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Behavioural markers for autism in infancy: scores on the Autism Observational Scale for Infants in a prospective study of at-risk siblings.

August 21, 2015 - 7:22am
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Behavioural markers for autism in infancy: scores on the Autism Observational Scale for Infants in a prospective study of at-risk siblings.

Infant Behav Dev. 2015 Feb;38:107-15

Authors: Gammer I, Bedford R, Elsabbagh M, Garwood H, Pasco G, Tucker L, Volein A, Johnson MH, Charman T, BASIS Team

Abstract
We investigated early behavioural markers of autism spectrum disorder (ASD) using the Autism Observational Scale for Infants (AOSI) in a prospective familial high-risk (HR) sample of infant siblings (N=54) and low-risk (LR) controls (N=50). The AOSI was completed at 7 and 14 month infant visits and children were seen again at age 24 and 36 months. Diagnostic outcome of ASD (HR-ASD) versus no ASD (HR-No ASD) was determined for the HR sample at the latter timepoint. The HR group scored higher than the LR group at 7 months and marginally but non-significantly higher than the LR group at 14 months, although these differences did not remain when verbal and nonverbal developmental level were covaried. The HR-ASD outcome group had higher AOSI scores than the LR group at 14 months but not 7 months, even when developmental level was taken into account. The HR-No ASD outcome group had scores intermediate between the HR-ASD and LR groups. At both timepoints a few individual items were higher in the HR-ASD and HR-No ASD outcome groups compared to the LR group and these included both social (e.g. orienting to name) and non-social (e.g. visual tracking) behaviours. AOSI scores at 14 months but not at 7 months were moderately correlated with later scores on the autism diagnostic observation schedule (ADOS) suggesting continuity of autistic-like behavioural atypicality but only from the second and not first year of life. The scores of HR siblings who did not go on to have ASD were intermediate between the HR-ASD outcome and LR groups, consistent with the notion of a broader autism phenotype.

PMID: 25656952 [PubMed - indexed for MEDLINE]

Autism and anxiety in males with fragile X syndrome: an exploratory analysis of neurobehavioral profiles from a parent survey.

August 21, 2015 - 7:22am
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Autism and anxiety in males with fragile X syndrome: an exploratory analysis of neurobehavioral profiles from a parent survey.

Am J Med Genet A. 2014 May;164A(5):1198-203

Authors: Talisa VB, Boyle L, Crafa D, Kaufmann WE

Abstract
Although it is suspected that anxiety modifies the clinical presentation of autism in fragile X syndrome (FXS), neuropsychiatric co-morbidity profiles of these two disorders have not been extensively studied. The National Fragile X Survey was completed for 1,027 males with FXS, for whom yes/no information regarding the presence of several disorders is provided. Although the survey exhibited limited depth and lacked validation by standardized measures, this exploratory study was conducted to take advantage of the data as an opportunity for identifying future lines of inquiry. We addressed the following questions: (i) how do the co-morbidity profiles of FXS males with both autism and anxiety compare to those without anxiety?; (ii) do individuals with autism exhibit specific co-morbidity profiles compared to FXS males with anxiety only, or without either autism or anxiety?; (iii) how do co-morbidity profiles in children ages 3-11 differ from profiles of individuals >12 years? The group with autism and anxiety reported the highest prevalence of attention problems, hyperactivity/impulsivity, self-injurious behavior and aggressiveness. In addition, the lowest prevalence rates of these conditions were often observed in non-anxious groups regardless of autism status. Overall, this exploratory analysis generated several hypotheses for further study: (i) anxiety increases the severity of autism in FXS, particularly through additional behavioral abnormalities; (ii) some neuropsychiatric and behavioral conditions (i.e., attention problems, hyperactivity/impulsivity, aggressiveness) are primarily related to comorbid anxiety, not autism; (iii) prevalence of behavioral abnormalities increases with age. Future studies evaluating these hypotheses should incorporate validated neurobehavioral assessments, and control for cognitive level.

PMID: 24664669 [PubMed - indexed for MEDLINE]

Scoliosis and vertebral anomalies: additional abnormal phenotypes associated with chromosome 16p11.2 rearrangement.

August 21, 2015 - 7:22am
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Scoliosis and vertebral anomalies: additional abnormal phenotypes associated with chromosome 16p11.2 rearrangement.

