Further confirmation of the association between anxiety and CTNND2: replication in humans

Behavioral Abnormalities, Cognitive Impairments, Synaptic Deficits, and Gene Replacement Therapy in a CRISPR Engineered Rat Model of 5p15.2 Deletion Associated With Cri du Chat Syndrome

The Cri du Chat Syndrome (CdCS), a devastating genetic disorder caused by a deletion on chromosome 5p, faces challenges in finding effective treatments and accurate animal models. Using CRISPR-Cas9, a novel CdCS rat model with a 2q22 deletion is developed, mirroring a common genetic alteration in CdCS patients. This model exhibits pronounced deficits in social behavior, cognition, and anxiety, accompanied by neuronal abnormalities and immune dysregulation in key brain regions such as the hippocampus and medial prefrontal cortex (mPFC). The immunostaining and RNA-seq analyses provide new insights into CdCS pathogenesis, revealing inflammatory and immune processes. Importantly, it is demonstrated that early gene replacement therapy with AAV-Ctnnd2 alleviates cognitive impairments in CdCS rats, highlighting the potential for early intervention. However, the effectiveness of this therapy is confined to the early developmental stages and does not fully restore all CdCS symptoms. The findings deepen the understanding of CdCS pathogenesis and suggest promising therapeutic directions.

The genetics of severe depression

Genome-wide association studies (GWASs) of major depressive disorder (MDD) have recently achieved extremely large sample sizes and yielded substantial numbers of genome-wide significant loci. Because of the approach to ascertainment and assessment in many of these studies, some of these loci appear to be associated with dysphoria rather than with MDD, potentially decreasing the clinical relevance of the findings. An alternative approach to MDD GWAS is to focus on the most severe forms of MDD, with the hope that this will enrich for loci of larger effect, rendering their identification plausible, and providing potentially more clinically actionable findings. Here we review the genetics of severe depression by using clinical markers of severity including: age of onset, recurrence, degree of impairment, and treatment with ECT. There is evidence for increased family-based and Single Nucleotide Polymorphism (SNP)-based estimates of heritability in recurrent and early-onset illness as well as severe functional impariment. GWAS have been performed looking at severe forms of MDD and a few genome-wide loci have been identified. Several whole exome sequencing studies have also been performed, identifying associated rare variants. Although these findings have not yet been rigorously replicated, the elevated heritability seen in severe MDD phenotypes suggests the value of pursuing additional genome-wide interrogation of samples from this population. The challenge now is generating a cohort of adequate size with consistent phenotyping that will allow for careful and robust classifications and distinctions to be made. We are currently pursuing such a strategy in our 50-site worldwide Gen-ECT-ics consortium.

Associations between DNA methylation and cognitive function in early-stage hormone receptor-positive breast cancer patients

Background

Approximately one-third of breast cancer (BC) patients show poorer cognitive function (CF) before receiving adjuvant therapy compared with age-matched healthy controls. However, the biological mechanisms driving CF variation in the context of BC remain unclear. In this study, we aimed to identify genes and biological pathways associated with CF in postmenopausal women with early-stage hormone receptor-positive (HR+) BC using DNA methylation (DNAm) data, a dynamic regulator of gene activity.

Methods

Epigenome-wide association studies (EWAS) and differentially methylated region analyses were performed for each CF phenotype (seven objective domains and one subjective phenotype) using DNAm data from whole blood samples (n=109) taken at time of enrollment. Post-EWAS functional analyses were performed to enhance the understanding of the CF-related cytosine-phosphate-guanine (CpG) sites.

Results

When adjusting for age, verbal IQ scores, and global DNAm signature, cg10331779 near CTNND2 (p-value= 9.65 × 10 -9 ) and cg25906741 in MLIP (p-value= 2.01 × 10 -8 ) were associated with processing speed and subjective CF, respectively, while regions in/near SLC6A11 , PRKG1/CSTF2T , and FAM3B for processing speed, and regions in/near PI4KB and SGCE/PEG10 for mental flexibility were differentially methylated. In addition, beta-estradiol was identified as a common upstream regulator for all the CF phenotypes, suggesting an essential role of estrogen in explaining variation in CF of HR+ BC patients.

Conclusions

In our EWAS of 8 CF phenotypes, we found two epigenome-wide significant signals, one at cg10331779 near CTNND2 with processing speed and the other at cg25906741 in MLIP with subjective CF. We also found three differentially methylated regions associated with processing speed and two associated with mental flexibility. These findings need replication in larger cohorts.

Prenatal exposure to valproic acid reduces synaptic δ-catenin levels and disrupts ultrasonic vocalization in neonates

Valproic acid (VPA) is an effective and commonly prescribed drug for epilepsy and bipolar disorder. However, children born from mothers treated with VPA during pregnancy exhibit an increased incidence of autism spectrum disorder (ASD). Although VPA may impair brain development at the cellular level, the mechanism of VPA-induced ASD has not been completely addressed. A previous study has found that VPA treatment strongly reduces δ-catenin mRNA levels in cultured human neurons. δ-catenin is important for the control of glutamatergic synapses and is strongly associated with ASD. VPA inhibits dendritic morphogenesis in developing neurons, an effect that is also found in neurons lacking δ-catenin expression. We thus hypothesize that prenatal exposure to VPA significantly reduces δ-catenin levels in the brain, which impairs glutamatergic synapses to cause ASD. Here, we found that prenatal exposure to VPA markedly reduced δ-catenin levels in the brain of mouse pups. VPA treatment also impaired dendritic branching in developing mouse cortical neurons, which was partially reversed by elevating δ-catenin expression. Prenatal VPA exposure significantly reduced synaptic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor levels and postsynaptic density 95 (PSD95) in the brain of mouse pups, indicating dysfunctions in glutamatergic synaptic transmission. VPA exposure also significantly altered ultrasonic vocalization (USV) in newly born pups when they were isolated from their nest. Moreover, VPA-exposed pups show impaired hypothalamic response to isolation, which is required to produce animals' USVs following isolation from the nest. Therefore, these results suggest that VPA-induced ASD pathology can be mediated by the loss of δ-catenin functions.

