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Uncovering the etiology of autism spectrum disorders: genomics, bioinformatics, environment, data collection and exploration, and future possibilities.

August 15, 2014 - 7:43am
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Uncovering the etiology of autism spectrum disorders: genomics, bioinformatics, environment, data collection and exploration, and future possibilities.

Pac Symp Biocomput. 2014;:422-6

Authors: Pendergrass S, Girirajan S, Selleck S

Abstract
A clear and predictive understanding of the etiology of autism spectrum disorders (ASD), a group of neurodevelopmental disorders characterized by varying deficits in social interaction and communication as well as repetitive behaviors, has not yet been achieved. There remains active debate about the origins of autism, and the degree to which genetic and environmental factors, and their interplay, produce the range and heterogeneity of cognitive, developmental, and behavioral features seen in children carrying a diagnosis of ASD. Unlocking the causes of these complex developmental disorders will require a collaboration of experts in many disciplines, including clinicians, environmental exposure experts, bioinformaticists, geneticists, and computer scientists. For this workshop we invited prominent researchers in the field of autism, covering a range of topics from genetic and environmental research to ethical considerations. The goal of this workshop: provide an introduction to the current state of autism research, highlighting the potential for multi-disciplinary collaborations that rigorously evaluate the many potential contributors to ASD. It is further anticipated that approaches that successfully advance the understanding of ASD can be applied to the study of other common, complex disorders. Herein we provide a short review of ASD and the work of the invited speakers.

PMID: 24297568 [PubMed - indexed for MEDLINE]

The glial perspective of autism spectrum disorders.

August 13, 2014 - 6:43am
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The glial perspective of autism spectrum disorders.

Neurosci Biobehav Rev. 2014 Jan;38:160-72

Authors: Zeidán-Chuliá F, Salmina AB, Malinovskaya NA, Noda M, Verkhratsky A, Moreira JC

Abstract
The aetiology of autism spectrum disorders remains unclear although a growing number of associated genetic abnormalities and environmental factors have been discovered in recent decades. These advancements coincided with a remarkable increase in the comprehension of physiological functions and pathological potential of neuroglia in the central nervous system that led to a notion of fundamental contribution of glial cells into multiple neuropathologies, including neuropsychiatric and developmental disorders. Growing evidence indicates a role for deregulation of astroglial control over homeostasis and plastic potential of neural networks as well as microglial malfunction and neuroinflammatory response in the brains of autistic patients. In this review, we shall summarize the status and pathological potential of neuroglia and argue for neuroglial roots of autistic disorders.

PMID: 24300694 [PubMed - in process]

Parental influence on a child's autistic traits.

August 13, 2014 - 6:43am
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Parental influence on a child's autistic traits.

J Dev Behav Pediatr. 2013 Nov-Dec;34(9):730-2

Authors: Phelps R, Nickel R, Eisert D, Stein MT

Abstract
CASE: Robbie is a 4-year-old boy whose parents are concerned about his speech, social skills, and repetitive behaviors. He has poor articulation; at time, he is difficult to understand. On the other hand, he has a fair vocabulary, and he has good intent to communicate. He is generally able to communicate his needs and wants. He likes to tell his parents about his day. When he begins the day at preschool, Robbie initially stands by himself and watches. He slowly warms up and eventually participates in activities. He engages in parallel play or follows other children. He knows names of children at preschool, and he is well liked. He is affectionate with his parents. When Robbie is excited, he wiggles his fingers, flaps his arms, and grimaces. He can be quite rigid; for example, he gets very distressed when his mother sets his cup down on his right side instead of his left. However, in general, Robbie has a sunny personality. He likes to watch children's television shows. He pretends plays with action figures. Robbie is an only child who lives with both parents. His mother works full-time, and his father is in home with Robbie during the day. When examined in the office, Robbie had a bright affect, good eye contact, and social referencing. He demonstrated good communicative intent, but poor articulation and some jargoning. He frequently wiggled his fingers and flapped his hands with excitement. Robbie had a borderline score on the Autism Diagnostic Observation Schedule. During the visit, the pediatrician noted that Robbie's father was rather quiet and rarely responded to questions. When he did respond, he had a monotone quality to his voice. He maintained either a flat or nervous affect throughout the visit. He made limited eye contact, and occasionally he stared excessively.

