Neuropsychological effects of theCSMD1genome-wide associated schizophrenia risk variant rs10503253

CSMD1 rs10503253 increases schizophrenia risk in a Tunisian population-group

OBJECTIVES

Schizophrenia is a complex and chronic neuropsychiatric disorder. Recent genome-wide association studies have identified several at risk genetic variants, including two single nucleotide polymorphisms, namely the rs10503253 and the rs1270942 respectively located in the CSMD1 and the CFB loci. The present case-control study was designed to assess potential associations between the two variants and the risk of developing schizophrenia and disease severity. Further we demonstrate the relationship between these variants and clinical characteristics in a population-group from Tunisia.

PATIENTS AND METHODS

In total, 216 patients diagnosed with schizophrenia along with176 healthy controls were included in this case-control study. The molecular analysis of the two polymorphisms was performed using tetra the Primer Amplification Refractory Mutation System-Polymerase Chain method. The statistical analysis was done using Compare V2.1 software, and correlations between genetic results and clinical characteristics were examined by Kruskal-Wallis testing.

RESULTS

The frequency of the rs10503253A allele was found significantly higher among patients with schizophrenia as compared to healthy controls and associated with high negative PANSS scores. While no association was found concerning the implication of the rs1270942 variant in schizophrenia risk, a positive correlation with high positive PANSS scores was further observed.

CONCLUSION

The present finding confirms the previously reported association between the Cub and Sushi multiple Domain 1 rs10503253A allele and the risk to develop schizophrenia and identified the rs1270942 variant as a potential disease risk modifier. Such observations may be important for the definition of the susceptible immunogenetic background in North African individuals at risk to develop mental disorders.

CSMD1 regulates brain complement activity and circuit development

Complement proteins facilitate synaptic elimination during neurodevelopmental pruning, but neural complement regulation is not well understood. CUB and Sushi Multiple Domains 1 (CSMD1) can regulate complement activity in vitro, is expressed in the brain, and is associated with increased schizophrenia risk. Beyond this, little is known about CSMD1 including whether it regulates complement activity in the brain or otherwise plays a role in neurodevelopment. We used biochemical, immunohistochemical, and proteomic techniques to examine the regional, cellular, and subcellular distribution as well as protein interactions of CSMD1 in the brain. To evaluate whether CSMD1 is involved in complement-mediated synapse elimination, we examined Csmd1-knockout mice and CSMD1-knockout human stem cell-derived neurons. We interrogated synapse and circuit development of the mouse visual thalamus, a process that involves complement pathway activity. We also quantified complement deposition on synapses in mouse visual thalamus and on cultured human neurons. Finally, we assessed uptake of synaptosomes by cultured microglia. We found that CSMD1 is present at synapses and interacts with complement proteins in the brain. Mice lacking Csmd1 displayed increased levels of complement component C3, an increased colocalization of C3 with presynaptic terminals, fewer retinogeniculate synapses, and aberrant segregation of eye-specific retinal inputs to the visual thalamus during the critical period of complement-dependent refinement of this circuit. Loss of CSMD1 in vivo enhanced synaptosome engulfment by microglia in vitro, and this effect was dependent on activity of the microglial complement receptor, CR3. Finally, human stem cell-derived neurons lacking CSMD1 were more vulnerable to complement deposition. These data suggest that CSMD1 can function as a regulator of complement-mediated synapse elimination in the brain during development.

Microglia and cognitive impairment in schizophrenia: translating scientific progress into novel therapeutic interventions

Cognitive impairment is a core clinical feature of schizophrenia, exerting profound adverse effects on social functioning and quality of life in a large proportion of patients with schizophrenia. However, the mechanisms underlying the pathogenesis of schizophrenia-related cognitive impairment are not well understood. Microglia, the primary resident macrophages in the brain, have been shown to play important roles in psychiatric disorders, including schizophrenia. Increasing evidence has revealed excessive microglial activation in cognitive deficits related to a broad range of diseases and medical conditions. Relative to that about age-related cognitive deficits, current knowledge about the roles of microglia in cognitive impairment in neuropsychiatric disorders, such as schizophrenia, is limited, and such research is in its infancy. Thus, we conducted this review of the scientific literature with a focus on the role of microglia in schizophrenia-associated cognitive impairment, aiming to gain insight into the roles of microglial activation in the onset and progression of such impairment and to consider how scientific advances could be translated to preventive and therapeutic interventions. Research has demonstrated that microglia, especially those in the gray matter of the brain, are activated in schizophrenia. Upon activation, microglia release key proinflammatory cytokines and free radicals, which are well-recognized neurotoxic factors contributing to cognitive decline. Thus, we propose that the inhibition of microglial activation holds potential for the prevention and treatment of cognitive deficits in patients with schizophrenia. This review identifies potential targets for the development of new treatment strategies and eventually the improvement of care for these patients. It might also help psychologists and clinical investigators in planning future research.

Multi-ancestry phenome-wide association of complement component 4 variation with psychiatric and brain phenotypes in youth

BACKGROUND

Increased expression of the complement component 4A (C4A) gene is associated with a greater lifetime risk of schizophrenia. In the brain, C4A is involved in synaptic pruning; yet, it remains unclear the extent to which upregulation of C4A alters brain development or is associated with the risk for psychotic symptoms in childhood. Here, we perform a multi-ancestry phenome-wide association study in 7789 children aged 9-12 years to examine the relationship between genetically regulated expression (GREx) of C4A, childhood brain structure, cognition, and psychiatric symptoms.

RESULTS

While C4A GREx is not related to childhood psychotic experiences, cognition, or global measures of brain structure, it is associated with a localized reduction in regional surface area (SA) of the entorhinal cortex. Furthermore, we show that reduced entorhinal cortex SA at 9-10 years predicts a greater number and severity of psychosis-like events at 1-year and 2-year follow-up time points. We also demonstrate that the effects of C4A on the entorhinal cortex are independent of genome-wide polygenic risk for schizophrenia.

CONCLUSIONS

Our results suggest neurodevelopmental effects of C4A on childhood medial temporal lobe structure, which may serve as a biomarker for schizophrenia risk prior to symptom onset.