Am J Med Genet A. 2014 May;164A(5):1118-26

Authors: Al-Kateb H, Khanna G, Filges I, Hauser N, Grange DK, Shen J, Smyser CD, Kulkarni S, Shinawi M

Abstract
The typical chromosome 16p11.2 rearrangements are estimated to occur at a frequency of approximately 0.6% of all samples tested clinically and have been identified as a major cause of autism spectrum disorders, developmental delay, behavioral abnormalities, and seizures. Careful examination of patients with these rearrangements revealed association with abnormal head size, obesity, dysmorphism, and congenital abnormalities. In this report, we extend this list of phenotypic abnormalities to include scoliosis and vertebral anomalies. We present detailed characterization of phenotypic and radiological data of 10 new patients, nine with the 16p11.2 deletion and one with the duplication within the coordinates chr16:29,366,195 and 30,306,956 (hg19) with a minimal size of 555 kb. We discuss the phenotypical and radiological findings in our patients and review 5 previously reported patients with 16p11.2 rearrangement and similar skeletal abnormalities. Our data suggest that patients with the recurrent 16p11.2 rearrangement have increased incidence of scoliosis and vertebral anomalies. However, additional studies are required to confirm this observation and to establish the incidence of these anomalies. We discuss the potential implications of our findings on the diagnosis, surveillance and genetic counseling of patients with 16p11.2 rearrangement.

PMID: 24458548 [PubMed - indexed for MEDLINE]

Variant Rett syndrome in a girl with a pericentric X-chromosome inversion leading to epigenetic changes and overexpression of the MECP2 gene.

August 20, 2015 - 6:14am

Variant Rett syndrome in a girl with a pericentric X-chromosome inversion leading to epigenetic changes and overexpression of the MECP2 gene.

Int J Dev Neurosci. 2015 Aug 10;

Authors: Vieira JP, Lopes F, Silva-Fernandes A, Sousa MV, Moura S, Sousa S, Costa BM, Barbosa M, Ylstra B, Temudo T, Lourenço T, Maciel P

Abstract
Rett syndrome is a neurodevelopmental disorder caused by mutations in the MECP2 gene. We investigated the genetic basis of disease in a female patient with a Rett-like clinical. Karyotype analysis revealed a pericentric inversion in the X chromosome -46,X,inv(X)(p22.1q28), with breakpoints in the cytobands where the MECP2 and CDKL5 genes are located. FISH analysis revealed that the MECP2 gene is not dislocated by the inversion. However, and in spite of a balanced pattern of X inactivation, this patient displayed hypomethylation and an overexpression of the MECP2 gene at the mRNA level in the lymphocytes (mean fold change: 2.55±0.38) in comparison to a group of control individuals; the expression of the CDKL5 gene was similar to that of controls (mean fold change: 0.98±0.10). No gains or losses were detected in the breakpoint regions encompassing known or suspected transcription regulatory elements. We propose that the de-regulation of MECP2 expression in this patient may be due to alterations in long-range genomic interactions caused by the inversion and hypothesize that this type of epigenetic de-regulation of the MECP2 may be present in other RTT-like patients.

PMID: 26287660 [PubMed - as supplied by publisher]

Association and gene-gene interactions study of reelin signaling pathway related genes with autism in the Han Chinese population.

August 20, 2015 - 6:14am
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Association and gene-gene interactions study of reelin signaling pathway related genes with autism in the Han Chinese population.

Autism Res. 2015 Aug 19;

Authors: Shen Y, Xun G, Guo H, He Y, Ou J, Dong H, Xia K, Zhao J

Abstract
Autism is a neurodevelopmental disorder with unclear etiology. Reelin had been proposed to participate in the etiology of autism due to its important role in brain development. The goal of this study was to explore the association and gene-gene interactions of reelin signaling pathway related genes (RELN, VLDLR, LRP8, DAB1, FYN, and CDK5) with autism in Han Chinese population. Genotyping data of the six genes were obtained from a recent genome-wide association study performed in 430 autistic children who fulfilled the DSM-IV-TR criteria for autistic disorder, and 1,074 healthy controls. Single marker case-control association analysis and haplotype case-control association analysis were conducted after the data was screened. Multifactor dimensionality reduction (MDR) was applied to further test gene-gene interactions. Neither the single marker nor the haplotype association tests found any significant difference between the autistic group and the control group after permutation test of 1,000 rounds. The 4-locus MDR model (comprising rs6143734, rs1858782, rs634500, and rs1924267 which belong to RELN and DAB1) was determined to be the model with the highest cross-validation consistency (CVC) and testing balanced accuracy. The results indicate that an interaction between RELN and DAB1 may increase the risk of autism in the Han Chinese population. Furthermore, it can also be inferred that the involvement of RELN in the etiology of autism would occur through interaction with DAB1. Autism Res 2015. © 2015 International Society for Autism Research, Wiley Periodicals, Inc.

