Effect of CACNA1C rs1006737 on neural correlates of verbal fluency in healthy individuals

Expanding the Phenotype of the CACNA1C-Associated Neurological Disorders in Children: Systematic Literature Review and Description of a Novel Mutation

Background: CACNA1C gene encodes the alpha 1 subunit of the CaV1.2 L-type Ca2+ channel. Pathogenic variants in this gene have been associated with cardiac rhythm disorders such as long QT syndrome, Brugada syndrome and Timothy syndrome. Recent evidence has suggested the possible association between CACNA1C mutations and neurologically-isolated (in absence of cardiac involvement) phenotypes in children, giving birth to a wider spectrum of CACNA1C-related clinical presentations. However, to date, little is known about the variety of both neurological and non-neurological signs/symptoms in the neurologically-predominant phenotypes. Methods and Results: We conducted a systematic review of neurologically-predominant presentations without cardiac conduction defects, associated with CACNA1C mutations. We also reported a novel de novo missense pathogenic variant in the CACNA1C gene of a children patient presenting with constructional, dressing and oro-buccal apraxia associated with behavioral abnormalities, mild intellectual disability, dental anomalies, gingival hyperplasia and mild musculoskeletal defects, without cardiac conduction defects. Conclusions: The present study highlights the importance of considering the investigation of the CACNA1C gene in children's neurological isolated syndromes, and expands the phenotype of the CACNA1C related conditions. In addition, the present study highlights that, even in absence of cardiac conduction defects, nuanced clinical manifestations of the Timothy syndrome (e.g., dental and gingival defects) could be found. These findings suggest the high variable expressivity of the CACNA1C gene and remark that the absence of cardiac involvement should not mislead the diagnosis of a CACNA1C related disorder.

Wildtype peers rescue social play and 50-kHz ultrasonic vocalization deficits in juvenile female Cacna1c heterozygous rats

Background

Healthy brain development depends on early social practices and experiences. The risk gene CACNA1C is implicated in numerous neuropsychiatric disorders, in which key characteristics include deficits in social functioning and communication. Recently, we reported sex-dependent impairments in social behavior and ultrasonic vocalizations (USV) in juvenile heterozygous Cacna1c+/- (HET) rats. Specifically, HET females displayed increases in rough-and-tumble play that eliminated the typically observed sex difference between male and female rats. Interestingly, female wild-type Cacna1c+/+ (WT) pairs also showed a similar increase in social play when housed with HET females, suggesting their behavior may be influenced by HET cage mates. This indicates that the genetic makeup of the social environment related to Cacna1c can influence social play, yet systematic studies are lacking.

Methods

In the present study, we housed juvenile females in MIXED- or SAME-genotype cages and tested them in a social play paradigm with a same- and opposite-genotype partner.

Results

The results show that the early social environment and the genotype of the play partner influence social play and 50-kHz USV emission. Experience with a WT play partner appears necessary for HET females to show comparable levels of play and 50-kHz USV emission. Same-genotype HET pairs played less and emitted fewer 50-kHz USV than same-genotype WT or opposite-genotype pairs; however, we found that the decrease in social play and 50-kHz USV in HET pairs can be rescued by playing with a WT partner. The effect was particularly prominent when the first play partner was WT, as we found it increased play and 50-kHz USV emission in all subsequent interactions with ensuing partners.

Conclusion

These findings suggest that the genetic makeup related to the social environment and/or social peers influences social play in Cacna1c+/- haploinsufficient rats. Specifically, our results show that WT peers can rescue behavior and communication alterations in Cacna1c female rats. Our findings have important implications because they show that the genetic makeup of the social environment can divulge phenotypic changes in genetic rat models of neuropsychiatric disorders.

CACNA1C-Related Channelopathies

The CACNA1C gene encodes the pore-forming subunit of the CaV1.2 L-type Ca2+ channel, a critical component of membrane physiology in multiple tissues, including the heart, brain, and immune system. As such, mutations altering the function of these channels have the potential to impact a wide array of cellular functions. The first mutations identified within CACNA1C were shown to cause a severe, multisystem disorder known as Timothy syndrome (TS), which is characterized by neurodevelopmental deficits, long-QT syndrome, life-threatening cardiac arrhythmias, craniofacial abnormalities, and immune deficits. Since this initial description, the number and variety of disease-associated mutations identified in CACNA1C have grown tremendously, expanding the range of phenotypes observed in affected patients. CACNA1C channelopathies are now known to encompass multisystem phenotypes as described in TS, as well as more selective phenotypes where patients may exhibit predominantly cardiac or neurological symptoms. Here, we review the impact of genetic mutations on CaV1.2 function and the resultant physiological consequences.

Small Molecules as Modulators of Voltage-Gated Calcium Channels in Neurological Disorders: State of the Art and Perspectives

Voltage-gated calcium channels (VGCCs) are widely expressed in the brain, heart and vessels, smooth and skeletal muscle, as well as in endocrine cells. VGCCs mediate gene transcription, synaptic and neuronal structural plasticity, muscle contraction, the release of hormones and neurotransmitters, and membrane excitability. Therefore, it is not surprising that VGCC dysfunction results in severe pathologies, such as cardiovascular conditions, neurological and psychiatric disorders, altered glycemic levels, and abnormal smooth muscle tone. The latest research findings and clinical evidence increasingly show the critical role played by VGCCs in autism spectrum disorders, Parkinson's disease, drug addiction, pain, and epilepsy. These findings outline the importance of developing selective calcium channel inhibitors and modulators to treat such prevailing conditions of the central nervous system. Several small molecules inhibiting calcium channels are currently used in clinical practice to successfully treat pain and cardiovascular conditions. However, the limited palette of molecules available and the emerging extent of VGCC pathophysiology require the development of additional drugs targeting these channels. Here, we provide an overview of the role of calcium channels in neurological disorders and discuss possible strategies to generate novel therapeutics.

Dissecting the neurobiology of linguistic disorganisation and impoverishment in schizophrenia

Schizophrenia provides a quintessential disease model of how disturbances in the molecular mechanisms of neurodevelopment lead to disruptions in the emergence of cognition. The central and often persistent feature of this illness is the disorganisation and impoverishment of language and related expressive behaviours. Though clinically more prominent, the periodic perceptual distortions characterised as psychosis are non-specific and often episodic. While several insights into psychosis have been gained based on study of the dopaminergic system, the mechanistic basis of linguistic disorganisation and impoverishment is still elusive. Key findings from cellular to systems-level studies highlight the role of ubiquitous, inhibitory processes in language production. Dysregulation of these processes at critical time periods, in key brain areas, provides a surprisingly parsimonious account of linguistic disorganisation and impoverishment in schizophrenia. This review links the notion of excitatory/inhibitory (E/I) imbalance at cortical microcircuits to the expression of language behaviour characteristic of schizophrenia, through the building blocks of neurochemistry, neurophysiology, and neurocognition.