The Diverse Role of CUB and Sushi Multiple Domains 1 (CSMD1) in Human Diseases

CUB and Sushi Multiple Domains 1 (CSMD1), a tumour suppressor gene, encodes a large membrane-bound protein including a single transmembrane domain. This transmembrane region has a potential tyrosine phosphorylation site, suggesting that CSMD1 is involved in controlling cellular functions. Although the specific mechanisms of action for CSMD1 have not yet been uncovered, it has been linked to a number of processes including development, complement control, neurodevelopment, and cancer progression. In this review, we summarise CSMD1 functions in the cellular processes involved in the complement system, metastasis, and Epithelial mesenchymal transition (EMT) and also in the diseases schizophrenia, Parkinson's disease, and cancer. Clarifying the association between CSMD1 and the aforementioned diseases will contribute to the development of new diagnosis and treatment methods for these diseases. Recent studies in certain cancer types, e.g., gastric cancer, oesophageal cancer, and head and neck squamous cell carcinomas, have indicated the involvement of CSMD1 in response to immunotherapy.

Deregulation of complement components C4A and CSMD1 peripheral expression in first-episode psychosis and links to cognitive ability

Up-regulation of the complement component 4A (C4A) in the brain has been associated with excessive synaptic pruning and increased schizophrenia (SZ) susceptibility. Over-expression of C4A has been observed in SZ postmortem brain tissue, and the gene encoding for a protein inhibitor of C4A activity, CUB and Sushi multiple domains 1 (CSMD1) gene, has been implicated in SZ risk and cognitive ability. Herein, we examined C4A and CSMD1 mRNA expression in peripheral blood from antipsychotic-naive individuals with first-episode psychosis (FEP; n = 73) and mentally healthy volunteers (n = 48). Imputed C4 locus structural alleles and C4A serum protein levels were investigated. Associations with symptom severity and cognitive domains performance were explored. A significant decrease in CSMD1 expression levels was noted among FEP patients compared to healthy volunteers, further indicating a positive correlation between C4A and CSMD1 mRNA levels in healthy volunteers but not in FEP cases. In addition, C4 copy number variants previously associated with SZ risk correlated with higher C4A mRNA levels in FEP cases, which confirms the regulatory effect of C4 structural variants on gene expression. Evidence also emerged for markedly elevated C4A serum concentrations in FEP cases. Within the FEP patient group, higher C4A mRNA levels correlated with more severe general psychopathology symptoms and lower CSMD1 mRNA levels predicted worse working memory performance. Overall, these findings suggest C4A complement pathway perturbations in individuals with FEP and corroborate the involvement of CSMD1 in prefrontal-mediated cognitive functioning.

Putative complement control protein CSMD3 dysfunction impairs synaptogenesis and induces neurodevelopmental disorders

Recent studies have reported that complement-related proteins modulate brain development through regulating synapse processes in the cortex. CSMD3 belongs to a group of putative complement control proteins. However, its role in the central nervous system and synaptogenesis remains largely unknown. Here we report that CSMD3 deleterious mutations occur frequently in patients with neurodevelopmental disorders (NDDs). Csmd3 is predominantly expressed in cortical neurons of the developing cortex. In mice, Csmd3 disruption induced retarded development and NDD-related behaviors. Csmd3 deficiency impaired synaptogenesis and neurogenesis, allowing fewer neurons reaching the cortical plate. Csmd3 deficiency also induced perturbed functional networks in the developing cortex, involving a number of downregulated synapse-associated genes that influence early synaptic organization and upregulated genes related to immune activity. Our study provides mechanistic insights into the endogenous regulation of complement-related proteins in synaptic development and supports the pathological role of CSMD3 in NDDs.

New Insight into the human genetic diversity in North African populations by genotyping of SNPs in DRD3, CSMD1 and NRG1 genes

BACKGROUND

The single nucleotide polymorphisms (SNPs) of the dopamine D3 receptor (DRD3), the CUB and sushi multiple domains 1 (CSMD1) and the neuregulin 1 (NRG1) genes were used to study the genetic diversity and affinity among North African populations and to examine their genetic relationships in worldwide populations.

METHODS

The rs3773678, rs3732783 and rs6280 SNPs of the DRD3 gene located on chromosome 3, the rs10108270 SNP of the CSMD1 gene and the rs383632, rs385396 and rs1462906 SNPs of the NRG1 gene located on chromosome 8 were analysed in 366 individuals from seven North African populations (Libya, Kairouan, Mehdia, Sousse, Kesra, Smar and Kerkennah).

RESULTS

The low values of FST indicated that only 0.27%-1.65% of the genetic variability was due to the differences between the populations. The Kairouan population has the lowest average heterozygosity among the North African populations. Haplotypes composed of the ancestral alleles ACC and ACAT were more frequent in the Kairouan population than in other North African populations. The PCA and the haplotypic analysis showed that the genetic structure of populations in North Africa was closer to that of Europeans, Admixed Americans, South Asians and East Asians. However, analysis of the rs3732783 and rs6280 SNPs revealed that the CT microhaplotype was specific to the North African population.

CONCLUSIONS

The Kairouan population exhibited a relatively low rate of genetic variability. The North African population has undergone significant gene flow but also evolutionary forces that have made it genetically distinct from other populations.

Microglial-expressed genetic risk variants, cognitive function and brain volume in patients with schizophrenia and healthy controls

Changes in immune function are associated with variance in cognitive functioning in schizophrenia. Given that microglia are the primary innate immune cells in the brain, we examined whether schizophrenia risk-associated microglial genes (measured via polygenic score analysis) explained variation in cognition in patients with schizophrenia and controls (n = 1,238) and tested whether grey matter mediated this association. We further sought to replicate these associations in an independent sample of UK Biobank participants (n = 134,827). We then compared the strength of these microglial associations to that of neuronal and astroglial (i.e., other brain-expressed genes) polygenic scores, and used MAGMA to test for enrichment of these gene-sets with schizophrenia risk. Increased microglial schizophrenia polygenic risk was associated with significantly lower performance across several measures of cognitive functioning in both samples; associations which were then found to be mediated via total grey matter volume in the UK Biobank. Unlike neuronal genes which did show evidence of enrichment, the microglial gene-set was not significantly enriched for schizophrenia, suggesting that the relevance of microglia may be for neurodevelopmental processes related more generally to cognition. Further, the microglial polygenic score was associated with performance on a range of cognitive measures in a manner comparable to the neuronal schizophrenia polygenic score, with fewer cognitive associations observed for the astroglial score. In conclusion, our study supports the growing evidence of the importance of immune processes to understanding cognition and brain structure in both patients and in the healthy population.

