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Disruption of mGluR5 in parvalbumin-positive interneurons induces core features of neurodevelopmental disorders.

August 2, 2016 - 11:14am
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Disruption of mGluR5 in parvalbumin-positive interneurons induces core features of neurodevelopmental disorders.

Mol Psychiatry. 2015 Oct;20(10):1161-72

Authors: Barnes SA, Pinto-Duarte A, Kappe A, Zembrzycki A, Metzler A, Mukamel EA, Lucero J, Wang X, Sejnowski TJ, Markou A, Behrens MM

Abstract
Alterations in glutamatergic transmission onto developing GABAergic systems, in particular onto parvalbumin-positive (Pv(+)) fast-spiking interneurons, have been proposed as underlying causes of several neurodevelopmental disorders, including schizophrenia and autism. Excitatory glutamatergic transmission, through ionotropic and metabotropic glutamate receptors, is necessary for the correct postnatal development of the Pv(+) GABAergic network. We generated mutant mice in which the metabotropic glutamate receptor 5 (mGluR5) was specifically ablated from Pv(+) interneurons postnatally, and investigated the consequences of such a manipulation at the cellular, network and systems levels. Deletion of mGluR5 from Pv(+) interneurons resulted in reduced numbers of Pv(+) neurons and decreased inhibitory currents, as well as alterations in event-related potentials and brain oscillatory activity. These cellular and sensory changes translated into domain-specific memory deficits and increased compulsive-like behaviors, abnormal sensorimotor gating and altered responsiveness to stimulant agents. Our findings suggest a fundamental role for mGluR5 in the development of Pv(+) neurons and show that alterations in this system can produce broad-spectrum alterations in brain network activity and behavior that are relevant to neurodevelopmental disorders.

PMID: 26260494 [PubMed - indexed for MEDLINE]

Monogenic and chromosomal causes of isolated speech and language impairment.

August 2, 2016 - 11:14am
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Monogenic and chromosomal causes of isolated speech and language impairment.

J Med Genet. 2015 Nov;52(11):719-29

Authors: Barnett CP, van Bon BW

Abstract
The importance of a precise molecular diagnosis for children with intellectual disability, autism spectrum disorder and epilepsy has become widely accepted and genetic testing is an integral part of the diagnostic evaluation of these children. In contrast, children with an isolated speech or language disorder are not often genetically evaluated, despite recent evidence supporting a role for genetic factors in the aetiology of these disorders. Several chromosomal copy number variants and single gene disorders associated with abnormalities of speech and language have been identified. Individuals without a precise genetic diagnosis will not receive optimal management including interventions such as early testosterone replacement in Klinefelter syndrome, otorhinolaryngological and audiometric evaluation in 22q11.2 deletion syndrome, cardiovascular surveillance in 7q11.23 duplications and early dietary management to prevent obesity in proximal 16p11.2 deletions. This review summarises the clinical features, aetiology and management options of known chromosomal and single gene disorders that are associated with speech and language pathology in the setting of normal or only mildly impaired cognitive function.

PMID: 26139234 [PubMed - indexed for MEDLINE]

Face processing among twins with and without autism: social correlates and twin concordance.

August 2, 2016 - 11:14am
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Face processing among twins with and without autism: social correlates and twin concordance.

Soc Cogn Affect Neurosci. 2016 Jan;11(1):44-54

Authors: Neuhaus E, Kresse A, Faja S, Bernier RA, Webb SJ

Abstract
Autism spectrum disorder (ASD) has a strong heritable basis, as evidenced by twin concordance rates. Within ASD, symptom domains may arise via independent genetic contributions, with varying heritabilities and genetic mechanisms. In this article, we explore social functioning in the form of (i) electrophysiological and behavioral measures of face processing (P1 and N170) and (ii) social behavior among child and adolescent twins with (N = 52) and without ASD (N = 66). Twins without ASD had better holistic face processing and face memory, faster P1 responses and greater sensitivity to the effects of facial inversion on P1. In contrast, N170 responses to faces were similar across diagnosis, with more negative amplitudes for faces vs non-face images. Across the sample, stronger social skills and fewer social difficulties were associated with faster P1 and N170 responses to upright faces, and better face memory. Twins were highly correlated within pairs across most measures, but correlations were significantly stronger for monozygotic vs dizygotic pairs on N170 latency and social problems. We suggest common developmental influences across twins for face processing and social behavior, but highlight (i) neural speed of face processing and (ii) social difficulties as important avenues in the search for genetic underpinnings in ASD.