Prenatal exposure to valproic acid reduces synaptic δ-catenin levels and disrupts ultrasonic vocalization in neonates

Valproic acid (VPA) is an effective and commonly prescribed drug for epilepsy and bipolar disorder. However, children born from mothers treated with VPA during pregnancy exhibit an increased incidence of autism spectrum disorder (ASD). Although VPA may impair brain development at the cellular level, the mechanism of VPA-induced ASD has not been completely addressed. A previous study has found that VPA treatment strongly reduces δ-catenin mRNA levels in cultured human neurons. δ-catenin is important for the control of glutamatergic synapses and is strongly associated with ASD. VPA inhibits dendritic morphogenesis in developing neurons, an effect that is also found in neurons lacking δ-catenin expression. We thus hypothesize that prenatal exposure to VPA significantly reduces δ-catenin levels in the brain, which impairs glutamatergic synapses to cause ASD. Here, we found that prenatal exposure to VPA markedly reduced δ-catenin levels in the brain of mouse pups. VPA treatment also impaired dendritic branching in developing mouse cortical neurons, which was reversed by elevating δ-catenin expression. Prenatal VPA exposure significantly reduced synaptic AMPA receptor levels and postsynaptic density 95 (PSD95) in the brain of mouse pups, indicating dysfunctions in glutamatergic synaptic transmission. VPA exposure also significantly altered ultrasonic vocalization (USV) in newly born pups when they were isolated from their nest. Moreover, VPA-exposed pups show impaired hypothalamic response to isolation, which is required to produce animals' USVs following isolation from the nest. Therefore, these results suggest that VPA-induced ASD pathology can be mediated by the loss of δ-catenin functions.

Highlights

Prenatal exposure of valproic acid (VPA) in mice significantly reduces synaptic δ-catenin protein and AMPA receptor levels in the pups' brains.VPA treatment significantly impairs dendritic branching in cultured cortical neurons, which is reversed by increased δ-catenin expression.VPA exposed pups exhibit impaired communication such as ultrasonic vocalization.Neuronal activation linked to ultrasonic vocalization is absent in VPA-exposed pups.The loss of δ-catenin functions underlies VPA-induced autism spectrum disorder (ASD) in early childhood.

δ-Catenin controls astrocyte morphogenesis via layer-specific astrocyte-neuron cadherin interactions

Astrocytes control the formation of specific synaptic circuits via cell adhesion and secreted molecules. Astrocyte synaptogenic functions are dependent on the establishment of their complex morphology. However, it is unknown if distinct neuronal cues differentially regulate astrocyte morphogenesis. δ-Catenin was previously thought to be a neuron-specific protein that regulates dendrite morphology. We found δ-catenin is also highly expressed by astrocytes and required both in astrocytes and neurons for astrocyte morphogenesis. δ-Catenin is hypothesized to mediate transcellular interactions through the cadherin family of cell adhesion proteins. We used structural modeling and biochemical analyses to reveal that δ-catenin interacts with the N-cadherin juxtamembrane domain to promote N-cadherin surface expression. An autism-linked δ-catenin point mutation impaired N-cadherin cell surface expression and reduced astrocyte complexity. In the developing mouse cortex, only lower-layer cortical neurons express N-cadherin. Remarkably, when we silenced astrocytic N-cadherin throughout the cortex, only lower-layer astrocyte morphology was disrupted. These findings show that δ-catenin controls astrocyte-neuron cadherin interactions that regulate layer-specific astrocyte morphogenesis.

Loss of ctnnd2b affects neuronal differentiation and behavior in zebrafish

Delta-catenin (CTNND2) is an adhesive junction associated protein belonging to the family of p120 catenins. The human gene is located on the short arm of chromosome 5, the region deleted in Cri-du-chat syndrome (OMIM #123450). Heterozygous loss of CTNND2 has been linked to a wide spectrum of neurodevelopmental disorders such as autism, schizophrenia, and intellectual disability. Here we studied how heterozygous loss of ctnnd2b affects zebrafish embryonic development, and larvae and adult behavior. First, we observed a disorganization of neuronal subtypes in the developing forebrain, namely the presence of ectopic isl1-expressing cells and a local reduction of GABA-positive neurons in the optic recess region. Next, using time-lapse analysis, we found that the disorganized distribution of is1l-expressing forebrain neurons resulted from an increased specification of Isl1:GFP neurons. Finally, we studied the swimming patterns of both larval and adult heterozygous zebrafish and observed an increased activity compared to wildtype animals. Overall, this data suggests a role for ctnnd2b in the differentiation cascade of neuronal subtypes in specific regions of the vertebrate brain, with repercussions in the animal's behavior.

Association of CTNND2 gene polymorphism with schizophrenia: Two-sample case-control study in Chinese Han population

OBJECTIVES

Genetic factors play an important role in the etiology of schizophrenia (SZ). Catenin Delta 2 (CTNND2) is one of the genes regulating neuronal development in the brain. It is unclear whether CTNND2 is involved in SZ. With the hypothesis that CTNND2 may be a risk gene for SZ, we performed a case-control association analysis to investigate if CTNND2 gene single nucleotide polymorphisms (SNPs) are implicated in SZ in a Han Chinese northern population.

MATERIALS AND METHODS

We recruited subjects from 2010 to 2022 from the Han population of northern Henan and divided them into two case-control samples, including a discovery sample (SZ = 528 and control = 528) and replication sample (SZ = 2458 and control = 6914). Twenty-one SNPs were genotyped on the Illumina BeadStation 500G platform using GoldenGate technology and analyzed by PLINK. Positive and Negative Syndrome Scale (PANSS) was used to assess clinical symptoms.

RESULTS

Rs16901943, rs7733427, and rs2168878 SNPs were associated with SZ (Chi² = 7.484, 11.576, and 5.391, respectively, df = 1; p = 0.006, 0.00067, and 0.02, respectively) in two samples. Rs10058868 was associated with SZ in male patients in the discovery sample (Chi² = 6.264, df = 1, p = .044). Only rs7733427 survived Bonferroni correction. Linkage disequilibrium block three haplotypes were associated with SZ in the discovery and total sample. PANSS analysis of the four SNPs implicated rs10058868 and rs2168878 with symptoms of depression and excitement, respectively, in the SZ patients.

CONCLUSION

Four SNPs were identified as being correlated with SZ. The CTNND2 gene may be involved in susceptibility to SZ.

