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Translational regulation of NeuroD1 expression by FMRP: involvement in glutamatergic neuronal differentiation of cultured rat primary neural progenitor cells.

October 17, 2014 - 2:58pm
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Translational regulation of NeuroD1 expression by FMRP: involvement in glutamatergic neuronal differentiation of cultured rat primary neural progenitor cells.

Cell Mol Neurobiol. 2014 Mar;34(2):297-305

Authors: Jeon SJ, Kim JW, Kim KC, Han SM, Go HS, Seo JE, Choi CS, Ryu JH, Shin CY, Song MR

Abstract
Fragile X mental retardation protein (FMRP) is encoded by Fmr1 gene in which mutation is known to cause fragile X syndrome characterized by mental impairment and other psychiatric symptoms similar to autism spectrum disorders. FMRP plays important roles in cellular mRNA biology such as transport, stability, and translation as an RNA-binding protein. In the present study, we identified potential role of FMRP in the neural differentiation, using cortical neural progenitor cells from Sprague-Dawley rat. We newly found NeuroD1, an essential regulator of glutamatergic neuronal differentiation, as a new mRNA target interacting with FMRP in co-immunoprecipitation experiments. We also identified FMRP as a regulator of neuronal differentiation by modulating NeuroD1 expression. Down-regulation of FMRP by siRNA also increased NeuroD1 expression along with increased pre- and post-synaptic development of glutamatergic neuron, as evidenced by Western blot and immunocytochemistry. On the contrary, cells harboring FMRP over-expression construct showed decreased NeuroD1 expression. Treatment of cultured neural precursor cells with a histone deacetylase inhibitor, valproic acid known as an inducer of hyper-glutamatergic neuronal differentiation, down-regulated the expression of FMRP, and induced NeuroD1 expression. Our study suggests that modulation of FMRP expression regulates neuronal differentiation by interaction with its binding target mRNA, and provides an example of the gene and environmental interaction regulating glutamatergic neuronal differentiation.

PMID: 24338128 [PubMed - indexed for MEDLINE]

Brief report: do the nature of communication impairments in autism spectrum disorders relate to the broader autism phenotype in parents?

October 17, 2014 - 2:58pm
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Brief report: do the nature of communication impairments in autism spectrum disorders relate to the broader autism phenotype in parents?

J Autism Dev Disord. 2013 Dec;43(12):2984-9

Authors: Taylor LJ, Maybery MT, Wray J, Ravine D, Hunt A, Whitehouse AJ

Abstract
Extensive empirical evidence indicates that the lesser variant of Autism Spectrum Disorders (ASD) involves a communication impairment that is similar to, but milder than, the deficit in clinical ASD. This research explored the relationship between the broader autism phenotype (BAP) among parents, an index of genetic liability for ASD, and proband communication difficulties. ASD probands with at least one BAP parent (identified using the Autism Spectrum Quotient) had greater structural and pragmatic language difficulties (assessed using the Children's Communication Checklist-2) than ASD probands with no BAP parent. This finding provides support for the position that genetic liability for ASD is associated with increased communication difficulties across structural and pragmatic domains.

PMID: 23619954 [PubMed - indexed for MEDLINE]

A Novel Ribosomopathy Caused by Dysfunction of RPL10 Disrupts Neurodevelopment and Causes X-Linked Microcephaly in Humans.

October 16, 2014 - 8:14am

A Novel Ribosomopathy Caused by Dysfunction of RPL10 Disrupts Neurodevelopment and Causes X-Linked Microcephaly in Humans.

Genetics. 2014 Oct;198(2):723-33

Authors: Brooks SS, Wall AL, Golzio C, Reid DW, Kondyles A, Willer JR, Botti C, Nicchitta CV, Katsanis N, Davis EE

Abstract
Neurodevelopmental defects in humans represent a clinically heterogeneous group of disorders. Here, we report the genetic and functional dissection of a multigenerational pedigree with an X-linked syndromic disorder hallmarked by microcephaly, growth retardation, and seizures. Using an X-linked intellectual disability (XLID) next-generation sequencing diagnostic panel, we identified a novel missense mutation in the gene encoding 60S ribosomal protein L10 (RPL10), a locus associated previously with autism spectrum disorders (ASD); the p.K78E change segregated with disease under an X-linked recessive paradigm while, consistent with causality, carrier females exhibited skewed X inactivation. To examine the functional consequences of the p.K78E change, we modeled RPL10 dysfunction in zebrafish. We show that endogenous rpl10 expression is augmented in anterior structures, and that suppression decreases head size in developing morphant embryos, concomitant with reduced bulk translation and increased apoptosis in the brain. Subsequently, using in vivo complementation, we demonstrate that p.K78E is a loss-of-function variant. Together, our findings suggest that a mutation within the conserved N-terminal end of RPL10, a protein in close proximity to the peptidyl transferase active site of the 60S ribosomal subunit, causes severe defects in brain formation and function.