Language impairment with a microduplication in 1q42.3q43

Deletions and duplications of the distal region of the long arm of chromosome 1 are associated with brain abnormalities and developmental delay. Because duplications are less frequent than deletions, no detailed account of the cognitive profile of the affected people is available, particularly, regarding their language (dis)abilities. In this paper we report on the cognitive and language capacities of a girl with one of the smallest interstitial duplications ever described in this region, affecting to 1q42.3q43 (arr[hg19] 1q42.3q43(235,963,632-236,972,276)x3), and advance potential candidate genes for the observed deficits. The proband's speech is severely impaired, exhibiting dysarthric-like features, with speech problems also resulting from a phonological deficit boiling down to a verbal auditory memory deficit. Lexical and grammatical knowledge are also impaired, impacting negatively on both expressive and receptive abilities, seemingly as a consequence of the phonological deficit. Still, her pragmatic abilities seem to be significantly spared, granting her a good command on the principles governing conversational exchanges. Genetic analyses point to several genes of interest. These include one gene within the duplicated region (LYST), one predicted functional partner (CMIP), and three genes outside the 1q42.3q43 region, which are all highly expressed in the cerebellum: DDIT4 and SLC29A1, found strongly downregulated in the proband compared to her healthy parents, and CNTNAP3, found strongly upregulated. The genes highlighted in the paper emerge as potential candidates for the phonological and speech deficits exhibited by the proband and ultimately, for her problems with language.

Social Behavior and Ultrasonic Vocalizations in a Genetic Rat Model Haploinsufficient for the Cross-Disorder Risk Gene Cacna1c

The top-ranked cross-disorder risk gene CACNA1C is strongly associated with multiple neuropsychiatric dysfunctions. In a recent series of studies, we applied a genomically informed approach and contributed extensively to the behavioral characterization of a genetic rat model haploinsufficient for the cross-disorder risk gene Cacna1c. Because deficits in processing social signals are associated with reduced social functioning as commonly seen in neuropsychiatric disorders, we focused on socio-affective communication through 22-kHz and 50-kHz ultrasonic vocalizations (USV). Specifically, we applied a reciprocal approach for studying socio-affective communication in sender and receiver by including rough-and-tumble play and playback of 22-kHz and 50-kHz USV. Here, we review the findings obtained in this recent series of studies and link them to the key features of 50-kHz USV emission during rough-and-tumble play and social approach behavior evoked by playback of 22-kHz and 50-kHz USV. We conclude that Cacna1c haploinsufficiency in rats leads to robust deficits in socio-affective communication through 22-kHz and 50-kHz USV and associated alterations in social behavior, such as rough-and-tumble play behavior.

CACNA1C methylation: association with cortisol, perceived stress, rs1006737 and childhood trauma in males

Aim: We investigated morning cortisol, stress, rs1006737 and childhood trauma relationship with CACNA1C methylation. Materials & methods: Morning cortisol release, childhood trauma and perceived stress were collected and genotyping for rs1006737 conducted in 103 adult males. Genomic DNA extracted from saliva was bisulphite converted and using pyrosequencing methylation determined at 11 CpG sites within intron 3 of CACNA1C. Results: A significant negative correlation between waking cortisol and overall mean methylation was found and a positive correlation between CpG5 methylation and perceived stress. Conclusion: CACNA1C methylation levels may be related to cortisol release and stress perception. Future work should evaluate the influence of altered CACNA1C methylation on stress reactivity to investigate this as a potential mechanism for mental health vulnerability.

A molecular approach to treating cognition in schizophrenia by calcium channel blockade: An open-label pilot study of the calcium-channel antagonist isradipine

Cognitive impairment is a prominent and difficult to treat symptom in schizophrenia (SZ), which is directly related to functional disability. A variant in the gene coding for the alpha 1C subunit of L-type voltage gated calcium channel (CACNA1C) has been shown to negatively affect several neurocognitive domains. We conducted a 4-week, open label, pilot study of isradipine, a calcium channel blocker, to determine its feasibility, safety, and efficacy in improving cognition in SZ patients. Ten adults with stable SZ were started on a flexible dose of isradipine 5 mg/day (up to 10 mg/day) for 4 weeks. Weekly in-person visits tracked side effects and symptoms while neurocognition and functional capacity were assessed at baseline and week 4. There were no serious adverse events reported. Newly emergent side effects were dizziness (1 new incidence at week 4); difficulty sleeping (2 new incidences at week 4); and decreased energy (3 new incidences at week 4). 1 patient discontinued medication and was withdrawn. Treatment did not exacerbate clinical symptoms. Although power is limited, results indicate no clear benefit on neurocognition but a positive effect (baseline mean = 6.8 ± 1.3 to week 4 mean = 7.9 ± 1.1; t = 2.91, p = 0.017) on functional capacity was noted. This open label, pilot study provides preliminary evidence that isradipine is a relatively safe medication when used adjunctively in SZ patients. This study suggests that isradipine offers no clear cognitive and only minimal functional benefit; however, additional studies may be warranted in symptomatic patients, or those with specific CACNA1C genotypes.

Genome-wide association study of word reading: Overlap with risk genes for neurodevelopmental disorders

Reading disabilities (RD) are the most common neurocognitive disorder, affecting 5% to 17% of children in North America. These children often have comorbid neurodevelopmental/psychiatric disorders, such as attention deficit/hyperactivity disorder (ADHD). The genetics of RD and their overlap with other disorders is incompletely understood. To contribute to this, we performed a genome-wide association study (GWAS) for word reading. Then, using summary statistics from neurodevelopmental/psychiatric disorders, we computed polygenic risk scores (PRS) and used them to predict reading ability in our samples. This enabled us to test the shared aetiology between RD and other disorders. The GWAS consisted of 5.3 million single nucleotide polymorphisms (SNPs) and two samples; a family-based sample recruited for reading difficulties in Toronto (n = 624) and a population-based sample recruited in Philadelphia [Philadelphia Neurodevelopmental Cohort (PNC)] (n = 4430). The Toronto sample SNP-based analysis identified suggestive SNPs (P ~ 5 × 10^-7 ) in the ARHGAP23 gene, which is implicated in neuronal migration/axon pathfinding. The PNC gene-based analysis identified significant associations (P < 2.72 × 10^-6 ) for LINC00935 and CCNT1, located in the region of the KANSL2/CCNT1/LINC00935/SNORA2B/SNORA34/MIR4701/ADCY6 genes on chromosome 12q, with near significant SNP-based analysis. PRS identified significant overlap between word reading and intelligence (R²  = 0.18, P = 7.25  × 10^-181 ), word reading and educational attainment (R²  = 0.07, P = 4.91 × 10^-48 ) and word reading and ADHD (R²  = 0.02, P = 8.70 × 10^-6 ; threshold for significance = 7.14 × 10^-3 ). Overlap was also found between RD and autism spectrum disorder (ASD) as top-ranked genes were previously implicated in autism by rare and copy number variant analyses. These findings support shared risk between word reading, cognitive measures, educational outcomes and neurodevelopmental disorders, including ASD.