PMID: 24217028 [PubMed - in process]

Different neurodevelopmental symptoms have a common genetic etiology.

August 13, 2014 - 6:43am
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Different neurodevelopmental symptoms have a common genetic etiology.

J Child Psychol Psychiatry. 2013 Dec;54(12):1356-65

Authors: Pettersson E, Anckarsäter H, Gillberg C, Lichtenstein P

Abstract
BACKGROUND: Although neurodevelopmental disorders are demarcated as discrete entities in the Diagnostic Statistical Manual of mental disorders, empirical evidence indicates that there is a high degree of overlap among them. The first aim of this investigation was to explore if a single general factor could account for the large degree of observed overlap among neurodevelopmental problems, and explore whether this potential factor was primarily genetic or environmental in origin. The second aim was to explore whether there was systematic covariation, either genetic or environmental, over and above that contributed by the potential general factor, unique to each syndrome.
METHOD: Parents of all Swedish 9- and 12-year-old twin pairs born between 1992 and 2002 were targeted for interview regarding problems typical of autism spectrum disorders, ADHD and other neurodevelopmental conditions (response rate: 80 percent). Structural equation modeling was conducted on 6,595 pairs to examine the genetic and environmental structure of 53 neurodevelopmental problems.
RESULTS: One general genetic factor accounted for a large proportion of the phenotypic covariation among the 53 symptoms. Three specific genetic subfactors identified 'impulsivity,' 'learning problems,' and 'tics and autism,' respectively. Three unique environment factors identified 'autism,' 'hyperactivity and impulsivity,' and 'inattention and learning problems,' respectively.
CONCLUSION: One general genetic factor was responsible for the wide-spread phenotypic overlap among all neurodevelopmental symptoms, highlighting the importance of addressing broad patient needs rather than specific diagnoses. The unique genetic factors may help guide diagnostic nomenclature, whereas the unique environmental factors may highlight that neurodevelopmental symptoms are responsive to change at the individual level and may provide clues into different mechanisms and treatments. Future research would benefit from assessing the general factor separately from specific factors to better understand observed overlap among neurodevelopmental problems.

PMID: 24127638 [PubMed - in process]

Autism traits in the RASopathies.

August 13, 2014 - 6:43am
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Autism traits in the RASopathies.

J Med Genet. 2014 Jan;51(1):10-20

Authors: Adviento B, Corbin IL, Widjaja F, Desachy G, Enrique N, Rosser T, Risi S, Marco EJ, Hendren RL, Bearden CE, Rauen KA, Weiss LA

Abstract
BACKGROUND: Mutations in Ras/mitogen-activated protein kinase (Ras/MAPK) pathway genes lead to a class of disorders known as RASopathies, including neurofibromatosis type 1 (NF1), Noonan syndrome (NS), Costello syndrome (CS), and cardio-facio-cutaneous syndrome (CFC). Previous work has suggested potential genetic and phenotypic overlap between dysregulation of Ras/MAPK signalling and autism spectrum disorders (ASD). Although the literature offers conflicting evidence for association of NF1 and autism, there has been no systematic evaluation of autism traits in the RASopathies as a class to support a role for germline Ras/MAPK activation in ASDs.
METHODS: We examined the association of autism traits with NF1, NS, CS and CFC, comparing affected probands with unaffected sibling controls and subjects with idiopathic ASDs using the qualitative Social Communication Questionnaire (SCQ) and the quantitative Social Responsiveness Scale (SRS).
RESULTS: Each of the four major RASopathies showed evidence for increased qualitative and quantitative autism traits compared with sibling controls. Further, each RASopathy exhibited a distinct distribution of quantitative social impairment. Levels of social responsiveness show some evidence of correlation between sibling pairs, and autism-like impairment showed a male bias similar to idiopathic ASDs.
CONCLUSIONS: Higher prevalence and severity of autism traits in RASopathies compared to unaffected siblings suggests that dysregulation of Ras/MAPK signalling during development may be implicated in ASD risk. Evidence for sex bias and potential sibling correlation suggests that autism traits in the RASopathies share characteristics with autism traits in the general population and clinical ASD population and can shed light on idiopathic ASDs.

PMID: 24101678 [PubMed - in process]

Candidate gene associations with withdrawn behavior.

