Genetic architectures of psychiatric disorders: the emerging picture and its implications

Shared genetic influences between attention-deficit/hyperactivity disorder (ADHD) traits in children and clinical ADHD

OBJECTIVE

Twin studies and genome-wide complex trait analysis (GCTA) are not in agreement regarding heritability estimates for behavioral traits in children from the general population. This has sparked a debate on the possible difference in genetic architecture between behavioral traits and psychiatric disorders. In this study, we test whether polygenic risk scores associated with variation in attention-deficit/hyperactivity disorder (ADHD) trait levels in children from the general population predict ADHD diagnostic status and severity in an independent clinical sample.

METHOD

Single nucleotide polymorphisms (SNPs) with p < .5 from a genome-wide association study of ADHD traits in 4,546 children (mean age, 7 years 7 months) from the Avon Longitudinal Study of Parents and Children (ALSPAC; general population sample) were selected to calculate polygenic risk scores in 508 children with an ADHD diagnosis (independent clinical sample) and 5,081 control participants. Polygenic scores were tested for association with case-control status and severity of disorder in the clinical sample.

RESULTS

Increased polygenic score for ADHD traits predicted ADHD case-control status (odds ratio = 1.17 [95% CI = 1.08-1.28], p = .0003), higher ADHD symptom severity (β = 0.29 [95% CI = 0.04-0.54], p = 0.02), and symptom domain severity in the clinical sample.

CONCLUSION

This study highlights the relevance of additive genetic variance in ADHD, and provides evidence that shared genetic factors contribute to both behavioral traits in the general population and psychiatric disorders at least in the case of ADHD.

The effect of ANK3 bipolar-risk polymorphisms on the working memory circuitry differs between loci and according to risk-status for bipolar disorder

Polymorphisms at the rs10994336 and rs9804190 loci of the Ankyrin 3 (ANK3) gene have been strongly associated with increased risk for bipolar disorder (BD). However, their potential pathogenetic effect on BD-relevant neural circuits remains unknown. We examined the effect of BD-risk polymorphisms at rs10994336 and rs9804190 on the working memory (WM) circuit using functional magnetic resonance imaging (fMRI) data obtained from euthymic patients with BD (n = 41), their psychiatrically healthy first-degree relatives (n = 25) and unrelated individuals without personal or family history of psychiatric disorders (n = 46) while performing the N-back task. In unrelated healthy individuals, the rs10994336-risk-allele was associated with reduced activation of the ventral visual cortical components of the WM circuit while the rs9804190-risk-allele was associated with inefficient hyperactivation of the prefrontal cortical components of the WM. In patients and their healthy relatives, risk alleles at either loci were associated with hyperactivation in the ventral anterior cingulate cortex. Additionally, Rs9804190-risk-allele carriers with BD evidenced abnormal hyperactivation within the posterior cingulate cortex. This study provides new insights on the neurogenetic correlates of allelic variation at different genome-wide supported BD-risk associated ANK3 loci that support their involvement in BD and highlight the modulatory influence of increased background genetic risk for BD.

Psychiatrist attitudes towards pharmacogenetic testing, direct-to-consumer genetic testing, and integrating genetic counseling into psychiatric patient care

Psychiatric treatment has not historically included genetic counseling or genetic testing. It has been shown that psychiatric patients and their families benefit from genetic counseling and pharmacogenetic testing for pharmacological treatment. To date, no study has investigated psychiatrists' attitudes towards incorporating pharmacogenetic testing and genetic counseling into patient treatment. This study employed a five item survey to solicit the opinions of psychiatrists on the benefit of pharmacogenetic data, direct to consumer (DTC) genetic testing, and genetic counseling. A total of 113 psychiatrists responded to the surveys. The vast majority (94.6%) indicated that genetic data would be useful in making pharmaceutical decisions, and 86% felt that pharmacogenetic testing would become standard of care. Attitudes were split towards the benefit of direct to consumer genetic testing; 55.8% of respondents would refer a patient for DTC genetic testing that might help with treatment decisions. The majority (72.6%) believed that it would be beneficial to include genetic counselors in psychiatric patient care. The results of our study suggest there is potential for collaboration between psychiatrists and genetic counselors to enhance patient care.

The 5-HTTLPR confers susceptibility to anorexia nervosa in Han Chinese: evidence from a case-control and family-based study

Accumulating evidence has implied that serotonin system dysfunction may be involved in the etiology of anorexia nervosa (AN). Serotonin-transporter-linked promoter region (5-HTTLPR) polymorphism is the genetic variant coding for the serotonin transporter and has a modulatory effect on its expression. This study aimed to investigate the possible association between the 5-HTTLPR and the susceptibility and severity of AN in Han Chinese using a case-control (255 patients and 351 controls) and family based study (198 trios). Eating disorder examination was used to measure the severity of AN behavioral symptoms. For the case-control study, the 5-HTTLPR showed significant association with AN in our sample (genotypic P = 0.03). The frequency of S allele was significantly higher in patients than that in controls (OR = 1.38, 95%CI: 1.06–1.79, P = 0.017). For the family-based study, the S allele of 5-HTTLPR was preferentially transmitted rather than non-transmitted from the parents to affected offspring (P = 0.013). The results of ANCOVA test revealed no significant association between the 5-HTTLPR polymorphism and severity of AN. Our findings suggested that 5-HTTLPR is able to confer susceptibility to AN in Han Chinese.

Copy number variants encompassing Mendelian disease genes in a large multigenerational family segregating bipolar disorder

BACKGROUND

Bipolar affective disorder (BP) is a common, highly heritable psychiatric disorder characterized by periods of depression and mania. Using dense SNP genotype data, we characterized CNVs in 388 members of an Old Order Amish Pedigree with bipolar disorder. We identified CNV regions arising from common ancestral mutations by utilizing the pedigree information. By combining this analysis with whole genome sequence data in the same individuals, we also explored the role of compound heterozygosity.

RESULTS

Here we describe 541 inherited CNV regions, of which 268 are rare in a control population of European origin but present in a large number of Amish individuals. In addition, we highlight a set of CNVs found at higher frequencies in BP individuals, and within genes known to play a role in human development and disease. As in prior reports, we find no evidence for an increased burden of CNVs in BP individuals, but we report a trend towards a higher burden of CNVs in known Mendelian disease loci in bipolar individuals (BPI and BPII, p = 0.06).

CONCLUSIONS

We conclude that CNVs may be contributing factors in the phenotypic presentation of mood disorders and co-morbid medical conditions in this family. These results reinforce the hypothesis of a complex genetic architecture underlying BP disorder, and suggest that the role of CNVs should continue to be investigated in BP data sets.

