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Leontiadis LJ, Trompoukis G, Tsotsokou G, Miliou A, Felemegkas P, Papatheodoropoulos C. Rescue of sharp wave-ripples and prevention of network hyperexcitability in the ventral but not the dorsal hippocampus of a rat model of fragile X syndrome. Front Cell Neurosci 2023; 17:1296235. [PMID: 38107412 PMCID: PMC10722241 DOI: 10.3389/fncel.2023.1296235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Accepted: 11/06/2023] [Indexed: 12/19/2023] Open
Abstract
Fragile X syndrome (FXS) is a genetic neurodevelopmental disorder characterized by intellectual disability and is related to autism. FXS is caused by mutations of the fragile X messenger ribonucleoprotein 1 gene (Fmr1) and is associated with alterations in neuronal network excitability in several brain areas including hippocampus. The loss of fragile X protein affects brain oscillations, however, the effects of FXS on hippocampal sharp wave-ripples (SWRs), an endogenous hippocampal pattern contributing to memory consolidation have not been sufficiently clarified. In addition, it is still not known whether dorsal and ventral hippocampus are similarly affected by FXS. We used a Fmr1 knock-out (KO) rat model of FXS and electrophysiological recordings from the CA1 area of adult rat hippocampal slices to assess spontaneous and evoked neural activity. We find that SWRs and associated multiunit activity are affected in the dorsal but not the ventral KO hippocampus, while complex spike bursts remain normal in both segments of the KO hippocampus. Local network excitability increases in the dorsal KO hippocampus. Furthermore, specifically in the ventral hippocampus of KO rats we found an increased effectiveness of inhibition in suppressing excitation and an upregulation of α1GABAA receptor subtype. These changes in the ventral KO hippocampus are accompanied by a striking reduction in its susceptibility to induced epileptiform activity. We propose that the neuronal network specifically in the ventral segment of the hippocampus is reorganized in adult Fmr1-KO rats by means of balanced changes between excitability and inhibition to ensure normal generation of SWRs and preventing at the same time derailment of the neural activity toward hyperexcitability.
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Maurer JJ, Choi A, An I, Sathi N, Chung S. Sleep disturbances in autism spectrum disorder: Animal models, neural mechanisms, and therapeutics. Neurobiol Sleep Circadian Rhythms 2023; 14:100095. [PMID: 37188242 PMCID: PMC10176270 DOI: 10.1016/j.nbscr.2023.100095] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 03/16/2023] [Accepted: 04/08/2023] [Indexed: 05/17/2023] Open
Abstract
Sleep is crucial for brain development. Sleep disturbances are prevalent in children with autism spectrum disorder (ASD). Strikingly, these sleep problems are positively correlated with the severity of ASD core symptoms such as deficits in social skills and stereotypic behavior, indicating that sleep problems and the behavioral characteristics of ASD may be related. In this review, we will discuss sleep disturbances in children with ASD and highlight mouse models to study sleep disturbances and behavioral phenotypes in ASD. In addition, we will review neuromodulators controlling sleep and wakefulness and how these neuromodulatory systems are disrupted in animal models and patients with ASD. Lastly, we will address how the therapeutic interventions for patients with ASD improve various aspects of sleep. Together, gaining mechanistic insights into the neural mechanisms underlying sleep disturbances in children with ASD will help us to develop better therapeutic interventions.
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Riggs NR, Hepburn SL, Pinks ME, Fidler DJ. A prevention science approach to promoting health and quality of life for individuals with intellectual and developmental disabilities. INFANT AND CHILD DEVELOPMENT 2021. [DOI: 10.1002/icd.2278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Nathaniel R. Riggs
- Human Development and Family Studies Colorado State University Fort Collins Colorado USA
- Prevention Research Center Colorado State University Fort Collins Colorado USA
| | - Susan L. Hepburn
- Human Development and Family Studies Colorado State University Fort Collins Colorado USA
| | - Miranda E. Pinks
- Human Development and Family Studies Colorado State University Fort Collins Colorado USA
| | - Deborah J. Fidler
- Human Development and Family Studies Colorado State University Fort Collins Colorado USA
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Svalina MN, Guthman EM, Cea-Del Rio CA, Kushner JK, Baca SM, Restrepo D, Huntsman MM. Hyperexcitability and Loss of Feedforward Inhibition Contribute to Aberrant Plasticity in the Fmr1KO Amygdala. eNeuro 2021; 8:ENEURO.0113-21.2021. [PMID: 33893168 PMCID: PMC8121259 DOI: 10.1523/eneuro.0113-21.2021] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/05/2021] [Accepted: 04/09/2021] [Indexed: 12/15/2022] Open
Abstract
Fragile X syndrome (FXS) is a neurodevelopmental disorder (NDD) characterized by intellectual disability, autism spectrum disorders (ASDs), and anxiety disorders. The disruption in the function of the FMR1 gene results in a range of alterations in cellular and synaptic function. Previous studies have identified dynamic alterations in inhibitory neurotransmission in early postnatal development in the amygdala of the mouse model of FXS. However, little is known about how these changes alter microcircuit development and plasticity in the lateral amygdala (LA). Using whole-cell patch clamp electrophysiology, we demonstrate that principal neurons (PNs) in the LA exhibit hyperexcitability with a concomitant increase in the synaptic strength of excitatory synapses in the BLA. Further, reduced feed-forward inhibition appears to enhance synaptic plasticity in the FXS amygdala. These results demonstrate that plasticity is enhanced in the amygdala of the juvenile Fmr1 knock-out (KO) mouse and that E/I imbalance may underpin anxiety disorders commonly seen in FXS and ASDs.
