Family-based association analysis to finemap bipolar linkage peak on chromosome 8q24 using 2,500 genotyped SNPs and 15,000 imputed SNPs

Exome sequencing identifies genes associated with sleep-related traits

Sleep is vital for human health and has a moderate heritability. Previous genome-wide association studies have limitations in capturing the role of rare genetic variants in sleep-related traits. Here we conducted a large-scale exome-wide association study of eight sleep-related traits (sleep duration, insomnia symptoms, chronotype, daytime sleepiness, daytime napping, ease of getting up in the morning, snoring and sleep apnoea) among 450,000 participants from UK Biobank. We identified 22 new genes associated with chronotype (ADGRL4, COL6A3, CLK4 and KRTAP3-3), daytime sleepiness (ST3GAL1 and ANKRD12), daytime napping (PLEKHM1, ANKRD12 and ZBTB21), snoring (WDR59) and sleep apnoea (13 genes). Notably, 20 of these genes were confirmed to be significantly associated with sleep disorders in the FinnGen cohort. Enrichment analysis revealed that these discovered genes were enriched in circadian rhythm and central nervous system neurons. Phenotypic association analysis showed that ANKRD12 was associated with cognition and inflammatory traits. Our results demonstrate the value of large-scale whole-exome analysis in understanding the genetic architecture of sleep-related traits and potential biological mechanisms.

Ca2+-stimulated ADCY1 and ADCY8 regulate distinct aspects of synaptic and cognitive flexibility

The type 1 and 8 adenylyl cyclase (ADCY1 and ADCY8) exclusively account for Ca2+-stimulated cyclic AMP (cAMP) production and regulate activity-dependent synaptic modification. In this study, we examined distinct forms of synaptic plasticity in the hippocampus of Adcy1-/- and Adcy8-/- mice. We found that, at the Schaffer collateral-CA1 synapses, while the Adcy8-/- mice displayed normal long-term potentiation (LTP) following various induction protocols with high-frequency stimulation (HFS), the Adcy1-/- mice showed protocol-dependent deficits in LTP. We also found that long-term depression (LTD) requires ADCY1 but not ADCY8. Interestingly, both Adcy1-/- and Adcy8-/- mice showed defective synaptic depotentiation (i.e., activity-dependent reversal of LTP); the deficits in Adcy8-/- mice were dependent on the induction protocol. Examination of spatial memory found that ADCY1 is required for the formation of both initial and reversal memory. ADCY8 is only required for reversal memory formation. These data demonstrate that ADCY1 and ADCY8 play distinct roles in regulating synaptic and cognitive flexibility that involves bidirectional modification of synaptic function.

Genomics in Treatment Development

The Human Genome Project mapped the 3 billion base pairs in the human genome, which ushered in a new generation of genomically focused treatment development. While this has been very successful in other areas, neuroscience has been largely devoid of such developments. This is in large part because there are very few neurological or mental health conditions that are related to single-gene variants. While developments in pharmacogenomics have been somewhat successful, the use of genetic information in practice has to do with drug metabolism and adverse reactions. Studies of drug metabolism related to genetic variations are an important part of drug development. However, outside of cancer biology, the actual translation of genomic information into novel therapies has been limited. Epigenetics, which relates in part to the effects of the environment on DNA, is a promising newer area of relevance to CNS disorders. The environment can induce chemical modifications of DNA (e.g., cytosine methylation), which can be induced by the environment and may represent either shorter- or longer-term changes. Given the importance of environmental influences on CNS disorders, epigenetics may identify important treatment targets in the future.

Ca2+-stimulated adenylyl cyclases as therapeutic targets for psychiatric and neurodevelopmental disorders

As the main secondary messengers, cyclic AMP (cAMP) and Ca2+ trigger intracellular signal transduction cascade and, in turn, regulate many aspects of cellular function in developing and mature neurons. The group I adenylyl cyclase (ADCY, also known as AC) isoforms, including ADCY1, 3, and 8 (also known as AC1, AC3, and AC8), are stimulated by Ca2+ and thus functionally positioned to integrate cAMP and Ca2+ signaling. Emerging lines of evidence have suggested the association of the Ca2+-stimulated ADCYs with bipolar disorder, schizophrenia, major depressive disorder, post-traumatic stress disorder, and autism. In this review, we discuss the molecular and cellular features as well as the physiological functions of ADCY1, 3, and 8. We further discuss the recent therapeutic development to target the Ca2+-stimulated ADCYs for potential treatments of psychiatric and neurodevelopmental disorders.