PMID: 25316788 [PubMed - in process]

Maternal pre-pregnancy weight and externalising behaviour problems in preschool children: a UK-based twin study.

October 16, 2014 - 8:14am

Maternal pre-pregnancy weight and externalising behaviour problems in preschool children: a UK-based twin study.

BMJ Open. 2014;4(10):e005974

Authors: Antoniou EE, Fowler T, Reed K, Southwood TR, McCleery JP, Zeegers MP

Abstract
OBJECTIVE: To estimate the heritability of child behaviour problems and investigate the association between maternal pre-pregnancy overweight and child behaviour problems in a genetically sensitive design.
DESIGN: Observational cross-sectional study.
SETTING: The Twins and Multiple Births Association Heritability Study (TAMBAHS) is an online UK-wide volunteer-based study investigating the development of twins from birth until 5 years of age.
PARTICIPANTS: A total of 443 (16% of the initial registered members) mothers answered questions on pre-pregnancy weight and their twins' internalising and externalising problems using the Child Behavior Checklist and correcting for important covariates including gestational age, twins' birth weight, age and sex, mother's educational level and smoking (before, during and after pregnancy).
PRIMARY OUTCOMES: The heritability of behaviour problems and their association with maternal pre-pregnancy weight.
RESULTS: The genetic analysis suggested that genetic and common environmental factors account for most of the variation in externalising disorders (an ACE model was the most parsimonious with genetic factors (A) explaining 46% (95% CI 33% to 60%) of the variance, common environment (C) explaining 42% (95% CI 27% to 54%) and non-shared environmental factors (E) explaining 13% (95% CI 10% to 16%) of the variance. For internalising problems, a CE model was the most parsimonious model with the common environment explaining 51% (95% CI 44% to 58%) of the variance and non-shared environment explaining 49% (95% CI 42% to 56%) of the variance. Moreover, the regression analysis results suggested that children of overweight mothers showed a trend (OR=1.10, 95% CI 0.58% to 2.06) towards being more aggressive and exhibit externalising behaviours compared to children of normal weight mothers.
CONCLUSIONS: Maternal pre-pregnancy weight may play a role in children's aggressive behaviour.

PMID: 25314961 [PubMed - in process]

[Diagnostics of the genetic causes of autism spectrum disorders - a clinical geneticist's view].

October 16, 2014 - 8:14am

[Diagnostics of the genetic causes of autism spectrum disorders - a clinical geneticist's view].

Psychiatr Pol. 2014 Jul-Aug;48(4):677-88

Authors: Szczaluba K

Abstract
Explanation of the genetic basis of autism spectrum disorders has, for many decades, been a part of interest of researchers and clinicians. In recent years, thanks to modern molecular and cytogenetic techniques, a significant progress has been achieved in the diagnosis of genetic causes of autism. This applies particularly, but not exclusively, to those cases of autism that are accompanied by other clinical signs (i. e. complex phenotypes). The important clinical markers belong to different categories, and include congenital defects/anomalies, dysmorphism and macro-/microcephaly, to name the few. Thus, the choice of the diagnostic strategy depends on the clinical and pedigree information and, under Polish circumstances, the availability of specific diagnostic techniques and the amount of reimbursement under the National Health Service. Overall, the identification of the genetic causes of autism spectrum disorders is possible in about 10-30% of patients. In this paper the practical aspects of the use of different diagnostic techniques are briefly described. Some clinical examples and current recommendations for the diagnosis of patients with autism spectrum disorders are also presented. The point of view of a specialist in clinical genetics, increasingly involved, as part of the multidisciplinary care team, in the diagnostics of an autistic child has been demonstrated.

PMID: 25314796 [PubMed - in process]

Increased CYFIP1 dosage alters cellular and dendritic morphology and dysregulates mTOR.

October 15, 2014 - 7:30am

Increased CYFIP1 dosage alters cellular and dendritic morphology and dysregulates mTOR.