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Affiliation(s)
- Matthew N Svalina
- Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
- Medical Scientist Training Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - E Mae Guthman
- Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Christian A Cea-Del Rio
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
- Centro de Investigación Biomédica y Aplicada, Escuela de Medicina, Facultad de Ciencias Médicas, Universidad de Santiago de Chile, Santiago 9160000, Chile
| | - J Keenan Kushner
- Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Serapio M Baca
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Diego Restrepo
- Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
| | - Molly M Huntsman
- Neuroscience Graduate Program, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
- Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
- Department of Pediatrics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
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Kim K, Hessl D, Randol JL, Espinal GM, Schneider A, Protic D, Aydin EY, Hagerman RJ, Hagerman PJ. Association between IQ and FMR1 protein (FMRP) across the spectrum of CGG repeat expansions. PLoS One 2019; 14:e0226811. [PMID: 31891607 PMCID: PMC6938341 DOI: 10.1371/journal.pone.0226811] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 12/05/2019] [Indexed: 12/20/2022] Open
Abstract
Fragile X syndrome, the leading heritable form of intellectual disability, is caused by hypermethylation and transcriptional silencing of large (CGG) repeat expansions (> 200 repeats) in the 5′ untranslated region of the fragile X mental retardation 1 (FMR1) gene. As a consequence of FMR1 gene silencing, there is little or no production of FMR1 protein (FMRP), an important element in normal synaptic function. Although the absence of FMRP has long been known to be responsible for the cognitive impairment in fragile X syndrome, the relationship between FMRP level and cognitive ability (IQ) is only imprecisely understood. To address this issue, a high-throughput, fluorescence resonance energy transfer (FRET) assay has been used to quantify FMRP levels in dermal fibroblasts, and the relationship between FMRP and IQ measures was assessed by statistical analysis in a cohort of 184 individuals with CGG-repeat lengths spanning normal (< 45 CGGs) to full mutation (> 200 CGGs) repeat ranges in fibroblasts. The principal findings of the current study are twofold: i) For those with normal CGG repeats, IQ is no longer sensitive to further increases in FMRP above an FMRP threshold of ~70% of the mean FMRP level; below this threshold, IQ decreases steeply with further decreases in FMRP; and ii) For the current cohort, a mean IQ of 85 (lower bound for the normal IQ range) is attained for FMRP levels that are only ~35% of the mean FMRP level among normal CGG-repeat controls. The current results should help guide expectations for efforts to induce FMR1 gene activity and for the levels of cognitive function expected for a given range of FMRP levels.
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Affiliation(s)
- Kyoungmi Kim
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
- Department of Public Health Sciences, University of California, Davis, School of Medicine, Davis, California, United States of America
| | - David Hessl
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
- Department of Psychiatry and Behavioral Sciences, University of California, Davis, School of Medicine, Sacramento, California, United States of America
| | - Jamie L. Randol
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California, United States of America
| | - Glenda M. Espinal
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California, United States of America
| | - Andrea Schneider
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
- Department of Pediatrics, University of California, Davis, School of Medicine, Sacramento, California, United States of America
| | - Dragana Protic
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
| | - Elber Yuksel Aydin
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
| | - Randi J. Hagerman
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
- Department of Pediatrics, University of California, Davis, School of Medicine, Sacramento, California, United States of America
| | - Paul J. Hagerman
- UC Davis MIND Institute, UC Davis Health, Sacramento, California, United States of America
- Department of Biochemistry and Molecular Medicine, University of California, Davis, School of Medicine, Davis, California, United States of America
- * E-mail:
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Schmitt LM, Shaffer RC, Hessl D, Erickson C. Executive Function in Fragile X Syndrome: A Systematic Review. Brain Sci 2019; 9:brainsci9010015. [PMID: 30654486 PMCID: PMC6356760 DOI: 10.3390/brainsci9010015] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2018] [Revised: 01/09/2019] [Accepted: 01/11/2019] [Indexed: 12/17/2022] Open
Abstract
Executive function (EF) supports goal-directed behavior and includes key aspects such as working memory, inhibitory control, cognitive flexibility, attention, processing speed, and planning. Fragile X syndrome (FXS) is the leading inherited monogenic cause of intellectual disability and is phenotypically characterized by EF deficits beyond what is expected given general cognitive impairments. Yet, a systematic review of behavioral studies using performance-based measures is needed to provide a summary of EF deficits across domains in males and females with FXS, discuss clinical and biological correlates of these EF deficits, identify critical limitations in available research, and offer suggestions for future studies in this area. Ultimately, this review aims to advance our understanding of the underlying pathophysiological mechanisms contributing to EF in FXS and to inform the development of outcome measures of EF and identification of new treatment targets in FXS.
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Affiliation(s)
- Lauren M Schmitt
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
| | - Rebecca C Shaffer
- Division of Developmental and Behavioral Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
| | - David Hessl
- MIND Institute, Department of Psychiatry and Behavioral Sciences, University of California, Davis, CA 95616, USA.
| | - Craig Erickson
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA.
- Department of Psychiatry and Behavioral Neuroscience, University of Cincinnati College of Medicine, Cincinnati, OH 45267, USA.
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Hall SS, Hustyi KM, Barnett RP. Examining the influence of social-environmental variables on self-injurious behaviour in adolescent boys with fragile X syndrome. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2018; 62:1072-1085. [PMID: 29693293 PMCID: PMC6609101 DOI: 10.1111/jir.12489] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2017] [Revised: 02/07/2018] [Accepted: 03/30/2018] [Indexed: 06/08/2023]
Abstract
BACKGROUND Individuals with fragile X syndrome (FXS), the most common known inherited form of intellectual disability, are at increased risk for showing specific forms of self-injurious behaviour (SIB) such as hand biting and head hitting, suggesting that biological factors associated with the syndrome confers increased risk for SIB. Few studies, however, have examined the extent to which social-environmental variables can influence the occurrence of these behaviours in this population. METHOD Twenty-two adolescent boys with FXS, aged 10 to 18 years were systematically exposed to seven environmental conditions in functional analyses of SIB conducted over 2 days at our research centre. RESULTS Fourteen (63.6%) boys with FXS engaged in SIB during the functional analyses. Ten (45.5%) boys engaged in SIB that was maintained by social-environmental variables, that is, gaining access to attention/tangibles and/or escaping from social interaction, task demands and/or transition demands. For two boys, SIB was undifferentiated across conditions, and for two boys, SIB appeared to be maintained by automatic reinforcement. CONCLUSIONS Social-environmental variables appeared to maintain SIB in a significant proportion of boys with FXS. Given that pharmacological treatments for SIB have limited efficacy in this population, the potential role of social-environmental factors on SIB should be examined before pharmacological treatments are implemented for these behaviours.
