-SANS) and expression of 43 highly annotated genes within the UPS pathway in blood from patients with psychosis. A sample of 19 psychotic patients diagnosed with schizophrenia (n = 13) or bipolar disorder (n = 6) were recruited. Pearson's partial correlations, adjusting for gender, ethnicity, age, education, medication, smoking, and past 6-month substance use, were performed between each of the selected UPS genes and both scales. Significant Bonferroni-adjusted positive associations were observed between SAPS scores and two ubiquitin conjugation genes (i.e., UBE2K, SIAH2), while a negative association was observed with one deubiquitination gene (i.e., USP2). No gene expression levels were significantly associated with scores on the SANS after correction for multiple testing. Our findings suggest that dysregulation of the UPS, specifically ubiquitin conjugation and deubiquitination, may point to a possible underlying biological mechanism for severity of positive but not negative symptoms.

Working memory abnormalities in chronic interictal epileptic psychosis and schizophrenia revealed by magnetoencephalography

Working memory (WM) deficits are considered a core cognitive dysfunction in schizophrenia. To determine cognitive abnormalities in chronic interictal psychosis (CIP), and to assess whether these abnormalities are distinguishable from those seen in schizophrenia in terms of WM deficits, we used magnetoencephalography during a WM task performed by patients with CIP, nonpsychotic epilepsy, and schizophrenia and by healthy subjects. Multiple Source Beamformer and Brain-Voyager were used for analysis. In both patients with CIP and those with schizophrenia, we found dorsolateral prefrontal hyperactivation and left inferior temporal hypoactivation, as indicated by alpha event-related desynchronization and synchronization, respectively. Patients with schizophrenia also showed alpha2 event-related desynchronization in the mid-prefrontal cortex relative to healthy controls. Direct comparison of patients with CIP and schizophrenia rendered no difference in source-power changes. Our findings indicate similar functional cognitive abnormalities in CIP and schizophrenia in the prefrontal and left temporal cortex, which supports the possibility that these disorders share common underlying pathophysiological mechanisms.