Physiological roles of mammalian transmembrane adenylyl cyclase isoforms

Adenylyl cyclases (ACs) catalyze the conversion of ATP to the ubiquitous second messenger cAMP. Mammals possess nine isoforms of transmembrane ACs, dubbed AC1-9, that serve as major effector enzymes of G protein-coupled receptors (GPCRs). The transmembrane ACs display varying expression patterns across tissues, giving the potential for them to have a wide array of physiological roles. Cells express multiple AC isoforms, implying that ACs have redundant functions. Furthermore, all transmembrane ACs are activated by Gαs, so it was long assumed that all ACs are activated by Gαs-coupled GPCRs. AC isoforms partition to different microdomains of the plasma membrane and form prearranged signaling complexes with specific GPCRs that contribute to cAMP signaling compartments. This compartmentation allows for a diversity of cellular and physiological responses by enabling unique signaling events to be triggered by different pools of cAMP. Isoform-specific pharmacological activators or inhibitors are lacking for most ACs, making knockdown and overexpression the primary tools for examining the physiological roles of a given isoform. Much progress has been made in understanding the physiological effects mediated through individual transmembrane ACs. GPCR-AC-cAMP signaling pathways play significant roles in regulating functions of every cell and tissue, so understanding each AC isoform's role holds potential for uncovering new approaches for treating a vast array of pathophysiological conditions.

Expression and functions of adenylyl cyclases in the CNS

Adenylyl cyclases (ADCYs), by generating second messenger cAMP, play important roles in various cellular processes. Their expression, regulation and functions in the CNS, however, remain largely unknown. In this review, we first introduce the classification and structure of ADCYs, followed by a discussion of the regulation of mammalian ADCYs (ADCY1-10). Next, the expression and function of each mammalian ADCY isoform are summarized in a region/cell-specific manner. Furthermore, the effects of GPCR-ADCY signaling on blood-brain barrier (BBB) integrity are reviewed. Last, current challenges and future directions are discussed. We aim to provide a succinct review on ADCYs to foster new research in the future.

Developmental Profile of Psychiatric Risk Associated With Voltage-Gated Cation Channel Activity

BACKGROUND

Recent breakthroughs in psychiatric genetics have implicated biological pathways onto which genetic risk for psychiatric disorders converges. However, these studies do not reveal the developmental time point(s) at which these pathways are relevant.

METHODS

We aimed to determine the relationship between psychiatric risk and developmental gene expression relating to discrete biological pathways. We used postmortem RNA sequencing data (BrainSeq and BrainSpan) from brain tissue at multiple prenatal and postnatal time points, with summary statistics from recent genome-wide association studies of schizophrenia, bipolar disorder, and major depressive disorder. We prioritized gene sets for overall enrichment of association with each disorder and then tested the relationship between the association of their constituent genes with their relative expression at each developmental stage.

RESULTS

We observed relationships between the expression of genes involved in voltage-gated cation channel activity during early midfetal, adolescence, and early adulthood time points and association with schizophrenia and bipolar disorder, such that genes more strongly associated with these disorders had relatively low expression during early midfetal development and higher expression during adolescence and early adulthood. The relationship with schizophrenia was strongest for the subset of genes related to calcium channel activity, while for bipolar disorder, the relationship was distributed between calcium and potassium channel activity genes.

CONCLUSIONS

Our results indicate periods during development when biological pathways related to the activity of calcium and potassium channels may be most vulnerable to the effects of genetic variants conferring risk for psychiatric disorders. Furthermore, they indicate key time points and potential targets for disorder-specific therapeutic interventions.

ATP-sensitive potassium channel subunits in the neuroinflammation: novel drug targets in neurodegenerative disorders

Arachidonic acids and its metabolites modulate plenty of ligand-gated, voltage-dependent ion channels, and metabolically regulated potassium channels including ATP-sensitive potassium channels (KATP). KATP channels are hetero-multimeric complexes of sulfonylureas receptors (SUR1, SUR2A or SUR2B) and the pore-forming subunits (Kir6.1 and Kir6.2) likewise expressed in the pre-post synapsis of neurons and inflammatory cells, thereby affecting their proliferation and activity. KATP channels are involved in amyloid-β (Aβ)-induced pathology, therefore emerging as therapeutic targets against Alzheimer's and related diseases. The modulation of these channels can represent an innovative strategy for the treatment of neurodegenerative disorders; nevertheless, the currently available drugs are not selective for brain KATP channels and show contrasting effects. This phenomenon can be a consequence of the multiple physiological roles of the different varieties of KATP channels. Openings of cardiac and muscular KATP channel subunits, is protective against caspase-dependent atrophy in these tissues and some neurodegenerative disorders, whereas in some neuroinflammatory diseases benefits can be obtained through the inhibition of neuronal KATP channel subunits. For example, glibenclamide exerts an anti-inflammatory effect in respiratory, digestive, urological, and central nervous system (CNS) diseases, as well as in ischemia-reperfusion injury associated with abnormal SUR1-Trpm4/TNF-α or SUR1-Trpm4/ Nos2/ROS signaling. Despite this strategy is promising, glibenclamide may have limited clinical efficacy due to its unselective blocking action of SUR2A/B subunits also expressed in cardiovascular apparatus with pro-arrhythmic effects and SUR1 expressed in pancreatic beta cells with hypoglycemic risk. Alternatively, neuronal selective dual modulators showing agonist/antagonist actions on KATP channels can be an option.