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Affiliation(s)
- S S Hall
- Department of Psychiatry and Behavioral Sciences, Center for Interdisciplinary Brain Sciences Research, Stanford University, Stanford, CA, USA
| | - K M Hustyi
- Department of Psychiatry and Behavioral Sciences, Center for Interdisciplinary Brain Sciences Research, Stanford University, Stanford, CA, USA
| | - R P Barnett
- Department of Psychiatry and Behavioral Sciences, Center for Interdisciplinary Brain Sciences Research, Stanford University, Stanford, CA, USA
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Boone CE, Davoudi H, Harrold JB, Foster DJ. Abnormal Sleep Architecture and Hippocampal Circuit Dysfunction in a Mouse Model of Fragile X Syndrome. Neuroscience 2018; 384:275-289. [PMID: 29775702 DOI: 10.1016/j.neuroscience.2018.05.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2018] [Revised: 05/03/2018] [Accepted: 05/07/2018] [Indexed: 12/19/2022]
Abstract
Fragile X syndrome (FXS) is the most common heritable cause of intellectual disability and single-gene cause of autism spectrum disorder. The Fmr1 null mouse models much of the human disease including hyperarousal, sensory hypersensitivity, seizure activity, and hippocampus-dependent cognitive impairment. Sleep architecture is disorganized in FXS patients, but has not been examined in Fmr1 knockout (Fmr1-KO) mice. Hippocampal neural activity during sleep, which is implicated in memory processing, also remains uninvestigated in Fmr1-KO mice. We performed in vivo electrophysiological studies of freely behaving Fmr1-KO mice to assess neural activity, in the form of single-unit spiking and local field potential (LFP), within the hippocampal CA1 region during multiple differentiated sleep and wake states. Here, we demonstrate that Fmr1-KO mice exhibited a deficit in rapid eye movement sleep (REM) due to a reduction in the frequency of bouts of REM, consistent with sleep architecture abnormalities of FXS patients. Fmr1-KO CA1 pyramidal cells (CA1-PCs) were hyperactive in all sleep and wake states. Increased low gamma power in CA1 suggests that this hyperactivity was related to increased input to CA1 from CA3. By contrast, slower sharp-wave ripple events (SWRs) in Fmr1-KO mice exhibited longer event duration, slower oscillation frequency, with reduced CA1-PC firing rates during SWRs, yet the incidence rate of SWRs remained intact. These results suggest abnormal neuronal activity in the Fmr1-KO mouse during SWRs, and hyperactivity during other wake and sleep states, with likely adverse consequences for memory processes.
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Affiliation(s)
- Christine E Boone
- Medical Scientist Training Program, Johns Hopkins University School of Medicine, Baltimore, MD, United States; Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Heydar Davoudi
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States; Department of Biomedical Engineering, Johns Hopkins University School of Medicine, Baltimore, MD, United States; Department of Psychology and Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States
| | - Jon B Harrold
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - David J Foster
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD, United States; Department of Psychology and Helen Wills Neuroscience Institute, University of California, Berkeley, CA, United States.
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Matherly SM, Klusek J, Thurman AJ, McDuffie A, Abbeduto L, Roberts JE. Cortisol profiles differentiated in adolescents and young adult males with fragile X syndrome versus autism spectrum disorder. Dev Psychobiol 2018; 60:78-89. [PMID: 29171019 PMCID: PMC5747975 DOI: 10.1002/dev.21578] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2017] [Accepted: 09/27/2017] [Indexed: 11/12/2022]
Abstract
BACKGROUND Fragile X syndrome (FXS) and non-syndromic autism spectrum disorder (ASD) are distinct disorders with overlapping behavioral features. Both disorders are also highly associated with anxiety with abnormal physiological regulation implied mechanistically. Some reports suggest atypical hypothalamus-pituitary-adrenal (HPA) axis function, indexed via aberrant cortisol reactivity, in both FXS and non-syndromic ASD. However, no study has compared cortisol reactivity across these two disorders, or its relationship to ASD symptom severity. METHODS Cortisol reactivity (prior to and following a day of assessments) was measured in 54 adolescent/young adult males with FXS contrasted to 15 males with non-syndromic ASD who had low cognitive abilities. RESULTS Greater ASD symptom severity was related to increased cortisol reactivity and higher levels at the end of the day, but only in the non-syndromic ASD group. Elevated anxiety was associated with increased HPA activation in the group with FXS alone. CONCLUSIONS Taken together, findings suggest a unique neuroendocrine profile that distinguishes adolescent/young adult males with FXS from those with non-syndromic ASD. Severity of ASD symptoms appears to be related to cortisol reactivity in the non-syndromic ASD sample, but not in FXS; while anxiety symptoms are associated with HPA activation in the FXS sample, but not in ASD despite a high prevalence of ASD, anxiety and physiological dysregulation characteristic in both populations.