PMID: 26285919 [PubMed - as supplied by publisher]

A new syndrome of intellectual disability with dysmorphism due to TBL1XR1 deletion.

August 20, 2015 - 6:14am
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A new syndrome of intellectual disability with dysmorphism due to TBL1XR1 deletion.

Am J Med Genet A. 2015 Jan;167A(1):164-8

Authors: Pons L, Cordier MP, Labalme A, Till M, Louvrier C, Schluth-Bolard C, Lesca G, Edery P, Sanlaville D

Abstract
We report here on an 8-year-old girl and her mother, both displaying similar facial dysmorphism, speech delay, and mild to moderate intellectual disability. Array-CGH studies revealed the same interstitial 3q26.32 microdeletion encompassing a single coding gene, TBL1XR1, in both patients. The TBL1XR1 protein, which has four WD40 repeats, has been shown to bind the nuclear corepressor (NCOR) and histone deacetylase-3 complexes (HDAC3). TBL1XR1 mutations have recently been implicated in autism spectrum disorders, but our patients displayed no autistic behavior. Our findings suggest that TBL1XR1 haploinsufficiency can cause intellectual disability with a recognizable dysmorphism, without necessarily causing autistic behavior.

PMID: 25425123 [PubMed - indexed for MEDLINE]

Complex de novo chromosomal rearrangement at 15q11-q13 involving an intrachromosomal triplication in a patient with a severe neuropsychological phenotype: clinical report and review of the literature.

August 20, 2015 - 6:14am
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Complex de novo chromosomal rearrangement at 15q11-q13 involving an intrachromosomal triplication in a patient with a severe neuropsychological phenotype: clinical report and review of the literature.

Am J Med Genet A. 2015 Jan;167A(1):221-30

Authors: Castronovo C, Crippa M, Bestetti I, Rusconi D, Russo S, Larizza L, Sangermani R, Bonati MT, Finelli P

Abstract
Interstitial triplications of 15q11-q13, leading to tetrasomy of the involved region, are very rare, with only 11 cases reported to date. Their pathogenicity is independent of the parental origin of the rearranged chromosome. The associated phenotype resembles, but is less severe, than that of patients bearing inv dup(15) marker chromosomes. Here, we describe a boy of 3 years and 9 months of age who exhibited very mild craniofacial dysmorphism (arched eyebrows, hypertelorism, and a wide mouth), developmental delay, generalized hypotonia, ataxic gait, severe intellectual disability, and autism. Array comparative genomic hybridization (CGH) analysis identified a heterozygous duplication of 1.1 Mb at 15q11.2 (between low-copy repeats BP1 and BP2), and a heterozygous triplication of 6.8 Mb at 15q11.2-q13.1 (BP2-BP4). Both acquisitions were de novo and contiguous. Microsatellite polymorphism analysis revealed the maternal origin of the triplication and the involvement of both maternal chromosomes 15. Furthermore, fluorescence in situ hybridization (FISH) analysis using BAC clones revealed that the rearrangement was complex, containing three differently sized tandem repeats of which the middle one was inverted. Our study confirms and extends the model proposed to explain the formation of intrachromosomal triplications through recombination events between non-allelic duplicons. The comparison of the proband's clinical presentation with those of previously described cases attests the existence of endophenotypes due to the parental origin of the 15q11-q13 triplicated segment and suggests a timetable for achievement of developmental milestones, thereby contributing to improved genotype-phenotype correlations.

PMID: 25339188 [PubMed - indexed for MEDLINE]

The co-occurrence of autistic and ADHD dimensions in adults: an etiological study in 17,770 twins.

August 20, 2015 - 6:14am
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The co-occurrence of autistic and ADHD dimensions in adults: an etiological study in 17,770 twins.

