Missense variants in ATP1A3 and FXYD gene family are associated with childhood-onset schizophrenia.

Childhood-onset schizophrenia (COS) is a rare and severe form of schizophrenia defined as onset before age of 13. Here we report on two unrelated cases diagnosed with both COS and alternating hemiplegia of childhood (AHC), and for whom two distinct pathogenic de novo variants were identified in the ATP1A3 gene. ATP1A3 encodes the α-subunit of a neuron-specific ATP-dependent transmembrane sodium-potassium pump. Using whole exome sequencing data derived from a cohort of 17 unrelated COS cases, we also examined ATP1A3 and all of its interactors known to be expressed in the brain to establish if variants could be identified. This led to the identification of a third case with a possibly damaging missense mutation in ATP1A3 and three others cases with predicted pathogenic missense variants in the FXYD gene family (FXYD1, FXYD6, and FXYD6-FXYD2 readthrough). FXYD genes encode proteins that modulate the ATP-dependant pump function. This report is the first to identify variants in the same pathway for COS. Our COS study illustrates the interest of stratifying a complex condition according to the age of onset for the identification of deleterious variants. Whereas ATP1A3 is a replicated gene in rare neuropediatric diseases, this gene has previously been linked with COS in only one case report. The association with rare variants in FXYD gene family is novel and highlights the interest of exploring these genes in COS as well as in pediatric neurodevelopmental disorders.

Sleep neurophysiology in childhood onset schizophrenia.

Altered sleep neurophysiology has consistently been reported in adult patients with schizophrenia. Converging evidence suggests that childhood onset schizophrenia (COS), a rare but severe form of schizophrenia, is continuous with adult onset schizophrenia. The aim of the current study was to characterize sleep neurophysiology in COS. An overnight sleep electroencephalogram (EEG) was recorded in 17 children and adolescents with COS (16 years ± 6.6) and 17 age and gender-matched controls. Non-rapid eye movement (NREM) and rapid eye movement (REM) sleep EEG power and coherence for the frequency bands delta (1.6-4.8 Hz), theta (5-8.4 Hz), alpha (8.6-11 Hz), beta 1 (16.4-20.2 Hz) and beta 2 (20.4-24.2 Hz) were compared between COS patients and controls. COS patients exhibited significant and widespread deficits in beta power during NREM and REM sleep. With regard to coherence, we found increases in COS patients across brain regions, frequency bands and sleep states. This study demonstrates the utility of the sleep EEG for studying vulnerable populations and its potential to aid diagnosis.

Exome sequencing of sporadic childhood-onset schizophrenia suggests the contribution of X-linked genes in males.

Childhood-onset schizophrenia (COS) is a rare and severe form of schizophrenia, defined as having an onset before the age of 13. The male COS cases have a slightly younger age of onset than female cases. They also present with a higher rate of comorbid developmental disorders. These sex differences are not explained by the frequency of chromosomal abnormalities, and the contribution of other forms of genetic variations remains unestablished. Using a whole-exome sequencing approach, we examined 12 COS trios where the unaffected parents had an affected male child. The sequencing data enabled us to test if the hemizygous variants, transmitted from the unaffected carrying mother, could mediate the phenotype (X-linked recessive inheritance model). Our results revealed that affected children have a significantly greater number of X-linked rare variants than their unaffected fathers. The variants identified in the male probands were mostly found in genes previously linked to other neuropsychiatric diseases like autism, intellectual disability, and epilepsy, including LUZP4, PCDH19, RPS6KA3, and OPHN1. The level of expression of the genes was assessed at different developmental periods in normal brain using the BrainSpan database. This approach revealed that some of them were expressed earlier in males than in females, consistent with the younger age of onset in male COS. In conclusion, this article suggests that X-linked genes might play a role in the pathophysiology of COS. Candidate genes detailed here could explain the higher level of comorbidities and the earlier age of onset observed in a subset of the male COS cases.

Disrupted sensorimotor and social-cognitive networks underlie symptoms in childhood-onset schizophrenia.