August 13, 2014 - 6:43am
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Candidate gene associations with withdrawn behavior.

J Child Psychol Psychiatry. 2013 Dec;54(12):1337-45

Authors: Rubin DH, Althoff RR, Ehli EA, Davies GE, Rettew DC, Crehan ET, Walkup JT, Hudziak JJ

Abstract
BACKGROUND: Social withdrawal is a core neuropsychiatric phenomenon in developmental psychopathology. Its presence predicts psychopathology across many domains, including depression, psychosis, autism, anxiety, and suicide. Withdrawn behavior is highly heritable, persistent, and characteristically worsens without intervention. To date, few studies have successfully identified genetic associations with withdrawn behavior, despite the abundance of evidence of its heritability. This may be due to reliance of categorical over dimensional measures of the behaviorally inhibited phenotype. The aim of this study is to identify associations between known psychiatric candidate genes and a dimensionally derived measure of withdrawn behavior.
METHODS: Genetic information was collected on 20 single-nucleotide polymorphisms (SNPs) from a custom-designed SNP chip and TAQMAN arrays of 4 variable number of tandem repeat (VNTR) genes for 551 individuals from 187 families. Linear mixed modeling was employed to examine the relationship between genotypes of interest and Child Behavior Checklist (CBCL) Withdrawn Behavior Subscale Score (WBS) while controlling for gender and age through multiple linear regressions.
RESULTS: Withdrawn behavior was highly associated with polymorphism rs6314 of the serotonin receptor 2A (HTR2A) [p = .009, estimate = 0.310 (bootstrap 95% CI 0.155-0.448), bootstrap p = .001] and rs1800544 of the alpha 2-adrenergic (ADRA2A) [p = .001, estimate = -0.310 (bootstrap 95% CI -0.479 to -0.126), bootstrap p = .001] genes after correction for gender and age. The association between withdrawn behavior and ADRA2A was stronger for younger children.
CONCLUSIONS: HTR2A and ADRA2A genes are associated with withdrawn behavior. This reinforces the role of catecholaminergic genes in the heritability of withdrawn behavior.

PMID: 23808549 [PubMed - in process]

Shank mutant mice as an animal model of autism.

August 12, 2014 - 8:46am
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Shank mutant mice as an animal model of autism.

Philos Trans R Soc Lond B Biol Sci. 2014 Jan 5;369(1633):20130143

Authors: Yoo J, Bakes J, Bradley C, Collingridge GL, Kaang BK

Abstract
In this review, we focus on the role of the Shank family of proteins in autism. In recent years, autism research has been flourishing. With genetic, molecular, imaging and electrophysiological studies being supported by behavioural studies using animal models, there is real hope that we may soon understand the fundamental pathology of autism. There is also genuine potential to develop a molecular-level pharmacological treatment that may be able to deal with the most severe symptoms of autism, and clinical trials are already underway. The Shank family of proteins has been strongly implicated as a contributing factor in autism in certain individuals and sits at the core of the alleged autistic pathway. Here, we analyse studies that relate Shank to autism and discuss what light this sheds on the possible causes of autism.

PMID: 24298145 [PubMed - indexed for MEDLINE]

Glycogen synthase kinase-3 inhibitors reverse deficits in long-term potentiation and cognition in fragile X mice.

August 12, 2014 - 8:46am
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Glycogen synthase kinase-3 inhibitors reverse deficits in long-term potentiation and cognition in fragile X mice.