PMID: 26137974 [PubMed - indexed for MEDLINE]

Nuclear Localization of the Autism Candidate Gene Neurobeachin and Functional Interaction with the NOTCH1 Intracellular Domain Indicate a Role in Regulating Transcription.

August 1, 2016 - 8:11am
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Nuclear Localization of the Autism Candidate Gene Neurobeachin and Functional Interaction with the NOTCH1 Intracellular Domain Indicate a Role in Regulating Transcription.

PLoS One. 2016;11(3):e0151954

Authors: Tuand K, Stijnen P, Volders K, Declercq J, Nuytens K, Meulemans S, Creemers J

Abstract
BACKGROUND: Neurobeachin (NBEA) is an autism spectrum disorders (ASD) candidate gene. NBEA deficiency affects regulated secretion, receptor trafficking, synaptic architecture and protein kinase A (PKA)-mediated phosphorylation. NBEA is a large multidomain scaffolding protein. From N- to C-terminus, NBEA has a concanavalin A-like lectin domain flanked by armadillo repeats (ACA), an A-kinase anchoring protein domain that can bind to PKA, a domain of unknown function (DUF1088) and a BEACH domain, preceded by a pleckstrin homology-like domain and followed by WD40 repeats (PBW). Although most of these domains mediate protein-protein interactions, no interaction screen has yet been performed.
METHODS: Yeast two-hybrid screens with the ACA and PBW domain modules of NBEA gave a list of interaction partners, which were analyzed for Gene Ontology (GO) enrichment. Neuro-2a cells were used for confocal microscopy and nuclear extraction analysis. NOTCH-mediated transcription was studied with luciferase reporter assays and qRT-PCR, combined with NBEA knockdown or overexpression.
RESULTS: Both domain modules showed a GO enrichment for the nucleus. PBW almost exclusively interacted with transcription regulators, while ACA interacted with a number of PKA substrates. NBEA was partially localized in the nucleus of Neuro-2a cells, albeit much less than in the cytoplasm. A nuclear localization signal was found in the DUF1088 domain, which was shown to contribute to the nuclear localization of an EGFP-DPBW fusion protein. Yeast two-hybrid identified the Notch1 intracellular domain as a physical interactor of the PBW domain and a role for NBEA as a negative regulator in Notch-mediated transcription was demonstrated.
CONCLUSION: Defining novel interaction partners of conserved NBEA domain modules identified a role for NBEA as transcriptional regulator in the nucleus. The physical interaction of NBEA with NOTCH1 is most relevant for ASD pathogenesis because NOTCH signaling is essential for neural development.

PMID: 26999814 [PubMed - indexed for MEDLINE]

CpG sites with continuously increasing or decreasing methylation from early to late human fetal brain development.

July 30, 2016 - 8:07am

CpG sites with continuously increasing or decreasing methylation from early to late human fetal brain development.

Gene. 2016 Jul 25;

Authors: Schneider E, Dittrich M, Böck J, Nanda I, Müller T, Seidmann L, Tralau T, Galetzka D, El Hajj N, Haaf T

Abstract
Normal human brain development is dependent on highly dynamic epigenetic processes for spatial and temporal gene regulation. Recent work identified wide-spread changes in DNA methylation during fetal brain development. We profiled CpG methylation in frontal cortex of 27 fetuses from gestational weeks 12-42, using Illumina 450K methylation arrays. Sites showing genome-wide significant correlation with gestational age were compared to a publicly available data set from gestational weeks 3-26. Altogether, we identified 2016 matching developmentally regulated differentially methylated positions (m-dDMPs): 1767m-dDMPs were hypermethylated and 1149 hypomethylated during fetal development. M-dDMPs are underrepresented in CpG islands and gene promoters, and enriched in gene bodies. They appear to cluster in certain chromosome regions. M-dDMPs are significantly enriched in autism-associated genes and CpGs. Our results promote the idea that reduced methylation dynamics during fetal brain may predispose to autism. In addition, m-dDMPs are enriched in genes with human-specific brain expression patterns and/or histone modifications. Collectively, we defined a subset of dDMPs exhibiting constant methylation changes from early to late pregnancy. The same epigenetic mechanisms involving methylation changes in cis-regulatory regions may have been adopted for human brain evolution and ontogeny.

PMID: 27468947 [PubMed - as supplied by publisher]

Gene expression in human brain implicates sexually dimorphic pathways in autism spectrum disorders.

July 28, 2016 - 8:03am
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Gene expression in human brain implicates sexually dimorphic pathways in autism spectrum disorders.