Association of adenylate cyclase-2 gene polymorphism with bipolar disorder

The pathogenesis of the Bipolar Disorder(BPD) is still unclear. Some studies suggest that abnormal signal transduction in specific pathways may play an important role in the pathogenesis of BPD (Sui et al., 2015). Adenylate cyclase (ADCY) is an essential component of the adenylate signaling pathway. Previous studies have shown that some SNPs within the adenylate cyclase gene could affect the therapeutic response to mood stabilizers and antidepressants. Moreover, in 2014, one whole-genome study suggested that the ADCY-2 gene may be associated with BPD (Mühleisen et al., 2014). This study aims to investigate the association between ADCY-2 gene polymorphism and BPD in Chinese Han population.

Differential Dorsolateral Prefrontal Cortex Proteomic Profiles of Suicide Victims with Mood Disorders

Suicide is a major public health concern; nevertheless, its neurobiology remains unknown. An area of interest in suicide research is the dorsolateral prefrontal cortex (DLPFC). We aimed to identify altered proteins and potential biological pathways in the DLPFC of individuals who died by suicide employing mass spectrometry-based untargeted proteomics. Postmortem DLPFC from age-matched male suicide mood disorder cases (n = 5) and non-suicide mood disorder cases (n = 5) were compared. The proteins that differed between groups at false discovery rate (FDR) adjusted p-values (Benjamini-Hochberg-Yekutieli) <0.3 and Log2 fold change (FC) >|0.4| were considered statistically significant and were subjected to pathway analysis by Qiagen Ingenuity software. Thirty-three of the 5162 detected proteins showed significantly altered expression levels in the suicide cases and two of them after adjustment for body mass index. The top differentially expressed protein was potassium voltage-gated channel subfamily Q member 3 (KCNQ3) (Log2FC = -0.481, p = 2.10 × 10-09, FDR = 5.93 × 10-06), which also showed a trend to downregulation in Western blot (p = 0.045, Bonferroni adjusted p = 0.090). The most notably enriched pathway was the GABA receptor signaling pathway (p < 0.001). Here, we report a reduction trend of KCNQ3 levels in the DLPFC of male suicide victims with mood disorders. Further studies with a larger sample size and equal sex representation are needed.

A systematic review of genome-wide association studies of antipsychotic response

Clinical symptom response to antipsychotic medications is highly variable. Genome-wide association studies (GWAS) provide a 'hypothesis-free' method of interrogating the genome for biomarkers of antipsychotic response. We performed a systematic review of GWAS findings for antipsychotic efficacy or effectiveness. 14 studies met our inclusion criteria, ten of which examined antipsychotic response using quantitative rating scales to measure symptom improvement. 15 genome-wide significant loci were identified, seven of which were replicated in other antipsychotic GWAS publications: CNTNAP5, GRID2, GRM7, 8q24 (KCNK9), PCDH7, SLC1A1 and TNIK. Notably, four replicated loci are involved in glutamatergic pathways. Additional validation and evaluation of the biological significance of these markers is warranted. These markers should also be evaluated for clinical utility, especially in the context of other validated pharmacogenomic variants (e.g., CYP450 genes). These findings may generate new avenues for development of novel antipsychotic treatments.

Autism spectrum disorder and epileptic encephalopathy: common causes, many questions