Mol Psychiatry. 2014 Oct 14;

Authors: Oguro-Ando A, Rosensweig C, Herman E, Nishimura Y, Werling D, Bill BR, Berg JM, Gao F, Coppola G, Abrahams BS, Geschwind DH

Abstract
Rare maternally inherited duplications at 15q11-13 are observed in ~1% of individuals with an autism spectrum disorder (ASD), making it among the most common causes of ASD. 15q11-13 comprises a complex region, and as this copy number variation encompasses many genes, it is important to explore individual genotype-phenotype relationships. Cytoplasmic FMR1-interacting protein 1 (CYFIP1) is of particular interest because of its interaction with Fragile X mental retardation protein (FMRP), its upregulation in transformed lymphoblastoid cell lines from patients with duplications at 15q11-13 and ASD and the presence of smaller overlapping deletions of CYFIP1 in patients with schizophrenia and intellectual disability. Here, we confirm that CYFIP1 is upregulated in transformed lymphoblastoid cell lines and demonstrate its upregulation in the post-mortem brain from 15q11-13 duplication patients for the first time. To investigate how increased CYFIP1 dosage might predispose to neurodevelopmental disease, we studied the consequence of its overexpression in multiple systems. We show that overexpression of CYFIP1 results in morphological abnormalities including cellular hypertrophy in SY5Y cells and differentiated mouse neuronal progenitors. We validate these results in vivo by generating a BAC transgenic mouse, which overexpresses Cyfip1 under the endogenous promotor, observing an increase in the proportion of mature dendritic spines and dendritic spine density. Gene expression profiling on embryonic day 15 suggested the dysregulation of mammalian target of rapamycin (mTOR) signaling, which was confirmed at the protein level. Importantly, similar evidence of mTOR-related dysregulation was seen in brains from 15q11-13 duplication patients with ASD. Finally, treatment of differentiated mouse neuronal progenitors with an mTOR inhibitor (rapamycin) rescued the morphological abnormalities resulting from CYFIP1 overexpression. Together, these data show that CYFIP1 overexpression results in specific cellular phenotypes and implicate modulation by mTOR signaling, further emphasizing its role as a potential convergent pathway in some forms of ASD.Molecular Psychiatry advance online publication, 14 October 2014; doi:10.1038/mp.2014.124.

PMID: 25311365 [PubMed - as supplied by publisher]

Generation of Mice Lacking DUF1220 Protein Domains: Effects on Fecundity and Hyperactivity.

October 14, 2014 - 7:12am

Generation of Mice Lacking DUF1220 Protein Domains: Effects on Fecundity and Hyperactivity.

Mamm Genome. 2014 Oct 12;

Authors: Keeney JG, O'Bleness MS, Anderson N, Davis JM, Arevalo N, Busquet N, Chick W, Rozman J, Hölter SM, Garrett L, Horsch M, Beckers J, Wurst W, Klingenspor M, Restrepo D, German Mouse Clinic Consortium, Sikela JM, de Angelis MH

Abstract
Sequences encoding DUF1220 protein domains show the most extreme human lineage-specific copy number increase of any coding region in the genome and have been linked to human brain evolution. In addition, DUF1220 copy number (dosage) has been implicated in influencing brain size within the human species, both in normal populations and in individuals associated with brain size pathologies (1q21-associated microcephaly and macrocephaly). More recently, increasing dosage of a subtype of DUF1220 has been linked with increasing severity of the primary symptoms of autism. Despite these intriguing associations, a function for these domains has not been described. As a first step in addressing this question, we have developed the first transgenic model of DUF1220 function by removing the single DUF1220 domain (the ancestral form) encoded in the mouse genome. In a hypothesis generating exercise, these mice were evaluated by 197 different phenotype measurements. While resulting DUF1220-minus (KO) mice show no obvious anatomical peculiarities, they exhibit a significantly reduced fecundity (χ (2) = 19.1, df = 2, p = 7.0 × 10(-5)). Further extensive phenotypic analyses suggest hyperactivity (p < 0.05) of DUF1220 mice and changes in gene expression levels of brain associated with distinct neurological functions and disease. Other changes that met statistical significance include an increase in plasma glucose concentration (as measured by area under the curve, AUC 0-30 and AUC 30-120) in male mutants, fasting glucose levels, reduce sodium levels in male mutants, increased levels of the liver functional indicator ALAT/GPT in males, levels of alkaline phosphatase (also an indicator of liver function), mean R and SR amplitude by electrocardiography, elevated IgG3 levels, a reduced ratio of CD4:CD8 cells, and a reduced frequency of T cells; though it should be noted that many of these differences are quite small and require further examination. The linking of DUF1220 loss to a hyperactive phenotype is consistent with separate findings in which DUF1220 over expression results in a down-regulation of mitochondrial function, and potentially suggests a role in developmental metabolism. Finally, the substantially reduced fecundity we observe associated with KO mice argues that the ancestral DUF1220 domain provides an important biological functionthat is critical to survivability and reproductive success.

PMID: 25308000 [PubMed - as supplied by publisher]

Autism associated gene, engrailed2, and flanking gene levels are altered in post-mortem cerebellum.

October 14, 2014 - 7:12am
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Autism associated gene, engrailed2, and flanking gene levels are altered in post-mortem cerebellum.