Nat Commun. 2016;7:10717

Authors: Werling DM, Parikshak NN, Geschwind DH

Abstract
Autism spectrum disorder (ASD) is more prevalent in males, and the mechanisms behind this sex-differential risk are not fully understood. Two competing, but not mutually exclusive, hypotheses are that ASD risk genes are sex-differentially regulated, or alternatively, that they interact with characteristic sexually dimorphic pathways. Here we characterized sexually dimorphic gene expression in multiple data sets from neurotypical adult and prenatal human neocortical tissue, and evaluated ASD risk genes for evidence of sex-biased expression. We find no evidence for systematic sex-differential expression of ASD risk genes. Instead, we observe that genes expressed at higher levels in males are significantly enriched for genes upregulated in post-mortem autistic brain, including astrocyte and microglia markers. This suggests that it is not sex-differential regulation of ASD risk genes, but rather naturally occurring sexually dimorphic processes, potentially including neuron-glial interactions, that modulate the impact of risk variants and contribute to the sex-skewed prevalence of ASD.

PMID: 26892004 [PubMed - indexed for MEDLINE]

Decreased Brain Levels of Vitamin B12 in Aging, Autism and Schizophrenia.

July 28, 2016 - 8:03am
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Decreased Brain Levels of Vitamin B12 in Aging, Autism and Schizophrenia.

PLoS One. 2016;11(1):e0146797

Authors: Zhang Y, Hodgson NW, Trivedi MS, Abdolmaleky HM, Fournier M, Cuenod M, Do KQ, Deth RC

Abstract
Many studies indicate a crucial role for the vitamin B12 and folate-dependent enzyme methionine synthase (MS) in brain development and function, but vitamin B12 status in the brain across the lifespan has not been previously investigated. Vitamin B12 (cobalamin, Cbl) exists in multiple forms, including methylcobalamin (MeCbl) and adenosylcobalamin (AdoCbl), serving as cofactors for MS and methylmalonylCoA mutase, respectively. We measured levels of five Cbl species in postmortem human frontal cortex of 43 control subjects, from 19 weeks of fetal development through 80 years of age, and 12 autistic and 9 schizophrenic subjects. Total Cbl was significantly lower in older control subjects (> 60 yrs of age), primarily reflecting a >10-fold age-dependent decline in the level of MeCbl. Levels of inactive cyanocobalamin (CNCbl) were remarkably higher in fetal brain samples. In both autistic and schizophrenic subjects MeCbl and AdoCbl levels were more than 3-fold lower than age-matched controls. In autistic subjects lower MeCbl was associated with decreased MS activity and elevated levels of its substrate homocysteine (HCY). Low levels of the antioxidant glutathione (GSH) have been linked to both autism and schizophrenia, and both total Cbl and MeCbl levels were decreased in glutamate-cysteine ligase modulatory subunit knockout (GCLM-KO) mice, which exhibit low GSH levels. Thus our findings reveal a previously unrecognized decrease in brain vitamin B12 status across the lifespan that may reflect an adaptation to increasing antioxidant demand, while accelerated deficits due to GSH deficiency may contribute to neurodevelopmental and neuropsychiatric disorders.

PMID: 26799654 [PubMed - indexed for MEDLINE]

Paternal sperm DNA methylation associated with early signs of autism risk in an autism-enriched cohort.

July 28, 2016 - 8:03am
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Paternal sperm DNA methylation associated with early signs of autism risk in an autism-enriched cohort.

Int J Epidemiol. 2015 Aug;44(4):1199-210

Authors: Feinberg JI, Bakulski KM, Jaffe AE, Tryggvadottir R, Brown SC, Goldman LR, Croen LA, Hertz-Picciotto I, Newschaffer CJ, Fallin MD, Feinberg AP