Transl Psychiatry. 2014;4:e435

Authors: Polderman TJ, Hoekstra RA, Posthuma D, Larsson H

Abstract
Autism spectrum disorder (ASD) and attention deficit/hyperactivity disorder (ADHD) often occur together. To obtain more insight in potential causes for the co-occurrence, this study examined the genetic and environmental etiology of the association between specific ASD and ADHD disorder dimensions. Self-reported data on ASD dimensions social and communication difficulties (ASDsc), and repetitive and restricted behavior and interests (ASDr), and ADHD dimensions inattention (IA), and hyperactivity/impulsivity (HI) were assessed in a community sample of 17,770 adult Swedish twins. Phenotypic, genetic and environmental associations between disorder dimensions were examined in a multivariate model, accounting for sex differences. ASDr showed the strongest associations with IA and HI in both sexes (r(p) 0.33 to 0.40). ASDsc also correlated moderately with IA (females r(p) 0.29 and males r(p) 0.35) but only modestly with HI (females r(p) 0.17 and males r(p) 0.20). Genetic correlations ranged from 0.22 to 0.64 and were strongest between ASDr and IA and HI. Sex differences were virtually absent. The ASDr dimension (reflecting restricted, repetitive and stereotyped patterns of behavior, interests and activities) showed the strongest association with dimensions of ADHD, on a phenotypic, genetic and environmental level. This study opens new avenues for molecular genetic research. As our findings demonstrated that genetic overlap between disorders is dimension-specific, future gene-finding studies on psychiatric comorbidity should focus on carefully selected genetically related dimensions of disorders.

PMID: 25180574 [PubMed - indexed for MEDLINE]

Prenatal maternal immune activation causes epigenetic differences in adolescent mouse brain.

August 20, 2015 - 6:14am
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Prenatal maternal immune activation causes epigenetic differences in adolescent mouse brain.

Transl Psychiatry. 2014;4:e434

Authors: Basil P, Li Q, Dempster EL, Mill J, Sham PC, Wong CC, McAlonan GM

Abstract
Epigenetic processes such as DNA methylation have been implicated in the pathophysiology of neurodevelopmental disorders including schizophrenia and autism. Epigenetic changes can be induced by environmental exposures such as inflammation. Here we tested the hypothesis that prenatal inflammation, a recognized risk factor for schizophrenia and related neurodevelopmental conditions, alters DNA methylation in key brain regions linked to schizophrenia, namely the dopamine rich striatum and endocrine regulatory centre, the hypothalamus. DNA methylation across highly repetitive elements (long interspersed element 1 (LINE1) and intracisternal A-particles (IAPs)) were used to proxy global DNA methylation. We also investigated the Mecp2 gene because it regulates transcription of LINE1 and has a known association with neurodevelopmental disorders. Brain tissue was harvested from 6 week old offspring of mice exposed to the viral analog PolyI:C or saline on gestation day 9. We used Sequenom EpiTYPER assay to quantitatively analyze differences in DNA methylation at IAPs, LINE1 elements and the promoter region of Mecp2. In the hypothalamus, prenatal exposure to PolyI:C caused significant global DNA hypomethylation (t=2.44, P=0.019, PolyI:C mean 69.67%, saline mean 70.19%), especially in females, and significant hypomethylation of the promoter region of Mecp2, (t=3.32, P=0.002; PolyI:C mean 26.57%, saline mean 34.63%). IAP methylation was unaltered. DNA methylation in the striatum was not significantly altered. This study provides the first experimental evidence that exposure to inflammation during prenatal life is associated with epigenetic changes, including Mecp2 promoter hypomethylation. This suggests that environmental and genetic risk factors associated with neurodevelopmental disorders may act upon similar pathways. This is important because epigenetic changes are potentially modifiable and their investigation may open new avenues for treatment.

PMID: 25180573 [PubMed - indexed for MEDLINE]

DNA methylation analysis of the autistic brain reveals multiple dysregulated biological pathways.

August 20, 2015 - 6:14am
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DNA methylation analysis of the autistic brain reveals multiple dysregulated biological pathways.

Transl Psychiatry. 2014;4:e433

Authors: Nardone S, Sams DS, Reuveni E, Getselter D, Oron O, Karpuj M, Elliott E

Abstract
Autism spectrum disorders (ASD) are a group of neurodevelopmental conditions characterized by dysfunction in social interaction, communication and stereotypic behavior. Genetic and environmental factors have been implicated in the development of ASD, but the molecular mechanisms underlying their interaction are not clear. Epigenetic modifications have been suggested as molecular mechanism that can mediate the interaction between the environment and the genome to produce adaptive or maladaptive behaviors. Here, using the Illumina 450 K methylation array we have determined the existence of many dysregulated CpGs in two cortical regions, Brodmann area 10 (BA10) and Brodmann area 24 (BA24), of individuals who had ASD. In BA10 we found a very significant enrichment for genomic areas responsible for immune functions among the hypomethylated CpGs, whereas genes related to synaptic membrane were enriched among hypermethylated CpGs. By comparing our methylome data with previously published transcriptome data, and by performing real-time PCR on selected genes that were dysregulated in our study, we show that hypomethylated genes are often overexpressed, and that there is an inverse correlation between gene expression and DNA methylation within the individuals. Among these genes there were C1Q, C3, ITGB2 (C3R), TNF-α, IRF8 and SPI1, which have recently been implicated in synaptic pruning and microglial cell specification. Finally, we determined the epigenetic dysregulation of the gene HDAC4, and we confirm that the locus encompassing C11orf21/TSPAN32 has multiple hypomethylated CpGs in the autistic brain, as previously demonstrated. Our data suggest a possible role for epigenetic processes in the etiology of ASD.