Neuronal migration abnormalities and its possible implications for schizophrenia

Schizophrenia is a complex mental disorder that displays behavioral deficits such as decreased sensory gating, reduced social interaction and working memory deficits. The neurodevelopmental model is one of the widely accepted hypotheses of the etiology of schizophrenia. Subtle developmental abnormalities of the brain which stated long before the onset of clinical symptoms are thought to lead to the emergence of illness. Schizophrenia has strong genetic components but its underlying molecular pathogenesis is still poorly understood. Genetic linkage and association studies have identified several genes involved in neuronal migrations as candidate susceptibility genes for schizophrenia, although their effect size is small. Recent progress in copy number variation studies also has identified much higher risk loci such as 22q11. Based on these genetic findings, we are now able to utilize genetically-defined animal models. Here we summarize the results of neurodevelopmental and behavioral analysis of genetically-defined animal models. Furthermore, animal model experiments have demonstrated that embryonic and perinatal neurodevelopmental insults in neurogenesis and neuronal migrations cause neuronal functional and behavioral deficits in affected adult animals, which are similar to those of schizophrenic patients. However, these findings do not establish causative relationship. Genetically-defined animal models are a critical approach to explore the relationship between neuronal migration abnormalities and behavioral abnormalities relevant to schizophrenia.

Genetics and Epigenetics of Eating Disorders

Eating disorders (EDs) are serious psychiatric conditions influenced by biological, psychological, and sociocultural factors. A better understanding of the genetics of these complex traits and the development of more sophisticated molecular biology tools have advanced our understanding of the etiology of EDs. The aim of this review is to critically evaluate the literature on the genetic research conducted on three major EDs: anorexia nervosa (AN), bulimia nervosa (BN), and binge eating disorder (BED). We will first review the diagnostic criteria, clinical features, prevalence, and prognosis of AN, BN, and BED, followed by a review of family, twin, and adoption studies. We then review the history of genetic studies of EDs covering linkage analysis, candidate gene association studies, genome-wide association studies, and the study of rare variants in EDs. Our review also incorporates a translational perspective by covering animal models of ED-related phenotypes. Finally, we review the nascent field of epigenetics of EDs and a look forward to future directions for ED genetic research.

The proteome of schizophrenia

On observing schizophrenia from a clinical point of view up to its molecular basis, one may conclude that this is likely to be one of the most complex human disorders to be characterized in all aspects. Such complexity is the reflex of an intricate combination of genetic and environmental components that influence brain functions since pre-natal neurodevelopment, passing by brain maturation, up to the onset of disease and disease establishment. The perfect function of tissues, organs, systems, and finally the organism depends heavily on the proper functioning of cells. Several lines of evidence, including genetics, genomics, transcriptomics, neuropathology, and pharmacology, have supported the idea that dysfunctional cells are causative to schizophrenia. Together with the above-mentioned techniques, proteomics have been contributing to understanding the biochemical basis of schizophrenia at the cellular and tissue level through the identification of differentially expressed proteins and consequently their biochemical pathways, mostly in the brain tissue but also in other cells. In addition, mass spectrometry-based proteomics have identified and precisely quantified proteins that may serve as biomarker candidates to prognosis, diagnosis, and medication monitoring in peripheral tissue. Here, we review all data produced by proteomic investigation in the last 5 years using tissue and/or cells from schizophrenic patients, focusing on postmortem brain tissue and peripheral blood serum and plasma. This information has provided integrated pictures of the biochemical systems involved in the pathobiology, and has suggested potential biomarkers, and warrant potential targets to alternative treatment therapies to schizophrenia.

Bipolar disorder and its relation to major psychiatric disorders: a family-based study in the Swedish population

OBJECTIVES

Bipolar disorder (BPD) shares genetic components with other psychiatric disorders; however, uncertainty remains about where in the psychiatric spectra BPD falls. To understand the etiology of BPD, we studied the familial aggregation of BPD and co-aggregation between BPD and schizophrenia, depression, anxiety disorders, attention-deficit hyperactivity disorder, drug abuse, personality disorders, and autism spectrum disorders.

METHODS

A population-based cohort was created by linking several Swedish national registers. A total of 54,723 individuals with BPD were identified among 8,141,033 offspring from 4,149,748 nuclear families. The relative risk of BPD in relatives and the co-occurrence of other psychiatric disorders in patients with BPD and their relatives were compared to those of matched-population controls. Structural equation modeling was used to estimate the heritability and tetrachoric correlation.

RESULTS

The familial risks for relatives of BPD probands were 5.8-7.9 in first-degree relatives, and decreased with genetic distance. Co-occurrence risks for other psychiatric disorders were 9.7-22.9 in individuals with BPD and 1.7-2.8 in full siblings of BPD probands. Heritability for BPD was estimated at 58%. The correlations between BPD and other psychiatric disorders were considerable (0.37-0.62) and primarily due to genetic effects. The correlation with depression was the highest (0.62), and was 0.44 for schizophrenia.

CONCLUSIONS

The high familial risks provide evidence that genetic factors play an important role in the etiology of BPD, and the shared genetic determinants suggest pleiotropic effects across different psychiatric disorders. Results also indicate that BPD is in both the mood and psychotic spectra, but possibly more closely related to mood disorders.

Social responsiveness, an autism endophenotype: genomewide significant linkage to two regions on chromosome 8

OBJECTIVE

Autism spectrum disorder is characterized by deficits in social function and the presence of repetitive and restrictive behaviors. Following a previous test of principle, the authors adopted a quantitative approach to discovering genes contributing to the broader autism phenotype by using social responsiveness as an endophenotype for autism spectrum disorder.

METHOD

Linkage analyses using scores from the Social Responsiveness Scale were performed in 590 families from the Autism Genetic Resource Exchange, a largely multiplex autism spectrum disorder cohort. Regional and genomewide association analyses were performed to search for common variants contributing to social responsiveness.

RESULTS

Social Responsiveness Scale scores were unimodally distributed in male offspring from multiplex autism families, in contrast with a bimodal distribution observed in female offspring. In correlated analyses differing by Social Responsiveness Scale respondent, genomewide significant linkage for social responsiveness was identified at chr8p21.3 (multipoint LOD=4.11; teacher/parent scores) and chr8q24.22 (multipoint LOD=4.54; parent-only scores), respectively. Genomewide or linkage-directed association analyses did not detect common variants contributing to social responsiveness.

CONCLUSIONS

The sex-differential distributions of Social Responsiveness Scale scores in multiplex autism families likely reflect mechanisms contributing to the sex ratio for autism observed in the general population and form a quantitative signature of reduced penetrance of inherited liability to autism spectrum disorder among females. The identification of two strong loci for social responsiveness validates the endophenotype approach for the identification of genetic variants contributing to complex traits such as autism spectrum disorder. While causal mutations have yet to be identified, these findings are consistent with segregation of rare genetic variants influencing social responsiveness and underscore the increasingly recognized role of rare inherited variants in the genetic architecture of autism spectrum disorder.