Epileptic encephalopathies represent a particularly severe form of epilepsy, associated with cognitive and behavioral deficits, including impaired social-communication and restricted, repetitive behaviors that are the hallmarks of autism spectrum disorder (ASD). With the advent of next-generation sequencing, the genetic landscape of epileptic encephalopathies is growing and demonstrates overlap with genes separately implicated in ASD. However, many questions remain about this connection, including whether epileptiform activity itself contributes to the development of ASD symptomatology. In this review, we compiled a database of genes associated with both epileptic encephalopathy and ASD, limiting our purview to Mendelian disorders not including inborn errors of metabolism, and we focused on the connection between ASD and epileptic encephalopathy rather than epilepsy broadly. Our review has four goals: to (1) discuss the overlapping presentations of ASD and monogenic epileptic encephalopathies; (2) examine the impact of the epilepsy itself on neurocognitive features, including ASD, in monogenic epileptic encephalopathies; (3) outline many of the genetic causes responsible for both ASD and epileptic encephalopathy; (4) provide an illustrative example of a final common pathway that may be implicated in both ASD and epileptic encephalopathy. We demonstrate that autistic features are a common association with monogenic epileptic encephalopathies. Certain epileptic encephalopathy syndromes, like infantile spasms, are especially linked to the development of ASD. The connection between seizures themselves and neurobehavioral deficits in these monogenic encephalopathies remains open to debate. Finally, advances in genetics have revealed many genes that overlap in ties to both ASD and epileptic encephalopathy and that play a role in diverse central nervous system processes. Increased attention to the autistic features of monogenic epileptic encephalopathies is warranted for both researchers and clinicians alike.

Bipolar disorder risk gene FOXO6 modulates negative symptoms in schizophrenia: a neuroimaging genetics study

BACKGROUND

Despite being diagnostically associated uniquely with schizophrenia, negative symptoms are also observed in bipolar disorder (BD). Genome-wide association studies (GWAS) have uncovered a number of shared risk genes between schizophrenia and BD. The objectives of this study were to examine whether previously identified risk genes for BD are associated with negative symptom severity within a first-episode schizophrenia (FES) cohort and to examine whether such genes influence brain morphology.

METHODS

Patients experiencing FES were genotyped for 21 previously identified BD risk genes; a series of univariate analyses of covariance examined the association between negative symptom severity, as measured using the Scale for the Assessment of Negative Symptoms (SANS), and genotype. A subset of participants underwent a structural 1.5 T MRI T₁ scan, analyzed for surface area and cortical thickness changes via the CIVET pipeline and LPBA40 atlas.

RESULTS

We included 133 patients with FES in our analysis; 61 of them underwent structural MRI. We observed a significant association between negative symptom severity and the BD risk gene FOXO6 (rs4660531). Individuals with the CC genotype presented significantly higher negative symptoms (Cohen d = 0.46, F = 5.854, p = 0.017) and significantly smaller surface area within the right middle orbitofrontal gyrus (Cohen d = 0.69, F = 7.289, p = 0.009) than carriers of allele A.

LIMITATIONS

Limitations of this study include its modest sample size and lack of a control sample.

CONCLUSION

Lacking the FOXO6 risk allele was associated with an increase in negative symptoms and surface area reduction in the right orbitofrontal gyrus - an area previously associated with negative symptoms - suggesting that presence of the FOXO6 risk allele confers resistance against negative symptoms and associated neuroanatomical changes in individuals with FES.

International Union of Basic and Clinical Pharmacology. CI. Structures and Small Molecule Modulators of Mammalian Adenylyl Cyclases

Adenylyl cyclases (ACs) generate the second messenger cAMP from ATP. Mammalian cells express nine transmembrane AC (mAC) isoforms (AC1-9) and a soluble AC (sAC, also referred to as AC10). This review will largely focus on mACs. mACs are activated by the G-protein Gαs and regulated by multiple mechanisms. mACs are differentially expressed in tissues and regulate numerous and diverse cell functions. mACs localize in distinct membrane compartments and form signaling complexes. sAC is activated by bicarbonate with physiologic roles first described in testis. Crystal structures of the catalytic core of a hybrid mAC and sAC are available. These structures provide detailed insights into the catalytic mechanism and constitute the basis for the development of isoform-selective activators and inhibitors. Although potent competitive and noncompetitive mAC inhibitors are available, it is challenging to obtain compounds with high isoform selectivity due to the conservation of the catalytic core. Accordingly, caution must be exerted with the interpretation of intact-cell studies. The development of isoform-selective activators, the plant diterpene forskolin being the starting compound, has been equally challenging. There is no known endogenous ligand for the forskolin binding site. Recently, development of selective sAC inhibitors was reported. An emerging field is the association of AC gene polymorphisms with human diseases. For example, mutations in the AC5 gene (ADCY5) cause hyperkinetic extrapyramidal motor disorders. Overall, in contrast to the guanylyl cyclase field, our understanding of the (patho)physiology of AC isoforms and the development of clinically useful drugs targeting ACs is still in its infancy.

Dissecting bipolar disorder complexity through epigenomic approach

In recent years, numerous studies of gene regulation mechanisms have emerged in neuroscience. Epigenetic modifications, described as heritable but reversible changes, include DNA methylation, DNA hydroxymethylation, histone modifications and noncoding RNAs. The pathogenesis of psychiatric disorders, such as bipolar disorder, may be ascribed to a complex gene-environment interaction (G × E) model, linking the genome, environmental factors and epigenetic marks. Both the high complexity and the high heritability of bipolar disorder make it a compelling candidate for neurobiological analyses beyond DNA sequencing. Questions that are being raised in this review are the precise phenotype of the disorder in question, and also the trait versus state debate and how these concepts are being implemented in a variety of study designs.