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Affiliation(s)
- Sara M Matherly
- Department of Psychology, University of South Carolina, Columbia, South Carolina
| | - Jessica Klusek
- Department of Communication Sciences and Disorders, University of South Carolina, Columbia, South Carolina
| | - Angela J Thurman
- Department of Psychiatry and Behavioral Sciences, MIND Institute, University of California, Davis, Sacramento, California
| | - Andrea McDuffie
- Department of Psychiatry and Behavioral Sciences, MIND Institute, University of California, Davis, Sacramento, California
| | - Leonard Abbeduto
- Department of Psychiatry and Behavioral Sciences, MIND Institute, University of California, Davis, Sacramento, California
| | - Jane E Roberts
- Department of Psychology, University of South Carolina, Columbia, South Carolina
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Abstract
Fragile X syndrome (FXS) is the leading inherited form of intellectual disability and autism spectrum disorder, and patients can present with severe behavioural alterations, including hyperactivity, impulsivity and anxiety, in addition to poor language development and seizures. FXS is a trinucleotide repeat disorder, in which >200 repeats of the CGG motif in FMR1 leads to silencing of the gene and the consequent loss of its product, fragile X mental retardation 1 protein (FMRP). FMRP has a central role in gene expression and regulates the translation of potentially hundreds of mRNAs, many of which are involved in the development and maintenance of neuronal synaptic connections. Indeed, disturbances in neuroplasticity is a key finding in FXS animal models, and an imbalance in inhibitory and excitatory neuronal circuits is believed to underlie many of the clinical manifestations of this disorder. Our knowledge of the proteins that are regulated by FMRP is rapidly growing, and this has led to the identification of multiple targets for therapeutic intervention, some of which have already moved into clinical trials or clinical practice.
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Aging-Resilient Associations between the Arcuate Fasciculus and Vocabulary Knowledge: Microstructure or Morphology? J Neurosci 2017; 36:7210-22. [PMID: 27383595 DOI: 10.1523/jneurosci.4342-15.2016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 05/27/2016] [Indexed: 11/21/2022] Open
Abstract
UNLABELLED Vocabulary knowledge is one of the few cognitive functions that is relatively preserved in older adults, but the reasons for this relative preservation have not been well delineated. We tested the hypothesis that individual differences in vocabulary knowledge are influenced by arcuate fasciculus macrostructure (i.e., shape and volume) properties that remain stable during the aging process, rather than white matter microstructure that demonstrates age-related declines. Vocabulary was not associated with age compared to pronounced age-related declines in cognitive processing speed across 106 healthy adults (19.92-88.29 years) who participated in this neuroimaging experiment. Fractional anisotropy in the left arcuate fasciculus was significantly related to individual variability in vocabulary. This effect was present despite marked age-related differences in a T1-weighted/T2-weighted ratio (T1w/T2w) estimate of myelin that were observed throughout the left arcuate fasciculus and associated with age-related differences in cognitive processing speed. However, atypical patterns of arcuate fasciculus morphology or macrostructure were associated with decreased vocabulary knowledge. These results suggest that deterioration of tissue in the arcuate fasciculus occurs with normal aging, while having limited impact on tract organization that underlies individual differences in the acquisition and retrieval of lexical and semantic information. SIGNIFICANCE STATEMENT Vocabulary knowledge is resilient to widespread age-related declines in brain structure that limit other cognitive functions. We tested the hypothesis that arcuate fasciculus morphology, which supports the development of reading skills that bolster vocabulary, could explain this relative preservation. We disentangled (1) the effects of age-related declines in arcuate microstructure (mean diffusivity; myelin content estimate) that predicted cognitive processing speed but not vocabulary, from (2) relatively stable arcuate macrostructure (shape/volume) that explained significant variance in an age-independent association between fractional anisotropy and vocabulary. This latter result may reflect differences in fiber trajectory and organization that are resilient to aging. We propose that developmental sculpting of the arcuate fasciculus determines acquisition, storage, and access of lexical information across the adult lifespan.
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Wheeler A, Raspa M, Hagerman R, Mailick M, Riley C. Implications of the FMR1 Premutation for Children, Adolescents, Adults, and Their Families. Pediatrics 2017; 139:S172-S182. [PMID: 28814538 PMCID: PMC5621635 DOI: 10.1542/peds.2016-1159d] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/24/2017] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Given the nature of FMR1 gene expansions, most biological mothers, and often multiple other family members of children with fragile X syndrome (FXS), will have a premutation, which may increase individual and family vulnerabilities. This article summarizes important gaps in knowledge and notes potential implications for pediatric providers with regard to developmental and medical risks for children and adolescents with an FMR1 premutation, including possible implications into adulthood. METHODS A structured electronic literature search was conducted on FMR1 pre- and full mutations, yielding a total of 306 articles examined. Of these, 116 focused primarily on the premutation and are included in this review. RESULTS Based on the literature review, 5 topic areas are discussed: genetics and epidemiology; phenotypic characteristics of individuals with the premutation; implications for carrier parents of children with FXS; implications for the extended family; and implications for pediatricians. CONCLUSIONS Although the premutation phenotype is typically less severe in clinical presentation than in FXS, premutation carriers are much more common and are therefore more likely to be seen in a typical pediatric practice. In addition, there is a wide range of medical, cognitive/developmental, and psychiatric associated features that individuals with a premutation are at increased risk for having, which underscores the importance of awareness on the part of pediatricians in identifying and monitoring premutation carriers and recognizing the impact this identification may have on family members.
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Affiliation(s)
- Anne Wheeler
- RTI International, Research Triangle Park, North Carolina;
| | - Melissa Raspa
- RTI International, Research Triangle Park, North Carolina
| | - Randi Hagerman
- MIND Institute, University of California at Davis, Sacramento, California
| | - Marsha Mailick
- Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin; and
| | - Catharine Riley
- National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia
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Abstract
OBJECTIVES The purpose of this systematic literature review is to describe what is known about fragile X syndrome (FXS) and to identify research gaps. The results can be used to help inform future public health research and provide pediatricians with up-to-date information about the implications of the condition for individuals and their families. METHODS An electronic literature search was conducted, guided by a variety of key words. The search focused on 4 areas of both clinical and public health importance: (1) the full mutation phenotype, (2) developmental trajectories across the life span, (3) available interventions and treatments, and (4) impact on the family. A total of 661 articles were examined and 203 were included in the review. RESULTS The information is presented in the following categories: developmental profile (cognition, language, functional skills, and transition to adulthood), social-emotional profile (cooccurring psychiatric conditions and behavior problems), medical profile (physical features, seizures, sleep, health problems, and physiologic features), treatment and interventions (educational/behavioral, allied health services, and pharmacologic), and impact on the family (family environment and financial impact). Research gaps also are presented. CONCLUSIONS The identification and treatment of FXS remains an important public health and clinical concern. The information presented in this article provides a more robust understanding of FXS and the impact of this complex condition for pediatricians. Despite a wealth of information about the condition, much work remains to fully support affected individuals and their families.