No Effect of Coenzyme Q10 on Cognitive Function, Psychological Symptoms, and Health-related Outcomes in Schizophrenia and Schizoaffective Disorder: Results of a Randomized, Placebo-Controlled Trial

BACKGROUND

Cognitive impairments, negative symptoms, affective symptoms, and low energy are highly prevalent features of schizophrenia. Mitochondrial dysfunction has been hypothesized as one of the numerous factors to underlie the manifestation of these symptoms. The objective of this study was to evaluate whether Coenzyme Q10 (CoQ10) has a role in the treatment of schizophrenia and schizoaffective disorder.

METHODS

A double-blind, randomized, placebo-controlled trial was conducted to assess the effects of CoQ10 supplementation (300 mg/day) on the co-primary outcomes of attention and working memory performance after 3 and 6 months. Secondary outcomes included plasma CoQ10 levels, mitochondrial function, energy, depression, anxiety, negative symptoms, and quality oflife.

FINDINGS

In total, 72 patients were randomized to intervention groups. Overall, there was no effect of CoQ10 supplementation on the primary outcome measures at 3 or 6 months. Further, with the exception of plasma CoQ10 levels, CoQ10 supplementation also had no effect on the secondary outcomes. At 3 months, CoQ10 concentration was significantly higher in the CoQ10 group (3.85 μg/mL) compared with placebo (1.13 μg/mL); this difference was not present at 6 months.

CONCLUSIONS

The results of the study suggest that CoQ10 supplementation at 300 mg/day for 6 months is unlikely to be beneficial for cognitive, psychological and health-related outcomes in schizophrenia and schizoaffective disorder. However, a number of limitations including low adherence, modest sample size, and attrition, likely reduce estimates of effects. As such, results should be considered preliminary.

Quantitative Proteomics Analysis of Susceptibility and Resilience to Stress in a Rat model of PTSD

Posttraumatic stress disorder (PTSD) is a prevalent psychiatric disorder and sometimes deadly consequence of exposure to severe psychological trauma. However, there has been little known about the definitive molecular changes involved in determining vulnerability to PTSD. In the current study, we used proteomics to quantify protein changes in the hippocampus of foot shocks rats. A total of 6151 proteins were quantified and 97 proteins were significantly differentially expressed. The protein-protein interaction (PPI) analysis showed that oxidation-reduction process and glutathione homeostasis may be the potential key progress of being vulnerable to PTSD. The Gene Ontology analysis revealed enriched GO terms in the protein groups of Susceptible group vs Control group rats for glutathione binding,oligopeptide binding,modified amino acid binding,and glutathione transferase activity for their molecular functions (MF) and in the process of cellular response to toxic substance,xenobiotic metabolic process, urea metabolic process, and response to drug for the biological process (BP).SIGNIFICANCE:In recent years, there has been a growing interest in mental illness associated with trauma exposure. We found that stress susceptibility was associated with increased expression of arginase 1 indicated as a potential treatment target. Our results also proposed that carbonic anhydrases 3 could be a biomarker for the development of PTSD. This research helps to explain the potential molecular mechanism in PTSD and supply a new method for ameliorating PTSD.

Aberrant Complement System Activation in Neurological Disorders

The complement system is an assembly of proteins that collectively participate in the functions of the healthy and diseased brain. The complement system plays an important role in the maintenance of uninjured (healthy) brain homeostasis, contributing to the clearance of invading pathogens and apoptotic cells, and limiting the inflammatory immune response. However, overactivation or underregulation of the entire complement cascade within the brain may lead to neuronal damage and disturbances in brain function. During the last decade, there has been a growing interest in the role that this cascading pathway plays in the neuropathology of a diverse array of brain disorders (e.g., acute neurotraumatic insult, chronic neurodegenerative diseases, and psychiatric disturbances) in which interruption of neuronal homeostasis triggers complement activation. Dysfunction of the complement promotes a disease-specific response that may have either beneficial or detrimental effects. Despite recent advances, the explicit link between complement component regulation and brain disorders remains unclear. Therefore, a comprehensible understanding of such relationships at different stages of diseases could provide new insight into potential therapeutic targets to ameliorate or slow progression of currently intractable disorders in the nervous system. Hence, the aim of this review is to provide a summary of the literature on the emerging role of the complement system in certain brain disorders.

Association between complement component 4A expression, cognitive performance and brain imaging measures in UK Biobank

Abstract.

BACKGROUND

Altered expression of the complement component C4A gene is a known risk factor for schizophrenia. Further, predicted brain C4A expression has also been associated with memory function highlighting that altered C4A expression in the brain may be relevant for cognitive and behavioral traits.

METHODS

We obtained genetic information and performance measures on seven cognitive tasks for up to 329 773 individuals from the UK Biobank, as well as brain imaging data for a subset of 33 003 participants. Direct genotypes for variants (n = 3213) within the major histocompatibility complex region were used to impute C4 structural variation, from which predicted expression of the C4A and C4B genes in human brain tissue were predicted. We investigated if predicted brain C4A or C4B expression were associated with cognitive performance and brain imaging measures using linear regression analyses.

RESULTS

We identified significant negative associations between predicted C4A expression and performance on select cognitive tests, and significant associations with MRI-based cortical thickness and surface area in select regions. Finally, we observed significant inconsistent partial mediation of the effects of predicted C4A expression on cognitive performance, by specific brain structure measures.

CONCLUSIONS

These results demonstrate that the C4 risk locus is associated with the central endophenotypes of cognitive performance and brain morphology, even when considered independently of other genetic risk factors and in individuals without mental or neurological disorders.

CUB and Sushi Multiple Domains (CSMD1) Gene Polymorphisms and Susceptibilities to Idiopathic Parkinson's Disease in Northern Chinese Han Population: A Case-Control Study