Variants in Ion Channel Genes Link Phenotypic Features of Bipolar Illness to Specific Neurobiological Process Domains

Recent advances in genome-wide association studies are pointing towards a major role for voltage-gated ion channels in neuropsychiatric disorders and, in particular, bipolar disorder (BD). The phenotype of BD is complex, with symptoms during mood episodes and deficits persisting between episodes. We have tried to elucidate the common neurobiological mechanisms associated with ion channel signaling in order to provide a new perspective on the clinical symptoms and possible endophenotypes seen in BD patients. We propose a model in which the multiple variants in genes coding for ion channel proteins would perturb motivational circuits, synaptic plasticity, myelination, hypothalamic-pituitary-adrenal axis function, circadian neuronal rhythms, and energy regulation. These changes in neurobiological mechanisms would manifest in endophenotypes of aberrant reward processing, white matter hyperintensities, deficits in executive function, altered frontolimbic connectivity, increased amygdala activity, increased melatonin suppression, decreased REM latency, and aberrant myo-inositol/ATP shuttling. The endophenotypes result in behaviors of poor impulse control, motivational changes, cognitive deficits, abnormal stress response, sleep disturbances, and energy changes involving different neurobiological process domains. The hypothesis is that these disturbances start with altered neural circuitry during development, following which multiple environmental triggers may disrupt the neuronal excitability balance through an activity-dependent molecular process, resulting in clinical mood episodes.

A genome-wide linkage scan of bipolar disorder in Latino families identifies susceptibility loci at 8q24 and 14q32

A genome-wide nonparametric linkage screen was performed to localize Bipolar Disorder (BP) susceptibility loci in a sample of 3757 individuals of Latino ancestry. The sample included 963 individuals with BP phenotype (704 relative pairs) from 686 families recruited from the US, Mexico, Costa Rica, and Guatemala. Non-parametric analyses were performed over a 5 cM grid with an average genetic coverage of 0.67 cM. Multipoint analyses were conducted across the genome using non-parametric Kong & Cox LOD scores along with Sall statistics for all relative pairs. Suggestive and significant genome-wide thresholds were calculated based on 1000 simulations. Single-marker association tests in the presence of linkage were performed assuming a multiplicative model with a population prevalence of 2%. We identified two genome-wide significant susceptibly loci for BP at 8q24 and 14q32, and a third suggestive locus at 2q13-q14. Within these three linkage regions, the top associated single marker (rs1847694, P = 2.40 × 10(-5)) is located 195 Kb upstream of DPP10 in Chromosome 2. DPP10 is prominently expressed in brain neuronal populations, where it has been shown to bind and regulate Kv4-mediated A-type potassium channels. Taken together, these results provide additional evidence that 8q24, 14q32, and 2q13-q14 are susceptibly loci for BP and these regions may be involved in the pathogenesis of BP in the Latino population.

Associations of genetic polymorphisms of Siglecs with human diseases

Genetic polymorphism studies in humans provide unique opportunities to understand human biology and the mechanisms of diseases. Correlations between polymorphisms in the genes encoding human Siglecs and various diseases have been reported. Leading examples, such as the CD33 polymorphism associated with late-onset Alzheimer's disease, are well supported by genetic replication and mechanistic studies, while some others (such as SIGLEC8 polymorphism associated with bronchial asthma and SIGLEC14 polymorphism associated with exacerbation of chronic obstructive pulmonary disease) may benefit reinforcement by independent genetic replication or mechanistic studies. In a few cases, such as MAG polymorphism associated with psychological disorder and CD22 polymorphism associated with autoimmune disease, the phenotype associated with a genetic polymorphism of a Siglec gene and that of an enzyme gene involved in the biosynthesis of Siglec ligand show some overlap, providing indirect support for the observed genotype-phenotype association. Although studies using engineered mutant mice have provided invaluable insights into the biological functions and mechanisms of diseases, it is not always possible to develop appropriate mouse model to replicate human situations because of significant species-to-species differences, which can be a major obstacle in understanding the biology of some of human CD33/Siglec-3-related Siglecs. Further studies in genetic polymorphisms of human Siglecs, combined with appropriate functional studies, may reveal unexpected biological roles of human Siglecs, and identify possible targets for prevention and/or treatment of certain diseases.