The autism-associated loss of δ-catenin functions disrupts social behaviors

δ-catenin is expressed in excitatory synapses and functions as an anchor for the glutamatergic AMPA receptor (AMPAR) GluA2 subunit in the postsynaptic density. The glycine 34 to serine (G34S) mutation in the δ-catenin gene is found in autism spectrum disorder (ASD) patients and induces loss of δ-catenin functions at excitatory synapses, which is presumed to underlie ASD pathogenesis in humans. However, how the G34S mutation causes loss of δ-catenin functions to induce ASD remains unclear. Here, using neuroblastoma cells, we discover that the G34S mutation generates an additional phosphorylation site for glycogen synthase kinase 3β (GSK3β). This promotes δ-catenin degradation and causes the reduction of δ-catenin levels, which likely contributes to the loss of δ-catenin functions. Synaptic δ-catenin and GluA2 levels in the cortex are significantly decreased in mice harboring the δ-catenin G34S mutation. The G34S mutation increases glutamatergic activity in cortical excitatory neurons while it is decreased in inhibitory interneurons, indicating changes in cellular excitation and inhibition. δ-catenin G34S mutant mice also exhibit social dysfunction, a common feature of ASD. Most importantly, inhibition of GSK3β activity reverses the G34S-induced loss of δ-catenin function effects in cells and mice. Finally, using δ-catenin knockout mice, we confirm that δ-catenin is required for GSK3β inhibition-induced restoration of normal social behaviors in δ-catenin G34S mutant animals. Taken together, we reveal that the loss of δ-catenin functions arising from the ASD-associated G34S mutation induces social dysfunction via alterations in glutamatergic activity and that GSK3β inhibition can reverse δ-catenin G34S-induced synaptic and behavioral deficits.

Significance Statement

δ-catenin is important for the localization and function of glutamatergic AMPA receptors at synapses in many brain regions. The glycine 34 to serine (G34S) mutation in the δ-catenin gene is found in autism patients and results in the loss of δ-catenin functions. δ-catenin expression is also closely linked to other autism-risk genes involved in synaptic structure and function, further implying that it is important for the autism pathophysiology. Importantly, social dysfunction is a key characteristic of autism. Nonetheless, the links between δ-catenin functions and social behaviors are largely unknown. The significance of the current research is thus predicated on filling this gap by discovering the molecular, cellular, and synaptic underpinnings of the role of δ-catenin in social behaviors.

Delta-Catenin as a Modulator of Rho GTPases in Neurons

Small Rho GTPases are molecular switches that are involved in multiple processes including regulation of the actin cytoskeleton. These GTPases are activated (turned on) and inactivated (turned off) through various upstream effector molecules to carry out many cellular functions. One such upstream modulator of small Rho GTPase activity is delta-catenin, which is a protein in the p120-catenin subfamily that is enriched in the central nervous system. Delta-catenin affects small GTPase activity to assist in the developmental formation of dendrites and dendritic spines and to maintain them once they mature. As the dendritic arbor and spine density are crucial for synapse formation and plasticity, delta-catenin's ability to modulate small Rho GTPases is necessary for proper learning and memory. Accordingly, the misregulation of delta-catenin and small Rho GTPases has been implicated in several neurological and non-neurological pathologies. While links between delta-catenin and small Rho GTPases have yet to be studied in many contexts, known associations include some cancers, Alzheimer's disease (AD), Cri-du-chat syndrome, and autism spectrum disorder (ASD). Drawing from established studies and recent discoveries, this review explores how delta-catenin modulates small Rho GTPase activity. Future studies will likely elucidate how PDZ proteins that bind delta-catenin further influence small Rho GTPases, how delta-catenin may affect small GTPase activity at adherens junctions when bound to N-cadherin, mechanisms behind delta-catenin's ability to modulate Rac1 and Cdc42, and delta-catenin's ability to modulate small Rho GTPases in the context of diseases, such as cancer and AD.

Genomic Effects Associated With Response to Placebo Treatment in a Randomized Trial of Irritable Bowel Syndrome

Background and Aims: Irritable bowel syndrome (IBS), a functional pain disorder of gut-brain interactions, is characterized by a high placebo response in randomized clinical trials (RCTs). Catechol-O-methyltransferase (COMT) rs4680, which encodes high-activity (val) or low-activity (met) enzyme variants, was previously associated with placebo response to sham-acupuncture in an IBS RCT. Examining COMT effects and identifying novel genomic factors that influence response to placebo pills is critical to identifying underlying mechanisms and predicting and managing placebos in RCTs. Methods: Participants with IBS (N = 188) were randomized to three placebo-related interventions, namely, double-blind placebo (DBP), open-label placebo (OLP), or simply trial enrollment without placebo treatment [no placebo (i.e., no pill) treatment control (NPC)], for 6 weeks. COMT rs4680, gene-set, and genome-wide suggestive (p < 10-5) loci effects on irritable bowel symptom severity score (IBS-SSS) across all participants were examined. Results: Participants with IBS homozygous for rs4680 met (met/met) had the greatest improvement across all arms, with significantly greater improvement compared to val/val in DBP (beta (SE), -89.4 (42.3); p = 0.04). Twelve genome-wide suggestive loci formed a gene regulatory network highly connected to EGR1, a transcription factor involved in placebo-related processes of learning, memory, and response to stress and reward. EGR1 gene expression in peripheral blood mononuclear cells (PBMC) was significantly reduced at the endpoint across all treatment arms (log fold-change, -0.15; p = 0.02). Gene-set enrichment analysis returned three genome-wide significant ontology terms (GO:0032968, GO:0070934, and GO:0070937) linked to transcription regulation and GO:0003918 associated with DNA topoisomerase regulation. Conclusion: These results suggest common molecular mechanisms in response to varying forms of placebo that may inform personalized IBS treatment and placebo response prediction. Clinical Trial Registration: ClinicalTrials.gov, Identifier: NCT0280224.

Transcriptome-Wide Association Study Provides Insights Into the Genetic Component of Gene Expression in Anxiety

Anxiety disorders are common mental disorders that often result in disability. Recently, large-scale genome-wide association studies (GWASs) have identified several novel risk variants and loci for anxiety disorders (or anxiety traits). Nevertheless, how the reported risk variants confer risk of anxiety remains unknown. To identify genes whose cis-regulated expression levels are associated with risk of anxiety traits, we conducted a transcriptome-wide association study (TWAS) by integrating genome-wide associations from a large-scale GWAS (N = 175,163) (which evaluated anxiety traits based on Generalized Anxiety Disorder 2-item scale (GAD-2) score) and brain expression quantitative trait loci (eQTL) data (from the PsychENCODE and GTEx). We identified 19 and 17 transcriptome-wide significant (TWS) genes in the PsychENCODE and GTEx, respectively. Intriguingly, 10 genes showed significant associations with anxiety in both datasets, strongly suggesting that genetic risk variants may confer risk of anxiety traits by regulating the expression of these genes. Top TWS genes included RNF123, KANSL1-AS1, GLYCTK, CRHR1, DND1P1, MAPT and ARHGAP27. Of note, 25 TWS genes were not implicated in the original GWAS. Our TWAS identified 26 risk genes whose cis-regulated expression were significantly associated with anxiety, providing important insights into the genetic component of gene expression in anxiety disorders/traits and new clues for future drug development.

Psychiatric Disease Susceptibility and Pain in Chronic Pancreatitis: Association or Causation?