PMID: 25180572 [PubMed - indexed for MEDLINE]

Genome-wide distribution of Auts2 binding localizes with active neurodevelopmental genes.

August 20, 2015 - 6:14am
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Genome-wide distribution of Auts2 binding localizes with active neurodevelopmental genes.

Transl Psychiatry. 2014;4:e431

Authors: Oksenberg N, Haliburton GD, Eckalbar WL, Oren I, Nishizaki S, Murphy K, Pollard KS, Birnbaum RY, Ahituv N

Abstract
The autism susceptibility candidate 2 gene (AUTS2) has been associated with multiple neurological diseases including autism spectrum disorders (ASDs). Previous studies showed that AUTS2 has an important neurodevelopmental function and is a suspected master regulator of genes implicated in ASD-related pathways. However, the regulatory role and targets of Auts2 are not well known. Here, by using ChIP-seq (chromatin immunoprecipitation followed by deep sequencing) and RNA-seq on mouse embryonic day 16.5 forebrains, we elucidated the gene regulatory networks of Auts2. We find that the majority of promoters bound by Auts2 belong to genes highly expressed in the developing forebrain, suggesting that Auts2 is involved in transcriptional activation. Auts2 non-promoter-bound regions significantly overlap developing brain-associated enhancer marks and are located near genes involved in neurodevelopment. Auts2-marked sequences are enriched for binding site motifs of neurodevelopmental transcription factors, including Pitx3 and TCF3. In addition, we characterized two functional brain enhancers marked by Auts2 near NRXN1 and ATP2B2, both ASD-implicated genes. Our results implicate Auts2 as an active regulator of important neurodevelopmental genes and pathways and identify novel genomic regions that could be associated with ASD and other neurodevelopmental diseases.

PMID: 25180570 [PubMed - indexed for MEDLINE]

Testing the accuracy of an observation-based classifier for rapid detection of autism risk.

August 20, 2015 - 6:14am
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Testing the accuracy of an observation-based classifier for rapid detection of autism risk.

Transl Psychiatry. 2014;4:e424

Authors: Duda M, Kosmicki JA, Wall DP

Abstract
Current approaches for diagnosing autism have high diagnostic validity but are time consuming and can contribute to delays in arriving at an official diagnosis. In a pilot study, we used machine learning to derive a classifier that represented a 72% reduction in length from the gold-standard Autism Diagnostic Observation Schedule-Generic (ADOS-G), while retaining >97% statistical accuracy. The pilot study focused on a relatively small sample of children with and without autism. The present study sought to further test the accuracy of the classifier (termed the observation-based classifier (OBC)) on an independent sample of 2616 children scored using ADOS from five data repositories and including both spectrum (n=2333) and non-spectrum (n=283) individuals. We tested OBC outcomes against the outcomes provided by the original and current ADOS algorithms, the best estimate clinical diagnosis, and the comparison score severity metric associated with ADOS-2. The OBC was significantly correlated with the ADOS-G (r=-0.814) and ADOS-2 (r=-0.779) and exhibited >97% sensitivity and >77% specificity in comparison to both ADOS algorithm scores. The correspondence to the best estimate clinical diagnosis was also high (accuracy=96.8%), with sensitivity of 97.1% and specificity of 83.3%. The correlation between the OBC score and the comparison score was significant (r=-0.628), suggesting that the OBC provides both a classification as well as a measure of severity of the phenotype. These results further demonstrate the accuracy of the OBC and suggest that reductions in the process of detecting and monitoring autism are possible.

PMID: 25116834 [PubMed - indexed for MEDLINE]

Cerebellar Purkinje cell p75 neurotrophin receptor and autistic behavior.

August 20, 2015 - 6:14am
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Cerebellar Purkinje cell p75 neurotrophin receptor and autistic behavior.