PLoS One. 2014;9(2):e87208

Authors: Choi J, Ababon MR, Soliman M, Lin Y, Brzustowicz LM, Matteson PG, Millonig JH

Abstract
BACKGROUND: Previous genetic studies demonstrated association between the transcription factor engrailed2 (EN2) and Autism Spectrum Disorder (ASD). Subsequent molecular analysis determined that the EN2 ASD-associated haplotype (rs1861972-rs1861973 A-C) functions as a transcriptional activator to increase gene expression. EN2 is flanked by 5 genes, serotonin receptor5a (HTR5A), insulin induced gene1 (INSIG1), canopy1 homolog (CNPY1), RNA binding motif protein33 (RBM33), and sonic hedgehog (SHH). These flanking genes are co-expressed with EN2 during development and coordinate similar developmental processes. To investigate if mRNA levels for these genes are altered in individuals with autism, post-mortem analysis was performed.
METHODS: qRT-PCR quantified mRNA levels for EN2 and the 5 flanking genes in 78 post-mortem cerebellar samples. mRNA levels were correlated with both affection status and rs1861972-rs1861973 genotype. Molecular analysis investigated whether EN2 regulates flanking gene expression.
RESULTS: EN2 levels are increased in affected A-C/G-T individuals (p = .0077). Affected individuals also display a significant increase in SHH and a decrease in INSIG1 levels. Rs1861972-rs1861973 genotype is correlated with significant increases for SHH (A-C/G-T) and CNPY1 (G-T/G-T) levels. Human cell line over-expression and knock-down as well as mouse knock-out analysis are consistent with EN2 and SHH being co-regulated, which provides a possible mechanism for increased SHH post-mortem levels.
CONCLUSIONS: EN2 levels are increased in affected individuals with an A-C/G-T genotype, supporting EN2 as an ASD susceptibility gene. SHH, CNPY1, and INSIG1 levels are also significantly altered depending upon affection status or rs1861972-rs1861973 genotype. Increased EN2 levels likely contribute to elevated SHH expression observed in the post-mortem samples.

PMID: 24520327 [PubMed - indexed for MEDLINE]

Increased placental trophoblast inclusions in placenta accreta.

October 13, 2014 - 6:36am

Increased placental trophoblast inclusions in placenta accreta.

Placenta. 2014 Oct 2;

Authors: Adler E, Madankumar R, Rosner M, Reznik SE

Abstract
INTRODUCTION: Trophoblast inclusions (TIs) are often found in placentas of genetically abnormal gestations. Although best documented in placentas from molar pregnancies and chromosomal aneuploidy, TIs are also associated with more subtle genetic abnormalities, and possibly autism. Less than 3% of non-aneuploid, non-accreta placentas have TIs. We hypothesize that placental genetics may play a role in the development of placenta accreta and aim to study TIs as a potential surrogate indicator of abnormal placental genetics.
METHODS: Forty cases of placenta accreta in the third trimester were identified in a search of the medical records at one institution. Forty two third trimester control placentas were identified by a review of consecutively received single gestation placentas with no known genetic abnormalities and no diagnosis of placenta accreta.
RESULTS: Forty percent of cases with placenta accreta demonstrated TIs compared to 2.4% of controls. More invasive placenta accretas (increta and percreta) were more likely to demonstrate TIs than accreta (47% versus 20%). Prior cesarean delivery was more likely in accreta patients than controls (67% versus 9.5%).
DISCUSSION: Placenta accreta is thought to be the result of damage to the endometrium predisposing to abnormal decidualization and invasive trophoblast growth into the myometrium. However, the etiology of accreta is incompletely understood with accreta frequently occurring in women without predisposing factors and failing to occur in predisposed patients.
CONCLUSION: This study has shown that TIs are present at increased rates in cases of PA. Further studies are needed to discern what underlying pathogenic mechanisms are in common between abnormal placentation and the formation of TIs.

PMID: 25305693 [PubMed - as supplied by publisher]

Novel IL1RAPL1 mutations associated with intellectual disability impair synaptogenesis.

October 12, 2014 - 6:15am

Novel IL1RAPL1 mutations associated with intellectual disability impair synaptogenesis.