Neurobiology of the major psychoses: a translational perspective on brain structure and function-the FOR2107 consortium

Genetic (G) and environmental (E) factors are involved in the etiology and course of the major psychoses (MP), i.e. major depressive disorder (MDD), bipolar disorder (BD), schizoaffective disorder (SZA) and schizophrenia (SZ). The neurobiological correlates by which these predispositions exert their influence on brain structure, function and course of illness are poorly understood. In the FOR2107 consortium, animal models and humans are investigated. A human cohort of MP patients, healthy subjects at genetic and/or environmental risk, and control subjects (N = 2500) has been established. Participants are followed up after 2 years and twice underwent extensive deep phenotyping (MR imaging, clinical course, neuropsychology, personality, risk/protective factors, biomaterials: blood, stool, urine, hair, saliva). Methods for data reduction, quality assurance for longitudinal MRI data, and (deep) machine learning techniques are employed. In the parallelised animal cluster, genetic risk was introduced by a rodent model (Cacna1c deficiency) and its interactions with environmental risk and protective factors are studied. The animals are deeply phenotyped regarding cognition, emotion, and social function, paralleling the variables assessed in humans. A set of innovative experimental projects connect and integrate data from the human and animal parts, investigating the role of microRNA, neuroplasticity, immune signatures, (epi-)genetics and gene expression. Biomaterial from humans and animals are analyzed in parallel. The FOR2107 consortium will delineate pathophysiological entities with common neurobiological underpinnings ("biotypes") and pave the way for an etiologic understanding of the MP, potentially leading to their prevention, the prediction of individual disease courses, and novel therapies in the future.

Unravelling the genetic basis of schizophrenia and bipolar disorder with GWAS: A systematic review

OBJECTIVES

To systematically review findings of GWAS in schizophrenia (SZ) and in bipolar disorder (BD); and to interpret findings, with a focus on identifying independent replications.

METHOD

PubMed search, selection and review of all independent GWAS in SZ or BD, published since March 2011, i.e. studies using non-overlapping samples within each article, between articles, and with those of the previous review (Li et al., 2012).

RESULTS

From the 22 GWAS included in this review, the genetic associations surviving standard GWAS-significance were for genetic markers in the regions of ACSL3/KCNE4, ADCY2, AMBRA1, ANK3, BRP44, DTL, FBLN1, HHAT, INTS7, LOC392301, LOC645434/NMBR, LOC729457, LRRFIP1, LSM1, MDM1, MHC, MIR2113/POU3F2, NDST3, NKAPL, ODZ4, PGBD1, RENBP, TRANK1, TSPAN18, TWIST2, UGT1A1/HJURP, WHSC1L1/FGFR1 and ZKSCAN4. All genes implicated across both reviews are discussed in terms of their function and implication in neuropsychiatry.

CONCLUSION

Taking all GWAS to date into account, AMBRA1, ANK3, ARNTL, CDH13, EFHD1 (albeit with different alleles), MHC, PLXNA2 and UGT1A1 have been implicated in either disorder in at least two reportedly non-overlapping samples. Additionally, evidence for a SZ/BD common genetic basis is most strongly supported by the implication of ANK3, NDST3, and PLXNA2.

Williams Syndrome, Human Self-Domestication, and Language Evolution

Language evolution resulted from changes in our biology, behavior, and culture. One source of these changes might be human self-domestication. Williams syndrome (WS) is a clinical condition with a clearly defined genetic basis which results in a distinctive behavioral and cognitive profile, including enhanced sociability. In this paper we show evidence that the WS phenotype can be satisfactorily construed as a hyper-domesticated human phenotype, plausibly resulting from the effect of the WS hemideletion on selected candidates for domestication and neural crest (NC) function. Specifically, we show that genes involved in animal domestication and NC development and function are significantly dysregulated in the blood of subjects with WS. We also discuss the consequences of this link between domestication and WS for our current understanding of language evolution.

CACNA1C risk variant affects microstructural connectivity of the amygdala

Deficits in perception of emotional prosody have been described in patients with affective disorders at behavioral and neural level. In the current study, we use an imaging genetics approach to examine the impact of CACNA1C, one of the most promising genetic risk factors for psychiatric disorders, on prosody processing on a behavioral, functional and microstructural level. Using functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI) we examined key areas involved in prosody processing, i.e. the amygdala and voice areas, in a healthy population. We found stronger activation to emotional than neutral prosody in the voice areas and the amygdala, but CACNA1C rs1006737 genotype had no influence on fMRI activity. However, significant microstructural differences (i.e. mean diffusivity) between CACNA1C rs1006737 risk allele carriers and non carriers were found in the amygdala, but not the voice areas. These modifications in brain architecture associated with CACNA1C might reflect a neurobiological marker predisposing to affective disorders and concomitant alterations in emotion perception.

Effectiveness of imaging genetics analysis to explain degree of depression in Parkinson's disease

Depression is one of the most common and important neuropsychiatric symptoms in Parkinson's disease and often becomes worse as Parkinson's disease progresses. However, the underlying mechanisms of depression in Parkinson's disease are not clear. The aim of our study was to find genetic features related to depression in Parkinson's disease using an imaging genetics approach and to construct an analytical model for predicting the degree of depression in Parkinson's disease. The neuroimaging and genotyping data were obtained from an openly accessible database. We computed imaging features through connectivity analysis derived from tractography of diffusion tensor imaging. The imaging features were used as intermediate phenotypes to identify genetic variants according to the imaging genetics approach. We then constructed a linear regression model using the genetic features from imaging genetics approach to describe clinical scores indicating the degree of depression. As a comparison, we constructed other models using imaging features and genetic features based on references to demonstrate the effectiveness of our imaging genetics model. The models were trained and tested in a five-fold cross-validation. The imaging genetics approach identified several brain regions and genes known to be involved in depression, with the potential to be used as meaningful biomarkers. Our proposed model using imaging genetic features predicted and explained the degree of depression in Parkinson's disease appropriately (adjusted R2 larger than 0.6 over five training folds) and with a lower error and higher correlation than with other models over five test folds.

The effects of CACNA1C gene polymorphism on prefrontal cortex in both schizophrenia patients and healthy controls

CACNA1C gene polymorphism rs2007044 has been reported to be associated with schizophrenia, but its underlying brain mechanism is not clear. First, we conducted an exploratory functional magnetic resonance imaging (fMRI) study using an N-BACK task and a Stroop task in 194 subjects (55 schizophrenia patients and 139 healthy controls). Our whole brain analysis found that the risk allele was associated with reduced activation of the left inferior frontal gyrus (IFG) during the Stroop task (cluster size = 390 voxels, P < 0.05 TFCE-FWE corrected; peak MNI coordinates: x = -57, y = -6, z = 30). We also conducted a functional near-infrared spectroscopy (fNIRS) study using the same Stroop task in an independent sample of 126 healthy controls to validate the fMRI finding. Our repeated-measures ANCOVA on the six channels (20, 27, 33, 34, 40 and 46) within the left IFG also found significant result. The polymorphism rs2007044 showed significant effect on the oxy-Hb data (F = 5.072, P = 0.026) and showed significant interaction effect with channels on the deoxy-Hb data (F = 2.841, P = 0.015). Taken together, results of this study suggested that rs2007044 could affect the activation of the left IFG, which was a possible brain mechanism underlying the association between CACNA1C gene polymorphism and schizophrenia.