Schizophrenia is increasingly recognized as a neurodevelopmental disorder with altered connectivity among brain networks. In the current study we examined large-scale network interactions in childhood-onset schizophrenia, a severe form of the disease with salient genetic and neurobiological abnormalities. Using a data-driven analysis of resting-state functional magnetic resonance imaging fluctuations, we characterized data from 19 patients with schizophrenia and 26 typically developing controls, group matched for age, sex, handedness, and magnitude of head motion during scanning. This approach identified 26 regions with decreased functional correlations in schizophrenia compared to controls. These regions were found to organize into two function-related networks, the first with regions associated with social and higher-level cognitive processing, and the second with regions involved in somatosensory and motor processing. Analyses of across- and within-network regional interactions revealed pronounced across-network decreases in functional connectivity in the schizophrenia group, as well as a set of across-network relationships with overall negative coupling indicating competitive or opponent network dynamics. Critically, across-network decreases in functional connectivity in schizophrenia predicted the severity of positive symptoms in the disorder, such as hallucinations and delusions. By contrast, decreases in functional connectivity within the social-cognitive network of regions predicted the severity of negative symptoms, such as impoverished speech and flattened affect. These results point toward the role that abnormal integration of sensorimotor and social-cognitive processing may play in the pathophysiology and symptomatology of schizophrenia.

15q13.3 duplication in two patients with childhood-onset schizophrenia.

We report two cases of paternally inherited 15q13.3 duplications in carriers diagnosed with childhood-onset schizophrenia (COS), a rare neurodevelopmental disorder of proposed polygenic origin with onset in children before age 13. This study documents that the 15q13.3 deletion and duplication exhibit pathogenicity for COS, with both copy number variants (CNVs) sharing a disrupted CHRNA7 gene. CHRNA7 encodes the neuronal alpha7 nicotinic acetylcholine receptor (α7nAChR) and is a candidate gene that has been suggested as a pathophysiological process mediating adult-onset schizophrenia (AOS) and other neurodevelopmental disorders. These results support the incomplete penetrance and variable expressivity of this CNV and represent the first report of 15q13.3 duplication carriers exhibiting COS. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. American Journal of Medical Genetics Part B: Neuropsychiatric Genetics published by Wiley Periodicals, Inc.

DUF1220-domain copy number implicated in human brain-size pathology and evolution.

DUF1220 domains show the largest human-lineage-specific increase in copy number of any protein-coding region in the human genome and map primarily to 1q21, where deletions and reciprocal duplications have been associated with microcephaly and macrocephaly, respectively. Given these findings and the high correlation between DUF1220 copy number and brain size across primate lineages (R(2) = 0.98; p = 1.8 × 10(-6)), DUF1220 sequences represent plausible candidates for underlying 1q21-associated brain-size pathologies. To investigate this possibility, we used specialized bioinformatics tools developed for scoring highly duplicated DUF1220 sequences to implement targeted 1q21 array comparative genomic hybridization on individuals (n = 42) with 1q21-associated microcephaly and macrocephaly. We show that of all the 1q21 genes examined (n = 53), DUF1220 copy number shows the strongest association with brain size among individuals with 1q21-associated microcephaly, particularly with respect to the three evolutionarily conserved DUF1220 clades CON1(p = 0.0079), CON2 (p = 0.0134), and CON3 (p = 0.0116). Interestingly, all 1q21 DUF1220-encoding genes belonging to the NBPF family show significant correlations with frontal-occipital-circumference Z scores in the deletion group. In a similar survey of a nondisease population, we show that DUF1220 copy number exhibits the strongest correlation with brain gray-matter volume (CON1, p = 0.0246; and CON2, p = 0.0334). Notably, only DUF1220 sequences are consistently significant in both disease and nondisease populations. Taken together, these data strongly implicate the loss of DUF1220 copy number in the etiology of 1q21-associated microcephaly and support the view that DUF1220 domains function as general effectors of evolutionary, pathological, and normal variation in brain size.

Striatal shape abnormalities as novel neurodevelopmental endophenotypes in schizophrenia: a longitudinal study.