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Affiliation(s)
- Melissa Raspa
- RTI International, Research Triangle Park, North Carolina; and
| | - Anne C Wheeler
- RTI International, Research Triangle Park, North Carolina; and
| | - Catharine Riley
- National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia
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Zorio DAR, Jackson CM, Liu Y, Rubel EW, Wang Y. Cellular distribution of the fragile X mental retardation protein in the mouse brain. J Comp Neurol 2017; 525:818-849. [PMID: 27539535 PMCID: PMC5558202 DOI: 10.1002/cne.24100] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 08/10/2016] [Accepted: 08/11/2016] [Indexed: 11/07/2022]
Abstract
The fragile X mental retardation protein (FMRP) plays an important role in normal brain development. Absence of FMRP results in abnormal neuronal morphologies in a selected manner throughout the brain, leading to intellectual deficits and sensory dysfunction in the fragile X syndrome (FXS). Despite FMRP importance for proper brain function, its overall expression pattern in the mammalian brain at the resolution of individual neuronal cell groups is not known. In this study we used FMR1 knockout and isogenic wildtype mice to systematically map the distribution of FMRP expression in the entire mouse brain. Using immunocytochemistry and cellular quantification analyses, we identified a large number of prominent cell groups expressing high levels of FMRP at the subcortical levels, in particular sensory and motor neurons in the brainstem and thalamus. In contrast, many cell groups in the midbrain and hypothalamus exhibit low FMRP levels. More important, we describe differential patterns of FMRP distribution in both cortical and subcortical brain regions. Almost all major brain areas contain high and low levels of FMRP cell groups adjacent to each other or between layers of the same cortical areas. These differential patterns indicate that FMRP expression appears to be specific to individual neuronal cell groups instead of being associated with all neurons in distinct brain regions, as previously considered. Taken together, these findings support the notion of FMRP differential neuronal regulation and strongly implicate the contribution of fundamental sensory and motor processing at subcortical levels to FXS pathology. J. Comp. Neurol. 525:818-849, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Diego A. R. Zorio
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
| | - Christine M. Jackson
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
| | - Yong Liu
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
| | - Edwin W Rubel
- Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington School of Medicine, Box 357923, Seattle, WA 98195, USA
| | - Yuan Wang
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL 32306, USA
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Schaafsma SM, Gagnidze K, Reyes A, Norstedt N, Månsson K, Francis K, Pfaff DW. Sex-specific gene-environment interactions underlying ASD-like behaviors. Proc Natl Acad Sci U S A 2017; 114:1383-1388. [PMID: 28115688 PMCID: PMC5307430 DOI: 10.1073/pnas.1619312114] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The male bias in the incidence of autism spectrum disorders (ASDs) is one of the most notable characteristics of this group of neurodevelopmental disorders. The etiology of this sex bias is far from known, but pivotal for understanding the etiology of ASDs in general. Here we investigate whether a "three-hit" (genetic load × environmental factor × sex) theory of autism may help explain the male predominance. We found that LPS-induced maternal immune activation caused male-specific deficits in certain social responses in the contactin-associated protein-like 2 (Cntnap2) mouse model for ASD. The three "hits" had cumulative effects on ultrasonic vocalizations at postnatal day 3. Hits synergistically affected social recognition in adulthood: only mice exposed to all three hits showed deficits in this aspect of social behavior. In brains of the same mice we found a significant three-way interaction on corticotropin-releasing hormone receptor-1 (Crhr1) gene expression, in the left hippocampus specifically, which co-occurred with epigenetic alterations in histone H3 N-terminal lysine 4 trimethylation (H3K4me3) over the Crhr1 promoter. Although it is highly likely that multiple (synergistic) interactions may be at work, change in the expression of genes in the hypothalamic-pituitary-adrenal/stress system (e.g., Crhr1) is one of them. The data provide proof-of-principle that genetic and environmental factors interact to cause sex-specific effects that may help explain the male bias in ASD incidence.
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Affiliation(s)
- Sara M Schaafsma
- Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10065
| | - Khatuna Gagnidze
- Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10065
| | - Anny Reyes
- Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10065
| | - Natalie Norstedt
- Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10065
| | - Karl Månsson
- Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10065
| | - Kerel Francis
- Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10065
| | - Donald W Pfaff
- Laboratory of Neurobiology and Behavior, The Rockefeller University, New York, NY 10065
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Wallach E, Bieth E, Sevely A, Cances C. [Fragile X syndrome and white matter abnormalities: Case study of two brothers]. Arch Pediatr 2017; 24:244-248. [PMID: 28131561 DOI: 10.1016/j.arcped.2016.12.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2016] [Revised: 06/21/2016] [Accepted: 12/04/2016] [Indexed: 10/20/2022]
Abstract
Fragile X syndrome is the most usual cause of hereditary intellectual deficiency. Typical symptoms combine intellectual deficiency, social anxiety, intense emotional vigilance, and a characteristic facial dysmorphy. This is subsequent to a complete mutation of the FMR1 gene, considering a semidominant transmission linked to the unstable X. The expansion of the CGG triplet greater than 200 units combined with a high methylation pattern lead to a transcriptional silence of the FMR1 gene, and the protein product, the FMRP, is not synthesized. This protein is involved in synaptic plasticity. Brain MRI can show an increased volume of the caudate nucleus and hippocampus, combined with hypoplasia of the cerebellar vermis. Fragile X Associated Tremor Ataxia Syndrome (FXTAS) syndrome is a neurodegenerative disorder occurring in carriers of the premutation in FMR1. Brain MRI shows an increased T2 signal in the middle cerebellar peduncles. This syndrome is linked to a premutation in the FMR1 gene. We report here the case of two brothers presenting a typical fragile X symptomatology. Brain MRI showed hyperintensities of the middle cerebellar peduncles. Such MRI findings support the assumption of a genetic mosaicism.