Abstract
BACKGROUND: Epigenetic mechanisms such as altered DNA methylation have been suggested to play a role in autism, beginning with the classical association of Prader-Willi syndrome, an imprinting disorder, with autistic features.
OBJECTIVES: Here we tested for the relationship of paternal sperm DNA methylation with autism risk in offspring, examining an enriched-risk cohort of fathers of autistic children.
METHODS: We examined genome-wide DNA methylation (DNAm) in paternal semen biosamples obtained from an autism spectrum disorder (ASD) enriched-risk pregnancy cohort, the Early Autism Risk Longitudinal Investigation (EARLI) cohort, to estimate associations between sperm DNAm and prospective ASD development, using a 12-month ASD symptoms assessment, the Autism Observation Scale for Infants (AOSI). We analysed methylation data from 44 sperm samples run on the CHARM 3.0 array, which contains over 4 million probes (over 7 million CpG sites), including 30 samples also run on the Illumina Infinium HumanMethylation450 (450K) BeadChip platform (∼485 000 CpG sites). We also examined associated regions in an independent sample of post-mortem human brain ASD and control samples for which Illumina 450K DNA methylation data were available.
RESULTS: Using region-based statistical approaches, we identified 193 differentially methylated regions (DMRs) in paternal sperm with a family-wise empirical P-value [family-wise error rate (FWER)] <0.05 associated with performance on the Autism Observational Scale for Infants (AOSI) at 12 months of age in offspring. The DMRs clustered near genes involved in developmental processes, including many genes in the SNORD family, within the Prader-Willi syndrome gene cluster. These results were consistent among the 75 probes on the Illumina 450K array that cover AOSI-associated DMRs from CHARM. Further, 18 of 75 (24%) 450K array probes showed consistent differences in the cerebellums of autistic individuals compared with controls.
CONCLUSIONS: These data suggest that epigenetic differences in paternal sperm may contribute to autism risk in offspring, and provide evidence that directionally consistent, potentially related epigenetic mechanisms may be operating in the cerebellum of individuals with autism.

PMID: 25878217 [PubMed - indexed for MEDLINE]

Novel de novo EEF1A2 missense mutations causing epilepsy and intellectual disability.

July 22, 2016 - 7:52am

Novel de novo EEF1A2 missense mutations causing epilepsy and intellectual disability.

Mol Genet Genomic Med. 2016 Jul;4(4):465-74

Authors: Lam WW, Millichap JJ, Soares DC, Chin R, McLellan A, FitzPatrick DR, Elmslie F, Lees MM, Schaefer GB, DDD study, Abbott CM

Abstract
BACKGROUND: Exome sequencing has led to the discovery of mutations in novel causative genes for epilepsy. One such gene is EEF1A2, encoding a neuromuscular specific translation elongation factor, which has been found to be mutated de novo in five cases of severe epilepsy. We now report on a further seven cases, each with a different mutation, of which five are newly described.
METHODS: New cases were identified and sequenced through the Deciphering Developmental Disabilities project, via direct contact with neurologists or geneticists, or recruited via our website.
RESULTS: All the mutations cause epilepsy and intellectual disability, but with a much wider range of severity than previously identified. All new cases share specific subtle facial dysmorphic features. Each mutation occurs at an evolutionarily highly conserved amino acid position indicating strong structural or functional selective pressure.
CONCLUSIONS: EEF1A2 should be considered as a causative gene not only in cases of epileptic encephalopathy but also in children with less severe epilepsy and intellectual disability. The emergence of a possible discernible phenotype, a broad nasal bridge, tented upper lip, everted lower lip and downturned corners of the mouth may help in identifying patients with mutations in EEF1A2.

PMID: 27441201 [PubMed]

[Research advances in candidate genes for autism spectrum disorder].

July 22, 2016 - 7:52am
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[Research advances in candidate genes for autism spectrum disorder].

Zhongguo Dang Dai Er Ke Za Zhi. 2016 Mar;18(3):282-7

Authors: Yang ZL, Sun GL

Abstract
Autism spectrum disorder (ASD) is a kind of neurodevelopmental multigenic disorder. More than one hundred of candidate genes for ASD have been reported. The candidate gene research for ASD involves in chromosome loci and screening of candidate genes and epigenetic abnormalities for candidate genes. The reported genes encode neural adhesion molecules, ion channels, scaffold proteins, protein kinases, receptor protein and carrier protein, signaling modulate molecules and circadian relevant proteins. The research of mutation screening and expression regulation of candidate genes can help to elucidate genetic mechanisms for ASD, and may provide new approaches for the diagnosis and treatment of this disorder. This article reviews the research advance in candidate genes for ASD.

PMID: 26975830 [PubMed - indexed for MEDLINE]

Autism Linked to Increased Oncogene Mutations but Decreased Cancer Rate.

July 22, 2016 - 7:52am
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Autism Linked to Increased Oncogene Mutations but Decreased Cancer Rate.