Toward stratified treatments for bipolar disorders

In bipolar disorders, there are unclear diagnostic boundaries with unipolar depression and schizophrenia, inconsistency of treatment guidelines, relatively long trial-and-error phases of treatment optimization, and increasing use of complex combination therapies lacking empirical evidence. These suggest that the current definition of bipolar disorders based on clinical symptoms reflects a clinically and etiologically heterogeneous entity. Stratification of treatments for bipolar disorders based on biomarkers and improved clinical markers are greatly needed to increase the efficacy of currently available treatments and improve the chances of developing novel therapeutic approaches. This review provides a theoretical framework to identify biomarkers and summarizes the most promising markers for stratification regarding beneficial and adverse treatment effects. State and stage specifiers, neuropsychological tests, neuroimaging, and genetic and epigenetic biomarkers will be discussed with respect to their ability to predict the response to specific pharmacological and psychosocial psychotherapies for bipolar disorders. To date, the most reliable markers are derived from psychopathology and history-taking, while no biomarker has been found that reliably predicts individual treatment responses. This review underlines both the importance of clinical diagnostic skills and the need for biological research to identify markers that will allow the targeting of treatment specifically to sub-populations of bipolar patients who are more likely to benefit from a specific treatment and less likely to develop adverse reactions.

The pharmacogenetics of alcohol use disorder

BACKGROUND

Annually, the use and abuse of alcohol contributes to millions of deaths and billions of dollars in societal costs. To determine the impact of genetic variation on the susceptibility to the disorder and its response to treatment, studies have been conducted to assess the contribution of a variety of candidate genetic variants. These variants, which we review here, were chosen based upon their observed or hypothesized functional relevance to alcohol use disorder (AUD) risk or to the mechanism by which medications used to treat the disorder exert their effects.

METHODS

This qualitative review examines studies in which candidate polymorphisms were tested as moderator variables to identify pharmacogenetic effects on either the subjective response to alcohol or the outcomes of pharmacotherapy.

RESULTS

Although findings from these studies provide evidence of a number of clinically relevant pharmacogenetic effects, the literature is limited and there are conflicting findings that require resolution.

CONCLUSIONS

Pharmacogenetic studies of AUD treatment that use greater methodological rigor and better statistical controls, such as corrections for multiple testing, may help to resolve inconsistent findings. These procedures could also lead to the discovery of more robust and clinically meaningful moderator effects. As the field evolves through methodological standardization and the use of larger study samples, pharmacogenetic research has the potential to inform clinical care by enhancing therapeutic effects and personalizing treatments. These efforts may also provide insights into the mechanisms by which medications reduce heavy drinking or promote abstinence in patients with an AUD.

Patterns of variation influencing antipsychotic treatment outcomes in South African first-episode schizophrenia patients

AIM

Many antipsychotic pharmacogenetics studies have been performed examining candidate genes or known variation; however, our understanding of the genetic factors involved in antipsychotic pharmacogenetic traits remains limited.

MATERIALS & METHODS

A well-characterized cohort of first-episode schizophrenia (FES) patients was used to identify a subset of nonresponders and responders to antipsychotic treatment for exome sequencing (n = 11). The variation observed in the responders and nonresponders was subsequently compared and a prioritization strategy was employed to identify variants for genotyping in the entire FES cohort (n = 103) as well as an additional Xhosa schizophrenia cohort (n = 222).

RESULTS

Examination of coding variation revealed a potential role for rare loss-of-function variants in treatment response outcomes. One variant, rs11368509, was found to be weakly associated with better treatment outcomes in the FES cohort (p = 0.057) and the Xhosa schizophrenia cohort (p = 0.016). In addition, the majority of the loss-of-function variation that was considered likely to be involved in antipsychotic treatment response was either novel or rare in Asian and European populations.

CONCLUSION

This pilot study has highlighted the importance of exome sequencing for antipsychotic pharmacogenomics studies, particularly in African individuals. Furthermore, the results emphasize once again the complexity of antipsychotic pharmacogenomics and the need for future research.

Genetic studies of schizophrenia: an update

Schizophrenia (SCZ) is a complex and heterogeneous mental disorder that affects about 1% of global population. In recent years, considerable progress has been made in genetic studies of SCZ. A number of common variants with small effects and rare variants with relatively larger effects have been identified. These variants include risk loci identified by genome-wide association studies, rare copy-number variants identified by comparative genomic analyses, and de novo mutations identified by high-throughput DNA sequencing. Collectively, they contribute to the heterogeneity of the disease. In this review, we update recent discoveries in the field of SCZ genetics, and outline the perspectives of future directions.

Single-cell, genome-wide sequencing identifies clonal somatic copy-number variation in the human brain

De novo copy-number variants (CNVs) can cause neuropsychiatric disease, but the degree to which they occur somatically, and during development, is unknown. Single-cell whole-genome sequencing (WGS) in >200 single cells, including >160 neurons from three normal and two pathological human brains, sensitively identified germline trisomy of chromosome 18 but found most (≥95%) neurons in normal brain tissue to be euploid. Analysis of a patient with hemimegalencephaly (HMG) due to a somatic CNV of chromosome 1q found unexpected tetrasomy 1q in ~20% of neurons, suggesting that CNVs in a minority of cells can cause widespread brain dysfunction. Single-cell analysis identified large (>1 Mb) clonal CNVs in lymphoblasts and in single neurons from normal human brain tissue, suggesting that some CNVs occur during neurogenesis. Many neurons contained one or more large candidate private CNVs, including one at chromosome 15q13.2-13.3, a site of duplication in neuropsychiatric conditions. Large private and clonal somatic CNVs occur in normal and diseased human brains.

Aetiological stratification as a conceptual framework for gene-by-environment interaction research in psychiatry

It has been argued that gene-by-environment interactions (G × E) research is unlikely to progress knowledge about psychiatric disorders, in contrast to genome-wide association (GWA) studies. However, G × E approaches are not alternatives for gene-hunting but a way to identify genetic and biological mechanisms within subgroups of patients exposed to a similar aetiological (environmental) factor via a process of 'aetiological stratification'. This is important as diagnostic categories targeted by GWA studies are inherently heterogeneous and lack biological validity. Aetiological stratification builds on examining possible phenotypic and/or molecular specificity associated with exposure to the environmental factor across multiple potentially relevant disorders, combined with efforts to identify an underlying biological substrate. G × E hypotheses within this framework investigate (1) which genes influence the degree to which individuals develop identified biological alterations that link environmental exposure to specific phenotypic and/or molecular characteristics within or across psychiatric disorders and (2) which genes are implicated in determining the development of psychopathology once this biological alteration has been brought about. As gene-hunting is not a goal in itself, the examination of pathway and/or polygenic risk scores may be more informative than the examination of individual markers, at the same time reducing multiple testing and the associated risk of spurious findings.