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Affiliation(s)
- E Wallach
- Unité de neuropédiatrie, hôpital des enfants, CHU Purpan, 330, avenue de Grande-Bretagne, TSA 70034, 31059 Toulouse cedex 9, France.
| | - E Bieth
- Service de génétique médicale, CHU Purpan, 330, avenue de Grande-Bretagne, 31059 Toulouse cedex 9, France
| | - A Sevely
- Service de neuroradiologie, CHU Purpan, 330, avenue de Grande-Bretagne, 31059 Toulouse cedex 9, France
| | - C Cances
- Unité de neuropédiatrie, hôpital des enfants, CHU Purpan, 330, avenue de Grande-Bretagne, TSA 70034, 31059 Toulouse cedex 9, France
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17
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Hardiman RL, Bratt A. Hypothalamic-pituitary-adrenal axis function in Fragile X Syndrome and its relationship to behaviour: A systematic review. Physiol Behav 2016; 167:341-353. [DOI: 10.1016/j.physbeh.2016.09.030] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2016] [Revised: 09/13/2016] [Accepted: 09/30/2016] [Indexed: 01/18/2023]
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Wheeler AC, Sideris J, Hagerman R, Berry-Kravis E, Tassone F, Bailey DB. Developmental profiles of infants with an FMR1 premutation. J Neurodev Disord 2016; 8:40. [PMID: 27822316 PMCID: PMC5095966 DOI: 10.1186/s11689-016-9171-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 10/16/2016] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Emerging evidence suggests that a subset of FMR1 premutation carriers is at an increased risk for cognitive, emotional, and medical conditions. However, because the premutation is rarely diagnosed at birth, the early developmental trajectories of children with a premutation are not known. METHODS This exploratory study examined the cognitive, communication, and social-behavioral profiles of 26 infants with a premutation who were identified through participation in a newborn screening for fragile X syndrome pilot study. In this study, families whose newborn screened positive for an FMR1 premutation were invited to participate in a longitudinal study of early development. Twenty-six infants with the premutation and 21 matched, screen-negative comparison babies were assessed using validated standardized measures at 6-month intervals starting as young as 3 months of age. The babies were assessed up to seven times over a 4-year period. RESULTS The premutation group was not statistically different from the comparison group on measures of cognitive development, adaptive behavior, temperament, or overall communication. However, the babies with the premutation had a significantly different developmental trajectory on measures of nonverbal communication and hyperresponsivity to sensory experiences. They also were significantly more hyporesponsive at all ages than the comparison group. Cytosine-guanine-guanine repeat length was linearly associated with overall cognitive development. CONCLUSIONS These results suggest that infants with a premutation may present with subtle developmental differences as young as 12 months of age that may be early markers of later anxiety, social deficits, or other challenges thought to be experienced by a subset of carriers.
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Affiliation(s)
- Anne C Wheeler
- RTI International, 3040 E. Cornwallis Road, P.O. Box 12194, Research Triangle Park, NC 27709 USA
| | - John Sideris
- University of North Carolina at Chapel Hill, Chapel Hill, NC USA
| | - Randi Hagerman
- Davis MIND (Medical Investigation of Neurodevelopmental Disorders) Institute, University of California at Davis, Davis, CA USA ; Department of Pediatrics, University of California at Davis, Davis, CA USA
| | | | - Flora Tassone
- Davis MIND (Medical Investigation of Neurodevelopmental Disorders) Institute, University of California at Davis, Davis, CA USA
| | - Donald B Bailey
- RTI International, 3040 E. Cornwallis Road, P.O. Box 12194, Research Triangle Park, NC 27709 USA
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Nistal M, Paniagua R, González-Peramato P, Reyes-Múgica M. Perspectives in Pediatric Pathology, Chapter 15. Macrorchidism as the Expression of Several Congenital and Acquired Pathologies. Pediatr Dev Pathol 2016; 19:202-18. [PMID: 25105801 DOI: 10.2350/14-05-1494-pb.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Manuel Nistal
- 1 Department of Pathology, Hospital La Paz, Universidad Autónoma de Madrid, Madrid, Spain
| | - Ricardo Paniagua
- 2 Department of Cell Biology, Universidad de Alcala, Madrid, Spain
| | | | - Miguel Reyes-Múgica
- 3 Department of Pathology, Children's Hospital of Pittsburgh, University of Pittsburgh Medical Center, Pittsburgh, PA 15224, USA
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20
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Regional brain volumes changes in adult male FMR1-KO mouse on the FVB strain. Neuroscience 2016; 318:12-21. [DOI: 10.1016/j.neuroscience.2016.01.021] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 01/06/2016] [Accepted: 01/09/2016] [Indexed: 11/17/2022]
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21
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Scherr JF, Hahn LJ, Hooper SR, Hatton D, Roberts JE. HPA axis function predicts development of working memory in boys with FXS. Brain Cogn 2016; 102:80-90. [PMID: 26760450 PMCID: PMC4724243 DOI: 10.1016/j.bandc.2015.12.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Revised: 11/18/2015] [Accepted: 12/10/2015] [Indexed: 11/22/2022]
Abstract
The present study examines verbal working memory over time in boys with fragile X syndrome (FXS) compared to nonverbal mental-age (NVMA) matched, typically developing (TD) boys. Concomitantly, the relationship between cortisol-a physiological marker for stress-and verbal working memory performance over time is examined to understand the role of physiological mechanisms in cognitive development in FXS. Participants were assessed between one and three times over a 2-year time frame using two verbal working memory tests that differ in complexity: memory for words and auditory working memory with salivary cortisol collected at the beginning and end of each assessment. Multilevel modeling results indicate specific deficits over time on the memory for words task in boys with FXS compared to TD controls that is exacerbated by elevated baseline cortisol. Similar increasing rates of growth over time were observed for boys with FXS and TD controls on the more complex auditory working memory task, but only boys with FXS displayed an association of increased baseline cortisol and lower performance. This study highlights the benefit of investigations of how dynamic biological and cognitive factors interact and influence cognitive development over time.