Pain perception in chronic pancreatitis (CP) is governed by the transmission of nociceptive inputs into the pain processing centers of the brain. These regions of the brain overlap with those that regulate and process emotions and cognition. Disorders in these regions also result in psychiatric conditions such as depression, anxiety, and posttraumatic stress disorder. The present study by Dunbar et al. evaluated 24 single nucleotide polymorphisms associated with anxiety and/or posttraumatic stress disorder and found correlations with constant and severe pain phenotypes in CP patients from a large cross-sectional cohort study. Although causation cannot be proven, the findings suggest that there may be a role for neuromodulator drugs for the treatment of pain in CP based on individual genetic susceptibility.

Novel truncating mutations in CTNND1 cause a dominant craniofacial and cardiac syndrome

CTNND1 encodes the p120-catenin (p120) protein, which has a wide range of functions, including the maintenance of cell–cell junctions, regulation of the epithelial-mesenchymal transition and transcriptional signalling. Due to advances in next-generation sequencing, CTNND1 has been implicated in human diseases including cleft palate and blepharocheilodontic (BCD) syndrome albeit only recently. In this study, we identify eight novel protein-truncating variants, six de novo, in 13 participants from nine families presenting with craniofacial dysmorphisms including cleft palate and hypodontia, as well as congenital cardiac anomalies, limb dysmorphologies and neurodevelopmental disorders. Using conditional deletions in mice as well as CRISPR/Cas9 approaches to target CTNND1 in Xenopus, we identified a subset of phenotypes that can be linked to p120-catenin in epithelial integrity and turnover, and additional phenotypes that suggest mesenchymal roles of CTNND1. We propose that CTNND1 variants have a wider developmental role than previously described and that variations in this gene underlie not only cleft palate and BCD but may be expanded to a broader velocardiofacial-like syndrome.

Prediction of Probable Major Depressive Disorder in the Taiwan Biobank: An Integrated Machine Learning and Genome-Wide Analysis Approach

In light of recent advancements in machine learning, personalized medicine using predictive algorithms serves as an essential paradigmatic methodology. Our goal was to explore an integrated machine learning and genome-wide analysis approach which targets the prediction of probable major depressive disorder (MDD) using 9828 individuals in the Taiwan Biobank. In our analysis, we reported a genome-wide significant association with probable MDD that has not been previously identified: FBN1 on chromosome 15. Furthermore, we pinpointed 17 single nucleotide polymorphisms (SNPs) which show evidence of both associations with probable MDD and potential roles as expression quantitative trait loci (eQTLs). To predict the status of probable MDD, we established prediction models with random undersampling and synthetic minority oversampling using 17 eQTL SNPs and eight clinical variables. We utilized five state-of-the-art models: logistic ridge regression, support vector machine, C4.5 decision tree, LogitBoost, and random forests. Our data revealed that random forests had the highest performance (area under curve = 0.8905 ± 0.0088; repeated 10-fold cross-validation) among the predictive algorithms to infer complex correlations between biomarkers and probable MDD. Our study suggests that an integrated machine learning and genome-wide analysis approach may offer an advantageous method to establish bioinformatics tools for discriminating MDD patients from healthy controls.

Genetic markers for depressive disorders with earlier age at onset

Age at onset has been considered a potential indicator of underlying genetic risk in depression research. However, the variants associated with earlier age at onset of depressive disorder have not been elucidated. To evaluate the genetic architecture of depression onset, whole-exome sequencing of samples from 1000 patients with depressive disorder was performed. Cox proportional hazard models with false discovery rate-adjusted P-values were used to estimate the hazard ratios; carriers and non-carriers of individual coding variants were compared in terms of age at onset of depression with adjustment for sociodemographic and clinical characteristics. The clinical relevance of the candidate variants was also examined. Whole-exome sequencing revealed four variants in the CCL14, FYB, GPRASP1, and CTNND2 genes associated with an increased risk of depressive disorder with earlier age at onset. Although no individual variant was associated with any clinical characteristic except AAO, together they were associated with younger AAO, younger age at visit for treatment, and recurrent and atypical depression. Our data suggest novel candidate genes for depressive disorder with earlier age at onset. These genes could serve as markers allowing early identification of patients at risk of depression, and thus earlier intervention.

Severe Pain in Chronic Pancreatitis Patients: Considering Mental Health and Associated Genetic Factors

Pain is the most distressing and disruptive feature of recurrent acute pancreatitis (RAP) and chronic pancreatitis (CP) resulting in low quality of life (QOL) and disabilities. There is no single, characteristic pain pattern in patients with RAP and CP. Abdominal imaging features of CP accurately reflect morphologic features but they do not correlate with pain. Pain is the major driver of poor quality of life (QOL) and it is the constant pain, rather than intermittent pain that drives poor QOL. Furthermore, the most severe constant pain experience in CP is also a complex condition. The ability to target the etiopathogenesis of severe pain requires new methods to detect the exact pain mechanisms in an individual at cellular, tissue, system and psychiatric levels. In patients with complex and severe disease, it is likely that multiple overlapping mechanisms are simultaneously driving pain, anxiety and depression. Quantitative sensory testing (QST) shows promise in detecting alterations in central processing of pain signals and to classify patients for mechanistic and therapeutic studies. New genetic research suggests that genetic loci for severe pain in CP overlap with genetic loci for depression and other psychiatric disorders, providing additional insights and therapeutic targets for individual patients with severe CP pain. Well-designed clinical trials that integrate clinical features, QST, genetics and psychological assessments with targeted treatment and assessment of responses are required for a quantum leap forward. A better understanding of the context and mechanisms contributing to severe pain experiences in individual patients is predicted to lead to better therapies and quality of life.

Rat models of human diseases and related phenotypes: a systematic inventory of the causative genes

The laboratory rat has been used for a long time as the model of choice in several biomedical disciplines. Numerous inbred strains have been isolated, displaying a wide range of phenotypes and providing many models of human traits and diseases. Rat genome mapping and genomics was considerably developed in the last decades. The availability of these resources has stimulated numerous studies aimed at discovering causal disease genes by positional identification. Numerous rat genes have now been identified that underlie monogenic or complex diseases and remarkably, these results have been translated to the human in a significant proportion of cases, leading to the identification of novel human disease susceptibility genes, helping in studying the mechanisms underlying the pathological abnormalities and also suggesting new therapeutic approaches. In addition, reverse genetic tools have been developed. Several genome-editing methods were introduced to generate targeted mutations in genes the function of which could be clarified in this manner [generally these are knockout mutations]. Furthermore, even when the human gene causing a disease had been identified without resorting to a rat model, mutated rat strains (in particular KO strains) were created to analyze the gene function and the disease pathogenesis. Today, over 350 rat genes have been identified as underlying diseases or playing a key role in critical biological processes that are altered in diseases, thereby providing a rich resource of disease models. This article is an update of the progress made in this research and provides the reader with an inventory of these disease genes, a significant number of which have similar effects in rat and humans.