Evidence has shown that the CUB and Sushi Multiple Domains (CSMD1) gene is an inhibitor of the complement activation pathway and is also involved in central nervous system inflammation. Previous studies have revealed that the CSMD1 gene is related to familial Parkinson's disease. This study aimed to investigate the relationship between CSMD1 gene and susceptibility to Parkinson's disease in population of northern China. A case-control study was performed on 423 Parkinson's disease patients and 465 healthy controls matched for age and sex. DNA from enrolled subjects were extracted from the peripheral blood, and single nucleotide polymorphisms (SNPs) rs12681349 (C＞T), rs10503253 (C＞A), and rs1983474 (T＞G) within CSMD1 gene were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Genotype frequency of rs10503253 (CA versus CC : OR = 1.554, 95% CI = 1.169–2.066, p=0.002) and rs1983474 (GG versus TT : OR = 0.599, 95% CI = 0.401–0.895, p=0.012) was significantly different between PD cases and controls, but not for rs12681349. Comprehensive and subgroup analysis indicated that rs10503252 showed significant statistical differences in the dominant model (AA + CA versus CC : OR = 0.677, 95% CI = 0.517–0.886, p=0.004), late-onset cohort (CA versus CC : OR = 1.570, 95% CI = 1.159–2.126, p=0.004), and the female cohort (CA versus CC : OR = 0.687, 95% CI = 0.497–0.952, p=0.023), compared with the matched control group. The difference of recessive model of rs1983474 (GG versus TT + TG : OR = 1.837, 95% CI = 1.287–2.620, p=0.001) was significant in Parkinson's disease. According to the subgroup analysis, results indicated that late-onset cohort (GG versus TT : OR = 0.643, 95% CI = 0.420–0.985, p=0.042), male cohort (TG versus TT : OR = 2.160, 95% CI = 1.162–4.016, p=0.015), and female group (GG versus TT : OR = 0.418, 95% CI = 0.234–0.746, p=0.003) of rs1983474 were significantly associated with Parkinson's disease susceptibility. In both genotype and subgroup analysis, we failed to find any relationship between rs12681349 polymorphism and Parkinson's disease risk. Our results indicate that the rs10503253 and rs1983474 gene polymorphism may be associated with idiopathic Parkinson's disease susceptibility in Chinese population. Nevertheless, these conclusions need to be further verified by more studies.

The Role of Csmd1 during Mammary Gland Development

The Cub Sushi Multiple Domains-1 (CSMD1) protein is a tumour suppressor which has been shown to play a role in regulating human mammary duct development in vitro. CSMD1 knockdown in vitro demonstrated increased cell proliferation, invasion and motility. However, the role of Csmd1 in vivo is poorly characterised when it comes to ductal development and is therefore an area which warrants further exploration. In this study a Csmd1 knockout (KO) mouse model was used to identify the role of Csmd1 in regulating mammary gland development during puberty. Changes in duct development and protein expression patterns were analysed by immunohistochemistry. This study identified increased ductal development during the early stages of puberty in the KO mice, characterised by increased ductal area and terminal end bud number at 6 weeks. Furthermore, increased expression of various proteins (Stat1, Fak, Akt, Slug/Snail and Progesterone receptor) was shown at 4 weeks in the KO mice, followed by lower expression levels from 6 weeks in the KO mice compared to the wild type mice. This study identifies a novel role for Csmd1 in mammary gland development, with Csmd1 KO causing significantly more rapid mammary gland development, suggesting an earlier adult mammary gland formation.

Effects of complement gene-set polygenic risk score on brain volume and cortical measures in patients with psychotic disorders and healthy controls

Multiple genome-wide association studies of schizophrenia have reported associations between genetic variants within the MHC region and disease risk, an association that has been partially accounted for by alleles of the complement component 4 (C4) gene. Following on previous findings of association between both C4 and other complement-related variants and memory function, we tested the hypothesis that polygenic scores calculated based on identified schizophrenia risk alleles within the "complement" system would be broadly associated with memory function and associated brain structure. We tested this using a polygenic risk score (PRS) calculated for complement genes, but excluding C4 variants. Higher complement-based PRS scores were observed to be associated with lower memory scores for the sample as a whole (N = 620, F change = 8.25; p = .004). A significant association between higher PRS and lower hippocampal volume was also observed (N = 216, R² change = 0.016, p = .015). However, after correcting for further testing of association with the more general indices of cortical thickness, surface area or total brain volume, none of which were associated with complement, the association with hippocampal volume became non-significant. A post-hoc analysis of hippocampal subfields suggested an association between complement PRS and several hippocampal subfields, findings that appeared to be particularly driven by the patient sample. In conclusion, our study yielded suggestive evidence of association between complement-based schizophrenia PRS and variation in memory function and hippocampal volume.

Complement System in Brain Architecture and Neurodevelopmental Disorders

Current evidence indicates that certain immune molecules such as components of the complement system are directly involved in neurobiological processes related to brain development, including neurogenesis, neuronal migration, synaptic remodeling, and response to prenatal or early postnatal brain insults. Consequently, complement system dysfunction has been increasingly implicated in disorders of neurodevelopmental origin, such as schizophrenia, autism spectrum disorder (ASD) and Rett syndrome. However, the mechanistic evidence for a causal relationship between impaired complement regulation and these disorders varies depending on the disease involved. Also, it is still unclear to what extent altered complement expression plays a role in these disorders through inflammation-independent or -dependent mechanisms. Furthermore, pathogenic mutations in specific complement components have been implicated in the etiology of 3MC syndrome, a rare autosomal recessive developmental disorder. The aims of this review are to discuss the current knowledge on the roles of the complement system in sculpting brain architecture and function during normal development as well as after specific inflammatory insults, such as maternal immune activation (MIA) during pregnancy, and to evaluate the existing evidence associating aberrant complement with developmental brain disorders.

The complement system in schizophrenia: where are we now and what's next?

The complement system is a set of immune proteins involved in first-line defense against pathogens and removal of waste materials. Recent evidence has implicated the complement cascade in diseases involving the central nervous system, including schizophrenia. Here, we provide an up-to-date narrative review and critique of the literature on the relationship between schizophrenia and complement gene polymorphisms, gene expression, protein concentration, and pathway activity. A literature search identified 23 new studies since the first review on this topic in 2008. Overall complement pathway activity appears to be elevated in schizophrenia. Recent studies have identified complement component 4 (C4) and CUB and Sushi Multiple Domains 1 (CSMD1) as potential genetic markers of schizophrenia. In particular, there is some evidence of higher rates of C4B/C4S deficiency, reduced peripheral C4B concentration, and elevated brain C4A mRNA expression in schizophrenia patients compared to controls. To better elucidate the additive effects of multiple complement genotypes, we also conducted gene- and gene-set analysis through MAGMA which supported the role of Human Leukocyte Antigen class (HLA) III genes and, to a lesser extent, CSMD1 in schizophrenia; however, the HLA-schizophrenia association was likely driven by the C4 gene. Lastly, we identified several limitations of the literature on the complement system and schizophrenia, including: small sample sizes, inconsistent methodologies, limited measurements of neural concentrations of complement proteins, little exploration of the link between complement and schizophrenia phenotype, and lack of studies exploring schizophrenia treatment response. Overall, recent findings highlight complement components-in particular, C4 and CSMD1-as potential novel drug targets in schizophrenia. Given the growing availability of complement-targeted therapies, future clinical studies evaluating their efficacy in schizophrenia hold the potential to accelerate treatment advances.