There are varying, often conflicting, reports with respect to altered striatal volume and morphometry in the major psychoses due to the influences of antipsychotic medications on striatal volume. Thus, disassociating disease effects from those of medication become exceedingly difficult. For the first time, using a longitudinally studied sample of structural magnetic resonance images from patients with childhood onset schizophrenia (COS; neurobiologically contiguous with the adult onset form of schizophrenia), their nonpsychotic siblings (COSSIBs), and novel shape mapping algorithms that are volume independent, we report the familial contribution of striatal morphology in schizophrenia. The results of our volumetric analyses demonstrate age-related increases in overall striatal volumes specific only to COS. However, both COS and COSSIBs showed overlapping shape differences in the striatal head, which normalized in COSSIBs by late adolescence. These results mirror previous studies from our group, demonstrating cortical thickness deficits in COS and COSSIBs as these deficits normalize in COSSIBs in the same age range as our striatal findings. Finally, there is a single region of nonoverlapping outward displacement in the dorsal aspect of the caudate body, potentially indicative of a response to medication. Striatal shape may be considered complimentary to volume as an endophenotype, and, in some cases may provide information that is not detectable using standard volumetric techniques. Our striatal shape findings demonstrate the striking localization of abnormalities in striatal the head. The neuroanatomical localization of these findings suggest the presence of abnormalities in the striatal-prefrontal circuits in schizophrenia and resilience mechanisms in COSSIBs with age dependent normalization.

Simple models of human brain functional networks.

Human brain functional networks are embedded in anatomical space and have topological properties--small-worldness, modularity, fat-tailed degree distributions--that are comparable to many other complex networks. Although a sophisticated set of measures is available to describe the topology of brain networks, the selection pressures that drive their formation remain largely unknown. Here we consider generative models for the probability of a functional connection (an edge) between two cortical regions (nodes) separated by some Euclidean distance in anatomical space. In particular, we propose a model in which the embedded topology of brain networks emerges from two competing factors: a distance penalty based on the cost of maintaining long-range connections; and a topological term that favors links between regions sharing similar input. We show that, together, these two biologically plausible factors are sufficient to capture an impressive range of topological properties of functional brain networks. Model parameters estimated in one set of functional MRI (fMRI) data on normal volunteers provided a good fit to networks estimated in a second independent sample of fMRI data. Furthermore, slightly detuned model parameters also generated a reasonable simulation of the abnormal properties of brain functional networks in people with schizophrenia. We therefore anticipate that many aspects of brain network organization, in health and disease, may be parsimoniously explained by an economical clustering rule for the probability of functional connectivity between different brain areas.

The anatomical distance of functional connections predicts brain network topology in health and schizophrenia.

The human brain is a topologically complex network embedded in anatomical space. Here, we systematically explored relationships between functional connectivity, complex network topology, and anatomical (Euclidean) distance between connected brain regions, in the resting-state functional magnetic resonance imaging brain networks of 20 healthy volunteers and 19 patients with childhood-onset schizophrenia (COS). Normal between-subject differences in average distance of connected edges in brain graphs were strongly associated with variation in topological properties of functional networks. In addition, a club or subset of connector hubs was identified, in lateral temporal, parietal, dorsal prefrontal, and medial prefrontal/cingulate cortical regions. In COS, there was reduced strength of functional connectivity over short distances especially, and therefore, global mean connection distance of thresholded graphs was significantly greater than normal. As predicted from relationships between spatial and topological properties of normal networks, this disorder-related proportional increase in connection distance was associated with reduced clustering and modularity and increased global efficiency of COS networks. Between-group differences in connection distance were localized specifically to connector hubs of multimodal association cortex. In relation to the neurodevelopmental pathogenesis of schizophrenia, we argue that the data are consistent with the interpretation that spatial and topological disturbances of functional network organization could arise from excessive "pruning" of short-distance functional connections in schizophrenia.

Activity-Dependent Transcriptional Program in NGN2+ Neurons Enriched for Genetic Risk for Brain-Related Disorders.

BACKGROUND: Converging evidence from large-scale genetic and postmortem studies highlights the role of aberrant neurotransmission and genetic regulation in brain-related disorders. However, identifying neuronal activity-regulated transcriptional programs in the human brain and understanding how changes contribute to disease remain challenging. METHODS: To better understand how the activity-dependent regulome contributes to risk for brain-related disorders, we profiled the transcriptomic and epigenomic changes following neuronal depolarization in human induced pluripotent stem cell-derived glutamatergic neurons (NGN2) from 6 patients with schizophrenia and 5 control participants. RESULTS: Multiomic data integration associated global patterns of chromatin accessibility with gene expression and identified enhancer-promoter interactions in glutamatergic neurons. Within 1 hour of potassium chloride-induced depolarization, independent of diagnosis, glutamatergic neurons displayed substantial activity-dependent changes in the expression of genes regulating synaptic function. Depolarization-induced changes in the regulome revealed significant heritability enrichment for schizophrenia and Parkinson's disease, adding to mounting evidence that sequence variation within activation-dependent regulatory elements contributes to the genetic risk for brain-related disorders. Gene coexpression network analysis elucidated interactions among activity-dependent and disease-associated genes and pointed to a key driver (NAV3) that interacted with multiple genes involved in axon guidance. CONCLUSIONS: Overall, we demonstrated that deciphering the activity-dependent regulome in glutamatergic neurons reveals novel targets for advanced diagnosis and therapy.