A genome-wide association study of clinical symptoms of dissociation in a trauma-exposed sample

BACKGROUND

Recent work suggests that a subset of individuals with posttraumatic stress disorder (PTSD) exhibit marked dissociative symptoms, as defined by derealization and depersonalization. A dissociative subtype of PTSD was added to the diagnostic criteria listed in the Diagnostic and Statistical Manual of Mental Disorders, Version 5 (DSM-5) to capture this presentation of PTSD. This study examined genetic polymorphisms for association with the symptoms that define the dissociative subtype of PTSD using a genome-wide approach.

METHODS

The sample comprised 484 White, non-Hispanic, trauma-exposed veterans and their partners who were assessed for lifetime PTSD and dissociation using a structured clinical interview. The prevalence of PTSD was 60.5%. Single-nucleotide polymorphisms (SNPs) from across the genome were obtained from a 2.5 million SNP array.

RESULTS

Ten SNPs evidenced suggestive association with dissociation (P < 10(-5)). No SNPs met genome-wide significance criteria (P < 5 × 10(-8)). The peak SNP was rs263232 (β = 1.4, P = 6.12 × 10(-7)), located in the adenylyl cyclase 8 (ADCY8) gene; a second SNP in the suggestive range was rs71534169 (β = 1.63, P = 3.79 × 10(-6)), located in the dipeptidyl-peptidase 6 (DPP6) gene.

CONCLUSIONS

ADCY8 is integral for long-term potentiation and synaptic plasticity and is implicated in fear-related learning and memory and long-term memory consolidation. DPP6 is critical for synaptic integration and excitation. These genes may exert effects on basic sensory integration and cognitive processes that underlie dissociative phenomena.

Genome-wide association study of the five-factor model of personality in young Korean women

Personality is a determinant of behavior and lifestyle associated with health and human diseases. Although personality is known to be a heritable trait, its polygenic nature has made the identification of genetic variants elusive. We performed a genome-wide association study on 1089 Korean women aged 18-40 years whose personality traits were measured with the Revised NEO Personality Inventory for the five-factor model of personality. To reduce environmental factors that may influence personality traits, this study was restricted to young adult women. In the discovery phase, we identified variants of PTPRD (protein tyrosine phosphatase, receptor type D) that associated this gene with the Openness domain. Other genes that were previously reported to be associated with neurological phenotypes were also associated with personality traits. In particular, DRD1 and OR1A2 were linked to Neuroticism, NKAIN2 with Extraversion, HTR5A with Openness and DRD3 with Agreeableness. Data from our replication study of 2090 subjects confirmed the association between OR1A2 and Neuroticism. We first identified and confirmed a novel region on OR1A2 associated with Neuroticism [corrected]. Candidate genes for psychiatric disorders were also enriched. These findings contribute to our understanding of the genetic architecture of personality traits and provide critical clues to the neurobiological mechanisms that influence them.

Genome-wide association study of obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) is a common, debilitating neuropsychiatric illness with complex genetic etiology. The International OCD Foundation Genetics Collaborative (IOCDF-GC) is a multi-national collaboration established to discover the genetic variation predisposing to OCD. A set of individuals affected with DSM-IV OCD, a subset of their parents, and unselected controls, were genotyped with several different Illumina SNP microarrays. After extensive data cleaning, 1465 cases, 5557 ancestry-matched controls and 400 complete trios remained, with a common set of 469,410 autosomal and 9657 X-chromosome single nucleotide polymorphisms (SNPs). Ancestry-stratified case-control association analyses were conducted for three genetically-defined subpopulations and combined in two meta-analyses, with and without the trio-based analysis. In the case-control analysis, the lowest two P-values were located within DLGAP1 (P=2.49 × 10(-6) and P=3.44 × 10(-6)), a member of the neuronal postsynaptic density complex. In the trio analysis, rs6131295, near BTBD3, exceeded the genome-wide significance threshold with a P-value=3.84 × 10(-8). However, when trios were meta-analyzed with the case-control samples, the P-value for this variant was 3.62 × 10(-5), losing genome-wide significance. Although no SNPs were identified to be associated with OCD at a genome-wide significant level in the combined trio-case-control sample, a significant enrichment of methylation QTLs (P<0.001) and frontal lobe expression quantitative trait loci (eQTLs) (P=0.001) was observed within the top-ranked SNPs (P<0.01) from the trio-case-control analysis, suggesting these top signals may have a broad role in gene expression in the brain, and possibly in the etiology of OCD.