Transl Psychiatry. 2014;4:e416

Authors: Lotta LT, Conrad K, Cory-Slechta D, Schor NF

Abstract
The p75 neurotrophin receptor (p75NTR) is normally expressed in cerebellar Purkinje cells throughout the lifespan. Children with autism spectrum behavior exhibit apparent cerebellar Purkinje cell loss. Cerebellar transcriptome changes seen in the murine prenatal valproate exposure model of autism include all of the proteins known to constitute the p75NTR interactome. p75NTR is a modulator of cytoplasmic and mitochondrial redox potential, and others have suggested that aberrant response to oxidant stress has a major role in the pathogenesis of autism. We have created Purkinje cell-selective p75NTR knockout mice that are the progeny of hemizygous Cre-Purkinje cell protein 2 C57Bl mice and p75NTR floxed C57Bl mice. These Cre-loxP mice exhibit complete knockout of p75NTR in ~50% of the cerebellar Purkinje cells. Relative to Cre-only mice and wild-type C57Bl mice, this results in a behavioral phenotype characterized by less allogrooming of (P<0.05; one-way analysis of variance) and socialization or fighting with (each P<0.05) other mice; less (1.2-fold) non-ambulatory exploration of their environment than wild-type (P<0.01) or Cre only (P<0.01) mice; and almost twofold more stereotyped jumping behavior than wild-type (P<0.05) or Cre (P<0.02) mice of the same strain. Wild-type mice have more complex dendritic arborization than Cre-loxP mice, with more neurites per unit area (P<0.025, Student's t-test), more perpendicular branches per unit area (P<0.025) and more short branches/long neurite (P<0.0005). Aberrant developmental regulation of expression of p75NTR in cerebellar Purkinje cells may contribute to the pathogenesis of autism.

PMID: 25072321 [PubMed - indexed for MEDLINE]

Jacobsen syndrome: Advances in our knowledge of phenotype and genotype.

August 19, 2015 - 10:43am

Jacobsen syndrome: Advances in our knowledge of phenotype and genotype.

Am J Med Genet C Semin Med Genet. 2015 Aug 18;

Authors: Favier R, Akshoomoff N, Mattson S, Grossfeld P

Abstract
In 1973, the Danish geneticist Petrea Jacobsen described a three-generation family in which the proband carried a presumed terminal deletion at the end of the long arm of chromosome 11 (11q). This patient had dysmorphic features, congenital heart disease, and intellectual disability. Since Dr. Jacobsen's initial report, over 200 patients with Jacobsen syndrome have been reported, suggesting that Jacobsen syndrome is a contiguous gene disorder. With the advent of high resolution deletion mapping and the completion of the human genome sequencing project, a comprehensive genotype/phenotype analysis for Jacobsen syndrome became possible. In this article, we review research describing individual causal genes in distal 11q that contribute to the overall Jacobsen syndrome clinical phenotype. Through a combination of human genetics and the use of genetically engineered animal models, causal genes have been identified for the clinical problems in JS that historically have caused the greatest morbidity and mortality: congenital heart disease, the Paris-Trousseau bleeding disorder, intellectual disability, autism, and immunodeficiency. Insights gained from these studies are being applied for future drug development and clinical trials, as well as for a potential strategy for the prevention of certain forms of congenital heart disease. The results of these studies will likely not only improve the prognostic and therapeutic approaches for patients with Jacobsen syndrome, but also for the general population afflicted with these problems. © 2015 Wiley Periodicals, Inc.

PMID: 26285164 [PubMed - as supplied by publisher]

hVGAT-mCherry: A novel molecular tool for analysis of GABAergic neurons derived from human pluripotent stem cells.

August 19, 2015 - 10:43am

hVGAT-mCherry: A novel molecular tool for analysis of GABAergic neurons derived from human pluripotent stem cells.

Mol Cell Neurosci. 2015 Aug 15;

Authors: DeRosa BA, Belle KC, Thomas BJ, Cukier HN, Pericak-Vance MA, Vance JM, Dykxhoorn DM