Hum Mol Genet. 2014 Oct 9;

Authors: Ramos-Brossier M, Montani C, Lebrun N, Gritti L, Martin C, Seminatore-Nole C, Toussaint A, Moreno S, Poirier K, Dorseuil O, Chelly J, Hackett A, Gecz J, Bieth E, Faudet A, Heron D, Kooy RF, Loeys B, Humeau Y, Sala C, Billuart P

Abstract
Mutations in interleukin-1 receptor accessory protein like 1 (IL1RAPL1) gene have been associated with non-syndromic intellectual disability and autism spectrum disorder. This protein interacts with synaptic partners like PSD-95 and PTPδ, regulating the formation and function of excitatory synapses. The aim of this work is to characterize the synaptic consequences of three IL1RAPL1 mutations, two novel causing the deletion of exon 6 (Δex6) and one point mutation (C31R), identified in patients with intellectual disability. Using immunofluorescence and electrophysiological recordings we examined the effects of IL1RAPL1 mutants over-expression on synapse formation and function in cultured rodent hippocampal neurons. Δex6 but not C31R mutation leads to IL1RAPL1 protein instability and mislocalization within dendrites. Analysis of different markers of excitatory synapses and sEPSC recording revealed that both mutants fail to induce pre- and post-synaptic differentiation, contrary to WT IL1RAPL1 protein. Cell aggregation and immunoprecipitation assays in HEK293 cells showed a reduction of the interaction between IL1RAPL1 mutants and PTPδ that could explain the observed synaptogenic defect in neurons. However, these mutants do not affect all cellular signaling since their over-expression still activates JNK pathway. We conclude that both mutations described in this study lead to a partial loss of function of the IL1RAPL1 protein through different mechanisms. Our work highlights the important function of the trans-synaptic PTPδ/ IL1RAPL1 interaction in synaptogenesis and as such, in intellectual disability in the patients.

PMID: 25305082 [PubMed - as supplied by publisher]

Common and rare variants of the THBS1 gene associated with the risk for autism.

October 12, 2014 - 6:15am

Common and rare variants of the THBS1 gene associated with the risk for autism.

Psychiatr Genet. 2014 Oct 10;

Authors: Lu L, Guo H, Peng Y, Xun G, Liu Y, Xiong Z, Tian D, Liu Y, Li W, Xu X, Zhao J, Hu Z, Xia K

Abstract
OBJECTIVES: Autism is a severe neurodevelopmental disorder. Many susceptible or causative genes have been identified, and most of them are related to synaptogenesis. The THBS1 gene encodes thrombospondin 1, which plays a critical role in synaptogenesis of the central nervous system in the developing brain. However, no study has been carried out revealing that THBS1 is an autism risk gene.
METHODS: We analyzed the whole coding region and the 5'-untranslated region of the THBS1 gene in 313 autistic patients by Sanger sequencing, which was also used to analyze the identified variants in 350 normal controls. Association analysis was carried out using PLINK or R. Haplotype analysis was carried out using Haploview. Functional prediction and conservation analysis of missense variants were carried out using ANNOVAR.
RESULTS: Twelve variants, including five common variants and seven rare variants, were identified in the THBS1 coding region and the 5'-untranslated region. Among them, one common variant (c.1567A>G:p.T523A) was significantly associated with autism (P<0.05). Two rare variants (c.2429G>A:p.R810Q, c.3496G>C:p.E1166Q) were absent in the 350 controls and were not reported in the single nucleotide polymorphism database (dbSNP). Combined association analysis of the rare variants (minor allele frequency<0.01) in patients and Asian samples in the 1000 genome project revealed a significant association between these rare variants and autism (P=0.039).
CONCLUSION: Our data revealed that both common and rare variants of the THBS1 gene are associated with risk for autism, suggesting that THBS1 is a novel susceptible gene for autism.

PMID: 25304225 [PubMed - as supplied by publisher]

A direct molecular link between the autism candidate gene RORa and the schizophrenia candidate MIR137.

October 11, 2014 - 8:57am
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A direct molecular link between the autism candidate gene RORa and the schizophrenia candidate MIR137.

Sci Rep. 2014;4:3994

Authors: Devanna P, Vernes SC

Abstract
Retinoic acid-related orphan receptor alpha gene (RORa) and the microRNA MIR137 have both recently been identified as novel candidate genes for neuropsychiatric disorders. RORa encodes a ligand-dependent orphan nuclear receptor that acts as a transcriptional regulator and miR-137 is a brain enriched small non-coding RNA that interacts with gene transcripts to control protein levels. Given the mounting evidence for RORa in autism spectrum disorders (ASD) and MIR137 in schizophrenia and ASD, we investigated if there was a functional biological relationship between these two genes. Herein, we demonstrate that miR-137 targets the 3'UTR of RORa in a site specific manner. We also provide further support for MIR137 as an autism candidate by showing that a large number of previously implicated autism genes are also putatively targeted by miR-137. This work supports the role of MIR137 as an ASD candidate and demonstrates a direct biological link between these previously unrelated autism candidate genes.

PMID: 24500708 [PubMed - indexed for MEDLINE]

Association of the FGA and SLC6A4 genes with autistic spectrum disorder in a Korean population.