Recent genetic findings in schizophrenia and their therapeutic relevance

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

Genetic pleiotropy between multiple sclerosis and schizophrenia but not bipolar disorder: differential involvement of immune-related gene loci

Converging evidence implicates immune abnormalities in schizophrenia (SCZ), and recent genome-wide association studies (GWAS) have identified immune-related single-nucleotide polymorphisms (SNPs) associated with SCZ. Using the conditional false discovery rate (FDR) approach, we evaluated pleiotropy in SNPs associated with SCZ (n=21,856) and multiple sclerosis (MS) (n=43,879), an inflammatory, demyelinating disease of the central nervous system. Because SCZ and bipolar disorder (BD) show substantial clinical and genetic overlap, we also investigated pleiotropy between BD (n=16,731) and MS. We found significant genetic overlap between SCZ and MS and identified 21 independent loci associated with SCZ, conditioned on association with MS. This enrichment was driven by the major histocompatibility complex (MHC). Importantly, we detected the involvement of the same human leukocyte antigen (HLA) alleles in both SCZ and MS, but with an opposite directionality of effect of associated HLA alleles (that is, MS risk alleles were associated with decreased SCZ risk). In contrast, we found no genetic overlap between BD and MS. Considered together, our findings demonstrate genetic pleiotropy between SCZ and MS and suggest that the MHC signals may differentiate SCZ from BD susceptibility.

Schizophrenia genetics: emerging themes for a complex disorder

After two decades of frustration, genetic studies of schizophrenia have entered an era of spectacular success. Advances in genotyping technologies and high throughput sequencing, increasing analytic rigour and collaborative efforts on a global scale have generated a profusion of new findings. The broad conclusions from these studies are threefold: (1) schizophrenia is a highly polygenic disorder with a complex array of contributing risk loci across the allelic frequency spectrum; (2) many psychiatric illnesses share risk genes and alleles, specifically, schizophrenia has substantial overlaps with bipolar disorder, intellectual disability, major depressive disorder and autism spectrum disorders; and (3) some convergent biological themes are emerging from studies of schizophrenia and related disorders. In this commentary, we focus on the very recent findings that have emerged in the past 12 months, and in particular, the areas of convergence that are beginning to emerge from multiple study designs.

Systems genetics identifies Sestrin 3 as a regulator of a proconvulsant gene network in human epileptic hippocampus

Gene-regulatory network analysis is a powerful approach to elucidate the molecular processes and pathways underlying complex disease. Here we employ systems genetics approaches to characterize the genetic regulation of pathophysiological pathways in human temporal lobe epilepsy (TLE). Using surgically acquired hippocampi from 129 TLE patients, we identify a gene-regulatory network genetically associated with epilepsy that contains a specialized, highly expressed transcriptional module encoding proconvulsive cytokines and Toll-like receptor signalling genes. RNA sequencing analysis in a mouse model of TLE using 100 epileptic and 100 control hippocampi shows the proconvulsive module is preserved across-species, specific to the epileptic hippocampus and upregulated in chronic epilepsy. In the TLE patients, we map the trans-acting genetic control of this proconvulsive module to Sestrin 3 (SESN3), and demonstrate that SESN3 positively regulates the module in macrophages, microglia and neurons. Morpholino-mediated Sesn3 knockdown in zebrafish confirms the regulation of the transcriptional module, and attenuates chemically induced behavioural seizures in vivo.

A kernel machine method for detecting effects of interaction between multidimensional variable sets: an imaging genetics application

Measurements derived from neuroimaging data can serve as markers of disease and/or healthy development, are largely heritable, and have been increasingly utilized as (intermediate) phenotypes in genetic association studies. To date, imaging genetic studies have mostly focused on discovering isolated genetic effects, typically ignoring potential interactions with non-genetic variables such as disease risk factors, environmental exposures, and epigenetic markers. However, identifying significant interaction effects is critical for revealing the true relationship between genetic and phenotypic variables, and shedding light on disease mechanisms. In this paper, we present a general kernel machine based method for detecting effects of the interaction between multidimensional variable sets. This method can model the joint and epistatic effect of a collection of single nucleotide polymorphisms (SNPs), accommodate multiple factors that potentially moderate genetic influences, and test for nonlinear interactions between sets of variables in a flexible framework. As a demonstration of application, we applied the method to the data from the Alzheimer's Disease Neuroimaging Initiative (ADNI) to detect the effects of the interactions between candidate Alzheimer's disease (AD) risk genes and a collection of cardiovascular disease (CVD) risk factors, on hippocampal volume measurements derived from structural brain magnetic resonance imaging (MRI) scans. Our method identified that two genes, CR1 and EPHA1, demonstrate significant interactions with CVD risk factors on hippocampal volume, suggesting that CR1 and EPHA1 may play a role in influencing AD-related neurodegeneration in the presence of CVD risks.

XRCC5 as a risk gene for alcohol dependence: evidence from a genome-wide gene-set-based analysis and follow-up studies in Drosophila and humans

Genetic factors have as large role as environmental factors in the etiology of alcohol dependence (AD). Although genome-wide association studies (GWAS) enable systematic searches for loci not hitherto implicated in the etiology of AD, many true findings may be missed owing to correction for multiple testing. The aim of the present study was to circumvent this limitation by searching for biological system-level differences, and then following up these findings in humans and animals. Gene-set-based analysis of GWAS data from 1333 cases and 2168 controls identified 19 significantly associated gene-sets, of which 5 could be replicated in an independent sample. Clustered in these gene-sets were novel and previously identified susceptibility genes. The most frequently present gene, ie in 6 out of 19 gene-sets, was X-ray repair complementing defective repair in Chinese hamster cells 5 (XRCC5). Previous human and animal studies have implicated XRCC5 in alcohol sensitivity. This phenotype is inversely correlated with the development of AD, presumably as more alcohol is required to achieve the desired effects. In the present study, the functional role of XRCC5 in AD was further validated in animals and humans. Drosophila mutants with reduced function of Ku80-the homolog of mammalian XRCC5-due to RNAi silencing showed reduced sensitivity to ethanol. In humans with free access to intravenous ethanol self-administration in the laboratory, the maximum achieved blood alcohol concentration was influenced in an allele-dose-dependent manner by genetic variation in XRCC5. In conclusion, our convergent approach identified new candidates and generated independent evidence for the involvement of XRCC5 in alcohol dependence.

The promise of psychiatric pharmacogenomics

Clinicians already face "personalized" medicine every day while experiencing the great variation in toxicities and drug efficacy among individual patients. Pharmacogenetics studies are the platform for discovering the DNA determinants of variability in drug response and tolerability. Research now focuses on the genome after its beginning with analyses of single genes. Therapeutic outcomes from several psychotropic drugs have been weakly linked to specific genetic variants without independent replication. Drug side effects show stronger associations to genetic variants, including human leukocyte antigen loci with carbamazepine-induced dermatologic outcome and MC4R with atypical antipsychotic weight gain. Clinical implementation has proven challenging, with barriers including a lack of replicable prospective evidence for clinical utility required for altering medical care. More recent studies show promising approaches for reducing these barriers to routine incorporation of pharmacogenetics data into clinical care.