A review of potassium channels in bipolar disorder

Although bipolar disorder (BP) is one of the most heritable psychiatric conditions, susceptibility genes for the disorder have yet to be conclusively identified. It is likely that variants in multiple genes across multiple pathways contribute to the genotype–phenotype relationship in the affected population. Recent evidence from genome-wide association studies implicates an entire class of genes related to the structure and regulation of ion channels, suggesting that the etiology of BP may arise from channelopathies. In this review, we examine the evidence for this hypothesis, with a focus on the potential role of voltage-gated potassium channels. We consider evidence from genetic and expression studies, and discuss the potential underlying biology. We consider animal models and treatment implications of the involvement of potassium ion channelopathy in BP. Finally, we explore intriguing parallels between BP and epilepsy, the signature channelopathy of the central nervous system.

Major channels involved in neuropsychiatric disorders and therapeutic perspectives

Voltage-gated ion channels are important mediators of physiological functions in the central nervous system. The cyclic activation of these channels influences neurotransmitter release, neuron excitability, gene transcription, and plasticity, providing distinct brain areas with unique physiological and pharmacological response. A growing body of data has implicated ion channels in the susceptibility or pathogenesis of psychiatric diseases. Indeed, population studies support the association of polymorphisms in calcium and potassium channels with the genetic risk for bipolar disorders (BPDs) or schizophrenia. Moreover, point mutations in calcium, sodium, and potassium channel genes have been identified in some childhood developmental disorders. Finally, antibodies against potassium channel complexes occur in a series of autoimmune psychiatric diseases. Here we report recent studies assessing the role of calcium, sodium, and potassium channels in BPD, schizophrenia, and autism spectrum disorders, and briefly summarize promising pharmacological strategies targeted on ion channels for the therapy of mental illness and related genetic tests.

Dysfunction of the Heteromeric KV7.3/KV7.5 Potassium Channel is Associated with Autism Spectrum Disorders

Heterozygous mutations in the KCNQ3 gene on chromosome 8q24 encoding the voltage-gated potassium channel KV7.3 subunit have previously been associated with rolandic epilepsy and idiopathic generalized epilepsy (IGE) including benign neonatal convulsions. We identified a de novo t(3;8) (q21;q24) translocation truncating KCNQ3 in a boy with childhood autism. In addition, we identified a c.1720C > T [p.P574S] nucleotide change in three unrelated individuals with childhood autism and no history of convulsions. This nucleotide change was previously reported in patients with rolandic epilepsy or IGE and has now been annotated as a very rare SNP (rs74582884) in dbSNP. The p.P574S KV7.3 variant significantly reduced potassium current amplitude in Xenopus laevis oocytes when co-expressed with KV7.5 but not with KV7.2 or KV7.4. The nucleotide change did not affect trafficking of heteromeric mutant KV7.3/2, KV7.3/4, or KV7.3/5 channels in HEK 293 cells or primary rat hippocampal neurons. Our results suggest that dysfunction of the heteromeric KV7.3/5 channel is implicated in the pathogenesis of some forms of autism spectrum disorders, epilepsy, and possibly other psychiatric disorders and therefore, KCNQ3 and KCNQ5 are suggested as candidate genes for these disorders.

Genome-wide copy number variation analysis in extended families and unrelated individuals characterized for musical aptitude and creativity in music

Music perception and practice represent complex cognitive functions of the human brain. Recently, evidence for the molecular genetic background of music related phenotypes has been obtained. In order to further elucidate the molecular background of musical phenotypes we analyzed genome wide copy number variations (CNVs) in five extended pedigrees and in 172 unrelated subjects characterized for musical aptitude and creative functions in music. Musical aptitude was defined by combination of the scores of three music tests (COMB scores): auditory structuring ability, Seashores test for pitch and for time. Data on creativity in music (herein composing, improvising and/or arranging music) was surveyed using a web-based questionnaire.

Several CNVRs containing genes that affect neurodevelopment, learning and memory were detected. A deletion at 5q31.1 covering the protocadherin-α gene cluster (Pcdha 1-9) was found co-segregating with low music test scores (COMB) in both sample sets. Pcdha is involved in neural migration, differentiation and synaptogenesis. Creativity in music was found to co-segregate with a duplication covering glucose mutarotase gene (GALM) at 2p22. GALM has influence on serotonin release and membrane trafficking of the human serotonin transporter. Interestingly, genes related to serotonergic systems have been shown to associate not only with psychiatric disorders but also with creativity and music perception. Both, Pcdha and GALM, are related to the serotonergic systems influencing cognitive and motor functions, important for music perception and practice. Finally, a 1.3 Mb duplication was identified in a subject with low COMB scores in the region previously linked with absolute pitch (AP) at 8q24. No differences in the CNV burden was detected among the high/low music test scores or creative/non-creative groups. In summary, CNVs and genes found in this study are related to cognitive functions. Our result suggests new candidate genes for music perception related traits and supports the previous results from AP study.