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Affiliation(s)
- Jessica F. Scherr
- Department of Psychology, 1512 Pendleton Street, University of South Carolina, Columbia, SC, 29208, USA
| | - Laura J. Hahn
- Department of Psychology, 1512 Pendleton Street, University of South Carolina, Columbia, SC, 29208, USA
| | - Stephen R. Hooper
- Departments of Allied Health Sciences and Psychiatry, 1028 Bondurant Hall, University of North Carolina School of Medicine, Chapel Hill, NC 27599-4120, USA
| | - Deborah Hatton
- Department of Special Education, Box 228 Peabody College, Vanderbilt University, Nashville, TN, 37203, USA,
| | - Jane E. Roberts
- Department of Psychology, 1512 Pendleton Street, University of South Carolina, Columbia, SC, 29208, USA
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22
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Reeb-Sutherland BC, Fox NA. Eyeblink conditioning: a non-invasive biomarker for neurodevelopmental disorders. J Autism Dev Disord 2015; 45:376-94. [PMID: 23942847 DOI: 10.1007/s10803-013-1905-9] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Eyeblink conditioning (EBC) is a classical conditioning paradigm typically used to study the underlying neural processes of learning and memory. EBC has a well-defined neural circuitry, is non-invasive, and can be employed in human infants shortly after birth making it an ideal tool to use in both developing and special populations. In addition, abnormalities in the cerebellum, a region of the brain highly involved in EBC, have been implicated in a number of neurodevelopmental disorders including autism spectrum disorders (ASDs). In the current paper, we review studies that have employed EBC as a biomarker for several neurodevelopmental disorders including fetal alcohol syndrome, Down syndrome, fragile X syndrome, attention deficit/hyperactivity disorder, dyslexia, specific language impairment, and schizophrenia. In addition, we discuss the benefits of using such a tool in individuals with ASD.
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Affiliation(s)
- Bethany C Reeb-Sutherland
- Department of Psychology, DM 256, Florida International University, 11200 SW 8th Street, Miami, FL, 33199, USA,
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23
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de Esch CE, Zeidler S, Willemsen R. Translational endpoints in fragile X syndrome. Neurosci Biobehav Rev 2014; 46 Pt 2:256-69. [DOI: 10.1016/j.neubiorev.2013.10.012] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Revised: 10/07/2013] [Accepted: 10/09/2013] [Indexed: 01/01/2023]
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de Diego-Otero Y, Calvo-Medina R, Quintero-Navarro C, Sánchez-Salido L, García-Guirado F, del Arco-Herrera I, Fernández-Carvajal I, Ferrando-Lucas T, Caballero-Andaluz R, Pérez-Costillas L. A combination of ascorbic acid and α-tocopherol to test the effectiveness and safety in the fragile X syndrome: study protocol for a phase II, randomized, placebo-controlled trial. Trials 2014; 15:345. [PMID: 25187257 PMCID: PMC4168067 DOI: 10.1186/1745-6215-15-345] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 07/18/2014] [Indexed: 01/18/2023] Open
Abstract
Background Fragile X syndrome (FXS) is an inherited neurodevelopmental condition characterised by behavioural, learning disabilities, phisical and neurological symptoms. In addition, an important degree of comorbidity with autism is also present. Considered a rare disorder affecting both genders, it first becomes apparent during childhood with displays of language delay and behavioural symptoms. Main aim: To show whether the combination of 10 mg/kg/day of ascorbic acid (vitamin C) and 10 mg/kg/day of α-tocopherol (vitamin E) reduces FXS symptoms among male patients ages 6 to 18 years compared to placebo treatment, as measured on the standardized rating scales at baseline, and after 12 and 24 weeks of treatment. Secondary aims: To assess the safety of the treatment. To describe behavioural and cognitive changes revealed by the Developmental Behaviour Checklist Short Form (DBC-P24) and the Wechsler Intelligence Scale for Children–Revised. To describe metabolic changes revealed by blood analysis. To measure treatment impact at home and in an academic environment. Methods/Design A phase II randomized, double-blind pilot clinical trial. Scope: male children and adolescents diagnosed with FXS, in accordance with a standardized molecular biology test, who met all the inclusion criteria and none of the exclusion criteria. Instrumentation: clinical data, blood analysis, Wechsler Intelligence Scale for Children–Revised, Conners parent and teacher rating scale scores and the DBC-P24 results will be obtained at the baseline (t0). Follow up examinations will take place at 12 weeks (t1) and 24 weeks (t2) of treatment. Discussion A limited number of clinical trials have been carried out on children with FXS, but more are necessary as current treatment possibilities are insufficient and often provoke side effects. In the present study, we sought to overcome possible methodological problems by conducting a phase II pilot study in order to calculate the relevant statistical parameters and determine the safety of the proposed treatment. The results will provide evidence to improve hyperactivity control and reduce behavioural and learning problems using ascorbic acid (vitamin C) and α-tocopherol (vitamin E). The study protocol was approved by the Regional Government Committee for Clinical Trials in Andalusia and the Spanish agency for drugs and health products. Trial registration ClinicalTrials.gov Identifier: NCT01329770 (29 March 2011)
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Affiliation(s)
- Yolanda de Diego-Otero
- Unidad de Gestión Clínica de Salud Mental, Hospital Regional Universitario de Málaga, Instituto de Investigación Biomédica de Málaga (IBIMA), Hospital Civil, Pabellón 2 bajo, Plaza del Hospital Civil S/N, 29009 Málaga, Spain.