Biol Psychiatry. 2014 Feb 1;75(3):198-206

Authors: Franklin AV, King MK, Palomo V, Martinez A, McMahon LL, Jope RS

Abstract
BACKGROUND: Identifying feasible therapeutic interventions is crucial for ameliorating the intellectual disability and other afflictions of fragile X syndrome (FXS), the most common inherited cause of intellectual disability and autism. Hippocampal glycogen synthase kinase-3 (GSK3) is hyperactive in the mouse model of FXS (FX mice), and hyperactive GSK3 promotes locomotor hyperactivity and audiogenic seizure susceptibility in FX mice, raising the possibility that specific GSK3 inhibitors may improve cognitive processes.
METHODS: We tested if specific GSK3 inhibitors improve deficits in N-methyl-D-aspartate receptor-dependent long-term potentiation at medial perforant path synapses onto dentate granule cells and dentate gyrus-dependent cognitive behavioral tasks.
RESULTS: GSK3 inhibitors completely rescued deficits in long-term potentiation at medial perforant path-dentate granule cells synapses in FX mice. Furthermore, synaptosomes from the dentate gyrus of FX mice displayed decreased inhibitory serine-phosphorylation of GSK3β compared with wild-type littermates. The potential therapeutic utility of GSK3 inhibitors was further tested on dentate gyrus-dependent cognitive behaviors. In vivo administration of GSK3 inhibitors completely reversed impairments in several cognitive tasks in FX mice, including novel object detection, coordinate and categorical spatial processing, and temporal ordering for visual objects.
CONCLUSIONS: These findings establish that synaptic plasticity and cognitive deficits in FX mice can be improved by intervention with inhibitors of GSK3, which may prove therapeutically beneficial in FXS.

PMID: 24041505 [PubMed - indexed for MEDLINE]

A girl with West syndrome and autistic features harboring a de novo TBL1XR1 mutation.

August 8, 2014 - 6:11am

A girl with West syndrome and autistic features harboring a de novo TBL1XR1 mutation.

J Hum Genet. 2014 Aug 7;

Authors: Saitsu H, Tohyama J, Walsh T, Kato M, Kobayashi Y, Lee M, Tsurusaki Y, Miyake N, Goto YI, Nishino I, Ohtake A, King MC, Matsumoto N

Abstract
Recently, de novo mutations in TBL1XR1 were found in two patients with autism spectrum disorders. Here, we report on a Japanese girl presenting with West syndrome, Rett syndrome-like and autistic features. Her initial development was normal until she developed a series of spasms at 5 months of age. Electroencephalogram at 7 months showed a pattern of hypsarrhythmia, which led to a diagnosis of West syndrome. Stereotypic hand movements appeared at 8 months of age, and autistic features such as deficits in communication, hyperactivity and excitability were observed later, at 4 years and 9 months. Whole exome sequencing of the patient and her parents revealed a de novo TBL1XR1 mutation [c.209 G>A (p.Gly70Asp)] occurring at an evolutionarily conserved amino acid in an F-box-like domain. Our report expands the clinical spectrum of TBL1XR1 mutations to West syndrome with Rett-like features, together with autistic features.Journal of Human Genetics advance online publication, 7 August 2014; doi:10.1038/jhg.2014.71.

PMID: 25102098 [PubMed - as supplied by publisher]

Role of Metabolic Genes in Blood Arsenic Concentrations of Jamaican Children with and without Autism Spectrum Disorder.

August 8, 2014 - 6:11am

Role of Metabolic Genes in Blood Arsenic Concentrations of Jamaican Children with and without Autism Spectrum Disorder.

Int J Environ Res Public Health. 2014;11(8):7874-7895

Authors: Rahbar MH, Samms-Vaughan M, Ma J, Bressler J, Loveland KA, Ardjomand-Hessabi M, Dickerson AS, Grove ML, Shakespeare-Pellington S, Beecher C, McLaughlin W, Boerwinkle E

Abstract
Arsenic is a toxic metalloid with known adverse effects on human health. Glutathione-S-transferase (GST) genes, including GSTT1, GSTP1, and GSTM1, play a major role in detoxification and metabolism of xenobiotics. We investigated the association between GST genotypes and whole blood arsenic concentrations (BASC) in Jamaican children with and without autism spectrum disorder (ASD). We used data from 100 ASD cases and their 1:1 age- and sex-matched typically developing (TD) controls (age 2-8 years) from Jamaica. Using log-transformed BASC as the dependent variable in a General Linear Model, we observed a significant interaction between GSTP1 and ASD case status while controlling for several confounding variables. However, for GSTT1 and GSTM1 we did not observe any significant associations with BASC. Our findings indicate that TD children who had the Ile/Ile or Ile/Val genotype for GSTP1 had a significantly higher geometric mean BASC than those with genotype Val/Val (3.67 µg/L vs. 2.69 µg/L, p < 0.01). Although, among the ASD cases, this difference was not statistically significant, the direction of the observed difference was consistent with that of the TD control children. These findings suggest a possible role of GSTP1 in the detoxification of arsenic.