Substance use: Interplay between polygenic risk and neighborhood environment

BACKGROUND

Tobacco, alcohol, and cannabis use are prevalent behaviors that pose considerable health risks. Genetic vulnerability and characteristics of the neighborhood of residence form important risk factors for substance use. Possibly, these factors do not act in isolation. This study tested the interaction between neighborhood characteristics and genetic risk (gene-environment interaction, GxE) and the association between these classes of risk factors (gene-environment correlation, rGE) in substance use.

METHODS

Two polygenic scores (PGS) each (based on different discovery datasets) were created for smoking initiation, cigarettes per day, and glasses of alcohol per week based on summary statistics of different genome-wide association studies (GWAS). For cannabis initiation one PGS was created. These PGS were used to predict their respective phenotype in a large population-based sample from the Netherlands Twin Register (N = 6,567). Neighborhood characteristics as retrieved from governmental registration systems were factor analyzed and resulting measures of socioeconomic status (SES) and metropolitanism were used as predictors.

RESULTS

There were (small) main effects of neighborhood characteristics and PGS on substance use. One of the 14 tested GxE effects was significant, such that the PGS was more strongly associated with alcohol use in individuals with high SES. This was effect was only significant for one out of two PGS. There were weak indications of rGE, mainly with age and cohort covariates.

CONCLUSION

We conclude that both genetic and neighborhood-level factors are predictors for substance use. More research is needed to establish the robustness of the findings on the interplay between these factors.

Testing Familial Transmission of Smoking With Two Different Research Designs

Introduction

Classical twin studies show that smoking is heritable. To determine if shared family environment plays a role in addition to genetic factors, and if they interact (G×E), we use a children-of-twins design. In a second sample, we measure genetic influence with polygenic risk scores (PRS) and environmental influence with a question on exposure to smoking during childhood.

Methods

Data on smoking initiation were available for 723 children of 712 twins from the Netherlands Twin Register (64.9% female, median birth year 1985). Children were grouped in ascending order of risk, based on smoking status and zygosity of their twin-parent and his/her co-twin: never smoking twin-parent with a never smoking co-twin; never smoking twin-parent with a smoking dizygotic co-twin; never smoking twin-parent with a smoking monozygotic co-twin; and smoking twin-parent with a smoking or never smoking co-twin. For 4072 participants from the Netherlands Twin Register (67.3% female, median birth year 1973), PRS for smoking were computed and smoking initiation, smoking heaviness, and exposure to smoking during childhood were available.

Results

Patterns of smoking initiation in the four group children-of-twins design suggested shared familial influences in addition to genetic factors. PRS for ever smoking were associated with smoking initiation in all individuals. PRS for smoking heaviness were associated with smoking heaviness in individuals exposed to smoking during childhood, but not in non-exposed individuals.

Conclusions

Shared family environment influences smoking, over and above genetic factors. Genetic risk of smoking heaviness was only important for individuals exposed to smoking during childhood, versus those not exposed (G×E).

Implications

This study adds to the very few existing children-of-twins (CoT) studies on smoking and combines a CoT design with a second research design that utilizes polygenic risk scores and data on exposure to smoking during childhood. The results show that shared family environment affects smoking behavior over and above genetic factors. There was also evidence for gene-environment interaction (G×E) such that genetic risk of heavy versus light smoking was only important for individuals who were also exposed to (second-hand) smoking during childhood. Together, these findings give additional incentive to recommending parents not to expose their children to cigarette smoking.

New insights into the pharmacogenomics of antidepressant response from the GENDEP and STAR*D studies: rare variant analysis and high-density imputation

Genome-wide association studies have generally failed to identify polymorphisms associated with antidepressant response. Possible reasons include limited coverage of genetic variants that this study tried to address by exome genotyping and dense imputation. A meta-analysis of Genome-Based Therapeutic Drugs for Depression (GENDEP) and Sequenced Treatment Alternatives to Relieve Depression (STAR*D) studies was performed at the single-nucleotide polymorphism (SNP), gene and pathway levels. Coverage of genetic variants was increased compared with previous studies by adding exome genotypes to previously available genome-wide data and using the Haplotype Reference Consortium panel for imputation. Standard quality control was applied. Phenotypes were symptom improvement and remission after 12 weeks of antidepressant treatment. Significant findings were investigated in NEWMEDS consortium samples and Pharmacogenomic Research Network Antidepressant Medication Pharmacogenomic Study (PGRN-AMPS) for replication. A total of 7062 950 SNPs were analyzed in GENDEP (n=738) and STAR*D (n=1409). rs116692768 (P=1.80e-08, ITGA9 (integrin α9)) and rs76191705 (P=2.59e-08, NRXN3 (neurexin 3)) were significantly associated with symptom improvement during citalopram/escitalopram treatment. At the gene level, no consistent effect was found. At the pathway level, the Gene Ontology (GO) terms GO: 0005694 (chromosome) and GO: 0044427 (chromosomal part) were associated with improvement (corrected P=0.007 and 0.045, respectively). The association between rs116692768 and symptom improvement was replicated in PGRN-AMPS (P=0.047), whereas rs76191705 was not. The two SNPs did not replicate in NEWMEDS. ITGA9 codes for a membrane receptor for neurotrophins and NRXN3 is a transmembrane neuronal adhesion receptor involved in synaptic differentiation. Despite their meaningful biological rationale for being involved in antidepressant effect, replication was partial. Further studies may help in clarifying their role.

Exploring the Wnt signaling pathway in schizophrenia and bipolar disorder

The Wnt signaling pathway plays a crucial role in neurodevelopment and in regulating the function and structure of the adult nervous system. Schizophrenia (SCZ) and bipolar disorder (BD) are severe mental disorders with evidence of subtle neurodevelopmental, structural and functional neuronal abnormalities. We aimed to elucidate the role of aberrant regulation of the Wnt system in these disorders by evaluating plasma levels of secreted Wnt modulators in patients (SCZ = 551 and BD = 246) and healthy controls (HCs = 639) using enzyme immune-assay. We also investigated the expression of 141 Wnt-related genes in whole blood in a subsample (SCZ = 338, BD = 241, and HCs = 263) using microarray analysis. Both SCZ and BD had dysregulated mRNA expression of Wnt-related genes favoring attenuated canonical (beta-catenin-dependent) signaling, and there were also indices of enhanced non-canonical Wnt signaling. In particular, FZD7, which may activate all Wnt pathways, but favors non-canonical signaling, and NFATc3, a downstream transcription factor and readout of the non-canonical Wnt/Ca²⁺ pathway, were significantly increased in SCZ and BD (p < 3 × 10^-4). Furthermore, patients had lower plasma levels of soluble dickkopf 1 and sclerostin (p < 0.01) compared with HC. Our findings suggest that SCZ and BD are characterized by abnormal Wnt gene expression and plasma protein levels, and we propose that drugs targeting the Wnt pathway may have a role in the treatment of severe mental disorders.