Toward the Language Oscillogenome

Language has been argued to arise, both ontogenetically and phylogenetically, from specific patterns of brain wiring. We argue that it can further be shown that core features of language processing emerge from particular phasal and cross-frequency coupling properties of neural oscillations; what has been referred to as the language ‘oscillome.’ It is expected that basic aspects of the language oscillome result from genetic guidance, what we will here call the language ‘oscillogenome,’ for which we will put forward a list of candidate genes. We have considered genes for altered brain rhythmicity in conditions involving language deficits: autism spectrum disorders, schizophrenia, specific language impairment and dyslexia. These selected genes map on to aspects of brain function, particularly on to neurotransmitter function. We stress that caution should be adopted in the construction of any oscillogenome, given the range of potential roles particular localized frequency bands have in cognition. Our aim is to propose a set of genome-to-language linking hypotheses that, given testing, would grant explanatory power to brain rhythms with respect to language processing and evolution.

The effect of psychosis associated CACNA1C, and its epistasis with ZNF804A, on brain function

CACNA1C-rs1006737 and ZNF804A-rs1344706 polymorphisms are among the most robustly associated with schizophrenia (SCZ) and bipolar disorder (BD), and recently with brain phenotypes. As these patients show abnormal verbal fluency (VF) and related brain activation, we asked whether the latter was affected by these polymorphisms (alone and in interaction)-to better understand how they might induce risk. We recently reported effects on functional VF-related (for ZNF804A-rs1344706) and structural (for both) connectivity. We genotyped and fMRI-scanned 54 SCZ, 40 BD and 80 controls during VF. With SPM, we assessed the main effect of CACNA1C-rs1006737, and its interaction with ZNF804A-rs1344706, and their interaction with diagnosis, on regional brain activation and functional connectivity (psychophysiological interactions-PPI). Using public data, we reported effects of CACNA1C-rs1006737 and diagnosis on brain expression. The CACNA1C-rs1006737 risk allele was associated with increased activation, particularly in the bilateral prefronto-temporal cortex and thalamus; decreased PPI, especially in the left temporal cortex; and gene expression in white matter and the cerebellum. We also found unprecedented evidence for epistasis (interaction between genetic polymorphisms) in the caudate nucleus, thalamus, and cingulate and temporal cortical activation; and CACNA1C up-regulation in SCZ and BD parietal cortices. Some effects were dependent on BD/SCZ diagnosis. All imaging results were whole-brain, voxel-wise, and familywise-error corrected. Our results support evidence implicating CACNA1C and ZNF804A in BD and SCZ, adding novel imaging evidence in clinical populations, and of epistasis-which needs further replication. Further scrutiny of the inherent neurobiological mechanisms may disclose their potential as putative drug targets.

Genome-wide association study and identification of chromosomal enhancer maps in multiple brain regions related to autism spectrum disorder

Autism spectrum disorder (ASD) is a complex developmental disorder with strong genetic components involved. Recent studies have demonstrated the importance of non-coding regulatory variants for complex diseases. To explore the roles of chromosomal enhancer regions in the pathogenesis of ASD, we conducted an integrative analysis of genome-wide association study (GWAS) and brain region related enhancer-gene networks for ASD. The GWAS data of ASD were driven from a published study, involving 7,387 ASD cases and 8,567 controls. The enhancer-gene networks of eight brain regions were used here. The GWAS of ASD was first merged respectively with the enhancer datasets of eight brain regions. Pathway enrichment analysis was then performed to detect ASD associated pathways based on the enhancer-related single nucleotide polymorphism (SNPs) of each brain region. We detected multiple genes with brain region specific or common association signals, such as PGM3 (P value = 1.93 × 10^-5 ) and RWDD2A (P value = 1.93 × 10^-5 ) for hippocampus middle, and ENPP4 (all P values <0.05), and ENPP5 (all P values <0.05) for seven brain regions. By comparing the pathway enrichment analysis results of various brain regions, several cross brain regions pathways were detected for ASD, such as REACTOME_POTASSIUM_CHANNELS (all P values <0.05) for six brain regions and KEGG_CELL_ADHESION_MOLECULES_CAMS (all P values <0.05) for seven brain regions. In addition, several pathways were also identified for specific brain regions, such as REACTOME_CD28_DEPENDENT_PI3K_AKT_SIGNALING (P value = 4.00 × 10^-3 ) for angular gyrus, REACTOME_SIGNALING_BY_CONSTITUTIVELY_ACTIVE_EGFR (P value = 2.22 × 10^-3 ) for anterior caudate, and KEGG_PRION_DISEASES (P value = 1.00 × 10^-4 ) for germinal matrix. Our results provide novel clues for understanding the genetic basis of ASD. Autism Research 2019, 12: 26-32. © 2018 International Society for Autism Research, Wiley Periodicals, Inc. LAY SUMMARY: ASD is a complex developmental disorder with strong genetic components, but the pathogenesis of ASD is still unclear. Using the latest GWAS data and enhancer map, we explored the brain region related biological pathways associated with ASD. Our results provide novel clues for revealing the functional relevance of enhancer variants with ASD and understanding the genetic basis of ASD.

Polygenic risk for schizophrenia affects working memory and its neural correlates in healthy subjects

Schizophrenia is a disorder with a high heritability. Patients as well as their first degree relatives display lower levels of performance in a number of cognitive domains compared to subjects without genetic risk. Several studies could link these aberrations to single genetic variants, however, only recently, polygenic risk scores as proxies for genetic risk have been associated with cognitive domains and their neural correlates. In the present study, a sample of healthy subjects (n=137) performed a letter version of the n-back task while scanned with 3-T fMRI. All subjects were genotyped with the PsychChip and polygenic risk scores were calculated based on the PGC2 schizophrenia GWAS results. Polygenic risk for schizophrenia was associated with a lower degree of brain activation in prefrontal areas during the 3-back compared to the 0-back baseline condition. Furthermore, polygenic risk was associated with lower levels of brain activation in the right inferior frontal gyrus during the 3-back compared to a 2-back condition. Polygenic risk leads to a shift in the underlying activation pattern to the left side, thus resembling results reported in patients with schizophrenia. The data may point to polygenic risk for schizophrenia being associated with brain function in a cognitive task known to be impaired in patients and their relatives.

Formal thought disorders: from phenomenology to neurobiology

Formal thought disorder (FTD) is present in most psychiatric disorders and in some healthy individuals. In this Review, we present a comprehensive, integrative, and multilevel account of what is known about FTD, covering genetic, cellular, and neurotransmitter effects, environmental influences, experimental psychology and neuropsychology, brain imaging, phenomenology, linguistics, and treatment. FTD is a dimensional, phenomenologically defined construct, which can be clinically subdivided into positive versus negative and objective versus subjective symptom clusters. Because FTDs have been traditionally linked to schizophrenia, studies in other diagnoses are scarce. Aetiologically, FTD is the only symptom under genetic influence in schizophrenia as shown in linkage studies, but familial communication patterns (allusive thinking) have also been associated with the condition. Positive FTDs are related to synaptic rarefication in the glutamate system of the superior and middle lateral temporal cortices. Cortical volume of the left superior temporal gyrus is decreased in patients with schizophrenia who have positive FTD in structural MRI studies and shows reversed hemispheric (right more than left) activation in functional MRI experiments during speech production. Semantic network dysfunction in positive FTD has been demonstrated in experiments of indirect semantic hyperpriming (reaction time). In acute positive FTD, antipsychotics are effective, but a subgroup of patients have treatment-resistant, chronic, positive or negative FTD. Specific psychotherapy as treatment for FTD has not yet been developed. With this solid data on the pathogenesis of FTD, we can now implement clinical studies to treat this condition.