Abstract
BACKGROUND: GABAergic synaptic transmission is known to play a critical role in the assembly of neuronal circuits during development and is responsible for maintaining the balance between excitatory and inhibitory signaling in the brain during maturation into adulthood. Importantly, defects in GABAergic neuronal function and signaling have been linked to a number of neurological diseases, including autism spectrum disorders, schizophrenia, and epilepsy. With patient-specific induced pluripotent stem cell (iPSC)-based models of neurological disease, it is now possible to investigate the disease mechanisms that underlie deficits in GABAergic function in affected human neurons. To that end, tools that enable the labeling and purification of viable GABAergic neurons from human pluripotent stem cells would be of great value.
RESULTS: To address the need for tools that facilitate the identification and isolation of viable GABAergic neurons from the in vitro differentiation of iPSC lines, a cell type-specific promoter-driven fluorescent reporter construct was developed that utilizes the human vesicular GABA transporter (hVGAT) promoter to drive the expression of mCherry specifically in VGAT-expressing neurons. The transduction of iPSC-derived forebrain neuronal cultures with the hVGAT promoter-mCherry lentiviral reporter construct specifically labeled GABAergic neurons. Immunocytochemical analysis of hVGAT-mCherry expression cells showed significant co-labeling with the GABAergic neuronal markers for endogenous VGAT, GABA, and GAD67. Expression of mCherry from the VGAT promoter showed expression in several cortical interneuron subtypes to similar levels. In addition, an effective and reproducible protocol was developed to facilitate the fluorescent activated cell sorting (FACS)-mediated purification of high yields of viable VGAT-positive cells.
CONCLUSIONS: These studies demonstrate the utility of the hVGAT-mCherry reporter construct as an effective tool for studying GABAergic neurons differentiated in vitro from human pluripotent stem cells. This approach could provide a means of obtaining large quantities of viable GABAergic neurons derived from disease-specific hiPSCs that could be used for functional assays or high-throughput screening of small molecule libraries.

PMID: 26284979 [PubMed - as supplied by publisher]

Genetic and environmental contributions to the inverse association between specific autistic traits and experience seeking in adults.

August 19, 2015 - 10:43am

Genetic and environmental contributions to the inverse association between specific autistic traits and experience seeking in adults.

Am J Med Genet B Neuropsychiatr Genet. 2015 Aug 18;

Authors: Romero-Martínez Á, Moya-Albiol L, Vinkhuyzen AA, Polderman TJ

Abstract
Autistic traits are characterized by social and communication problems, restricted, repetitive and stereotyped patterns of behavior, interests and activities. The relation between autistic traits and personality characteristics is largely unknown. This study focused on the relation between five specific autistic traits measured with the abridged version of the Autism Spectrum Quotient ("social problems," "preference for routine," "attentional switching difficulties," "imagination impairments," "fascination for numbers and patterns") and Experience Seeking (ES) in a general population sample of adults, and subsequently investigated the genetic and environmental etiology between these traits. Self-reported data on autistic traits and ES were collected in a population sample (n = 559) of unrelated individuals, and in a population based family sample of twins and siblings (n = 560). Phenotypic, genetic and environmental associations between traits were examined in a bivariate model, accounting for sex and age differences. Phenotypically, ES correlated significantly with "preference for routine" and "imagination impairments" in both samples but was unrelated to the other autistic traits. Genetic analyses in the family sample revealed that the association between ES and "preference for routine" and "imagination impairments" could largely be explained by a shared genetic factor (89% and 70%, respectively). Our analyses demonstrated at a phenotypic and genetic level an inverse relationship between ES and specific autistic traits in adults. ES is associated with risk taking behavior such as substance abuse, antisocial behavior and financial problems. Future research could investigate whether autistic traits, in particular strong routine preference and impaired imagination skills, serve as protective factors for such risky behaviors. © 2015 Wiley Periodicals, Inc.

PMID: 26284829 [PubMed - as supplied by publisher]

Two New Cases of 1p21.3 Deletions and an Unbalanced Translocation t(8;12) among Individuals with Syndromic Obesity.

August 19, 2015 - 10:43am
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Two New Cases of 1p21.3 Deletions and an Unbalanced Translocation t(8;12) among Individuals with Syndromic Obesity.

Mol Syndromol. 2015 Jul;6(2):63-70

Authors: D'Angelo CS, Moller Dos Santos MF, Alonso LG, Koiffmann CP

Abstract
Obesity is a highly heritable but genetically heterogeneous disorder. Various well-known microdeletion syndromes (e.g. 1p36, 2q37, 6q16, 9q34, 17p11.2) can cause this phenotype along with intellectual disability (ID) and other findings. Chromosomal microarrays have identified 'new' microdeletion/duplication syndromes often associated with obesity. We report on 2 unrelated patients with an overlapping region of deletion at 1p21.3p21.2, and a third patient with a de novo recurrent unbalanced translocation der(8)t(8;12)(p23.1;p13.31), detected by 180K array CGH in a prospective cohort of syndromic obesity patients. Deletion of 1p21.3 is a rare condition, and there have been only 11 cases of the same recurrent translocation between chromosomes 8 and 12 [t(8;12)] reported to date. The former has been associated with ID, autistic spectrum disorder (ASD) and mild dysmorphic features, and in 4 patients who were obese or had a tendency to obesity, a minimal overlapping region of 2 genes, DPYD and MIR137, was detected; t(8;12) has recently been recognized to cause a childhood obesity syndrome due to duplication of the GNB3 gene. Thus, our findings add to the existing literature on the clinical description of these new syndromes, providing additional support that these loci are associated with syndromic obesity. We suggest that heterozygous loss of MIR137 may contribute to obesity as well as ID and ASD.