Direct measure of the de novo mutation rate in autism and schizophrenia cohorts.

The role of de novo mutations (DNMs) in common diseases remains largely unknown. Nonetheless, the rate of de novo deleterious mutations and the strength of selection against de novo mutations are critical to understanding the genetic architecture of a disease. Discovery of high-impact DNMs requires substantial high-resolution interrogation of partial or complete genomes of families via resequencing. We hypothesized that deleterious DNMs may play a role in cases of autism spectrum disorders (ASD) and schizophrenia (SCZ), two etiologically heterogeneous disorders with significantly reduced reproductive fitness. We present a direct measure of the de novo mutation rate (µ) and selective constraints from DNMs estimated from a deep resequencing data set generated from a large cohort of ASD and SCZ cases (n = 285) and population control individuals (n = 285) with available parental DNA. A survey of ∼430 Mb of DNA from 401 synapse-expressed genes across all cases and 25 Mb of DNA in controls found 28 candidate DNMs, 13 of which were cell line artifacts. Our calculated direct neutral mutation rate (1.36 × 10(-8)) is similar to previous indirect estimates, but we observed a significant excess of potentially deleterious DNMs in ASD and SCZ individuals. Our results emphasize the importance of DNMs as genetic mechanisms in ASD and SCZ and the limitations of using DNA from archived cell lines to identify functional variants.

Longitudinally mapping the influence of sex and androgen signaling on the dynamics of human cortical maturation in adolescence.

Humans have systematic sex differences in brain-related behavior, cognition, and pattern of mental illness risk. Many of these differences emerge during adolescence, a developmental period of intense neurostructural and endocrine change. Here, by creating "movies" of sexually dimorphic brain development using longitudinal in vivo structural neuroimaging, we show regionally specific sex differences in development of the cerebral cortex during adolescence. Within cortical subsystems known to underpin domains of cognitive behavioral sex difference, structural change is faster in the sex that tends to perform less well within the domain in question. By stratifying participants through molecular analysis of the androgen receptor gene, we show that possession of an allele conferring more efficient functioning of this sex steroid receptor is associated with "masculinization" of adolescent cortical maturation. Our findings extend models first established in rodents, and suggest that in humans too, sex and sex steroids shape brain development in a spatiotemporally specific manner, within neural systems known to underpin sexually dimorphic behaviors.

De novo mutations in the gene encoding the synaptic scaffolding protein SHANK3 in patients ascertained for schizophrenia.

Schizophrenia likely results from poorly understood genetic and environmental factors. We studied the gene encoding the synaptic protein SHANK3 in 285 controls and 185 schizophrenia patients with unaffected parents. Two de novo mutations (R1117X and R536W) were identified in two families, one being found in three affected brothers, suggesting germline mosaicism. Zebrafish and rat hippocampal neuron assays revealed behavior and differentiation defects resulting from the R1117X mutant. As mutations in SHANK3 were previously reported in autism, the occurrence of SHANK3 mutations in subjects with a schizophrenia phenotype suggests a molecular genetic link between these two neurodevelopmental disorders.

Sleep spindles across youth affected by schizophrenia or anti-N-methyl-D-aspartate-receptor encephalitis.