Interaction between the FTO gene, body mass index and depression: meta-analysis of 13701 individuals

BackgroundDepression and obesity are highly prevalent, and major impacts on public health frequently co-occur. Recently, we reported that having depression moderates the effect of the FTO gene, suggesting its implication in the association between depression and obesity.AimsTo confirm these findings by investigating the FTO polymorphism rs9939609 in new cohorts, and subsequently in a meta-analysis.MethodThe sample consists of 6902 individuals with depression and 6799 controls from three replication cohorts and two original discovery cohorts. Linear regression models were performed to test for association between rs9939609 and body mass index (BMI), and for the interaction between rs9939609 and depression status for an effect on BMI. Fixed and random effects meta-analyses were performed using METASOFT.ResultsIn the replication cohorts, we observed a significant interaction between FTO, BMI and depression with fixed effects meta-analysis (β = 0.12, P = 2.7 × 10^-4) and with the Han/Eskin random effects method (P = 1.4 × 10^-7) but not with traditional random effects (β = 0.1, P = 0.35). When combined with the discovery cohorts, random effects meta-analysis also supports the interaction (β = 0.12, P = 0.027) being highly significant based on the Han/Eskin model (P = 6.9 × 10^-8). On average, carriers of the risk allele who have depression have a 2.2% higher BMI for each risk allele, over and above the main effect of FTOConclusionsThis meta-analysis provides additional support for a significant interaction between FTO, depression and BMI, indicating that depression increases the effect of FTO on BMI. The findings provide a useful starting point in understanding the biological mechanism involved in the association between obesity and depression.

Smoking and caffeine consumption: a genetic analysis of their association

Smoking and caffeine consumption show a strong positive correlation, but the mechanism underlying this association is unclear. Explanations include shared genetic/environmental factors or causal effects. This study employed three methods to investigate the association between smoking and caffeine. First, bivariate genetic models were applied to data of 10 368 twins from the Netherlands Twin Register in order to estimate genetic and environmental correlations between smoking and caffeine use. Second, from the summary statistics of meta-analyses of genome-wide association studies on smoking and caffeine, the genetic correlation was calculated by LD-score regression. Third, causal effects were tested using Mendelian randomization analysis in 6605 Netherlands Twin Register participants and 5714 women from the Avon Longitudinal Study of Parents and Children. Through twin modelling, a genetic correlation of r0.47 and an environmental correlation of r0.30 were estimated between current smoking (yes/no) and coffee use (high/low). Between current smoking and total caffeine use, this was r0.44 and r0.00, respectively. LD-score regression also indicated sizeable genetic correlations between smoking and coffee use (r0.44 between smoking heaviness and cups of coffee per day, r0.28 between smoking initiation and coffee use and r0.25 between smoking persistence and coffee use). Consistent with the relatively high genetic correlations and lower environmental correlations, Mendelian randomization provided no evidence for causal effects of smoking on caffeine or vice versa. Genetic factors thus explain most of the association between smoking and caffeine consumption. These findings suggest that quitting smoking may be more difficult for heavy caffeine consumers, given their genetic susceptibility.

Functional roles of p120ctn family of proteins in central neurons

The cadherin-catenin complex in central neurons is associated with a variety of cytosolic partners, collectively called catenins. The p120ctn members are a family of catenins that are distinct from the more ubiquitously expressed α- and β-catenins. It is becoming increasingly clear that the functional roles of the p120ctn family of catenins in central neurons extend well beyond their functional roles in non-neuronal cells in partnering with cadherin to regulate adhesion. In this review, we will provide an overview of the p120ctn family in neurons and their varied functional roles in central neurons. Finally, we will examine the emerging roles of this family of proteins in neurodevelopmental disorders.

Conditional eQTL analysis reveals allelic heterogeneity of gene expression

In recent years, multiple eQTL (expression quantitative trait loci) catalogs have become available that can help understand the functionality of complex trait-related single nucleotide polymorphisms (SNPs). In eQTL catalogs, gene expression is often strongly associated with multiple SNPs, which may reflect either one or multiple independent associations. Conditional eQTL analysis allows a distinction between dependent and independent eQTLs. We performed conditional eQTL analysis in 4,896 peripheral blood microarray gene expression samples. Our analysis showed that 35% of genes with a cis eQTL have at least two independent cis eQTLs; for several genes up to 13 independent cis eQTLs were identified. Also, 12% (671) of the independent cis eQTLs identified in conditional analyses were not significant in unconditional analyses. The number of GWAS catalog SNPs identified as eQTL in the conditional analyses increases with 24% as compared to unconditional analyses. We provide an online conditional cis eQTL mapping catalog for whole blood (https://eqtl.onderzoek.io/), which can be used to lookup eQTLs more accurately than in standard unconditional whole blood eQTL databases.

Identifying genes for neurobehavioural traits in rodents: progress and pitfalls

Identifying genes and pathways that contribute to differences in neurobehavioural traits is a key goal in psychiatric research. Despite considerable success in identifying quantitative trait loci (QTLs) associated with behaviour in laboratory rodents, pinpointing the causal variants and genes is more challenging. For a long time, the main obstacle was the size of QTLs, which could encompass tens if not hundreds of genes. However, recent studies have exploited mouse and rat resources that allow mapping of phenotypes to narrow intervals, encompassing only a few genes. Here, we review these studies, showcase the rodent resources they have used and highlight the insights into neurobehavioural traits provided to date. We discuss what we see as the biggest challenge in the field - translating QTLs into biological knowledge by experimentally validating and functionally characterizing candidate genes - and propose that the CRISPR/Cas genome-editing system holds the key to overcoming this obstacle. Finally, we challenge traditional views on inbred versus outbred resources in the light of recent resource and technology developments.

Short communication: Genetic association between schizophrenia and cannabis use

BACKGROUND AND AIM

Previous studies have shown a relationship between schizophrenia and cannabis use. As both traits are substantially heritable, a shared genetic liability could explain the association. We use two recently developed genomics methods to investigate the genetic overlap between schizophrenia and cannabis use.