BCL9 and C9orf5 are associated with negative symptoms in schizophrenia: meta-analysis of two genome-wide association studies

Schizophrenia is a chronic and debilitating psychiatric condition affecting slightly more than 1% of the population worldwide and it is a multifactorial disorder with a high degree of heritability (80%) based on family and twin studies. Increasing lines of evidence suggest intermediate phenotypes/endophenotypes are more associated with causes of the disease and are less genetically complex than the broader disease spectrum. Negative symptoms in schizophrenia are attractive intermediate phenotypes based on their clinical and treatment response features. Therefore, our objective was to identify genetic variants underlying the negative symptoms of schizophrenia by analyzing two genome-wide association (GWA) data sets consisting of a total of 1,774 European-American patients and 2,726 controls. Logistic regression analysis of negative symptoms as a binary trait (adjusted for age and sex) was performed using PLINK. For meta-analysis of two datasets, the fixed-effect model in PLINK was applied. Through meta-analysis we identified 25 single nucleotide polymorphisms (SNPs) associated with negative symptoms with p<5×10(-5). Especially we detected five SNPs in the first two genes/loci strongly associated with negative symptoms of schizophrenia (P(meta-analysis)<6.22×10(-6)), which included three SNPs in the BCL9 gene: rs583583 showed the strongest association at a P(meta-analysis) of 6.00×10(-7) and two SNPs in the C9orf5 (the top SNP is rs643410 with a p = 1.29 ×10(-6)). Through meta-analysis, we identified several additional negative symptoms associated genes (ST3GAL1, RNF144, CTNNA3 and ZNF385D). This is the first report of the common variants influencing negative symptoms of schizophrenia. These results provide direct evidence of using of negative symptoms as an intermediate phenotype to dissect the complex genetics of schizophrenia. However, additional studies are warranted to examine the underlying mechanisms of these disease-associated SNPs in these genes.

Coupling diffusion imaging with histological and gene expression analysis to examine the dynamics of cortical areas across the fetal period of human brain development

As a prominent component of the human fetal brain, the structure of the cerebral wall is characterized by its laminar organization which includes the radial glial scaffold during fetal development. Diffusion tensor imaging (DTI) is useful to quantitatively delineate the microstructure of the developing brain and to clearly identify transient fetal layers in the cerebral wall. In our study, the spatio-temporal microstructural changes in the developing human fetal cerebral wall were quantitatively characterized with high-resolution DTI data of postmortem fetal brains from 13 to 21 gestational weeks. Eleven regions of interest for each layer in the entire cerebral wall were included. Distinctive time courses of microstructural changes were revealed for 11 regions of the neocortical plate. A histological analysis was also integrated to elucidate the relationship between DTI fractional anisotropy (FA) and histology. High FA values correlated with organized radial architecture in histological image. Expression levels of 17565 genes were quantified for each of 11 regions of human fetal neocortex from 13 to 21 gestational weeks to identify transcripts showing significant correlation with FA change. These correlations suggest that the heterogeneous and regionally specific microstructural changes of the human neocortex are related to different gene expression patterns.

Absence of Ca2+-stimulated adenylyl cyclases leads to reduced synaptic plasticity and impaired experience-dependent fear memory

Ca(2+)-stimulated adenylyl cyclase (AC) 1 and 8 are two genes that have been shown to play critical roles in fear memory. AC1 and AC8 couple neuronal activity and intracellular Ca(2+) increases to the production of cyclic adenosine monophosphate and are localized synaptically, suggesting that Ca(2+)-stimulated ACs may modulate synaptic plasticity. Here, we first established that Ca(2+)-stimulated ACs modulate protein markers of synaptic activity at baseline and after learning. Primary hippocampal cell cultures showed that AC1/AC8 double-knockout (DKO) mice have reduced SV2, a synaptic vesicle protein, abundance along their dendritic processes, and this reduction can be rescued through lentivirus delivery of AC8 to the DKO cells. Additionally, phospho-synapsin, a protein implicated in the regulation of neurotransmitter release at the synapse, is decreased in vivo 1 h after conditioned fear (CF) training in DKO mice. Importantly, additional experiments showed that long-term potentiation deficits present in DKO mice are rescued by acutely replacing AC8 in the forebrain, further supporting the idea that Ca(2+)-stimulated AC activity is a crucial modulator of synaptic plasticity. Previous studies have demonstrated that memory is continually modulated by gene-environment interactions. The last set of experiments evaluated the effects of knocking out AC1 and AC8 genes on experience-dependent changes in CF memory. We showed that the strength of CF memory in wild-type mice is determined by previous environment, minimal or enriched, whereas memory in DKO mice is unaffected. Thus, overall these results show that AC1 and AC8 modulate markers of synaptic activity and help integrate environmental information to modulate fear memory.