PMID: 25101770 [PubMed - as supplied by publisher]

Dysregulated nitric oxide signaling as a candidate mechanism of fragile X syndrome and other neuropsychiatric disorders.

August 8, 2014 - 6:11am

Dysregulated nitric oxide signaling as a candidate mechanism of fragile X syndrome and other neuropsychiatric disorders.

Front Genet. 2014;5:239

Authors: Colvin SM, Kwan KY

Abstract
A mechanistic understanding of the pathophysiology underpinning psychiatric disorders is essential for the development of targeted molecular therapies. For fragile X syndrome (FXS), recent mechanistic studies have been focused on the metabotropic glutamate receptor (mGluR) signaling pathway. This line of research has led to the discovery of promising candidate drugs currently undergoing various phases of clinical trial, and represents a model of how biological insights can inform therapeutic strategies in neurodevelopmental disorders. Although mGluR signaling is a key mechanism at which targeted treatments can be directed, it is likely to be one of many mechanisms contributing to FXS. A more complete understanding of the molecular and neural underpinnings of the disorder is expected to inform additional therapeutic strategies. Alterations in the assembly of neural circuits in the neocortex have been recently implicated in genetic studies of autism and schizophrenia, and may also contribute to FXS. In this review, we explore dysregulated nitric oxide signaling in the developing neocortex as a novel candidate mechanism of FXS. This possibility stems from our previous work demonstrating that neuronal nitric oxide synthase 1 (NOS1 or nNOS) is regulated by the FXS protein FMRP in the mid-fetal human neocortex. Remarkably, in the mid-late fetal and early postnatal neocortex of human FXS patients, NOS1 expression is severely diminished. Given the role of nitric oxide in diverse neural processes, including synaptic development and plasticity, the loss of NOS1 in FXS may contribute to the etiology of the disorder. Here, we outline the genetic and neurobiological data that implicate neocortical dysfunction in FXS, review the evidence supporting dysregulated nitric oxide signaling in the developing FXS neocortex and its contribution to the disorder, and discuss the implications for targeting nitric oxide signaling in the treatment of FXS and other psychiatric illnesses.

PMID: 25101118 [PubMed]

Bias towards large genes in autism.

August 8, 2014 - 6:11am

Bias towards large genes in autism.

Nature. 2014 Aug 7;512(7512):E1-2

Authors: Shohat S, Shifman S

PMID: 25100484 [PubMed - in process]

BDNF in fragile X syndrome.

August 7, 2014 - 8:32am
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BDNF in fragile X syndrome.

Neuropharmacology. 2014 Jan;76 Pt C:729-36

Authors: Castrén ML, Castrén E

Abstract
Fragile X syndrome (FXS) is a monogenic disorder that is caused by the absence of FMR1 protein (FMRP). FXS serves as an excellent model disorder for studies investigating disturbed molecular mechanisms and synapse function underlying cognitive impairment, autism, and behavioral disturbance. Abnormalities in dendritic spines and synaptic transmission in the brain of FXS individuals and mouse models for FXS indicate perturbations in the development, maintenance, and plasticity of neuronal network connectivity. However, numerous alterations are found during the early development in FXS, including abnormal differentiation of neural progenitors and impaired migration of newly born neurons. Several aspects of FMRP function are modulated by brain-derived neurotrophic factor (BDNF) signaling. Here, we review the evidence of the role for BDNF in the developing and adult FXS brain. This article is part of the Special Issue entitled 'BDNF Regulation of Synaptic Structure, Function, and Plasticity'.

PMID: 23727436 [PubMed - indexed for MEDLINE]

Age-related sperm DNA methylation changes are transmitted to offspring and associated with abnormal behavior and dysregulated gene expression.

August 6, 2014 - 7:35am

Age-related sperm DNA methylation changes are transmitted to offspring and associated with abnormal behavior and dysregulated gene expression.