Sex-specific effects of Cacna1c haploinsufficiency on object recognition, spatial memory, and reversal learning capabilities in rats

The CACNA1C gene is strongly implicated in the etiology of multiple major neuropsychiatric disorders, such as bipolar disorder, major depression, and schizophrenia, with cognitive deficits being a common feature. It is unclear, however, by which mechanisms CACNA1C variants advance the risk of developing neuropsychiatric disorders. This study set out to investigate cognitive functioning in a newly developed genetic Cacna1c rat model. Specifically, spatial and reversal learning, as well as object recognition memory were assessed in heterozygous Cacna1c^+/- rats and compared to wildtype Cacna1c^+/+ littermate controls in both sexes. Our results show that both Cacna1c^+/+ and Cacna1c^+/- animals were able to learn the rewarded arm configuration of a radial maze over the course of seven days. Both groups also showed reversal learning patterns indicative of intact abilities. In females, genotype differences were evident in the initial spatial learning phase, with Cacna1c^+/- females showing hypo-activity and fewer mixed errors. In males, a difference was found during probe trials for both learning phases, with Cacna1c^+/- rats displaying better distinction between previously baited and non-baited arms; and regarding cognitive flexibility in favor of the Cacna1c^+/+ animals. All experimental groups proved to be sensitive to reward magnitude and fully able to distinguish between novel and familiar objects in the novel object recognition task. Taken together, these results indicate that Cacna1c haploinsufficiency has a minor, but positive impact on (spatial) memory functions in rats.

Interactive effects of early life stress and CACNA1C genotype on cortisol awakening response

The rs1006737 (A/G) single nucleotide polymorphism within the gene encoding the Ca_v1.2 subunit of the L-type voltage-dependent calcium channel (CACNA1C) has been strongly implicated in psychiatric disorders. In addition, calcium channels are sensitive to the effects of glucocorticoids and functional variation may contribute to altered stress responsivity. This study aimed to investigate the role of early life stress (ELS) and its interaction with CACNA1C rs1006737 in affecting the cortisol awakening response (CAR), an indicator of HPA-axis function. Salivary cortisol was measured in 103 healthy adult males (aged 21-63) on two consecutive days at awakening and 30 min later. The ELS measure investigated self-reported adverse life events prior to age 17. The results revealed a marginally significant main effect of CACNA1C, a significant main effect of ELS, and a significant genotype-by-ELS interaction on the CAR, whereby non-risk allele carriers (GG) who had experienced early adversity showed higher CAR compared to the other groups. Further exploratory analyses showed that this interaction may have arisen from individuals who had experienced ELS before adolescence (prior to age 13). This study is the first to provide evidence that the effect of ELS on CAR may be partially moderated via CACNA1C rs1006737 genotype, whereby the heightened CAR in the GG-ELS group may be an indicator of mental health resilience in response to ELS.

Association of CACNA1C with bipolar disorder among the Pakistani population

Many single nucleotide polymorphisms (SNPs) have been identified for Bipolar disorder (BD), but association between SNPs and BD can vary depending on the population tested. SNPs rs10994336 and rs9804190 in ANK3 and rs1006737 in CACNA1C have emerged as the most highly replicated SNPs significantly associated with BD. The aim of the present study was to assess the association of these SNPs with BD in the Pakistani population, which has never before been examined. A total of 120 BD and 120 control individuals from Pakistan were examined in this analysis. Genotyping results indicated that rs1006737 in CACNA1C was significantly associated with BD, while rs10994336 or rs9804190 in ANK3 was not significant when examined individually. However, risk score assessment found that the presence of two or more risk alleles was significantly associated with disease, indicating that risk alleles from ANK3 and CACNA1C may additively contribute to BD. A protein-protein interaction network was generated using STRING to probe the relationship between ANK3 and CACNA1C interactors and their associations with BD. While none of the interactors are directly linked to BD, they play a role in pathways linked to BD, including oxytocin and dopamine signaling pathways. Collectively, these results reveal a significant association of CACNA1C with BD among the Pakistani population, extending results from other ethnic groups to the Pakistani population for the first time.

CACNA1C polymorphisms Impact Cognitive Recovery in Patients with Bipolar Disorder in a Six-week Open-label Trial

Cognitive impairments in bipolar patients deteriorate as the disorder progresses. Little is known about whether genetic risks impact cognitive recovery during the course from depression to remission. In this six-week open-label trial, we shed light on the impacts of six single nucleotide polymorphisms (SNPs) in the calcium voltage-gated channel subunit alpha1 C (CACNA1C) gene on cognitive recovery in 192 bipolar patients suffering a major depressive episode (MDE). The primary outcome measures were changes in a battery of neuropsychological tests following 6-week treatment. Carriers with rs10466907 GT genotype did not significantly improve their executive function total scores on the Wisconsin Card Sorting Test after six weeks of treatment compared to the TT genotypes (β = −0.944, 95% Confidence Interval (CI) = −1.482–−0.405). Moreover, during a MDE carriers with rs58619945 GG and GA genotypes performed significantly worse than those with AA genotype on the categories completed (p = 0.013 and p = 0.001), total errors (p = 0.039 and p = 0.009), and random errors (p = 0.055 and p = 0.014, respectively). Our data suggest that the tested CACNA1C SNPs may have impacts on cognitive recovery from depression.

The CACNA1C risk allele rs1006737 is associated with age-related prefrontal cortical thinning in bipolar I disorder

Calcium channels control the inflow of calcium ions into cells and are involved in diverse cellular functions. The CACNA1C gene polymorphism rs1006737 A allele has been strongly associated with increased risk for bipolar disorder (BD) and with modulation of brain morphology. The medial prefrontal cortex (mPFC) has been widely associated with mood regulation in BD, but the role of this CACNA1C polymorphism in mPFC morphology and brain aging has yet to be elucidated. One hundred seventeen euthymic BD type I subjects were genotyped for CACNA1C rs1006737 and underwent 3 T three-dimensional structural magnetic resonance imaging scans to determine cortical thickness of mPFC components (superior frontal cortex (sFC), medial orbitofrontal cortex (mOFC), caudal anterior cingulate cortex (cACC) and rostral anterior cingulate cortex (rACC)). Carriers of the CACNA1C allele A exhibited greater left mOFC thickness compared to non-carriers. Moreover, CACNA1C A carriers showed age-related cortical thinning of the left cACC, whereas among A non-carriers there was not an effect of age on left cACC cortical thinning. In the sFC, mOFC and rACC (left or right), a negative correlation was observed between age and cortical thickness, regardless of CACNA1C rs1006737 A status. Further studies investigating the direct link between cortical thickness, calcium channel function, apoptosis mechanism and their underlying relationship with aging-associated cognitive decline in BD are warranted.