Novel MED12 variant in a multiplex Fragile X syndrome family: dual molecular etiology of two X-linked intellectual disabilities with autism in the same family

Studies of X-linked pedigrees were the first to identify genes implicated in intellectual disability (ID) and autism spectrum disorder (ASD). However, some pedigrees present a huge clinical variability between the affected members. This intrafamilial heterogeneity may be due to cooccurrence of two disorders. In the present study, we describe a multiplex X-linked pedigree in which three siblings have ID, ASD and dysmorphic features but with variable severity. Through Fragile X syndrome test, we identified the full FMR1 mutation in only two males. Whole exome sequencing allowed us to identify a novel hemizygous variant (p.Gln2080_Gln2083del) in MED12 gene in two males. So, the first patient has FXS, the second has both FMR1 and MED12 mutations while the third has only the MED12 variant. MED12 mutations are implicated in several forms of X-linked ID. Family segregation and genotype-phenotype-correlation were in favor of a cooccurrence of two forms of X-linked ID. Our work provides further evidence of the involvement of MED12 in XLID. Moreover, through these results, it is noteworthy to raise awareness that intrafamilial heterogeneity in FXS multiplex families could result from the cooccurrence of multiple clinical entities involving at least two separate genetic loci. This should be taken into consideration for genetic testing and counselling in patients/families with atypical disease symptoms.

Csmd2 Is a Synaptic Transmembrane Protein that Interacts with PSD-95 and Is Required for Neuronal Maturation

Mutations and copy number variants of the CUB and Sushi multiple domains 2 (CSMD2) gene are associated with neuropsychiatric disease. CSMD2 encodes a single-pass transmembrane protein with a large extracellular domain comprising repeats of CUB and Sushi domains. High expression of CSMD2 in the developing and mature brain suggests possible roles in neuron development or function, but the cellular functions of CSMD2 are not known. In this study, we show that mouse Csmd2 is expressed in excitatory and inhibitory neurons in the forebrain. Csmd2 protein exhibits a somatodendritic localization in the neocortex and hippocampus, with smaller puncta localizing to the neuropil. Using immunohistochemical and biochemical methods, we demonstrate that Csmd2 localizes to dendritic spines and is enriched in the postsynaptic density (PSD). Accordingly, we show that the cytoplasmic tail domain of Csmd2 interacts with synaptic scaffolding proteins of the membrane-associated guanylate kinase (MAGUK) family. The association between Csmd2 and MAGUK member PSD-95 is dependent on a PDZ-binding domain on the Csmd2 tail, which is also required for synaptic targeting of Csmd2. Finally, we show that knock-down of Csmd2 expression in hippocampal neuron cultures results in reduced complexity of dendritic arbors and deficits in dendritic spine density. Knock-down of Csmd2 in immature developing neurons results in reduced filopodia density, whereas Csmd2 knock-down in mature neurons causes significant reductions in dendritic spine density and dendrite complexity. Together, these results point toward a function for Csmd2 in development and maintenance of dendrites and synapses, which may account for its association with certain psychiatric disorders.

Altered expression of the CSMD1 gene in the peripheral blood of schizophrenia patients

BACKGROUND

Schizophrenia (SCZ) is a heritable, refractory, and devastating psychiatric disorder. Previous studies have shown that the variants of CUB and sushi multiple domains 1 (CSMD1) demonstrate significant genome-wide association with SCZ. However, few studies have been conducted on the effect of antipsychotics on the expression levels of CSMD1. This study explored whether a change occurs in the expression of the CSMD1 gene before and after antipsychotic treatment in SCZ patients.

METHODS

The study population comprised Han Chinese patients from eastern China, including 32 SCZ patients and 48 healthy controls. The expression of CSMD1 before and after treatment in the SCZ group and between the two groups was analyzed using real-time quantitative polymerase chain reaction (RT-qPCR).

RESULTS

The expression levels of the CSMD1 gene in the peripheral blood mononuclear cells (PBMCs) of SCZ patients were lower than those in the healthy controls. The expression levels of the CSMD1 gene in the PBMCs of the SCZ patients after antipsychotic treatment were higher than those in the baseline SCZ patients (all P <  0.05).

CONCLUSIONS

Our results showed that the expression levels of CSMD1 are correlated with the development and treatment of SCZ, providing further evidence for the involvement of CSMD1 in SCZ.

Leveraging genome-wide association and clinical data in revealing schizophrenia subgroups

Schizophrenia (SCZ) has long been recognized as a highly heterogeneous disorder. Patients differed in their clinical manifestations, prognosis, and underlying pathophysiologies. Here we presented and applied a framework for finding subtypes of SCZ utilizing genome-wide association study (GWAS) and clinical data. We postulated that genetic information may help stratify patient into useful subgroups, and incorporation of other clinical information and cognitive profiles will further improve patient subtyping. We conducted cluster analysis in 387 Hong Kong Chinese with SCZ. First we performed 'single-view' clustering using genetic or clinical data alone, then proceeded to 'multi-view' clustering (MVC) accounting for both types of information. We validated clustering results by assessing subgroup differences in various outcomes. We found significant differences in outcomes including treatment response, disease course and symptom severity (Simes overall p-value using MVC = 1.64E-9). Overall speaking, we identified three subgroups with good, intermediate and poor prognosis respectively. MVC generally out-performed single-view methods. The analysis was repeated for different sets of input SNPs, and stratified analysis of male and female patients, and the results remained largely robust. We also found significant enrichment for SCZ loci among the SNPs selected by the cluster algorithm. Numerous selected genes (e.g. NRG1, ERBB4, NRXN1, ANK3) and pathways (e.g. neuregulin-ErbB4 and calcium signaling) were implicated in SCZ or related pathophysiological processes. This is first study to combine both genetic and clinical data for subtyping SCZ, and to employ genome-wide SNP data in cluster analysis of a complex disease. This work points to a new way of GWAS analysis of translational potential.