METHODS

Firstly, polygenic risk scores for schizophrenia were created based on summary statistics from the largest schizophrenia genome-wide association (GWA) meta-analysis to date. We analysed the association between these schizophrenia polygenic scores and multiple cannabis use phenotypes (lifetime use, regular use, age at initiation, and quantity and frequency of use) in a sample of 6,931 individuals. Secondly, we applied LD-score regression to the GWA summary statistics of schizophrenia and lifetime cannabis use to calculate the genome-wide genetic correlation.

RESULTS

Polygenic risk scores for schizophrenia were significantly (α<0.05) associated with five of the eight cannabis use phenotypes, including lifetime use, regular use, and quantity of use, with risk scores explaining up to 0.5% of the variance. Associations were not significant for age at initiation of use and two measures of frequency of use analyzed in lifetime users only, potentially because of reduced power due to a smaller sample size. The LD-score regression revealed a significant genetic correlation of r_g=0.22 (SE=0.07, p=0.003) between schizophrenia and lifetime cannabis use.

CONCLUSIONS

Common genetic variants underlying schizophrenia and lifetime cannabis use are partly overlapping. Individuals with a stronger genetic predisposition to schizophrenia are more likely to initiate cannabis use, use cannabis more regularly, and consume more cannabis over their lifetime.

Effect of childhood maltreatment and brain-derived neurotrophic factor on brain morphology

Childhood maltreatment (CM) has been associated with altered brain morphology, which may partly be due to a direct impact on neural growth, e.g. through the brain-derived neurotrophic factor (BDNF) pathway. Findings on CM, BDNF and brain volume are inconsistent and have never accounted for the entire BDNF pathway. We examined the effects of CM, BDNF (genotype, gene expression and protein level) and their interactions on hippocampus, amygdala and anterior cingulate cortex (ACC) morphology. Data were collected from patients with depression and/or an anxiety disorder and healthy subjects within the Netherlands Study of Depression and Anxiety (NESDA) (N = 289). CM was assessed using the Childhood Trauma Interview. BDNF Val66Met genotype, gene expression and serum protein levels were determined in blood and T1 MRI scans were acquired at 3T. Regional brain morphology was assessed using FreeSurfer. Covariate-adjusted linear regression analyses were performed. Amygdala volume was lower in maltreated individuals. This was more pronounced in maltreated met-allele carriers. The expected positive relationship between BDNF gene expression and volume of the amygdala is attenuated in maltreated subjects. Finally, decreased cortical thickness of the ACC was identified in maltreated subjects with the val/val genotype. CM was associated with altered brain morphology, partly in interaction with multiple levels of the BNDF pathway. Our results suggest that CM has different effects on brain morphology in met-carriers and val-homozygotes and that CM may disrupt the neuroprotective effect of BDNF.

Genetic alterations of δ-catenin/NPRAP/Neurojungin (CTNND2): functional implications in complex human diseases

Some genes involved in complex human diseases are particularly vulnerable to genetic variations such as single nucleotide polymorphism, copy number variations, and mutations. For example, Ras mutations account for over 30 % of all human cancers. Additionally, there are some genes that can display different variations with functional impact in different diseases that are unrelated. One such gene stands out: δ-catenin/NPRAP/Neurojungin with gene designation as CTNND2 on chromosome 5p15.2. Recent advances in genome wide association as well as molecular biology approaches have uncovered striking involvement of δ-catenin gene variations linked to complex human disorders. These disorders include cancer, bipolar disorder, schizophrenia, autism, Cri-du-chat syndrome, myopia, cortical cataract-linked Alzheimer's disease, and infectious diseases. This list has rapidly grown longer in recent years, underscoring the pivotal roles of δ-catenin in critical human diseases. δ-Catenin is an adhesive junction-associated protein in the delta subfamily of the β-catenin superfamily. δ-Catenin functions in Wnt signaling to regulate gene expression and modulate Rho GTPases of the Ras superfamily in cytoskeletal reorganization. δ-Catenin likely lies where Wnt signaling meets Rho GTPases and is a unique and vulnerable common target for mutagenesis in different human diseases.

The brain-derived neurotrophic factor pathway, life stress, and chronic multi-site musculoskeletal pain

Introduction

Brain-derived neurotrophic factor (BDNF) disturbances and life stress, both independently and in interaction, have been hypothesized to induce chronic pain. We examined whether (a) the BDNF pathway (val⁶⁶met genotype, gene expression, and serum levels), (b) early and recent life stress, and (c) their interaction are associated with the presence and severity of chronic multi-site musculoskeletal pain.

Methods

Cross-sectional data are from 1646 subjects of the Netherlands Study of Depression and Anxiety. The presence and severity of chronic multi-site musculoskeletal pain were determined using the Chronic Pain Grade (CPG) questionnaire. The BDNF val⁶⁶met polymorphism, BDNF gene expression, and BDNF serum levels were measured. Early life stress before the age of 16 was assessed by calculating a childhood trauma index using the Childhood Trauma Interview. Recent life stress was assessed as the number of recent adverse life events using the List of Threatening Events Questionnaire.

Results

Compared to val⁶⁶val, BDNF met carriers more often had chronic pain, whereas no differences were found for BDNF gene expression and serum levels. Higher levels of early and recent stress were both associated with the presence and severity of chronic pain (p < 0.001). No interaction effect was found for the BDNF pathway with life stress in the associations with chronic pain presence and severity.

Conclusions

This study suggests that the BDNF gene marks vulnerability for chronic pain. Although life stress did not alter the impact of BDNF on chronic pain, it seems an independent factor in the onset and persistence of chronic pain.

Candidate genes in panic disorder: meta-analyses of 23 common variants in major anxiogenic pathways