Mol Psychiatry. 2014 Aug 5;

Authors: Milekic MH, Xin Y, O'Donnell A, Kumar KK, Bradley-Moore M, Malaspina D, Moore H, Brunner D, Ge Y, Edwards J, Paul S, Haghighi FG, Gingrich JA

Abstract
Advanced paternal age (APA) has been shown to be a significant risk factor in the offspring for neurodevelopmental psychiatric disorders, such as schizophrenia and autism spectrum disorders. During aging, de novo mutations accumulate in the male germline and are frequently transmitted to the offspring with deleterious effects. In addition, DNA methylation during spermatogenesis is an active process, which is susceptible to errors that can be propagated to subsequent generations. Here we test the hypothesis that the integrity of germline DNA methylation is compromised during the aging process. A genome-wide DNA methylation screen comparing sperm from young and old mice revealed a significant loss of methylation in the older mice in regions associated with transcriptional regulation. The offspring of older fathers had reduced exploratory and startle behaviors and exhibited similar brain DNA methylation abnormalities as observed in the paternal sperm. Offspring from old fathers also had transcriptional dysregulation of developmental genes implicated in autism and schizophrenia. Our findings demonstrate that DNA methylation abnormalities arising in the sperm of old fathers are a plausible mechanism to explain some of the risks that APA poses to resulting offspring.Molecular Psychiatry advance online publication, 5 August 2014; doi:10.1038/mp.2014.84.

PMID: 25092244 [PubMed - as supplied by publisher]

Clinical and genomic evaluation of 201 patients with Phelan-McDermid syndrome.

August 5, 2014 - 7:07am
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Clinical and genomic evaluation of 201 patients with Phelan-McDermid syndrome.

Hum Genet. 2014 Jul;133(7):847-59

Authors: Sarasua SM, Boccuto L, Sharp JL, Dwivedi A, Chen CF, Rollins JD, Rogers RC, Phelan K, DuPont BR

Abstract
This study is the first to describe age-related changes in a large cohort of patients with Phelan-McDermid syndrome (PMS), also known as 22q13 deletion syndrome. Over a follow-up period of up to 12 years, physical examinations and structured interviews were conducted for 201 individuals diagnosed with PMS, 120 patients had a focused, high-resolution 22q12q13 array CGH, and 92 patients' deletions were assessed for parent-of-origin. 22q13 genomic anomalies include terminal deletions of 22q13 (89 %), terminal deletions and interstitial duplications (9 %), and interstitial deletions (2 %). Considering different age groups, in older patients, behavioral problems tended to subside, developmental abilities improved, and some features such as large or fleshy hands, full or puffy eyelids, hypotonia, lax ligaments, and hyperextensible joints were less frequent. However, the proportion reporting an autism spectrum disorder, seizures, and cellulitis, or presenting with lymphedema or abnormal reflexes increased with age. Some neurologic and dysmorphic features such as speech and developmental delay and macrocephaly correlated with deletion size. Deletion sizes in more recently diagnosed patients tend to be smaller than those diagnosed a decade earlier. Seventy-three percent of de novo deletions were of paternal origin. Seizures were reported three times more often among patients with a de novo deletion of the maternal rather than paternal chromosome 22. This analysis improves the understanding of the clinical presentation and natural history of PMS and can serve as a reference for the prevalence of clinical features in the syndrome.

PMID: 24481935 [PubMed - indexed for MEDLINE]

Prefrontal cognitive deficits in mice with altered cerebral cortical GABAergic interneurons.

August 5, 2014 - 7:07am
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Prefrontal cognitive deficits in mice with altered cerebral cortical GABAergic interneurons.

Behav Brain Res. 2014 Feb 1;259:143-51

Authors: Bissonette GB, Bae MH, Suresh T, Jaffe DE, Powell EM

Abstract
Alterations of inhibitory GABAergic neurons are implicated in multiple psychiatric and neurological disorders, including schizophrenia, autism and epilepsy. In particular, interneuron deficits in prefrontal areas, along with presumed decreased inhibition, have been reported in several human patients. The majority of forebrain GABAergic interneurons arise from a single subcortical source before migrating to their final regional destination. Factors that govern the interneuron populations have been identified, demonstrating that a single gene mutation may globally affect forebrain structures or a single area. In particular, mice lacking the urokinase plasminogen activator receptor (Plaur) gene have decreased GABAergic interneurons in frontal and parietal, but not caudal, cortical regions. Plaur assists in the activation of hepatocyte growth factor/scatter factor (HGF/SF), and several of the interneuron deficits are correlated with decreased levels of HGF/SF. In some cortical regions, the interneuron deficit can be remediated by endogenous overexpression of HGF/SF. In this study, we demonstrate decreased parvalbumin-expressing interneurons in the medial frontal cortex, but not in the hippocampus or basal lateral amygdala in the Plaur null mouse. The Plaur null mouse demonstrates impaired medial frontal cortical function in extinction of cued fear conditioning and the inability to form attentional sets. Endogenous HGF/SF overexpression increased the number of PV-expressing cells in medial frontal cortical areas to levels greater than found in wildtype mice, but did not remediate the behavioral deficits. These data suggest that proper medial frontal cortical function is dependent upon optimum levels of inhibition and that a deficit or excess of interneuron numbers impairs normal cognition.