PMID: 26279650 [PubMed]

[Autistic spectrum disorders associated with chromosome Mar15q11.2: a case report].

August 19, 2015 - 10:43am
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[Autistic spectrum disorders associated with chromosome Mar15q11.2: a case report].

Zhongguo Dang Dai Er Ke Za Zhi. 2015 Mar;17(3):290-1

Authors: Zhao JH, Zhang LH, Shen GZ, Yuan AY, Yu R, Hou M

PMID: 25815503 [PubMed - indexed for MEDLINE]

Genome engineering of isogenic human ES cells to model autism disorders.

August 19, 2015 - 10:43am
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Genome engineering of isogenic human ES cells to model autism disorders.

Nucleic Acids Res. 2015 May 26;43(10):e65

Authors: Martinez RA, Stein JL, Krostag AR, Nelson AM, Marken JS, Menon V, May RC, Yao Z, Kaykas A, Geschwind DH, Grimley JS

Abstract
Isogenic pluripotent stem cells are critical tools for studying human neurological diseases by allowing one to study the effects of a mutation in a fixed genetic background. Of particular interest are the spectrum of autism disorders, some of which are monogenic such as Timothy syndrome (TS); others are multigenic such as the microdeletion and microduplication syndromes of the 16p11.2 chromosomal locus. Here, we report engineered human embryonic stem cell (hESC) lines for modeling these two disorders using locus-specific endonucleases to increase the efficiency of homology-directed repair (HDR). We developed a system to: (1) computationally identify unique transcription activator-like effector nuclease (TALEN) binding sites in the genome using a new software program, TALENSeek, (2) assemble the TALEN genes by combining golden gate cloning with modified constructs from the FLASH protocol, and (3) test the TALEN pairs in an amplification-based HDR assay that is more sensitive than the typical non-homologous end joining assay. We applied these methods to identify, construct, and test TALENs that were used with HDR donors in hESCs to generate an isogenic TS cell line in a scarless manner and to model the 16p11.2 copy number disorder without modifying genomic loci with high sequence similarity.

PMID: 25765640 [PubMed - indexed for MEDLINE]

Pharmacogenetic inhibition of eIF4E-dependent Mmp9 mRNA translation reverses fragile X syndrome-like phenotypes.

August 19, 2015 - 10:43am
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Pharmacogenetic inhibition of eIF4E-dependent Mmp9 mRNA translation reverses fragile X syndrome-like phenotypes.

Cell Rep. 2014 Dec 11;9(5):1742-55

Authors: Gkogkas CG, Khoutorsky A, Cao R, Jafarnejad SM, Prager-Khoutorsky M, Giannakas N, Kaminari A, Fragkouli A, Nader K, Price TJ, Konicek BW, Graff JR, Tzinia AK, Lacaille JC, Sonenberg N

Abstract
Fragile X syndrome (FXS) is the leading genetic cause of autism. Mutations in Fmr1 (fragile X mental retardation 1 gene) engender exaggerated translation resulting in dendritic spine dysmorphogenesis, synaptic plasticity alterations, and behavioral deficits in mice, which are reminiscent of FXS phenotypes. Using postmortem brains from FXS patients and Fmr1 knockout mice (Fmr1(-/y)), we show that phosphorylation of the mRNA 5' cap binding protein, eukaryotic initiation factor 4E (eIF4E), is elevated concomitant with increased expression of matrix metalloproteinase 9 (MMP-9) protein. Genetic or pharmacological reduction of eIF4E phosphorylation rescued core behavioral deficits, synaptic plasticity alterations, and dendritic spine morphology defects via reducing exaggerated translation of Mmp9 mRNA in Fmr1(-/y) mice, whereas MMP-9 overexpression produced several FXS-like phenotypes. These results uncover a mechanism of regulation of synaptic function by translational control of Mmp-9 in FXS, which opens the possibility of new treatment avenues for the diverse neurological and psychiatric aspects of FXS.

PMID: 25466251 [PubMed - indexed for MEDLINE]

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