Genetically predicted complement component 4A expression: effects on memory function and middle temporal lobe activation

BACKGROUND

The longstanding association between the major histocompatibility complex (MHC) locus and schizophrenia (SZ) risk has recently been accounted for, partially, by structural variation at the complement component 4 (C4) gene. This structural variation generates varying levels of C4 RNA expression, and genetic information from the MHC region can now be used to predict C4 RNA expression in the brain. Increased predicted C4A RNA expression is associated with the risk of SZ, and C4 is reported to influence synaptic pruning in animal models.

METHODS

Based on our previous studies associating MHC SZ risk variants with poorer memory performance, we tested whether increased predicted C4A RNA expression was associated with reduced memory function in a large (n = 1238) dataset of psychosis cases and healthy participants, and with altered task-dependent cortical activation in a subset of these samples.

RESULTS

We observed that increased predicted C4A RNA expression predicted poorer performance on measures of memory recall (p = 0.016, corrected). Furthermore, in healthy participants, we found that increased predicted C4A RNA expression was associated with a pattern of reduced cortical activity in middle temporal cortex during a measure of visual processing (p < 0.05, corrected).

CONCLUSIONS

These data suggest that the effects of C4 on cognition were observable at both a cortical and behavioural level, and may represent one mechanism by which illness risk is mediated. As such, deficits in learning and memory may represent a therapeutic target for new molecular developments aimed at altering C4's developmental role.

The Genetics of Endophenotypes of Neurofunction to Understand Schizophrenia (GENUS) consortium: A collaborative cognitive and neuroimaging genetics project

BACKGROUND

Schizophrenia has a large genetic component, and the pathways from genes to illness manifestation are beginning to be identified. The Genetics of Endophenotypes of Neurofunction to Understand Schizophrenia (GENUS) Consortium aims to clarify the role of genetic variation in brain abnormalities underlying schizophrenia. This article describes the GENUS Consortium sample collection.

METHODS

We identified existing samples collected for schizophrenia studies consisting of patients, controls, and/or individuals at familial high-risk (FHR) for schizophrenia. Samples had single nucleotide polymorphism (SNP) array data or genomic DNA, clinical and demographic data, and neuropsychological and/or brain magnetic resonance imaging (MRI) data. Data were subjected to quality control procedures at a central site.

RESULTS

Sixteen research groups contributed data from 5199 psychosis patients, 4877 controls, and 725 FHR individuals. All participants have relevant demographic data and all patients have relevant clinical data. The sex ratio is 56.5% male and 43.5% female. Significant differences exist between diagnostic groups for premorbid and current IQ (both p<1×10^-10). Data from a diversity of neuropsychological tests are available for 92% of participants, and 30% have structural MRI scans (half also have diffusion-weighted MRI scans). SNP data are available for 76% of participants. The ancestry composition is 70% European, 20% East Asian, 7% African, and 3% other.

CONCLUSIONS

The Consortium is investigating the genetic contribution to brain phenotypes in a schizophrenia sample collection of >10,000 participants. The breadth of data across clinical, genetic, neuropsychological, and MRI modalities provides an important opportunity for elucidating the genetic basis of neural processes underlying schizophrenia.

Genetic Variants in CSMD1 Gene Are Associated with Cognitive Performance in Normal Elderly Population

Recently, genetic markers rs10503253 and rs2616984 in the CUB and Sushi multiple domains-1 (CSMD1) gene have been reported to be associated with schizophrenia and cognitive functions in genome-wide association studies. We examined the associations of the above SNPs with cognitive performance evaluated by the Montreal Cognitive Assessment (MoCA) tool in a cohort of the normal elderly from the Russian population. Significant association of rs2616984 genotypes with the MoCA scores was found using nonparametric analysis. No association of rs10503253 with MoCA scores was observed using both parametric and nonparametric statistics. Significant combined effect of two-locus CSMD1 genotypes on MoCA scores was demonstrated by median test. Allele "A" and genotype "AA" of rs2616984 were significantly associated with the lower MoCA scores in comparison of 1st and 4th quartiles of MoCA total score distribution. The results suggest that genetic variants in CSMD1 gene are likely a part of genetic component of cognitive performance in the elderly.

Isolated chromosome 8p23.2‑pter deletion: Novel evidence for developmental delay, intellectual disability, microcephaly and neurobehavioral disorders

The current study presents a patient carrying a de novo ~6 Mb deletion of the isolated chromosome 8p23.2-pter that was identified with a single-nucleotide polymorphism array. The patient was characterized by developmental delay (DD)/intellectual disability (ID), microcephaly, autism spectrum disorder, attention-deficit/hyperactivity disorders and mildly dysmorphic features. The location, size and gene content of the deletion observed in this patient were compared with those in 7 patients with isolated 8p23.2 to 8pter deletions reported in previous studies (4 patients) or recorded in the Database of Chromosomal Imbalance and Phenotype in Humans Using Ensembl Resources (DECIPHER) database (3 patients). The deletions reported in previous studies were assessed using a chromosomal microarray analysis. The 8p23.2-pter deletion was a distinct microdeletion syndrome, as similar phenotypes were observed in patients with this deletion. Furthermore, following a detailed review of the potential associations between the genes located from 8p23.2 to 8pter and their clinical significance, it was hypothesized that DLG associated protein 2, ceroid-lipofuscinosis neuronal 8, Rho guanine nucleotide exchange factor 10 and CUB and sushi multiple domains 1 may be candidate genes for DD/ID, microcephaly and neurobehavioral disorders. However, firm evidence should be accumulated from high-resolution studies of patients with small, isolated, overlapping and interstitial deletions involving the region from 8p23.2 to 8pter. These studies will allow determination of genotype-phenotype associations for the specific genes crucial to 8p23.2-pter.

Genome-Wide Supported Risk Variants in MIR137, CACNA1C, CSMD1, DRD2, and GRM3 Contribute to Schizophrenia Susceptibility in Pakistani Population

OBJECTIVE

Schizophrenia is a chronic neuropsychiatric disease afflicting around 1.1% of the population worldwide. Recently, MIR137, CACNA1C, CSMD1, DRD2, and GRM3 have been reported as the most robustly emerging candidates involved in the etiology of schizophrenia. In this case control study, we performed an association analysis of rs1625579 (MIR137), rs1006737, rs4765905 (CACNA1C), rs10503253 (CSMD1), rs1076560 (DRD2), rs12704290, rs6465084, and rs148754219 (GRM3) in Pakistani population.

METHODS

Schizophrenia was diagnosed on the basis of the Diagnostic and Statistical Manual of Mental Disorders 4th ed (DSM-IV). Detailed clinical information, family history of all patients and healthy controls were collected. RFLP based case control association study was performed in a Pakistani cohort of 508 schizophrenia patients and 300 healthy control subjects. Alleles and genotype frequencies were calculated using SPSS.