PLoS One. 2016;11(3):e0149041

Authors: Darbro BW, Singh R, Zimmerman MB, Mahajan VB, Bassuk AG

Abstract
Autism spectrum disorder (ASD) is one phenotypic aspect of many monogenic, hereditary cancer syndromes. Pleiotropic effects of cancer genes on the autism phenotype could lead to repurposing of oncology medications to treat this increasingly prevalent neurodevelopmental condition for which there is currently no treatment. To explore this hypothesis we sought to discover whether autistic patients more often have rare coding, single-nucleotide variants within tumor suppressor and oncogenes and whether autistic patients are more often diagnosed with neoplasms. Exome-sequencing data from the ARRA Autism Sequencing Collaboration was compared to that of a control cohort from the Exome Variant Server database revealing that rare, coding variants within oncogenes were enriched for in the ARRA ASD cohort (p<1.0 x 10(-8)). In contrast, variants were not significantly enriched in tumor suppressor genes. Phenotypically, children and adults with ASD exhibited a protective effect against cancer, with a frequency of 1.3% vs. 3.9% (p<0.001), but the protective effect decreased with age. The odds ratio of neoplasm for those with ASD relative to controls was 0.06 (95% CI: 0.02, 0.19; p<0.0001) in the 0 to 14 age group; 0.35 (95% CI: 0.14, 0.87; p = 0.024) in the 15 to 29 age group; 0.41 (95% CI: 0.15, 1.17; p = 0.095) in the 30 to 54 age group; and 0.49 (95% CI: 0.14, 1.74; p = 0.267) in those 55 and older. Both males and females demonstrated the protective effect. These findings suggest that defects in cellular proliferation, and potentially senescence, might influence both autism and neoplasm, and already approved drugs targeting oncogenic pathways might also have therapeutic value for treating autism.

PMID: 26934580 [PubMed - indexed for MEDLINE]

Social Cognition Impairments in Mice Overexpressing Alpha-Synuclein Under the Thy1 Promoter, a Model of Pre-manifest Parkinson's Disease.

July 22, 2016 - 7:52am
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Social Cognition Impairments in Mice Overexpressing Alpha-Synuclein Under the Thy1 Promoter, a Model of Pre-manifest Parkinson's Disease.

J Parkinsons Dis. 2015;5(3):669-80

Authors: Magen I, Torres ER, Dinh D, Chung A, Masliah E, Chesselet MF

Abstract
BACKGROUND: Patients with Parkinson's disease (PD) may exhibit deficits in "Theory of Mind", the ability to read others' mental states and react appropriately, a prerequisite for successful social interaction. Alpha-synuclein overexpression is widely distributed in the brain of patients with sporadic PD, suggesting that it may contribute to the non-motor deficits observed in PD patients. Mice over-expressing human wild-type alpha-synuclein under the Thy1 promoter (Thy1-aSyn mice) have synaptic deficits in the frontostriatal pathway, low cortical acetylcholine, and high level of expression of mGluR5 receptors, which have all been implicated in social recognition deficits.
OBJECTIVE: To determine whether Thy1-aSyn mice present alterations in their response to social stimuli.
METHODS: We have submitted Thy1-aSyn mice to tests adapted from autism models.
RESULTS: At 7-8 month of age Thy1-aSyn mice explored their conspecifics significantly less than did wild-type littermates, without differences in exploration of inanimate objects, and pairs of Thy1-aSyn mice were involved in reciprocal interactions for a shorter duration than wild-type mice at this age. These deficits persisted when the test animal was enclosed in a beaker and were not present at 3-4 months of age despite the presence of olfactory deficits at that age, indicating that they were not solely caused by impairment in olfaction.
CONCLUSION: Thy1-aSyn mice present progressive deficits in social recognition, supporting an association between alpha-synuclein overexpression and Theory of Mind deficits in PD and providing a useful model for identifying mechanisms and testing novel treatments for these deficits which impact patients and caretakers quality of life.

PMID: 25588356 [PubMed - indexed for MEDLINE]

De novo nonsense and frameshift variants of TCF20 in individuals with intellectual disability and postnatal overgrowth.

July 21, 2016 - 1:49pm
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De novo nonsense and frameshift variants of TCF20 in individuals with intellectual disability and postnatal overgrowth.

Eur J Hum Genet. 2016 Jul 20;

Authors: Schäfgen J, Cremer K, Becker J, Wieland T, Zink AM, Kim S, Windheuser IC, Kreiß M, Aretz S, Strom TM, Wieczorek D, Engels H