October 11, 2014 - 8:57am
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Association of the FGA and SLC6A4 genes with autistic spectrum disorder in a Korean population.

Neuropsychobiology. 2013;68(4):212-20

Authors: Ro M, Won S, Kang H, Kim SY, Lee SK, Nam M, Bang HJ, Yang JW, Choi KS, Kim SK, Chung JH, Kwack K

Abstract
BACKGROUND: Autism spectrum disorder (ASD) is a neurobiological disorder characterized by distinctive impairments in cognitive function, language, and behavior. Linkage and population studies suggest a genetic association between solute carrier family 6 member 4 (SLC6A4) variants and ASD.
METHOD: Logistic regression was used to identify associations between single-nucleotide polymorphisms (SNPs) and ASD with 3 alternative models (additive, dominant, and recessive). Linear regression analysis was performed to determine the influence of SNPs on Childhood Autism Rating Scale (CARS) scores as a quantitative phenotype.
RESULTS: In the present study, we examined the associations of SNPs in the SLC6A4 gene and the fibrinogen alpha chain (FGA) gene. Logistic regression analysis showed a significant association between the risk of ASD and rs2070025 and rs2070011 in the FGA gene. The gene-gene interaction between SLC6A4 and FGA was not significantly associated with ASD susceptibility. However, polymorphisms in both SLC6A4 and the FGA gene significantly affected the symptoms of ASD.
CONCLUSION: Our findings indicate that FGA and SLC6A4 gene interactions may contribute to the phenotypes of ASD rather than the incidence of ASD.

PMID: 24192574 [PubMed - indexed for MEDLINE]

Acetylcholine elevation relieves cognitive rigidity and social deficiency in a mouse model of autism.

October 11, 2014 - 8:57am
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Acetylcholine elevation relieves cognitive rigidity and social deficiency in a mouse model of autism.

Neuropsychopharmacology. 2014 Mar;39(4):831-40

Authors: Karvat G, Kimchi T

Abstract
Autism spectrum disorders (ASD) are defined by behavioral deficits in social interaction and communication, repetitive stereotyped behaviors, and restricted interests/cognitive rigidity. Recent studies in humans and animal-models suggest that dysfunction of the cholinergic system may underlie autism-related behavioral symptoms. Here we tested the hypothesis that augmentation of acetylcholine (ACh) in the synaptic cleft by inhibiting acetylcholinesterase may ameliorate autistic phenotypes. We first administered the acetylcholinesterase inhibitor (AChEI) Donepezil systemically by intraperitoneal (i.p.) injections. Second, the drug was injected directly into the rodent homolog of the caudate nucleus, the dorsomedial striatum (DMS), of the inbred mouse strain BTBR T+tf/J (BTBR), a commonly-used model presenting all core autism-related phenotypes and expressing low brain ACh levels. We found that i.p. injection of AChEI to BTBR mice significantly relieved autism-relevant phenotypes, including decreasing cognitive rigidity, improving social preference, and enhancing social interaction, in a dose-dependent manner. Microinjection of the drug directly into the DMS, but not into the ventromedial striatum, led to significant amelioration of the cognitive-rigidity and social-deficiency phenotypes. Taken together, these findings provide evidence of the key role of the cholinergic system and the DMS in the etiology of ASD, and suggest that elevated cognitive flexibility may result in enhanced social attention. The potential therapeutic effect of AChEIs in ASD patients is discussed.

PMID: 24096295 [PubMed - indexed for MEDLINE]

CHD8 regulates neurodevelopmental pathways associated with autism spectrum disorder in neural progenitors.

October 9, 2014 - 7:53am

CHD8 regulates neurodevelopmental pathways associated with autism spectrum disorder in neural progenitors.

Proc Natl Acad Sci U S A. 2014 Oct 7;

Authors: Sugathan A, Biagioli M, Golzio C, Erdin S, Blumenthal I, Manavalan P, Ragavendran A, Brand H, Lucente D, Miles J, Sheridan SD, Stortchevoi A, Kellis M, Haggarty SJ, Katsanis N, Gusella JF, Talkowski ME