RESULTS

A significant difference in the genotype and allele frequencies for rs4765905, rs1076560 and rs6465084 were found between the patients and controls (p=0.000).

CONCLUSION

This study provides substantial evidence supporting the role of CACNA1C, GRM3 and DRD2 as schizophrenia susceptibility genes in Pakistani population.

Identification of NCAN as a candidate gene for developmental dyslexia

A whole-genome linkage analysis in a Finnish pedigree of eight cases with developmental dyslexia (DD) revealed several regions shared by the affected individuals. Analysis of coding variants from two affected individuals identified rs146011974G > A (Ala1039Thr), a rare variant within the NCAN gene co-segregating with DD in the pedigree. This variant prompted us to consider this gene as a putative candidate for DD. The RNA expression pattern of the NCAN gene in human tissues was highly correlated (R > 0.8) with that of the previously suggested DD susceptibility genes KIAA0319, CTNND2, CNTNAP2 and GRIN2B. We investigated the association of common variation in NCAN to brain structures in two data sets: young adults (Brainchild study, Sweden) and infants (FinnBrain study, Finland). In young adults, we found associations between a common genetic variant in NCAN, rs1064395, and white matter volume in the left and right temporoparietal as well as the left inferior frontal brain regions. In infants, this same variant was found to be associated with cingulate and prefrontal grey matter volumes. Our results suggest NCAN as a new candidate gene for DD and indicate that NCAN variants affect brain structure.

Whole-genome sequencing of monozygotic twins discordant for schizophrenia indicates multiple genetic risk factors for schizophrenia

Schizophrenia is a common disorder with a high heritability, but its genetic architecture is still elusive. We implemented whole-genome sequencing (WGS) analysis of 8 families with monozygotic (MZ) twin pairs discordant for schizophrenia to assess potential association of de novo mutations (DNMs) or inherited variants with susceptibility to schizophrenia. Eight non-synonymous DNMs (including one splicing site) were identified and shared by twins, which were either located in previously reported schizophrenia risk genes (p.V24689I mutation in TTN, p.S2506T mutation in GCN1L1, IVS3+1G > T in DOCK1) or had a benign to damaging effect according to in silico prediction analysis. By searching the inherited rare damaging or loss-of-function (LOF) variants and common susceptible alleles from three classes of schizophrenia candidate genes, we were able to distill genetic alterations in several schizophrenia risk genes, including GAD1, PLXNA2, RELN and FEZ1. Four inherited copy number variations (CNVs; including a large deletion at 16p13.11) implicated for schizophrenia were identified in four families, respectively. Most of families carried both missense DNMs and inherited risk variants, which might suggest that DNMs, inherited rare damaging variants and common risk alleles together conferred to schizophrenia susceptibility. Our results support that schizophrenia is caused by a combination of multiple genetic factors, with each DNM/variant showing a relatively small effect size.

A genetic association study of CSMD1 and CSMD2 with cognitive function

The complement cascade plays a role in synaptic pruning and synaptic plasticity, which seem to be involved in cognitive functions and psychiatric disorders. Genetic variants in the closely related CSMD1 and CSMD2 genes, which are implicated in complement regulation, are associated with schizophrenia. Since patients with schizophrenia often show cognitive impairments, we tested whether variants in CSMD1 and CSMD2 are also associated with cognitive functions per se. We took a discovery-replication approach, using well-characterized Scandinavian cohorts. A total of 1637 SNPs in CSMD1 and 206 SNPs in CSMD2 were tested for association with cognitive functions in the NCNG sample (Norwegian Cognitive NeuroGenetics; n=670). Replication testing of SNPs with p-value<0.001 (7 in CSMD1 and 3 in CSMD2) was carried out in the TOP sample (Thematically Organized Psychosis; n=1025) and the BETULA sample (Betula Longitudinal Study on aging, memory and dementia; n=1742). Finally, we conducted a meta-analysis of these SNPs using all three samples. The previously identified schizophrenia marker in CSMD1 (SNP rs10503253) was also included. The strongest association was observed between the CSMD1 SNP rs2740931 and performance in immediate episodic memory (p-value=5×10^-6, minor allele A, MAF 0.48-0.49, negative direction of effect). This association reached the study-wide significance level (p⩽1.2×10^-5). SNP rs10503253 was not significantly associated with cognitive functions in our samples. In conclusion, we studied n=3437 individuals and found evidence that a variant in CSMD1 is associated with cognitive function. Additional studies of larger samples with cognitive phenotypes will be needed to further clarify the role of CSMD1 in cognitive phenotypes in health and disease.

No association between the rs10503253 polymorphism in the CSMD1 gene and schizophrenia in a Han Chinese population

BACKGROUND

Schizophrenia (SCZ) is a complex, heritable, and devastating psychiatric disorder. Recent genome-wide association studies have identified a single-nucleotide polymorphism (SNP; rs10503253) in the CUB and SUSHI multiple domains 1 (CSMD1) gene as a risk factor for SCZ. In this study, we investigated whether the rs10503253 in CSMD1 contributes to the risk of SCZ in a Han Chinese population.

METHODS

We conducted a case-control study in a population from eastern China, involving 1378 SCZ patients and 1091 unrelated healthy controls, using the ligase detection reaction-polymerase chain reaction method to genotype the rs10503253 polymorphism in the CSMD1 gene.

RESULTS

No significant association was found between the SCZ patients and controls for any allele or genotype frequency of the SNP rs10503253 (all P > 0.05).

CONCLUSIONS

Our findings do not support an association between CSMD1 rs10503253 and SCZ in a Han Chinese population.