The Tourette International Collaborative Genetics (TIC Genetics) study, finding the genes causing Tourette syndrome: objectives and methods

Tourette syndrome (TS) is a neuropsychiatric disorder characterized by recurrent motor and vocal tics, often accompanied by obsessive-compulsive disorder and/or attention-deficit/hyperactivity disorder. While the evidence for a genetic contribution is strong, its exact nature has yet to be clarified fully. There is now mounting evidence that the genetic risks for TS include both common and rare variants and may involve complex multigenic inheritance or, in rare cases, a single major gene. Based on recent progress in many other common disorders with apparently similar genetic architectures, it is clear that large patient cohorts and open-access repositories will be essential to further advance the field. To that end, the large multicenter Tourette International Collaborative Genetics (TIC Genetics) study was established. The goal of the TIC Genetics study is to undertake a comprehensive gene discovery effort, focusing both on familial genetic variants with large effects within multiply affected pedigrees and on de novo mutations ascertained through the analysis of apparently simplex parent-child trios with non-familial tics. The clinical data and biomaterials (DNA, transformed cell lines, RNA) are part of a sharing repository located within the National Institute for Mental Health Center for Collaborative Genomics Research on Mental Disorders, USA, and will be made available to the broad scientific community. This resource will ultimately facilitate better understanding of the pathophysiology of TS and related disorders and the development of novel therapies. Here, we describe the objectives and methods of the TIC Genetics study as a reference for future studies from our group and to facilitate collaboration between genetics consortia in the field of TS.

CRY1 Variations Impacts on the Depressive Relapse Rate in a Sample of Bipolar Patients

OBJECTIVE

A relevant part of the social and personal burden caused by Bipolar Disorder (BD) is related to depressive phases. Authors investigated the genetic impact of a set of variations located in CRY1, a gene involved in the control of the circadian rhythms, towards depressive episodes in a sample of bipolar patients from the STEP-BD sample. As a secondary analysis, CYR1 variations were analyzed as predictors of sleep disruption.

METHODS

654 bipolar patients were included in the analysis. Data were available genome-wide. The part of the genome coding for the CRY1 was imputed and pruned according to standards in the field. 7 SNPs were available for the analysis. A correction for multitesting was applied and we had sufficient power (0.80) to detect a small-medium effect size (0.22) between two allelic frequencies each one represented by at least 300 subjects.

RESULTS

Intronic rs10861688 was associated with the number of depressive events corrected for the times patients were assessed during the period of observation. In particular, AA subjects (n=21) had 4.46±3.15 events, AG (n=141) had 3.08±3.17 and GG (n=342) 2.65±2.97 (p=0.0048, beta=-0.22). No other significant associations were reported.

CONCLUSION

We bring further evidence that genes involved in the regulation of circadian rhythms may be relevant to depressive bipolar phases. Independent confirmation analyses are mandatory.

Genetic risk for schizophrenia: convergence on synaptic pathways involved in plasticity

Recent large-scale genomic studies have revealed two broad classes of risk alleles for schizophrenia: a polygenic component of risk mediated through multiple common risk variants and rarer more highly penetrant submicroscopic chromosomal deletions and duplications, known as copy number variants. The focus of this review is on the emerging findings from the latter and subsequent exome sequencing data of smaller, deleterious single nucleotide variants and indels. In these studies, schizophrenia patients were found to have enriched de novo mutations in genes belonging to the postsynaptic density at glutamatergic synapses, particularly components of the N-methyl-D-aspartate receptor signaling complex, including the PSD-95 complex, activity-regulated cytoskeleton-associated protein interactors, the fragile X mental retardation protein complex, voltage-gated calcium channels, and genes implicated in actin cytoskeletal dynamics. The convergence of these implicated genes onto a coherent biological pathway at the synapse, with a specific role in plasticity, provides a significant advance in understanding pathogenesis and points to new targets for biological investigation. We consider the implications of these studies in the context of existing genetic data and the potential need to reassess diagnostic boundaries of neuropsychiatric disorders before discussing ways forward for more directed mechanistic studies to develop stratified, novel therapeutic approaches in the future.

Schizophrenia and Depression Co-Morbidity: What We have Learned from Animal Models

Patients with schizophrenia are at an increased risk for the development of depression. Overlap in the symptoms and genetic risk factors between the two disorders suggests a common etiological mechanism may underlie the presentation of comorbid depression in schizophrenia. Understanding these shared mechanisms will be important in informing the development of new treatments. Rodent models are powerful tools for understanding gene function as it relates to behavior. Examining rodent models relevant to both schizophrenia and depression reveals a number of common mechanisms. Current models which demonstrate endophenotypes of both schizophrenia and depression are reviewed here, including models of CUB and SUSHI multiple domains 1, PDZ and LIM domain 5, glutamate Delta 1 receptor, diabetic db/db mice, neuropeptide Y, disrupted in schizophrenia 1, and its interacting partners, reelin, maternal immune activation, and social isolation. Neurotransmission, brain connectivity, the immune system, the environment, and metabolism emerge as potential common mechanisms linking these models and potentially explaining comorbid depression in schizophrenia.

Refinement of schizophrenia GWAS loci using methylome-wide association data

Recent genome-wide association studies (GWAS) have made substantial progress in identifying disease loci. The next logical step is to design functional experiments to identify disease mechanisms. This step, however, is often hampered by the large size of loci identified in GWAS that is caused by linkage disequilibrium between SNPs. In this study, we demonstrate how integrating methylome-wide association study (MWAS) results with GWAS findings can narrow down the location for a subset of the putative casual sites. We use the disease schizophrenia as an example. To handle "data analytic" variation, we first combined our MWAS results with two GWAS meta-analyses (N = 32,143 and 21,953), that had largely overlapping samples but different data analysis pipelines, separately. Permutation tests showed significant overlapping association signals between GWAS and MWAS findings. This significant overlap justified prioritizing loci based on the concordance principle. To further ensure that the methylation signal was not driven by chance, we successfully replicated the top three methylation findings near genes SDCCAG8, CREB1 and ATXN7 in an independent sample using targeted pyrosequencing. In contrast to the SNPs in the selected region, the methylation sites were largely uncorrelated explaining why the methylation signals implicated much smaller regions (median size 78 bp). The refined loci showed considerable enrichment of genomic elements of possible functional importance and suggested specific hypotheses about schizophrenia etiology. Several hypotheses involved possible variation in transcription factor-binding efficiencies.