Abstract
Truncating mutations of chromodomain helicase DNA-binding protein 8 (CHD8), and of many other genes with diverse functions, are strong-effect risk factors for autism spectrum disorder (ASD), suggesting multiple mechanisms of pathogenesis. We explored the transcriptional networks that CHD8 regulates in neural progenitor cells (NPCs) by reducing its expression and then integrating transcriptome sequencing (RNA sequencing) with genome-wide CHD8 binding (ChIP sequencing). Suppressing CHD8 to levels comparable with the loss of a single allele caused altered expression of 1,756 genes, 64.9% of which were up-regulated. CHD8 showed widespread binding to chromatin, with 7,324 replicated sites that marked 5,658 genes. Integration of these data suggests that a limited array of direct regulatory effects of CHD8 produced a much larger network of secondary expression changes. Genes indirectly down-regulated (i.e., without CHD8-binding sites) reflect pathways involved in brain development, including synapse formation, neuron differentiation, cell adhesion, and axon guidance, whereas CHD8-bound genes are strongly associated with chromatin modification and transcriptional regulation. Genes associated with ASD were strongly enriched among indirectly down-regulated loci (P < 10(-8)) and CHD8-bound genes (P = 0.0043), which align with previously identified coexpression modules during fetal development. We also find an intriguing enrichment of cancer-related gene sets among CHD8-bound genes (P < 10(-10)). In vivo suppression of chd8 in zebrafish produced macrocephaly comparable to that of humans with inactivating mutations. These data indicate that heterozygous disruption of CHD8 precipitates a network of gene-expression changes involved in neurodevelopmental pathways in which many ASD-associated genes may converge on shared mechanisms of pathogenesis.

PMID: 25294932 [PubMed - as supplied by publisher]

Childhood acne in a boy with XYY syndrome.

October 9, 2014 - 7:53am
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Childhood acne in a boy with XYY syndrome.

BMJ Case Rep. 2014;2014

Authors: Kasparis C, Loffeld A

Abstract
A 3-year-old boy was referred to the dermatology department with a 12-month history of facial erythema associated with a papular-pustular facial eruption consistent with childhood acne. He had been diagnosed with XYY syndrome identified during genetic analysis for cardiac anomalies at birth. XYY syndrome is an aneuploidy of the sex chromosomes which affects 1 in 1000 male births. It is often asymptomatic and identified incidentally following genetic analysis for other conditions. The syndrome can be associated with an increased risk of learning difficulties and delayed language skills. Early diagnosis could alert physicians to the possibility of subtle developmental and learning abnormalities and result in prompt management. Our case highlights the fact that the presence of childhood acne could aid in the early detection of XYY syndrome.

PMID: 24395875 [PubMed - indexed for MEDLINE]

Elevated 5-hydroxymethylcytosine in the Engrailed-2 (EN-2) promoter is associated with increased gene expression and decreased MeCP2 binding in autism cerebellum.

October 8, 2014 - 7:42am

Elevated 5-hydroxymethylcytosine in the Engrailed-2 (EN-2) promoter is associated with increased gene expression and decreased MeCP2 binding in autism cerebellum.

Transl Psychiatry. 2014;4:e460

Authors: James SJ, Shpyleva S, Melnyk S, Pavliv O, Pogribny IP

Abstract
Epigenetic mechanisms regulate programmed gene expression during prenatal neurogenesis and serve as a mediator between genetics and environment in postnatal life. The recent discovery of 5-hydroxymethylcytosine (5-hmC), with highest concentration in the brain, has added a new dimension to epigenetic regulation of neurogenesis and the development of complex behavior disorders. Here, we take a candidate gene approach to define the role 5-hmC in Engrailed-2 (EN-2) gene expression in the autism cerebellum. The EN-2 homeobox transcription factor, previously implicated in autism, is essential for normal cerebellar patterning and development. We previously reported EN-2 overexpression associated with promoter DNA hypermethylation in the autism cerebellum but because traditional DNA methylation methodology cannot distinguish 5-methylcytosine (5-mC) from 5-hmC, we now extend our investigation by quantifying global and gene-specific 5-mC and 5-hmC. Globally, 5-hmC was significantly increased in the autism cerebellum and accompanied by increases in the expression of de novo methyltransferases DNMT3A and DNMT3B, ten-eleven translocase genes TET1 and TET3, and in 8-oxo-deoxyguanosine (8-oxo-dG) content, a marker of oxidative DNA damage. Within the EN-2 promoter, there was a significant positive correlation between 5-hmC content and EN-2 gene expression. Based on reports of reduced MeCP2 affinity for 5-hmC, MeCP2 binding studies in the EN-2 promoter revealed a significant decrease in repressive MeCP2 binding that may contribute to the aberrant overexpression of EN-2. Because normal cerebellar development depends on perinatal EN-2 downregulation, the sustained postnatal overexpression suggests that a critical window of cerebellar development may have been missed in some individuals with autism with downstream developmental consequences. Epigenetic regulation of the programmed on-off switches in gene expression that occur at birth and during early brain development warrants further investigation.

PMID: 25290267 [PubMed - as supplied by publisher]

Autism spectrum disorder severity reflects the average contribution of de novo and familial influences.

October 8, 2014 - 7:42am

Autism spectrum disorder severity reflects the average contribution of de novo and familial influences.