Individual risk alleles of susceptibility to schizophrenia are associated with poor clinical and social outcomes

Many patients with schizophrenia have poor clinical and social outcomes. Some risk alleles closely related to the onset of schizophrenia have been reported to be associated with their clinical phenotypes, but the direct relationship between genetic vulnerability to schizophrenia and clinical/social outcomes of schizophrenia, as evaluated by both practical clinical scales and 'real-world' function, has not been investigated. We evaluated the clinical and social outcomes of 455 Japanese patients with schizophrenia by severity of illness according to the Clinical Global Impression-Severity Scale (CGI-S) and social outcomes by social adjustment/maladjustment at 5 years after the first visit. We examined whether 46 single nucleotide polymorphisms (SNPs) selected from a Japanese genome-wide association study of susceptibility to schizophrenia were associated with clinical and social outcomes. We also investigated the polygenic risk scores of 46 SNPs. Allele-wise association analysis detected three SNPs, including rs2623659 in the CUB and Sushi multiple domains-1 (CSMD1) gene, associated with severity of illness at end point. The severity of illness at end point was associated with treatment response, but not with the severity of illness at baseline. Three SNPs, including rs2294424 in the C6orf105 gene, were associated with social outcomes. Point estimates of odds ratios showed positive relationships between polygenic risk scores and clinical/social outcomes; however, the results were not statistically significant. Because these results are exploratory, we need to replicate them with a larger sample in a future study.

Altered CSMD1 Expression Alters Cocaine-Conditioned Place Preference: Mutual Support for a Complex Locus from Human and Mouse Models

The CUB and sushi multiple domains 1 (CSMD1) gene harbors signals provided by clusters of nearby SNPs with 10-2 > p > 10-8 associations in genome wide association (GWAS) studies of addiction-related phenotypes. A CSMD1 intron 3 SNP displays p < 10-8 association with schizophrenia and more modest associations with individual differences in performance on tests of cognitive abilities. CSDM1 encodes a cell adhesion molecule likely to influence development, connections and plasticity of brain circuits in which it is expressed. We tested association between CSMD1 genotypes and expression of its mRNA in postmortem human brains (n = 181). Expression of CSMD1 mRNA in human postmortem cerebral cortical samples differs 15-25%, in individuals with different alleles of simple sequence length and SNP polymorphisms located in the gene's third/fifth introns, providing nominal though not Bonferroni-corrected significance. These data support mice with altered CSMD1 expression as models for common human CSMD1 allelic variation. We tested baseline and/or cocaine-evoked addiction, emotion, motor and memory-related behaviors in +/- and -/- csmd1 knockout mice on mixed and on C57-backcrossed genetic backgrounds. Initial csmd1 knockout mice on mixed genetic backgrounds displayed a variety of coat colors and sizable individual differences in responses during behavioral testing. Backcrossed mice displayed uniform black coat colors. Cocaine conditioned place preference testing revealed significant influences of genotype (p = 0.02). Homozygote knockouts displayed poorer performance on aspects of the Morris water maze task. They displayed increased locomotion in some, though not all, environments. The combined data thus support roles for common level-of-expression CSMD1 variation in a drug reward phenotype relevant to addiction and in cognitive differences that might be relevant to schizophrenia. Mouse model results can complement data from human association findings of modest magnitude that identify likely polygenic influences.

Pharmacogenetics of second-generation antipsychotics

This review considers pharmacogenetics of the so called 'second-generation' antipsychotics. Findings for polymorphisms replicating in more than one study are emphasized and compared and contrasted with larger-scale candidate gene studies and genome-wide association study analyses. Variants in three types of genes are discussed: pharmacokinetic genes associated with drug metabolism and disposition, pharmacodynamic genes encoding drug targets, and pharmacotypic genes impacting disease presentation and subtype. Among pharmacokinetic markers, CYP2D6 metabolizer phenotype has clear clinical significance, as it impacts dosing considerations for aripiprazole, iloperidone and risperidone, and variants of the ABCB1 gene hold promise as biomarkers for dosing for olanzapine and clozapine. Among pharmacodynamic variants, the TaqIA1 allele of the DRD2 gene, the DRD3 (Ser9Gly) polymorphism, and the HTR2C -759C/T polymorphism have emerged as potential biomarkers for response and/or side effects. However, large-scale candidate gene studies and genome-wide association studies indicate that pharmacotypic genes may ultimately prove to be the richest source of biomarkers for response and side effect profiles for second-generation antipsychotics.

The CSMD1 genome-wide associated schizophrenia risk variant rs10503253 affects general cognitive ability and executive function in healthy males

BACKGROUND

The single-nucleotide polymorphism (SNP) rs10503253, located within the CUB and Sushi multiple domains-1 (CSMD1) gene on 8p23.2, has reached genome-wide support as a risk factor for schizophrenia. There is initial but inconclusive evidence for a role of this variant in aspects of cognition.

METHODS

We investigated the neurocognitive effects of the CSMD1 rs10503253 (C/A) polymorphism in a large, demographically homogeneous sample of young, healthy Greek Caucasian males (n=1149) phenotyped for a wide range of neuropsychological measures, most of which have been shown to be reliable endophenotypes for schizophrenia.

RESULTS

The risk 'A' allele was associated with poorer performance on measures of general cognitive ability, strategy formation, spatial and visual working memory, set shifting, target detection and planning for problem solving but not for emotional decision making. Most of these effects were dependent on risk "A" allele dose, with AA and CC homozygotes being the worse and the best respectively, while CA individuals were intermediate. Potential genotype effects in Stroop and verbal memory performance were also suggested by our dataset.

DISCUSSION

These results underline the relevance of the risk "A" allele to neurocognitive functioning and suggest that its detrimental effects on cognition, may be part of the mechanism by which the CSMD1 mediates risk for schizophrenia.

Neural effects of the CSMD1 genome-wide associated schizophrenia risk variant rs10503253

The single nucleotide polymorphism rs10503253 within the CUB and Sushi multiple domains-1 (CSMD1) gene on 8p23.2 has been identified as genome-wide significant for schizophrenia (SZ). This gene is of unknown function but has been implicated in multiple neurodevelopmental disorders that impact upon cognition, leading us to hypothesize that an effect on brain structure and function underlying cognitive processes may be part of the mechanism by which CMSD1 increases illness risk. To test this hypothesis, we investigated this CSMD1 variant in vivo in healthy participants in a magnetic resonance imaging (MRI) study comprised of both fMRI of spatial working memory (N = 50) and a voxel-based morphometry investigation of grey and white matter (WM) volume (N = 150). Analyses of these data indicated that the risk "A" allele was associated with comparatively reduced cortical activations in BA18, that is, middle occipital gyrus and cuneus; posterior brain regions that support maintenance processes during performance of a spatial working memory task. Conversely, there was an absence of significant structural differences in brain volume (i.e., grey or WM). In accordance with previous evidence, these data suggest that CSMD1 may mediate brain function related to cognitive processes (i.e., executive function); with the relatively deleterious effects of the identified "A" risk allele on brain activity possibly constituting part of the mechanism by which CSMD1 increases schizophrenia risk.