Candidate gene-environment interaction research: reflections and recommendations

Studying how genetic predispositions come together with environmental factors to contribute to complex behavioral outcomes has great potential for advancing the understanding of the development of psychopathology. It represents a clear theoretical advance over studying these factors in isolation. However, research at the intersection of multiple fields creates many challenges. We review several reasons why the rapidly expanding candidate gene-environment interaction (cG×E) literature should be considered with a degree of caution. We discuss lessons learned about candidate gene main effects from the evolving genetics literature and how these inform the study of cG×E. We review the importance of the measurement of the gene and environment of interest in cG×E studies. We discuss statistical concerns with modeling cG×E that are frequently overlooked. Furthermore, we review other challenges that have likely contributed to the cG×E literature being difficult to interpret, including low power and publication bias. Many of these issues are similar to other concerns about research integrity (e.g., high false-positive rates) that have received increasing attention in the social sciences. We provide recommendations for rigorous research practices for cG×E studies that we believe will advance its potential to contribute more robustly to the understanding of complex behavioral phenotypes.

Convergence of advances in genomics, team science, and repositories as drivers of progress in psychiatric genomics

After many years of unfilled promise, psychiatric genetics has seen an unprecedented number of successes in recent years. We hypothesize that the field has reached an inflection point through a confluence of four key developments: advances in genomics; the orientation of the scientific community around large collaborative team science projects; the development of sample and data repositories; and a policy framework for sharing and accessing these resources. We discuss these domains and their effect on scientific progress and provide a perspective on why we think this is only the beginning of a new era in scientific discovery.

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

BACKGROUND

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

METHOD

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

RESULTS

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

CONCLUSIONS

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

Association analysis of the Cadherin13 gene with schizophrenia in the Japanese population

BACKGROUND

Cadherin13 (CDH13) is a glycosylphosphatidylinositol-anchored cell adhesion molecule that plays a crucial role in morphogenesis and the maintenance of neuronal circuitry. CDH13 has been implicated in the susceptibility to a variety of psychiatric diseases. A recent genome-wide association study using Danish samples showed, for the first time, the involvement of a single nucleotide polymorphism (SNP) of CDH13 (intronic SNP rs8057927) in schizophrenia. Here, we investigated the association between other SNPs of CDH13 and schizophrenia and tried to replicate the association for the SNP of rs8057927, in the Japanese population.

METHODS

Using TaqMan(®) SNP genotyping assays, five tag SNPs (rs12925602, rs7193788, rs736719, rs6565051, and rs7204454) in the promoter region of CDH13 were examined for their association with schizophrenia in two independent samples. The first sample comprised 665 patients and 760 controls, and the second sample comprised 677 patients and 667 controls. One tag SNP for rs8057927 was also examined for the association with schizophrenia in the first sample set.

RESULTS

A GACAG haplotype of the five SNPs in the promoter region of CDH13 was significantly associated with schizophrenia in the first sample set (P=0.016 and corrected P=0.098). A combined analysis of the GACAG haplotype with the second sample set enhanced the significance (P=0.0026 and corrected P=0.021). We found no association between rs8057927 and schizophrenia in the first sample set.

CONCLUSION

Our results suggest that CDH13 may contribute to the genetic risk of schizophrenia. Further replication on the association of CDH13 with schizophrenia and functional studies are required to confirm the current findings.

The Role of Infections and Autoimmune Diseases for Schizophrenia and Depression: Findings from Large-Scale Epidemiological Studies

An immunologic component to schizophrenia and depression has been increasingly recognized, which has led to extensive research into the associations with infections and autoimmune diseases. Large-scale nationwide epidemiological studies have displayed an increased prevalence of both autoimmune diseases and infections among persons with schizophrenia and depression. Autoimmune diseases, and especially the number of infections requiring hospitalization, increase the risk of schizophrenia and depression in a dose–response relationship. Infections are a common exposure and a broad spectrum of infections are associated with schizophrenia and depression. Particularly the autoimmune diseases with a potential presence of brain-reactive antibodies were associated with psychiatric disorders. However, the associations seem to be bidirectional, since the risk of autoimmune diseases and infections is also increased after diagnosis with schizophrenia and depression. The risk of autoimmune diseases was particularly increased in individuals with prior hospital contacts for infections.

It has been suggested that inflammation and autoimmunity could be involved in the etiology and pathogenesis of some patients with symptoms of schizophrenia and depression. The psychiatric symptoms can be directly triggered by immune components, such as brain-reactive antibodies and cytokines, or infections reaching the central nervous system (CNS), or be secondary to systemic inflammation indirectly affecting the brain. However, the associations could also be caused by shared genetic factors, other environmental factors, or common etiological components. Nonetheless, autoimmune diseases and infections should be considered by clinicians in the treatment of individuals with psychiatric symptoms, since treatment would probably improve the psychiatric symptoms, quality of life, and the survival of the individuals.

PD_NGSAtlas: a reference database combining next-generation sequencing epigenomic and transcriptomic data for psychiatric disorders

Background

Psychiatric disorders such as schizophrenia (SZ) and bipolar disorder (BP) are projected to lead the global disease burden within the next decade. Several lines of evidence suggest that epigenetic- or genetic-mediated dysfunction is frequently present in these disorders. To date, the inheritance patterns have been complicated by the problem of integrating epigenomic and transcriptomic factors that have yet to be elucidated. Therefore, there is a need to build a comprehensive database for storing epigenomic and transcriptomic data relating to psychiatric disorders.

Description

We have developed the PD_NGSAtlas, which focuses on the efficient storage of epigenomic and transcriptomic data based on next-generation sequencing and on the quantitative analyses of epigenetic and transcriptional alterations involved in psychiatric disorders. The current release of the PD_NGSAtlas contains 43 DNA methylation profiles and 37 transcription profiles detected by MeDIP-Seq and RNA-Seq, respectively, in two distinct brain regions and peripheral blood of SZ, BP and non-psychiatric controls. In addition to these data that were generated in-house, we have included, and will continue to include, published DNA methylation and gene expression data from other research groups, with a focus on psychiatric disorders. A flexible query engine has been developed for the acquisition of methylation profiles and transcription profiles for special genes or genomic regions of interest of the selected samples. Furthermore, the PD_NGSAtlas offers online tools for identifying aberrantly methylated and expressed events involved in psychiatric disorders. A genome browser has been developed to provide integrative and detailed views of multidimensional data in a given genomic context, which can help researchers understand molecular mechanisms from epigenetic and transcriptional perspectives. Moreover, users can download the methylation and transcription data for further analyses.

Conclusions

The PD_NGSAtlas aims to provide storage of epigenomic and transcriptomic data as well as quantitative analyses of epigenetic and transcriptional alterations involved in psychiatric disorders. The PD_NGSAtlas will be a valuable data resource and will enable researchers to investigate the pathophysiology and aetiology of disease in detail. The database is available at http://bioinfo.hrbmu.edu.cn/pd_ngsatlas/.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-014-0071-z) contains supplementary material, which is available to authorized users.