Background: Sleep disturbances are intertwined with the progression and pathophysiology of psychotic symptoms in schizophrenia. Reductions in sleep spindles, a major electrophysiological oscillation during non-rapid eye movement sleep, have been identified in patients with schizophrenia as a potential biomarker representing the impaired integrity of the thalamocortical network. Altered glutamatergic neurotransmission within this network via a hypofunction of the N-methyl-D-aspartate receptor (NMDAR) is one of the hypotheses at the heart of schizophrenia. This pathomechanism and the symptomatology are shared by anti-NMDAR encephalitis (NMDARE), where antibodies specific to the NMDAR induce a reduction of functional NMDAR. However, sleep spindle parameters have yet to be investigated in NMDARE and a comparison of these rare patients with young individuals with schizophrenia and healthy controls (HC) is lacking. This study aims to assess and compare sleep spindles across young patients affected by Childhood-Onset Schizophrenia (COS), Early-Onset Schizophrenia, (EOS), or NMDARE and HC. Further, the potential relationship between sleep spindle parameters in COS and EOS and the duration of the disease is examined. Methods: Sleep EEG data of patients with COS (N = 17), EOS (N = 11), NMDARE (N = 8) aged 7-21 years old, and age- and sex-matched HC (N = 36) were assessed in 17 (COS, EOS) or 5 (NMDARE) electrodes. Sleep spindle parameters (sleep spindle density, maximum amplitude, and sigma power) were analyzed. Results: Central sleep spindle density, maximum amplitude, and sigma power were reduced when comparing all patients with psychosis to all HC. Between patient group comparisons showed no differences in central spindle density but lower central maximum amplitude and sigma power in patients with COS compared to patients with EOS or NMDARE. Assessing the topography of spindle density, it was significantly reduced over 15/17 electrodes in COS, 3/17 in EOS, and 0/5 in NMDARE compared to HC. In the pooled sample of COS and EOS, a longer duration of illness was associated with lower central sigma power. Conclusions: Patients with COS demonstrated more pronounced impairments of sleep spindles compared to patients with EOS and NMDARE. In this sample, there is no strong evidence that changes in NMDAR activity are related to spindle deficits.

Mutations in SYNGAP1 in autosomal nonsyndromic mental retardation.

Although autosomal forms of nonsyndromic mental retardation account for the majority of cases of mental retardation, the genes that are involved remain largely unknown. We sequenced the autosomal gene SYNGAP1, which encodes a ras GTPase-activating protein that is critical for cognition and synapse function, in 94 patients with nonsyndromic mental retardation. We identified de novo truncating mutations (K138X, R579X, and L813RfsX22) in three of these patients. In contrast, we observed no de novo or truncating mutations in SYNGAP1 in samples from 142 subjects with autism spectrum disorders, 143 subjects with schizophrenia, and 190 control subjects. These results indicate that SYNGAP1 disruption is a cause of autosomal dominant nonsyndromic mental retardation.

Annual research review: impact of advances in genetics in understanding developmental psychopathology.

It was hoped that diagnostic guidelines for, and treatment of, child psychiatric disorders in DSM-5 would be informed by the wealth of clinical genetic research related to neurodevelopmental disorders. In spite of remarkable advances in genetic technology, this has not been the case. Candidate gene, genome-wide association, and rare copy number variant (CNV) studies have been carried out for attention-deficit/hyperactivity disorder (ADHD), Autism, Tourette's Syndrome, and schizophrenia, with intriguing results, but environmental factors, incomplete penetrance, pleiotropy, and genetic heterogeneity, underlying any given phenotype have limited clinical translation. One promising approach may be the use of developmental brain imaging measures as more relevant phenotypes. This is particularly important, as subtle abnormalities in timing and expression of gene pathways underlying brain development may well link these disorders and be the ultimate target of treatments.

Catechol-o-methyl transferase (COMT) val158met polymorphism and adolescent cortical development in patients with childhood-onset schizophrenia, their non-psychotic siblings, and healthy controls.