Abstract
Recently, germline variants of the transcriptional co-regulator gene TCF20 have been implicated in the aetiology of autism spectrum disorders (ASD). However, the knowledge about the associated clinical picture remains fragmentary. In this study, two individuals with de novo TCF20 sequence variants were identified in a cohort of 313 individuals with intellectual disability of unknown aetiology, which was analysed by whole exome sequencing using a child-parent trio design. Both detected variants - one nonsense and one frameshift variant - were truncating. A comprehensive clinical characterisation of the patients yielded mild intellectual disability, postnatal tall stature and macrocephaly, obesity and muscular hypotonia as common clinical signs while ASD was only present in one proband. The present report begins to establish the clinical picture of individuals with de novo nonsense and frameshift variants of TCF20 which includes features such as proportionate overgrowth and muscular hypotonia. Furthermore, intellectual disability/developmental delay seems to be fully penetrant amongst known individuals with de novo nonsense and frameshift variants of TCF20, whereas ASD is shown to be incompletely penetrant. The transcriptional co-regulator gene TCF20 is hereby added to the growing number of genes implicated in the aetiology of both ASD and intellectual disability. Furthermore, such de novo variants of TCF20 may represent a novel differential diagnosis in the overgrowth syndrome spectrum.European Journal of Human Genetics advance online publication, 20 July 2016; doi:10.1038/ejhg.2016.90.

PMID: 27436265 [PubMed - as supplied by publisher]

Reciprocal Effects on Neurocognitive and Metabolic Phenotypes in Mouse Models of 16p11.2 Deletion and Duplication Syndromes.

July 20, 2016 - 4:47pm
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Reciprocal Effects on Neurocognitive and Metabolic Phenotypes in Mouse Models of 16p11.2 Deletion and Duplication Syndromes.

PLoS Genet. 2016 Feb;12(2):e1005709

Authors: Arbogast T, Ouagazzal AM, Chevalier C, Kopanitsa M, Afinowi N, Migliavacca E, Cowling BS, Birling MC, Champy MF, Reymond A, Herault Y

Abstract
The 16p11.2 600 kb BP4-BP5 deletion and duplication syndromes have been associated with developmental delay; autism spectrum disorders; and reciprocal effects on the body mass index, head circumference and brain volumes. Here, we explored these relationships using novel engineered mouse models carrying a deletion (Del/+) or a duplication (Dup/+) of the Sult1a1-Spn region homologous to the human 16p11.2 BP4-BP5 locus. On a C57BL/6N inbred genetic background, Del/+ mice exhibited reduced weight and impaired adipogenesis, hyperactivity, repetitive behaviors, and recognition memory deficits. In contrast, Dup/+ mice showed largely opposite phenotypes. On a F1 C57BL/6N × C3B hybrid genetic background, we also observed alterations in social interaction in the Del/+ and the Dup/+ animals, with other robust phenotypes affecting recognition memory and weight. To explore the dosage effect of the 16p11.2 genes on metabolism, Del/+ and Dup/+ models were challenged with high fat and high sugar diet, which revealed opposite energy imbalance. Transcriptomic analysis revealed that the majority of the genes located in the Sult1a1-Spn region were sensitive to dosage with a major effect on several pathways associated with neurocognitive and metabolic phenotypes. Whereas the behavioral consequence of the 16p11 region genetic dosage was similar in mice and humans with activity and memory alterations, the metabolic defects were opposite: adult Del/+ mice are lean in comparison to the human obese phenotype and the Dup/+ mice are overweight in comparison to the human underweight phenotype. Together, these data indicate that the dosage imbalance at the 16p11.2 locus perturbs the expression of modifiers outside the CNV that can modulate the penetrance, expressivity and direction of effects in both humans and mice.

PMID: 26872257 [PubMed - indexed for MEDLINE]

Deciphering H3K4me3 broad domains associated with gene-regulatory networks and conserved epigenomic landscapes in the human brain.

July 20, 2016 - 4:47pm
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Deciphering H3K4me3 broad domains associated with gene-regulatory networks and conserved epigenomic landscapes in the human brain.

Transl Psychiatry. 2015;5:e679

Authors: Dincer A, Gavin DP, Xu K, Zhang B, Dudley JT, Schadt EE, Akbarian S

Abstract
Regulators of the histone H3-trimethyl lysine-4 (H3K4me3) mark are significantly associated with the genetic risk architecture of common neurodevelopmental disease, including schizophrenia and autism. Typical H3K4me3 is primarily localized in the form of sharp peaks, extending in neuronal chromatin on average only across 500-1500 base pairs mostly in close proximity to annotated transcription start sites. Here, through integrative computational analysis of epigenomic and transcriptomic data based on next-generation sequencing, we investigated H3K4me3 landscapes of sorted neuronal and non-neuronal nuclei in human postmortem, non-human primate and mouse prefrontal cortex (PFC), and blood. To explore whether H3K4me3 peak signals could also extend across much broader domains, we examined broadest domain cell-type-specific H3K4me3 peaks in an unbiased manner with an innovative approach on 41+12 ChIP-seq and RNA-seq data sets. In PFC neurons, broadest H3K4me3 distribution ranged from 3.9 to 12 kb, with extremely broad peaks (~10 kb or broader) related to synaptic function and GABAergic signaling (DLX1, ELFN1, GAD1, IGSF9B and LINC00966). Broadest neuronal peaks showed distinct motif signatures and were centrally positioned in prefrontal gene-regulatory Bayesian networks and sensitive to defective neurodevelopment. Approximately 120 of the broadest H3K4me3 peaks in human PFC neurons, including many genes related to glutamatergic and dopaminergic signaling, were fully conserved in chimpanzee, macaque and mouse cortical neurons. Exploration of spread and breadth of lysine methylation markings could provide novel insights into epigenetic mechanism involved in neuropsychiatric disease and neuronal genome evolution.