PMID: 24211452 [PubMed - indexed for MEDLINE]

Temporal and spectral differences in the ultrasonic vocalizations of fragile X knock out mice during postnatal development.

August 5, 2014 - 7:07am
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Temporal and spectral differences in the ultrasonic vocalizations of fragile X knock out mice during postnatal development.

Behav Brain Res. 2014 Feb 1;259:119-30

Authors: Lai JK, Sobala-Drozdowski M, Zhou L, Doering LC, Faure PA, Foster JA

Abstract
The fmr1 knock out (KO) mouse has been a useful animal model to understand pathology and treatment of FXS, both anatomically and behaviorally. Ultrasonic vocalizations (USVs) are a behavioral tool to assess early life communication deficits in mice. Here, we report on the temporal and spectral features of USVs emitted after maternal separation in wild type (FVB/N) and fmr1 KO pups at postnatal days (P) P4, P7 and P10. The results show changes in the number and duration of calls in fmr1 KO pups and wild type pups were dependent on age and call type. Fmr1 KO pups showed an increased number of USVs at P7 but not at P4 or P10. This increase was specific to Frequency Jump calls. In addition, fmr1 KO mice showed a developmental shift in the temporal distribution of calls, with P10 mice calling in distinct bout patterns. Overall, these findings provide evidence that changes in USV outcomes were specific to certain call types and ages in fmr1 KO mice. Because early postnatal life is a window during which multiple neural systems activate and become established, behavioral measures such as using USVs as a measure of communication, may be useful as a predictor of brain changes and later developmental behavioral changes. Work is needed to better understand the functional outcomes of altered development of USVs and how these changes contribute to later emergence of autistic-like behaviors in animal models of autism.

PMID: 24211451 [PubMed - indexed for MEDLINE]

Repetitive behavior profile and supersensitivity to amphetamine in the C58/J mouse model of autism.

August 5, 2014 - 7:07am
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Repetitive behavior profile and supersensitivity to amphetamine in the C58/J mouse model of autism.

Behav Brain Res. 2014 Feb 1;259:200-14

Authors: Moy SS, Riddick NV, Nikolova VD, Teng BL, Agster KL, Nonneman RJ, Young NB, Baker LK, Nadler JJ, Bodfish JW

Abstract
Restricted repetitive behaviors are core symptoms of autism spectrum disorders (ASDs). The range of symptoms encompassed by the repetitive behavior domain includes lower-order stereotypy and self-injury, and higher-order indices of circumscribed interests and cognitive rigidity. Heterogeneity in clinical ASD profiles suggests that specific manifestations of repetitive behavior reflect differential neuropathology. The present studies utilized a set of phenotyping tasks to determine a repetitive behavior profile for the C58/J mouse strain, a model of ASD core symptoms. In an observational screen, C58/J demonstrated overt motor stereotypy, but not over-grooming, a commonly-used measure for mouse repetitive behavior. Amphetamine did not exacerbate motor stereotypy, but had enhanced stimulant effects on locomotion and rearing in C58/J, compared to C57BL/6J. Both C58/J and Grin1 knockdown mice, another model of ASD-like behavior, had marked deficits in marble-burying. In a nose poke task for higher-order repetitive behavior, C58/J had reduced holeboard exploration and preference for non-social, versus social, olfactory stimuli, but did not demonstrate cognitive rigidity following familiarization to an appetitive stimulus. Analysis of available high-density genotype data indicated specific regions of divergence between C58/J and two highly-sociable strains with common genetic lineage. Strain genome comparisons identified autism candidate genes, including Cntnap2 and Slc6a4, located within regions divergent in C58/J. However, Grin1, Nlgn1, Sapap3, and Slitrk5, genes linked to repetitive over-grooming, were not in regions of divergence. These studies suggest that specific repetitive phenotypes can be used to distinguish ASD mouse models, with implications for divergent underlying mechanisms for different repetitive behavior profiles.