Neuropsychiatric genetics in developing countries: Current challenges

Neuropsychiatric disorders (NPDs) constitute a heavy burden on public health systems around the world and studies have demonstrated that the negative impact of NPDs is larger in Low and Middle Income Countries (LMICs). In recent decades, several studies have come to the understanding that genetic factors play a major role in the risk for a large number of NPDs. However, few neuropsychiatric genetics studies have been published from LMICs. In this Editorial, we discuss important issues impinging on advances in neuropsychiatric genetics research in LMICs. It is essential that scientists educate policymakers and officials of funding agencies on the importance of providing adequate funding for research in these areas. Development of local well-supported research programs focused on NPD genetics should be an important asset to develop; it would facilitate the establishment of sustainable research efforts that could lead to appropriate diagnosis and specific, affordable and feasible interventions in LMICs. It is important to point out that research into the biological basis of human NPDs is not only an academic effort reserved for a few elite institutions in economically developed countries, but it is vitally important for the mental health of people around the world.

Heritability and molecular genetic basis of antisaccade eye tracking error rate: a genome-wide association study

Antisaccade deficits reflect abnormalities in executive function linked to various disorders including schizophrenia, externalizing psychopathology, and neurological conditions. We examined the genetic bases of antisaccade error in a sample of community-based twins and parents (N = 4,469). Biometric models showed that about half of the variance in the antisaccade response was due to genetic factors and half due to nonshared environmental factors. Molecular genetic analyses supported these results, showing that the heritability accounted for by common molecular genetic variants approximated biometric estimates. Genome-wide analyses revealed several SNPs as well as two genes-B3GNT7 and NCL-on Chromosome 2 associated with antisaccade error. SNPs and genes hypothesized to be associated with antisaccade error based on prior work, although generating some suggestive findings for MIR137, GRM8, and CACNG2, could not be confirmed.

Genome-wide scans of genetic variants for psychophysiological endophenotypes: a methodological overview

This article provides an introductory overview of the investigative strategy employed to evaluate the genetic basis of 17 endophenotypes examined as part of a 20-year data collection effort from the Minnesota Center for Twin and Family Research. Included are characterization of the study samples, descriptive statistics for key properties of the psychophysiological measures, and rationale behind the steps taken in the molecular genetic study design. The statistical approach included (a) biometric analysis of twin and family data, (b) heritability analysis using 527,829 single nucleotide polymorphisms (SNPs), (c) genome-wide association analysis of these SNPs and 17,601 autosomal genes, (d) follow-up analyses of candidate SNPs and genes hypothesized to have an association with each endophenotype, (e) rare variant analysis of nonsynonymous SNPs in the exome, and (f) whole genome sequencing association analysis using 27 million genetic variants. These methods were used in the accompanying empirical articles comprising this special issue, Genome-Wide Scans of Genetic Variants for Psychophysiological Endophenotypes.

Applying polygenic risk scores to postpartum depression

The etiology of major depressive disorder (MDD) is likely to be heterogeneous, but postpartum depression (PPD) is hypothesized to represent a more homogenous subset of MDD. We use genome-wide SNP data to explore this hypothesis. We assembled a total cohort of 1,420 self-report cases of PPD and 9,473 controls with genome-wide genotypes from Australia, The Netherlands, Sweden and the UK. We estimated the total variance attributable to genotyped variants. We used association results from the Psychiatric Genomics Consortia (PGC) of bipolar disorder (BPD) and MDD to create polygenic scores in PPD and related MDD data sets to estimate the genetic overlap between the disorders. We estimated that the percentage of variance on the liability scale explained by common genetic variants to be 0.22 with a standard error of 0.12, p = 0.02. The proportion of variance (R (2)) from a logistic regression of PPD case/control status in all four cohorts on a SNP profile score weighted by PGC-BPD association results was small (0.1 %) but significant (p = 0.004) indicating a genetic overlap between BPD and PPD. The results were highly significant in the Australian and Dutch cohorts (R (2) > 1.1 %, p < 0.008), where the majority of cases met criteria for MDD. The genetic overlap between BPD and MDD was not significant in larger Australian and Dutch MDD case/control cohorts after excluding PPD cases (R (2) = 0.06 %, p = 0.08), despite the larger MDD group affording more power. Our results suggest an empirical genetic evidence for a more important shared genetic etiology between BPD and PPD than between BPD and MDD.

Changes in the adolescent brain and the pathophysiology of psychotic disorders

Adolescence is a time of extensive neuroanatomical, functional, and chemical reorganisation of the brain which parallels substantial maturational changes in cognition and affect regulation. This period is characterised by stabilisation of synapses to diminish redundancy and increase efficiency of neural function, fine-tuning of excitatory and inhibitory neurotransmitter systems, beginning of integration between late maturing and early maturing brain structures, and development of effective connections. In effect, these so-called moving parts create a state of dynamic change that might underlie adolescent behaviours. Imbalances or changes in timing of these developmental processes clearly increase the risk for psychiatric disorders. Genetic, environmental, and epigenetic factors that shape brain development and hormonal changes that affect stress reactivity could be reasons why some, but not all, adolescents are at a heightened risk of developing a psychopathological disorder. In this Series paper, we assess the neurobiology of the changing adolescent brain, implications of this knowledge, and future research in major psychiatric disorders, particularly for psychotic disorders.

Genetics of cognition in epilepsy

With the completion of the Human Genome Project and the advent of more advanced sequencing platforms capable of high throughput genotyping at reduced cost, research on the genetics/genomics of cognition has expanded rapidly over the past several decades. This has been facilitated even further by global consortia including HapMap, 1000 Genomes Project, ENCODE, and others, which have made information regarding genetic variation and genomic functional elements readily available to all researchers. Thus, the goal of this Targeted Review is not to provide an exhaustive review of the existing literature on the role of genetic factors in cognition. Rather, we will highlight some of the most consistent findings in this field, review the research in epilepsy to date, and provide a background within which to set forth unique opportunities epilepsy may provide to further elucidate the role of genetics in cognition.

Identification of schizophrenia-associated loci by combining DNA methylation and gene expression data from whole blood

Emerging evidence suggests that schizophrenia (SZ) susceptibility involves variation at genetic, epigenetic and transcriptome levels. We describe an integrated approach that leverages DNA methylation and gene expression data to prioritize genetic variation involved in disease. DNA methylation levels were obtained from whole blood of 260 SZ patients and 250 unaffected controls of which a subset with gene expression data was available. By assessing DNA methylation and gene expression in cases and controls, we identified 432 CpG sites with differential methylation levels that are associated with differential gene expression. We hypothesized that genetic factors involved in these methylation levels may be associated with the genetic risk of SZ susceptibility. To test this hypothesis, we used results from the Psychiatric Genomics Consortium SZ genome-wide association study (GWAS). We observe an enrichment of SZ-associated SNPs in the mQTLs of which the associated CpG site is also correlated with differential gene expression in SZ. While this enrichment was already apparent when using nominal significant thresholds, enrichment was even more pronounced when applying more stringent significance levels. One locus, previously identified as susceptibility locus in a SZ GWAS, involves SNP rs11191514:C>T, which regulates DNA methylation of calcium homeostasis modulator 1 that is also associated with differential gene expression in patients. Overall, our results suggest that epigenetic variation plays an important role in SZ susceptibility and that the integration of analyses of genetic, epigenetic and gene expression profiles may be a biologically meaningful approach for identifying disease susceptibility loci, even when using whole blood data in studies of brain-related disorders.