Proc Natl Acad Sci U S A. 2014 Oct 6;

Authors: Robinson EB, Samocha KE, Kosmicki JA, McGrath L, Neale BM, Perlis RH, Daly MJ

Abstract
Autism spectrum disorders (ASDs) are a highly heterogeneous group of conditions-phenotypically and genetically-although the link between phenotypic variation and differences in genetic architecture is unclear. This study aimed to determine whether differences in cognitive impairment and symptom severity reflect variation in the degree to which ASD cases reflect de novo or familial influences. Using data from more than 2,000 simplex cases of ASD, we examined the relationship between intelligence quotient (IQ), behavior and language assessments, and rate of de novo loss of function (LOF) mutations and family history of broadly defined psychiatric disease (depressive disorders, bipolar disorder, and schizophrenia; history of psychiatric hospitalization). Proband IQ was negatively associated with de novo LOF rate (P = 0.03) and positively associated with family history of psychiatric disease (P = 0.003). Female cases had a higher frequency of sporadic genetic events across the severity distribution (P = 0.01). High rates of LOF mutation and low frequencies of family history of psychiatric illness were seen in individuals who were unable to complete a traditional IQ test, a group with the greatest degree of language and behavioral impairment. These analyses provide strong evidence that familial risk for neuropsychiatric disease becomes more relevant to ASD etiology as cases become higher functioning. The findings of this study reinforce that there are many routes to the diagnostic category of autism and could lead to genetic studies with more specific insights into individual cases.

PMID: 25288738 [PubMed - as supplied by publisher]

DUF1220 copy number is linearly associated with increased cognitive function as measured by total IQ and mathematical aptitude scores.

October 8, 2014 - 7:42am

DUF1220 copy number is linearly associated with increased cognitive function as measured by total IQ and mathematical aptitude scores.

Hum Genet. 2014 Oct 7;

Authors: Davis JM, Searles VB, Anderson N, Keeney J, Raznahan A, Horwood LJ, Fergusson DM, Kennedy MA, Giedd J, Sikela JM

Abstract
DUF1220 protein domains exhibit the greatest human lineage-specific copy number expansion of any protein-coding sequence in the genome, and variation in DUF1220 copy number has been linked to both brain size in humans and brain evolution among primates. Given these findings, we examined associations between DUF1220 subtypes CON1 and CON2 and cognitive aptitude. We identified a linear association between CON2 copy number and cognitive function in two independent populations of European descent. In North American males, an increase in CON2 copy number corresponded with an increase in WISC IQ (R (2) = 0.13, p = 0.02), which may be driven by males aged 6-11 (R (2) = 0.42, p = 0.003). We utilized ddPCR in a subset as a confirmatory measurement. This group had 26-33 copies of CON2 with a mean of 29, and each copy increase of CON2 was associated with a 3.3-point increase in WISC IQ (R (2) = 0.22, p = 0.045). In individuals from New Zealand, an increase in CON2 copy number was associated with an increase in math aptitude ability (R (2) = 0.10 p = 0.018). These were not confounded by brain size. To our knowledge, this is the first study to report a replicated association between copy number of a gene coding sequence and cognitive aptitude. Remarkably, dosage variations involving DUF1220 sequences have now been linked to human brain expansion, autism severity and cognitive aptitude, suggesting that such processes may be genetically and mechanistically inter-related. The findings presented here warrant expanded investigations in larger, well-characterized cohorts.

PMID: 25287832 [PubMed - as supplied by publisher]

Fragile X Syndrome: A Review of Associated Medical Problems.

October 8, 2014 - 7:42am

Fragile X Syndrome: A Review of Associated Medical Problems.

Pediatrics. 2014 Oct 6;

Authors: Kidd SA, Lachiewicz A, Barbouth D, Blitz RK, Delahunty C, McBrien D, Visootsak J, Berry-Kravis E

Abstract
Fragile X syndrome (FXS) is the most common known genetic cause of inherited intellectual disability and the most common known single-gene cause of autism spectrum disorder. It has been reported that a spectrum of medical problems are commonly experienced by people with FXS, such as otitis media, seizures, and gastrointestinal problems. Previous studies examining the prevalence of medical problems related to FXS have been challenging to interpret because of their marked differences in population, setting, and sampling. Through this comprehensive review, we update the literature by reviewing studies that have reported on prominent medical problems associated with FXS. We then compare prevalence results from those studies with results from a large cross-sectional database consisting of data collected by fragile X clinics that specialize in the care of children with FXS and are part of the Fragile X Clinical and Research Consortium. It is vital for pediatricians and other clinicians to be familiar with the medical problems related to FXS so that affected patients may receive proper diagnosis and treatment; improved care may lead to better quality of life for these patients and their families.

PMID: 25287458 [PubMed - as supplied by publisher]

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