PMID: 26575220 [PubMed - indexed for MEDLINE]

Functional genomics of human brain development and implications for autism spectrum disorders.

July 20, 2016 - 4:47pm
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Functional genomics of human brain development and implications for autism spectrum disorders.

Transl Psychiatry. 2015;5:e665

Authors: Ziats MN, Grosvenor LP, Rennert OM

Abstract
Transcription of the inherited DNA sequence into copies of messenger RNA is the most fundamental process by which the genome functions to guide development. Encoded sequence information, inherited epigenetic marks and environmental influences all converge at the level of mRNA gene expression to allow for cell-type-specific, tissue-specific, spatial and temporal patterns of expression. Thus, the transcriptome represents a complex interplay between inherited genomic structure, dynamic experiential demands and external signals. This property makes transcriptome studies uniquely positioned to provide insight into complex genetic-epigenetic-environmental processes such as human brain development, and disorders with non-Mendelian genetic etiologies such as autism spectrum disorders. In this review, we describe recent studies exploring the unique functional genomics profile of the human brain during neurodevelopment. We then highlight two emerging areas of research with great potential to increase our understanding of functional neurogenomics-non-coding RNA expression and gene interaction networks. Finally, we review previous functional genomics studies of autism spectrum disorder in this context, and discuss how investigations at the level of functional genomics are beginning to identify convergent molecular mechanisms underlying this genetically heterogeneous disorder.

PMID: 26506051 [PubMed - indexed for MEDLINE]

Genetic modulation of oxytocin sensitivity: a pharmacogenetic approach.

July 20, 2016 - 4:47pm
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Genetic modulation of oxytocin sensitivity: a pharmacogenetic approach.

Transl Psychiatry. 2015;5:e664

Authors: Chen FS, Kumsta R, Dvorak F, Domes G, Yim OS, Ebstein RP, Heinrichs M

Abstract
Intranasal administration of the neuropeptide oxytocin has been shown to influence a range of complex social cognitions and social behaviors, and it holds therapeutic potential for the treatment of mental disorders characterized by social functioning deficits such as autism, social phobia and borderline personality disorder. However, considerable variability exists in individual responses to oxytocin administration. Here, we undertook a study to investigate the role of genetic variation in sensitivity to exogenous oxytocin using a socioemotional task. In a randomized, double-blind, placebo-controlled experiment with a repeated-measures (crossover) design, we assessed the performance of 203 men on an emotion recognition task under oxytocin and placebo. We took a haplotype-based approach to investigate the association between oxytocin receptor gene variation and oxytocin sensitivity. We identified a six-marker haplotype block spanning the promoter region and intron 3 that was significantly associated with our measure of oxytocin sensitivity. Specifically, the TTCGGG haplotype comprising single-nucleotide polymorphisms rs237917-rs2268498-rs4564970-rs237897-rs2268495-rs53576 is associated with increased emotion recognition performance under oxytocin versus placebo, and the CCGAGA haplotype with the opposite pattern. These results on the genetic modulation of sensitivity to oxytocin document a significant source of individual differences with implications for personalized treatment approaches using oxytocin administration.

PMID: 26506050 [PubMed - indexed for MEDLINE]

Genome-wide differential expression of synaptic long noncoding RNAs in autism spectrum disorder.

July 20, 2016 - 4:47pm
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Genome-wide differential expression of synaptic long noncoding RNAs in autism spectrum disorder.