Association of CACNA1C and SYNE1 in offspring of patients with psychiatric disorders

Schizophrenia (SZ) and bipolar disorder (BD) are severe mental diseases associated with cognitive impairment, mood disturbance, and psychosis. Both disorders are highly heritable and share a common genetic background. The present study assesses, for the first time, differences in genotype frequencies of polymorphisms located in genes involved in neurodevelopment and synaptic plasticity between genetic high-risk individuals (offspring of patients with SZ or BD; N=100: 31 and 69, respectively) and control subjects (offspring of community controls; N=96). Individuals from both groups had similar ages, around 12 years. A higher percentage of men were included in the genetic high-risk group (58%) compared with the control group (40.6%). A total of 244 validated SNPs located in 35 candidate gene regions were analyzed in 196 participants. Multivariate methods based on logistic regression analysis were performed to assess differences in genotype frequencies. Bonferroni correction was applied for the multiple comparisons performed. Two polymorphisms, CACNA1C rs10848683 and SYNE1 rs214950, showed significant differences. The frequency of heterozygotes for CACNA1C rs10848683 in genetic high-risk individuals was double that in controls (OR=3.15; P=0.00016). For SYNE1 rs214950, higher frequencies of heterozygotes (OR=1.97) and homozygotes for the minor allele (OR=17.89; P=0.00020) were found in the genetic high-risk group than in the control group. In conclusion, polymorphisms in CACNA1C and SYNE1 could confer a greater risk of developing SZ and BD in individuals who are already at high risk because of their family history. This could help identify subjects with a very high genetic risk, in whom early detection and early intervention could lead to better prognosis.

The polygenic risk for bipolar disorder influences brain regional function relating to visual and default state processing of emotional information

Genome-wise association studies have identified a number of common single-nucleotide polymorphisms (SNPs), each of small effect, associated with risk to bipolar disorder (BD). Several risk-conferring SNPs have been individually shown to influence regional brain activation thus linking genetic risk for BD to altered brain function. The current study examined whether the polygenic risk score method, which models the cumulative load of all known risk-conferring SNPs, may be useful in the identification of brain regions whose function may be related to the polygenic architecture of BD. We calculated the individual polygenic risk score for BD (PGR-BD) in forty-one patients with the disorder, twenty-five unaffected first-degree relatives and forty-six unrelated healthy controls using the most recent Psychiatric Genomics Consortium data. Functional magnetic resonance imaging was used to define task-related brain activation patterns in response to facial affect and working memory processing. We found significant effects of the PGR-BD score on task-related activation irrespective of diagnostic group. There was a negative association between the PGR-BD score and activation in the visual association cortex during facial affect processing. In contrast, the PGR-BD score was associated with failure to deactivate the ventromedial prefrontal region of the default mode network during working memory processing. These results are consistent with the threshold-liability model of BD, and demonstrate the usefulness of the PGR-BD score in identifying brain functional alternations associated with vulnerability to BD. Additionally, our findings suggest that the polygenic architecture of BD is not regionally confined but impacts on the task-dependent recruitment of multiple brain regions.

L-type Ca2+ channels in mood, cognition and addiction: integrating human and rodent studies with a focus on behavioural endophenotypes

Brain Cav 1.2 and Cav 1.3 L-type Ca2+ channels play key physiological roles in various neuronal processes that contribute to brain function. Genetic studies have recently identified CACNA1C as a candidate risk gene for bipolar disorder (BD), schizophrenia (SCZ), major depressive disorder (MDD) and autism spectrum disorder (ASD), and CACNA1D for BD and ASD, suggesting a contribution of Cav 1.2 and Cav 1.3 Ca2+ signalling to the pathophysiology of neuropsychiatric disorders. Once considered sole clinical entities, it is now clear that BD, SCZ, MDD and ASD share common phenotypic features, most likely due to overlapping neurocircuitry and common molecular mechanisms. A major future challenge lies in translating the human genetic findings to pathological mechanisms that are translatable back to the patient. One approach for tackling such a daunting scientific endeavour for complex behaviour-based neuropsychiatric disorders is to examine intermediate biological phenotypes in the context of endophenotypes within distinct behavioural domains. This will better allow us to integrate findings from genes to behaviour across species, and improve the chances of translating preclinical findings to clinical practice.

Brain Arousal Regulation in Carriers of Bipolar Disorder Risk Alleles

OBJECTIVES

Recent genome-wide association studies identified a number of chromosomal risk loci for bipolar disorder (BD, 'manic-depressive illness'). According to the vigilance regulation model, the regulation of brain arousal (referred to as 'vigilance') when assessed via EEG is an emerging biomarker linked to the pathogenesis of manic and depressive episodes. On this basis, the present study aimed to assess whether carriers of BD risk alleles differ in brain arousal regulation.

METHODS

Healthy participants of the population-based Leipzig Health Care Study (LIFE) underwent a 20-min eyes-closed resting EEG paradigm. Brain arousal was assessed applying the computer-based Vigilance Algorithm Leipzig (VIGALL). The primary sample (n = 540) was genotyped for ten of the most reliable BD risk variants, of which two qualified for replication (n = 509).

RESULTS

Primary sample analyses revealed Bonferroni-adjusted significance for rs1006737 in CACNA1C (encoding a calcium channel subunit), with risk allele carriers exhibiting relatively steep brain arousal declines. Further, carriers of two risk alleles of rs472913 at 1p32.1 showed generally lower brain arousal levels for the duration of the resting paradigm. However, both associations failed replication.

CONCLUSION

Although our initial findings are in line with the vigilance regulation model and convincing in view of the previously reported notable role of ion channelopathies in BD, our results do not provide consistent evidence for a link between BD risk variants and brain arousal regulation. Several between-sample differences may account for this inconsistency. The molecular genetics of brain arousal regulation remain to be clarified.

Bridging the Gap between Genes and Language Deficits in Schizophrenia: An Oscillopathic Approach

Schizophrenia is characterized by marked language deficits, but it is not clear how these deficits arise from the alteration of genes related to the disease. The goal of this paper is to aid the bridging of the gap between genes and schizophrenia and, ultimately, give support to the view that the abnormal presentation of language in this condition is heavily rooted in the evolutionary processes that brought about modern language. To that end we will focus on how the schizophrenic brain processes language and, particularly, on its distinctive oscillatory profile during language processing. Additionally, we will show that candidate genes for schizophrenia are overrepresented among the set of genes that are believed to be important for the evolution of the human faculty of language. These genes crucially include (and are related to) genes involved in brain rhythmicity. We will claim that this translational effort and the links we uncover may help develop an understanding of language evolution, along with the etiology of schizophrenia, its clinical/linguistic profile, and its high prevalence among modern populations.

CACNA1C risk variant is associated with increased amygdala volume

Genome-wide association studies suggest that genetic variation within L-type calcium channel subunits confer risk to psychosis. The single nucleotide polymorphism at rs1006737 in CACNA1C has been associated with both schizophrenia and bipolar disorder and with several intermediate phenotypes that may serve as neurobiological antecedents, linking psychosis to genetic aetiology. Amongst others, it has been implicated in alterations in amygdala structure and function. In the present study, we show that the risk allele (A) is associated with increased amygdala volume in healthy individuals (n = 258). This observation reinforces a hypothesis that genetic variation may confer risk to psychosis via alterations in limbic structures. Further study of CACNA1C using intermediate phenotypes for psychosis will determine the mechanisms by which variation in this gene confers risk.