PMID: 24211371 [PubMed - indexed for MEDLINE]

SYN2 is an autism predisposing gene: loss-of-function mutations alter synaptic vesicle cycling and axon outgrowth.

August 5, 2014 - 7:07am
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SYN2 is an autism predisposing gene: loss-of-function mutations alter synaptic vesicle cycling and axon outgrowth.

Hum Mol Genet. 2014 Jan 1;23(1):90-103

Authors: Corradi A, Fadda M, Piton A, Patry L, Marte A, Rossi P, Cadieux-Dion M, Gauthier J, Lapointe L, Mottron L, Valtorta F, Rouleau GA, Fassio A, Benfenati F, Cossette P

Abstract
An increasing number of genes predisposing to autism spectrum disorders (ASDs) has been identified, many of which are implicated in synaptic function. This 'synaptic autism pathway' notably includes disruption of SYN1 that is associated with epilepsy, autism and abnormal behavior in both human and mice models. Synapsins constitute a multigene family of neuron-specific phosphoproteins (SYN1-3) present in the majority of synapses where they are implicated in the regulation of neurotransmitter release and synaptogenesis. Synapsins I and II, the major Syn isoforms in the adult brain, display partially overlapping functions and defects in both isoforms are associated with epilepsy and autistic-like behavior in mice. In this study, we show that nonsense (A94fs199X) and missense (Y236S and G464R) mutations in SYN2 are associated with ASD in humans. The phenotype is apparent in males. Female carriers of SYN2 mutations are unaffected, suggesting that SYN2 is another example of autosomal sex-limited expression in ASD. When expressed in SYN2  knockout neurons, wild-type human Syn II fully rescues the SYN2 knockout phenotype, whereas the nonsense mutant is not expressed and the missense mutants are virtually unable to modify the SYN2 knockout phenotype. These results identify for the first time SYN2  as a novel predisposing gene for ASD and strengthen the hypothesis that a disturbance of synaptic homeostasis underlies ASD.

PMID: 23956174 [PubMed - indexed for MEDLINE]

Diagnostic yield of array comparative genomic hybridization in adults with autism spectrum disorders.

August 5, 2014 - 7:07am
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Diagnostic yield of array comparative genomic hybridization in adults with autism spectrum disorders.

Genet Med. 2014 Jan;16(1):70-7

Authors: Stobbe G, Liu Y, Wu R, Hudgings LH, Thompson O, Hisama FM

Abstract
PURPOSE: Array comparative genomic hybridization is available for the evaluation of autism spectrum disorders. The diagnostic yield of testing is 5-18% in children with developmental disabilities, including autism spectrum disorders and multiple congenital anomalies. The yield of array comparative genomic hybridization in the adult autism spectrum disorder population is unknown.
METHODS: We performed a retrospective chart review for 40 consecutive patients referred for genetic evaluation of autism from July 2009 through April 2012. Four pediatric patients were excluded. Medical history and prior testing were reviewed. Clinical genetic evaluation and testing were offered to all patients.
RESULTS: The study population comprised 36 patients (age range 18-45, mean 25.3 years). An autism spectrum disorder diagnosis was confirmed in 34 of 36 patients by medical record review. One patient had had an abnormal karyotype; none had prior array comparative genomic hybridization testing. Of the 23 patients with autism who underwent array comparative genomic hybridization, 2 of 23 (8.7%) had pathogenic or presumed pathogenic abnormalities and 2 of 23 (8.7%) had likely pathogenic copy-number variants. An additional 5 of 23 (22%) of autism patients had variants of uncertain significance without subclassification.
CONCLUSION: Including one patient newly diagnosed with fragile X syndrome, our data showed abnormal or likely pathogenic findings in 5 of 24 (21%) adult autism patients. Genetic reevaluation in adult autism patients is warranted.

PMID: 23765050 [PubMed - indexed for MEDLINE]

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