Transl Psychiatry. 2015;5:e660

Authors: Wang Y, Zhao X, Ju W, Flory M, Zhong J, Jiang S, Wang P, Dong X, Tao X, Chen Q, Shen C, Zhong M, Yu Y, Brown WT, Zhong N

Abstract
A genome-wide differential expression of long noncoding RNAs (lncRNAs) was identified in blood specimens of autism spectrum disorder (ASD). A total of 3929 lncRNAs were found to be differentially expressed in ASD peripheral leukocytes, including 2407 that were upregulated and 1522 that were downregulated. Simultaneously, 2591 messenger RNAs (mRNAs), including 1789 upregulated and 821 downregulated, were also identified in ASD leukocytes. Functional pathway analysis of these lncRNAs revealed neurological pathways of the synaptic vesicle cycling, long-term depression and long-term potentiation to be primarily involved. Thirteen synaptic lncRNAs, including nine upregulated and four downregulated, and 19 synaptic mRNAs, including 12 upregulated and seven downregulated, were identified as being differentially expressed in ASD. Our identification of differential expression of synaptic lncRNAs and mRNAs suggested that synaptic vesicle transportation and cycling are important for the delivery of synaptosomal protein(s) between presynaptic and postsynaptic membranes in ASD. Finding of 19 lncRNAs, which are the antisense, bi-directional and intergenic, of HOX genes may lead us to investigate the role of HOX genes involved in the development of ASD. Discovery of the lncRNAs of SHANK2-AS and BDNF-AS, the natural antisense of genes SHANK2 and BDNF, respectively, indicates that in addition to gene mutations, deregulation of lncRNAs on ASD-causing gene loci presents a new approach for exploring possible epigenetic mechanisms underlying ASD. Our study also opened a new avenue for exploring the use of lncRNA(s) as biomarker(s) for the early detection of ASD.

PMID: 26485544 [PubMed - indexed for MEDLINE]

Copy Number Variants Associated with 14 Cases of Self-Injurious Behavior.

July 19, 2016 - 7:45pm
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Copy Number Variants Associated with 14 Cases of Self-Injurious Behavior.

PLoS One. 2016;11(3):e0149646

Authors: Shirley MD, Frelin L, López JS, Jedlicka A, Dziedzic A, Frank-Crawford MA, Silverman W, Hagopian L, Pevsner J

Abstract
Copy number variants (CNVs) were detected and analyzed in 14 probands with autism and intellectual disability with self-injurious behavior (SIB) resulting in tissue damage. For each proband we obtained a clinical history and detailed behavioral descriptions. Genetic anomalies were observed in all probands, and likely clinical significance could be established in four cases. This included two cases having novel, de novo copy number variants and two cases having variants likely to have functional significance. These cases included segmental trisomy 14, segmental monosomy 21, and variants predicted to disrupt the function of ZEB2 (encoding a transcription factor) and HTR2C (encoding a serotonin receptor). Our results identify variants in regions previously implicated in intellectual disability and suggest candidate genes that could contribute to the etiology of SIB.

PMID: 26933844 [PubMed - indexed for MEDLINE]

Patient Mutations of the Intellectual Disability Gene KDM5C Downregulate Netrin G2 and Suppress Neurite Growth in Neuro2a Cells.

July 17, 2016 - 7:38am

Patient Mutations of the Intellectual Disability Gene KDM5C Downregulate Netrin G2 and Suppress Neurite Growth in Neuro2a Cells.

J Mol Neurosci. 2016 Jul 16;

Authors: Wei G, Deng X, Agarwal S, Iwase S, Disteche C, Xu J

Abstract
The X-linked lysine (K)-specific demethylase 5C (KDM5C) gene plays an important role in brain development and behavior. It encodes a histone demethylase that is involved in gene regulation in neuronal differentiation and morphogenesis. When mutated, it causes neuropsychiatric symptoms, such as intellectual disability, delayed language development, epilepsy, and impulsivity. To better understand how the patient mutations affect neuronal development, we expressed KDM5C mutants in Neuro2a cells, a mouse neuroblastoma cell line. Retinoic acid (RA)-induced neurite growth was suppressed by the mutation KDM5C (Y751C) , KDM5C (H514A) , and KDM5C (F642L) , but not KDM5C (D87G) or KDM5C (A388P) . RNA-seq analysis indicated an upregulation of genes important for neuronal development, such as Ntng2, Enah, Gas1, Slit2, and Dscam, in response to the RA treatment in control Neuro2a cells transfected with GFP or wild-type KDM5C. In contrast, in cells transfected with KDM5C (Y751C) , these genes were not upregulated by RA. Ntng2 was downregulated in cells with KDM5C mutations, concordant with the lower levels of H3K4 methylation at its promoter. Moreover, knocking down Ntng2 in control Neuro2a cells led to the phenotype of short neurites similar to that of cells with KDM5C (Y751C) , whereas Ntng2 overexpression in the mutant cells rescued the morphological phenotype. These findings provide new insight into the pathogenesis of phenotypes associated with KDM5C mutations.

PMID: 27421841 [PubMed - as supplied by publisher]

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