Non-psychotic individuals at increased risk for schizophrenia show alterations in fronto-striatal dopamine signaling and cortical gray matter maturation reminiscent of those seen in schizophrenia. It remains unclear however if variations in dopamine signaling influence rates of structural cortical maturation in typically developing individuals, and whether such influences are disrupted in patients with schizophrenia and their non-psychotic siblings. We sought to address these issues by relating a functional Val→Met polymorphism within the gene encoding catechol-o-methyltransferase (COMT)-a key enzymatic regulator of cortical dopamine levels-to longitudinal structural neuroimaging measures of cortical gray matter thickness. We included a total of 792 magnetic resonance imaging brain scans, acquired between ages 9 and 22 years from patients with childhood-onset schizophrenia (COS), their non-psychotic full siblings, and matched healthy controls. Whereas greater Val allele dose (which confers enhanced dopamine catabolism and is proposed to aggravate cortical deficits in schizophrenia) accelerated adolescent cortical thinning in both schizophrenia probands and their siblings, it attenuated cortical thinning in healthy controls. This similarity between COS patients and their siblings was accompanied by differences between the two groups in the timing and spatial distribution of disrupted COMT influences on cortical maturation. Consequently, whereas greater Val "dose" conferred persistent dorsolateral prefrontal cortical deficits amongst affected probands by adulthood, cortical thickness differences associated with varying Val dose in non-psychotic siblings resolved over the age-range studied. These findings suggest that cortical abnormalities in pedigrees affected by schizophrenia may be contributed to by a disruption of dopaminergic infleunces on cortical maturation.

Childhood-onset schizophrenia: the challenge of diagnosis.

During the past two decades, the Child Psychiatry Branch at the National Institute of Mental Health has conducted a longitudinal study (including long-term prospective follow-up) of childhood-onset schizophrenia, a rare form of the disorder. Critical to this research has been accurate diagnosis. Outpatient screening has accurately diagnosed 55% of the 121 childhood-onset schizophrenia patients in the study to date. However, inpatient observation including drug-free observation has proven crucial to ruling out 96 children with alternative diagnoses who had been provisionally admitted for inpatient study. Standardized clinical ratings from outpatient screening only predicted 62% of these nonschizophrenia patients. Historically, medication-free observation was standard clinical care for difficult and unusual patients; this should be employed when possible in similar situations.

Cerebellar development in childhood onset schizophrenia and non-psychotic siblings.

We explored regional and total volumetric cerebellar differences in probands and their unaffected full siblings relative to typically developing participants. Participants included 94 (51 males) patients diagnosed with childhood onset schizophrenia (COS), 80 related non-psychotic siblings (37 males) and 110 (64 males) typically developing participants scanned longitudinally. The sample mean age was 16.87(S.D.=4.7; range 6.5 to 29). We performed mixed model regressions to examine group differences in trajectory and volume. The COS group had smaller bilateral anterior lobes and anterior and total vermis volumes than controls. The COS group diverged from controls over time in total, left, right, and bilateral posterior inferior cerebellum. Siblings did not have any fixed volumetric differences relative to controls but differed from controls in developmental trajectories of total and right cerebellum, left inferior posterior, left superior posterior, and superior vermis. Results are consistent with previous COS findings and several reports of decreased cerebellar volume in adult onset schizophrenia. Sibling trajectories may represent a trait marker, although the effect size for volumetric differences in early adulthood may be small.

Three-dimensional brain growth abnormalities in childhood-onset schizophrenia visualized by using tensor-based morphometry.

Earlier studies revealed progressive cortical gray matter (GM) loss in childhood-onset schizophrenia (COS) across both lateral and medial surfaces of the developing brain. Here, we use tensor-based morphometry to visualize white matter (WM) growth abnormalities in COS throughout the brain. Using high-dimensional elastic image registration, we compared 3D maps of local WM growth rates in COS patients and healthy children over a 5-year period, based on analyzing longitudinal brain MRIs from 12 COS patients and 12 healthy controls matched for age, gender, and scan interval. COS patients showed up to 2.2% slower growth rates per year than healthy controls in WM (P = 0.02, all P values corrected). The greatest differences were in the right hemisphere (P = 0.006). This asymmetry was attributable to a right slower than left hemisphere growth rate mapped in COS patients (P = 0.037) but not in healthy controls. WM growth rates reached 2.6% per year in healthy controls (P = 0.0002). COS patients showed only a 1.3% per year trend for growth in the left hemisphere (P = 0.066). In COS, WM growth rates were associated with improvement in the Children's Global Assessment Scale (R = 0.64, P = 0.029). Growth rates were reduced throughout the brain in COS, but this process appeared to progress in a front-to-back (frontal-parietal) fashion, and this effect was not attributable to lower IQ. Growth rates were correlated with functional prognosis and were visualized as detailed 3D maps. Finally, these findings also confirm that the progressive GM deficits seen in schizophrenia are not the result of WM overgrowth.