Synaptic dysregulation in a human iPS cell model of mental disorders

Dysregulated neurodevelopment with altered structural and functional connectivity is believed to underlie many neuropsychiatric disorders, and 'a disease of synapses' is the major hypothesis for the biological basis of schizophrenia. Although this hypothesis has gained indirect support from human post-mortem brain analyses and genetic studies, little is known about the pathophysiology of synapses in patient neurons and how susceptibility genes for mental disorders could lead to synaptic deficits in humans. Genetics of most psychiatric disorders are extremely complex due to multiple susceptibility variants with low penetrance and variable phenotypes. Rare, multiply affected, large families in which a single genetic locus is probably responsible for conferring susceptibility have proven invaluable for the study of complex disorders. Here we generated induced pluripotent stem (iPS) cells from four members of a family in which a frameshift mutation of disrupted in schizophrenia 1 (DISC1) co-segregated with major psychiatric disorders and we further produced different isogenic iPS cell lines via gene editing. We showed that mutant DISC1 causes synaptic vesicle release deficits in iPS-cell-derived forebrain neurons. Mutant DISC1 depletes wild-type DISC1 protein and, furthermore, dysregulates expression of many genes related to synapses and psychiatric disorders in human forebrain neurons. Our study reveals that a psychiatric disorder relevant mutation causes synapse deficits and transcriptional dysregulation in human neurons and our findings provide new insight into the molecular and synaptic etiopathology of psychiatric disorders.

Genetics in psychiatry

Today, psychiatrists are focusing on genetics aspects of various psychiatric disorders not only for a future classification of psychiatric disorders but also a notion that genetics would aid in the development of new medications to treat these disabling illnesses. This review therefore emphasizes on the basics of genetics in psychiatry as well as focuses on the emerging picture of genetics in psychiatry and their future implications.

Resequencing and association analysis of PTPRA, a possible susceptibility gene for schizophrenia and autism spectrum disorders

Background

The PTPRA gene, which encodes the protein RPTP-α, is critical to neurodevelopment. Previous linkage studies, genome-wide association studies, controlled expression analyses and animal models support an association with both schizophrenia and autism spectrum disorders, both of which share a substantial portion of genetic risks.

Methods

We sequenced the protein-encoding areas of the PTPRA gene for single nucleotide polymorphisms or small insertions/deletions (InDel) in 382 schizophrenia patients. To validate their association with the disorders, rare (minor allele frequency <1%), missense mutations as well as one InDel in the 3′UTR region were then genotyped in another independent sample set comprising 944 schizophrenia patients, 336 autism spectrum disorders patients, and 912 healthy controls.

Results

Eight rare mutations, including 3 novel variants, were identified during the mutation-screening phase. In the following association analysis, L59P, one of the two missense mutations, was only observed among patients of schizophrenia. Additionally, a novel duplication in the 3′UTR region, 174620_174623dupTGAT, was predicted to be located within a Musashi Binding Element.

Major Conclusions

No evidence was seen for the association of rare, missense mutations in the PTPRA gene with schizophrenia or autism spectrum disorders; however, we did find some rare variants with possibly damaging effects that may increase the susceptibility of carriers to the disorders.

Mind-controlled transgene expression by a wireless-powered optogenetic designer cell implant

Synthetic devices for traceless remote control of gene expression may provide new treatment opportunities in future gene- and cell-based therapies. Here we report the design of a synthetic mind-controlled gene switch that enables human brain activities and mental states to wirelessly programme the transgene expression in human cells. An electroencephalography (EEG)-based brain–computer interface (BCI) processing mental state-specific brain waves programs an inductively linked wireless-powered optogenetic implant containing designer cells engineered for near-infrared (NIR) light-adjustable expression of the human glycoprotein SEAP (secreted alkaline phosphatase). The synthetic optogenetic signalling pathway interfacing the BCI with target gene expression consists of an engineered NIR light-activated bacterial diguanylate cyclase (DGCL) producing the orthogonal second messenger cyclic diguanosine monophosphate (c-di-GMP), which triggers the stimulator of interferon genes (STING)-dependent induction of synthetic interferon-β promoters. Humans generating different mental states (biofeedback control, concentration, meditation) can differentially control SEAP production of the designer cells in culture and of subcutaneous wireless-powered optogenetic implants in mice.

Brain–machine interfaces offer the possibility of controlling prosthetic devices using changes in brain activity. Folcher et al. couple such a system wirelessly to an optogenetic implant in mice to control expression of a transgene, demonstrating its potential for mind-controlled drug delivery.

The Amsterdam Sexual Abuse Case (ASAC)-study in day care centers: longitudinal effects of sexual abuse on infants and very young children and their parents, and the consequences of the persistence of abusive images on the internet

BACKGROUND

Little research has been done on the signs of child sexual abuse (CSA) in infants and very young children, or on the consequences that such abuse - including the persistence of the abusive pornographic images on the internet - might have for the children and their parents. The effects of CSA can be severe, and a variety of risk- and protective factors, may influence those effects. CSA may affect the psychosocial-, emotional-, cognitive-, and physical development of children, their relationships with their parent(s), and the relations between parents. In the so called 'the Amsterdam sexual abuse case' (ASAC), infants and very young children were victimized by a day-care employee and most of the victims were boys. Research involving the children and their parents would enable recognition of the signs of CSA in very young children and understanding the consequences the abuse might have on the long term.

METHODS/DESIGN

The proposed research project consists of three components: (I) An initial assessment to identify physical- or psychological signs of CSA in infants and very young children who are thought to have been sexually abused (n = 130); (II) A cross-sequential longitudinal study of children who have experienced sexual abuse, or for whom there are strong suspicions; (III) A qualitative study in which interviews are conducted with parents (n = 25) and with therapists treating children from the ASAC. Parents will be interviewed on the perceived condition of their child and family situation, their experiences with the service responses to the abuse, the effects of legal proceedings and media attention, and the impact of knowing that pornographic material has been disseminated on the internet. Therapists will be interviewed on their clinical experiences in treating children and parents. The assessments will extend over a period of several years. The outcome measures will be symptoms of posttraumatic stress disorder (PTSD), dissociative symptoms, age-inappropriate sexual behaviors and knowledge, behavioral problems, attachment disturbances, the quality of parent-child interaction, parental PTSD, parental partner relation, and biological outcomes (BMI and DNA).

DISCUSSION

The ASAC-project would facilitate early detection of symptoms and prompt therapeutic intervention when CSA is suspected in very young children.