The impact of CACNA1C allelic variation on regional gray matter volume in Chinese population

The SNP rs1006737 in CACNA1C gene has been significantly associated with psychiatric disorders (e.g., schizophrenia and bipolar disorder) in European populations. In Han Chinese, rs1006737 is also strongly associated with schizophrenia, although the effects of the psychosis risk SNP on related brain functions and structures in this population remain unclear. Here, we examined the association of rs1006737 with gray matter volume in a sample of 278 healthy Han Chinese. A whole-brain voxel-based morphometry (VBM) analysis revealed a significant association in the region around right superior occipital gyrus (family-wise error corrected, P = 0.023). Our data provides initial evidence for the involvement of this psychosis genetic risk locus in brain structure variations in Chinese population, and calls for further investigations.

CACNA1C risk variant affects facial emotion recognition in healthy individuals

Recognition and correct interpretation of facial emotion is essential for social interaction and communication. Previous studies have shown that impairments in this cognitive domain are common features of several psychiatric disorders. Recent association studies identified CACNA1C as one of the most promising genetic risk factors for psychiatric disorders and previous evidence suggests that the most replicated risk variant in CACNA1C (rs1006737) is affecting emotion recognition and processing. However, studies investigating the influence of rs1006737 on this intermediate phenotype in healthy subjects at the behavioral level are largely missing to date. Here, we applied the “Reading the Mind in the Eyes” test, a facial emotion recognition paradigm in a cohort of 92 healthy individuals to address this question. Whereas accuracy was not affected by genotype, CACNA1C rs1006737 risk-allele carries (AA/AG) showed significantly slower mean response times compared to individuals homozygous for the G-allele, indicating that healthy risk-allele carriers require more information to correctly identify a facial emotion. Our study is the first to provide evidence for an impairing behavioral effect of the CACNA1C risk variant rs1006737 on facial emotion recognition in healthy individuals and adds to the growing number of studies pointing towards CACNA1C as affecting intermediate phenotypes of psychiatric disorders.

Evaluating the association between CACNA1C rs1006737 and schizophrenia risk: A meta-analysis

INTRODUCTION

Genetic analyses including genome-wide association studies have reported an intronic single nucleotide polymorphism (SNP) rs1006737 in CACNA1C gene (encoded calcium channel, voltage-dependent, L type, alpha 1C subunit) as a risk factor for schizophrenia in European populations. The replications in other ethnic populations such as East Asians have also been conducted, but the results were inconsistent, either likely due to the limited sample size of single study or genetic heterogeneity between continental populations on this locus.

METHODS

We performed a comprehensive meta-analysis of all available samples from existing studies of East Asian populations, including a total of 9,432 cases and 10,661 controls, to further confirm whether CACNA1C rs1006737 is an authentic risk SNP for schizophrenia in East Asian populations.

RESULTS

Our results revealed a significant association between rs1006737 and schizophrenia (allelic model, P = 4.39 × 10(-6) , pooled odds ratio [OR] = 1.20), and the results were much strengthened when the European and East Asian samples were combined together (P = 2.40 × 10(-17) , pooled OR = 1.12). There is no significant heterogeneity or publication bias between individual studies, and removal of any single study still remained significant associations between rs1006737 and schizophrenia.

DISCUSSION

Our results further confirmed that rs1006737 should be categorized as an authentic risk SNP for schizophrenia in the general populations.

Microwave frequency electromagnetic fields (EMFs) produce widespread neuropsychiatric effects including depression

Non-thermal microwave/lower frequency electromagnetic fields (EMFs) act via voltage-gated calcium channel (VGCC) activation. Calcium channel blockers block EMF effects and several types of additional evidence confirm this mechanism. Low intensity microwave EMFs have been proposed to produce neuropsychiatric effects, sometimes called microwave syndrome, and the focus of this review is whether these are indeed well documented and consistent with the known mechanism(s) of action of such EMFs. VGCCs occur in very high densities throughout the nervous system and have near universal roles in release of neurotransmitters and neuroendocrine hormones. Soviet and Western literature shows that much of the impact of non-thermal microwave exposures in experimental animals occurs in the brain and peripheral nervous system, such that nervous system histology and function show diverse and substantial changes. These may be generated through roles of VGCC activation, producing excessive neurotransmitter/neuroendocrine release as well as oxidative/nitrosative stress and other responses. Excessive VGCC activity has been shown from genetic polymorphism studies to have roles in producing neuropsychiatric changes in humans. Two U.S. government reports from the 1970s to 1980s provide evidence for many neuropsychiatric effects of non-thermal microwave EMFs, based on occupational exposure studies. 18 more recent epidemiological studies, provide substantial evidence that microwave EMFs from cell/mobile phone base stations, excessive cell/mobile phone usage and from wireless smart meters can each produce similar patterns of neuropsychiatric effects, with several of these studies showing clear dose-response relationships. Lesser evidence from 6 additional studies suggests that short wave, radio station, occupational and digital TV antenna exposures may produce similar neuropsychiatric effects. Among the more commonly reported changes are sleep disturbance/insomnia, headache, depression/depressive symptoms, fatigue/tiredness, dysesthesia, concentration/attention dysfunction, memory changes, dizziness, irritability, loss of appetite/body weight, restlessness/anxiety, nausea, skin burning/tingling/dermographism and EEG changes. In summary, then, the mechanism of action of microwave EMFs, the role of the VGCCs in the brain, the impact of non-thermal EMFs on the brain, extensive epidemiological studies performed over the past 50 years, and five criteria testing for causality, all collectively show that various non-thermal microwave EMF exposures produce diverse neuropsychiatric effects.

Schizophrenia Related Variants in CACNA1C also Confer Risk of Autism

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders with a strong genetic component. Many lines of evidence indicated that ASD shares common genetic variants with other psychiatric disorders (for example, schizophrenia). Previous studies detected that calcium channels are involved in the etiology of many psychiatric disorders including schizophrenia and autism. Significant association between CACNA1C (calcium channel, voltage-dependent, L type, alpha 1C subunit) and schizophrenia was detected. Furthermore, rare mutation in CACNA1C is suggested to cause Timothy syndrome, a multisystem disorder including autism-associated phenotype. However, there is no evidence for association between CACNA1C and autism in Chinese Han population. To investigate the association between single nucleotide polymorphisms (SNP) in CACNA1C and autism, we first performed a family-based association study between eighteen SNPs in CACNA1C and autism in 239 trios. All SNPs were genotyped by using Sequenom genotyping platform. Two SNPs (rs1006737 and rs4765905) have a trend of association with autism. To further confirm the association between these two SNPs with autism, we expanded the sample size to 553 trios by adding 314 trios. Association analyses for SNPs and haplotype were performed by using family-based association test (FBAT) and Haploview software. Permutation tests were used for multiple testing corrections of the haplotype analyses (n=10,000). The significance level for all statistical tests was two-tailed (p<0.05). The results demonstrated that G allele of rs1006737 and G allele of rs4765905 showed a preferential transmission to affected offspring in 553 trios (p=0.035). Haplotype analyses showed that two haplotypes constructed from rs1006737 and rs4765905 were significantly associated with autism (p=0.030, 0.023, respectively; Global p=0.046). These results were still significant after permutation correction (n=10,000, p=0.027). Our research suggests that CACNA1C might play a role in the genetic etiology of autism in Chinese Han population.