The utilization of molecular genetics approaches in examination of panic disorder (PD) has implicated several variants as potential susceptibility factors for panicogenesis. However, the identification of robust PD susceptibility genes has been complicated by phenotypic diversity, underpowered association studies and ancestry-specific effects. In the present study, we performed a succinct review of case-control association studies published prior to April 2015. Meta-analyses were performed for candidate gene variants examined in at least three studies using the Cochrane Mantel-Haenszel fixed-effect model. Secondary analyses were also performed to assess the influences of sex, agoraphobia co-morbidity and ancestry-specific effects on panicogenesis. Meta-analyses were performed on 23 variants in 20 PD candidate genes. Significant associations after correction for multiple testing were observed for three variants, TMEM132D rs7370927 (T allele: odds ratio (OR)=1.27, 95% confidence interval (CI): 1.15-1.40, P=2.49 × 10(-6)), rs11060369 (CC genotype: OR=0.65, 95% CI: 0.53-0.79, P=1.81 × 10(-5)) and COMT rs4680 (Val (G) allele: OR=1.27, 95% CI: 1.14-1.42, P=2.49 × 10(-5)) in studies with samples of European ancestry. Nominal associations that did not survive correction for multiple testing were observed for NPSR1 rs324891 (T allele: OR=1.22, 95% CI: 1.07-1.38, P=0.002), TPH1 rs1800532 (AA genotype: OR=1.46, 95% CI: 1.14-1.89, P=0.003) and HTR2A rs6313 (T allele: OR=1.19, 95% CI: 1.07-1.33, P=0.002) in studies with samples of European ancestry and for MAOA-uVNTR in female PD (low-active alleles: OR=1.21, 95% CI: 1.07-1.38, P=0.004). No significant associations were observed in the secondary analyses considering sex, agoraphobia co-morbidity and studies with samples of Asian ancestry. Although these findings highlight a few associations, PD likely involves genetic variation in a multitude of biological pathways that is diverse among populations. Future studies must incorporate larger sample sizes and genome-wide approaches to further quantify the observed genetic variation among populations and subphenotypes of PD.

The Genetics of Stress-Related Disorders: PTSD, Depression, and Anxiety Disorders

Research into the causes of psychopathology has largely focused on two broad etiologic factors: genetic vulnerability and environmental stressors. An important role for familial/heritable factors in the etiology of a broad range of psychiatric disorders was established well before the modern era of genomic research. This review focuses on the genetic basis of three disorder categories-posttraumatic stress disorder (PTSD), major depressive disorder (MDD), and the anxiety disorders-for which environmental stressors and stress responses are understood to be central to pathogenesis. Each of these disorders aggregates in families and is moderately heritable. More recently, molecular genetic approaches, including genome-wide studies of genetic variation, have been applied to identify specific risk variants. In this review, I summarize evidence for genetic contributions to PTSD, MDD, and the anxiety disorders including genetic epidemiology, the role of common genetic variation, the role of rare and structural variation, and the role of gene-environment interaction. Available data suggest that stress-related disorders are highly complex and polygenic and, despite substantial progress in other areas of psychiatric genetics, few risk loci have been identified for these disorders. Progress in this area will likely require analysis of much larger sample sizes than have been reported to date. The phenotypic complexity and genetic overlap among these disorders present further challenges. The review concludes with a discussion of prospects for clinical translation of genetic findings and future directions for research.

Meta-analysis of Genome-wide Association Studies for Neuroticism, and the Polygenic Association With Major Depressive Disorder

IMPORTANCE

Neuroticism is a pervasive risk factor for psychiatric conditions. It genetically overlaps with major depressive disorder (MDD) and is therefore an important phenotype for psychiatric genetics. The Genetics of Personality Consortium has created a resource for genome-wide association analyses of personality traits in more than 63,000 participants (including MDD cases).

OBJECTIVES

To identify genetic variants associated with neuroticism by performing a meta-analysis of genome-wide association results based on 1000 Genomes imputation; to evaluate whether common genetic variants as assessed by single-nucleotide polymorphisms (SNPs) explain variation in neuroticism by estimating SNP-based heritability; and to examine whether SNPs that predict neuroticism also predict MDD.

DESIGN, SETTING, AND PARTICIPANTS

Genome-wide association meta-analysis of 30 cohorts with genome-wide genotype, personality, and MDD data from the Genetics of Personality Consortium. The study included 63,661 participants from 29 discovery cohorts and 9786 participants from a replication cohort. Participants came from Europe, the United States, or Australia. Analyses were conducted between 2012 and 2014.

MAIN OUTCOMES AND MEASURES

Neuroticism scores harmonized across all 29 discovery cohorts by item response theory analysis, and clinical MDD case-control status in 2 of the cohorts.

RESULTS

A genome-wide significant SNP was found on 3p14 in MAGI1 (rs35855737; P = 9.26 × 10-9 in the discovery meta-analysis). This association was not replicated (P = .32), but the SNP was still genome-wide significant in the meta-analysis of all 30 cohorts (P = 2.38 × 10-8). Common genetic variants explain 15% of the variance in neuroticism. Polygenic scores based on the meta-analysis of neuroticism in 27 cohorts significantly predicted neuroticism (1.09 × 10-12 < P < .05) and MDD (4.02 × 10-9 < P < .05) in the 2 other cohorts.

CONCLUSIONS AND RELEVANCE

This study identifies a novel locus for neuroticism. The variant is located in a known gene that has been associated with bipolar disorder and schizophrenia in previous studies. In addition, the study shows that neuroticism is influenced by many genetic variants of small effect that are either common or tagged by common variants. These genetic variants also influence MDD. Future studies should confirm the role of the MAGI1 locus for neuroticism and further investigate the association of MAGI1 and the polygenic association to a range of other psychiatric disorders that are phenotypically correlated with neuroticism.

Polygenic risk scores for schizophrenia and bipolar disorder predict creativity

We tested whether polygenic risk scores for schizophrenia and bipolar disorder would predict creativity. Higher scores were associated with artistic society membership or creative profession in both Icelandic (P = 5.2 × 10(-6) and 3.8 × 10(-6) for schizophrenia and bipolar disorder scores, respectively) and replication cohorts (P = 0.0021 and 0.00086). This could not be accounted for by increased relatedness between creative individuals and those with psychoses, indicating that creativity and psychosis share genetic roots.

Genome-Wide Definition of Promoter and Enhancer Usage during Neural Induction of Human Embryonic Stem Cells

Genome-wide mapping of transcriptional regulatory elements is an essential tool for understanding the molecular events orchestrating self-renewal, commitment and differentiation of stem cells. We combined high-throughput identification of transcription start sites with genome-wide profiling of histones modifications to map active promoters and enhancers in embryonic stem cells (ESCs) induced to neuroepithelial-like stem cells (NESCs). Our analysis showed that most promoters are active in both cell types while approximately half of the enhancers are cell-specific and account for most of the epigenetic changes occurring during neural induction, and most likely for the modulation of the promoters to generate cell-specific gene expression programs. Interestingly, the majority of the promoters activated or up-regulated during neural induction have a “bivalent” histone modification signature in ESCs, suggesting that developmentally-regulated promoters are already poised for transcription in ESCs, which are apparently pre-committed to neuroectodermal differentiation. Overall, our study provides a collection of differentially used enhancers, promoters, transcription starts sites, protein-coding and non-coding RNAs in human ESCs and ESC-derived NESCs, and a broad, genome-wide description of promoter and enhancer usage and of gene expression programs characterizing the transition from a pluripotent to a neural-restricted cell fate.