Toward Probabilistic Diagnosis and Understanding of Depression Based on Functional MRI Data Analysis with Logistic Group LASSO

Diagnosis of psychiatric disorders based on brain imaging data is highly desirable in clinical applications. However, a common problem in applying machine learning algorithms is that the number of imaging data dimensions often greatly exceeds the number of available training samples. Furthermore, interpretability of the learned classifier with respect to brain function and anatomy is an important, but non-trivial issue. We propose the use of logistic regression with a least absolute shrinkage and selection operator (LASSO) to capture the most critical input features. In particular, we consider application of group LASSO to select brain areas relevant to diagnosis. An additional advantage of LASSO is its probabilistic output, which allows evaluation of diagnosis certainty. To verify our approach, we obtained semantic and phonological verbal fluency fMRI data from 31 depression patients and 31 control subjects, and compared the performances of group LASSO (gLASSO), and sparse group LASSO (sgLASSO) to those of standard LASSO (sLASSO), Support Vector Machine (SVM), and Random Forest. Over 90% classification accuracy was achieved with gLASSO, sgLASSO, as well as SVM; however, in contrast to SVM, LASSO approaches allow for identification of the most discriminative weights and estimation of prediction reliability. Semantic task data revealed contributions to the classification from left precuneus, left precentral gyrus, left inferior frontal cortex (pars triangularis), and left cerebellum (c rus1). Weights for the phonological task indicated contributions from left inferior frontal operculum, left post central gyrus, left insula, left middle frontal cortex, bilateral middle temporal cortices, bilateral precuneus, left inferior frontal cortex (pars triangularis), and left precentral gyrus. The distribution of normalized odds ratios further showed, that predictions with absolute odds ratios higher than 0.2 could be regarded as certain.

What is the impact of genome-wide supported risk variants for schizophrenia and bipolar disorder on brain structure and function? A systematic review

The powerful genome-wide association studies (GWAS) revealed common mutations that increase susceptibility for schizophrenia (SZ) and bipolar disorder (BD), but the vast majority were not known to be functional or associated with these illnesses. To help fill this gap, their impact on human brain structure and function has been examined. We systematically discuss this output to facilitate its timely integration in the psychosis research field; and encourage reflection for future research. Irrespective of imaging modality, studies addressing the effect of SZ/BD GWAS risk genes (ANK3, CACNA1C, MHC, TCF4, NRGN, DGKH, PBRM1, NCAN and ZNF804A) were included. Most GWAS risk variations were reported to affect neuroimaging phenotypes implicated in SZ/BD: white-matter integrity (ANK3 and ZNF804A), volume (CACNA1C and ZNF804A) and density (ZNF804A); grey-matter (CACNA1C, NRGN, TCF4 and ZNF804A) and ventricular (TCF4) volume; cortical folding (NCAN) and thickness (ZNF804A); regional activation during executive tasks (ANK3, CACNA1C, DGKH, NRGN and ZNF804A) and functional connectivity during executive tasks (CACNA1C and ZNF804A), facial affect recognition (CACNA1C and ZNF804A) and theory-of-mind (ZNF804A); but inconsistencies and non-replications also exist. Further efforts such as standardizing reporting and exploring complementary designs, are warranted to test the reproducibility of these early findings.

Assessing the utility of intermediate phenotypes for genetic mapping of psychiatric disease

Intermediate phenotypes are traits positioned somewhere between genetic variation and disease. They represent a target for attempts to find disease-associated genetic variants and elucidation of mechanisms. Psychiatry has been particularly enamoured with intermediate phenotypes, due to uncertainty about disease aetiology, inconclusive results in early psychiatric genetic studies, and their appeal relative to traditional diagnostic categories. In this review, we argue that new genetic findings are relevant to the question of the utility of these constructs. In particular, results from genome-wide association studies of psychiatric disorders now allow an assessment of the potential role of particular intermediate phenotypes. Based on such an analysis, as well as other recent results, we conclude that intermediate phenotypes are likely to be most valuable in understanding mechanism.

CACNA1C risk variant affects reward responsiveness in healthy individuals

The variant at rs1006737 in the L-type voltage-gated calcium channel (alpha 1c subunit) CACNA1C gene is reliably associated with both bipolar disorder and schizophrenia. We investigated whether this risk variant affects reward responsiveness because reward processing is one of the central cognitive-motivational domains implicated in both disorders. In a sample of 164 young, healthy individuals, we show a dose-dependent response, where the rs1006737 risk genotype was associated with blunted reward responsiveness, whereas discriminability did not significantly differ between genotype groups. This finding suggests that the CACNA1C risk locus may have a role in neural pathways that facilitate value representation for rewarding stimuli. Impaired reward processing may be a transdiagnostic phenotype of variation in CACNA1C that could contribute to anhedonia and other clinical features common to both affective and psychotic disorders.

An informatics approach to integrating genetic and neurological data in speech and language neuroscience

A number of heritable disorders impair the normal development of speech and language processes and occur in large numbers within the general population. While candidate genes and loci have been identified, the gap between genotype and phenotype is vast, limiting current understanding of the biology of normal and disordered processes. This gap exists not only in our scientific knowledge, but also in our research communities, where genetics researchers and speech, language, and cognitive scientists tend to operate independently. Here we describe a web-based, domain-specific, curated database that represents information about genotype-phenotype relations specific to speech and language disorders, as well as neuroimaging results demonstrating focal brain differences in relevant patients versus controls. Bringing these two distinct data types into a common database ( http://neurospeech.org/sldb ) is a first step toward bringing molecular level information into cognitive and computational theories of speech and language function. One bridge between these data types is provided by densely sampled profiles of gene expression in the brain, such as those provided by the Allen Brain Atlases. Here we present results from exploratory analyses of human brain gene expression profiles for genes implicated in speech and language disorders, which are annotated in our database. We then discuss how such datasets can be useful in the development of computational models that bridge levels of analysis, necessary to provide a mechanistic understanding of heritable language disorders. We further describe our general approach to information integration, discuss important caveats and considerations, and offer a specific but speculative example based on genes implicated in stuttering and basal ganglia function in speech motor control.

A genome-wide supported psychiatric risk variant in NCAN influences brain function and cognitive performance in healthy subjects

The A allele of the single nucleotide polymorphism (SNP) rs1064395 in the NCAN gene has recently been identified as a susceptibility factor for bipolar disorder and schizophrenia. NCAN encodes neurocan, a brain-specific chondroitin sulfate proteoglycan that is thought to influence neuronal adhesion and migration. Several lines of research suggest an impact of NCAN on neurocognitive functioning. In the present study, we investigated the effects of rs1064395 genotype on neural processing and cognitive performance in healthy subjects. Brain activity was measured with functional magnetic resonance imaging (fMRI) during an overt semantic verbal fluency task in 110 healthy subjects who were genotyped for the NCAN SNP rs1064395. Participants additionally underwent comprehensive neuropsychological testing. Whole brain analyses revealed that NCAN risk status, defined as AA or AG genotype, was associated with a lack of task-related deactivation in a large left lateral temporal cluster extending from the middle temporal gyrus to the temporal pole. Regarding neuropsychological measures, risk allele carriers demonstrated poorer immediate and delayed verbal memory performance when compared to subjects with GG genotype. Better verbal memory performance was significantly associated with greater deactivation of the left temporal cluster during the fMRI task in subjects with GG genotype. The current data demonstrate that common genetic variation in NCAN influences both neural processing and cognitive performance in healthy subjects. Our study provides new evidence for a specific genetic influence on human brain function.