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Wheeler AC, Bailey DB, Berry-Kravis E, Greenberg J, Losh M, Mailick M, Milà M, Olichney JM, Rodriguez-Revenga L, Sherman S, Smith L, Summers S, Yang JC, Hagerman R. Associated features in females with an FMR1 premutation. J Neurodev Disord 2014; 6:30. [PMID: 25097672 PMCID: PMC4121434 DOI: 10.1186/1866-1955-6-30] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/16/2013] [Accepted: 03/19/2014] [Indexed: 12/31/2022] Open
Abstract
Changes in the fragile X mental retardation 1 gene (FMR1) have been associated with specific phenotypes, most specifically those of fragile X syndrome (FXS), fragile X tremor/ataxia syndrome (FXTAS), and fragile X primary ovarian insufficiency (FXPOI). Evidence of increased risk for additional medical, psychiatric, and cognitive features and conditions is now known to exist for individuals with a premutation, although some features have been more thoroughly studied than others. This review highlights the literature on medical, reproductive, cognitive, and psychiatric features, primarily in females, that have been suggested to be associated with changes in the FMR1 gene. Based on this review, each feature is evaluated with regard to the strength of evidence of association with the premutation. Areas of need for additional focused research and possible intervention strategies are suggested.
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Affiliation(s)
- Anne C Wheeler
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709, USA ; Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Donald B Bailey
- RTI International, 3040 Cornwallis Road, Research Triangle Park, NC 27709, USA
| | | | - Jan Greenberg
- Waisman Center, University of Wisconsin, 1500 Highland Avenue, Madison, WI 53705, USA
| | - Molly Losh
- Northwestern University, 2240 Campus Drive, Evanston, IL 60208-3507, USA
| | - Marsha Mailick
- Waisman Center, University of Wisconsin, 1500 Highland Avenue, Madison, WI 53705, USA
| | - Montserrat Milà
- Biochemistry and Molecular Genetics Department, Hospital Clinic, Villarroel 170, 08036 Barcelona, Spain
| | - John M Olichney
- Center for Mind and Brain, University of California-Davis, 1 Shields Avenue, Davis, CA 95616, USA ; MIND Institute, University of California Davis, 2825 50th Street, Sacramento, CA 95817, USA
| | - Laia Rodriguez-Revenga
- Biochemistry and Molecular Genetics Department, Hospital Clinic, Villarroel 170, 08036 Barcelona, Spain
| | | | - Leann Smith
- Waisman Center, University of Wisconsin, 1500 Highland Avenue, Madison, WI 53705, USA
| | - Scott Summers
- Center for Mind and Brain, University of California-Davis, 1 Shields Avenue, Davis, CA 95616, USA ; MIND Institute, University of California Davis, 2825 50th Street, Sacramento, CA 95817, USA
| | - Jin-Chen Yang
- Center for Mind and Brain, University of California-Davis, 1 Shields Avenue, Davis, CA 95616, USA ; MIND Institute, University of California Davis, 2825 50th Street, Sacramento, CA 95817, USA
| | - Randi Hagerman
- Center for Mind and Brain, University of California-Davis, 1 Shields Avenue, Davis, CA 95616, USA ; MIND Institute, University of California Davis, 2825 50th Street, Sacramento, CA 95817, USA
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Turkstra LS, Abbeduto L, Meulenbroek P. Social cognition in adolescent girls with fragile x syndrome. AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES 2014; 119:319-39. [PMID: 25007297 PMCID: PMC4285382 DOI: 10.1352/1944-7558-119.4.319] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This study aimed to characterize social cognition, executive functions (EFs), and everyday social functioning in adolescent girls with fragile X syndrome, and identify relationships among these variables. Participants were 20 girls with FXS and 20 age-matched typically developing peers. Results showed significant between-groups differences in social cognition, accounted for by differences in IQ and language. Within the FXS group, IQ and language were related to social cognition; parent-reported social functioning was related to language and EFs; and self-reported social functioning was generally good and not related to cognitive or social cognition variables. Results suggest that intervention might focus on managing language and cognitive contributions to social functioning, rather than social cognition, and underscore the importance of considering parent and adolescent perspectives.
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Rotschafer SE, Razak KA. Auditory processing in fragile x syndrome. Front Cell Neurosci 2014; 8:19. [PMID: 24550778 PMCID: PMC3912505 DOI: 10.3389/fncel.2014.00019] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 01/12/2014] [Indexed: 11/24/2022] Open
Abstract
Fragile X syndrome (FXS) is an inherited form of intellectual disability and autism. Among other symptoms, FXS patients demonstrate abnormalities in sensory processing and communication. Clinical, behavioral, and electrophysiological studies consistently show auditory hypersensitivity in humans with FXS. Consistent with observations in humans, the Fmr1 KO mouse model of FXS also shows evidence of altered auditory processing and communication deficiencies. A well-known and commonly used phenotype in pre-clinical studies of FXS is audiogenic seizures. In addition, increased acoustic startle response is seen in the Fmr1 KO mice. In vivo electrophysiological recordings indicate hyper-excitable responses, broader frequency tuning, and abnormal spectrotemporal processing in primary auditory cortex of Fmr1 KO mice. Thus, auditory hyper-excitability is a robust, reliable, and translatable biomarker in Fmr1 KO mice. Abnormal auditory evoked responses have been used as outcome measures to test therapeutics in FXS patients. Given that similarly abnormal responses are present in Fmr1 KO mice suggests that cellular mechanisms can be addressed. Sensory cortical deficits are relatively more tractable from a mechanistic perspective than more complex social behaviors that are typically studied in autism and FXS. The focus of this review is to bring together clinical, functional, and structural studies in humans with electrophysiological and behavioral studies in mice to make the case that auditory hypersensitivity provides a unique opportunity to integrate molecular, cellular, circuit level studies with behavioral outcomes in the search for therapeutics for FXS and other autism spectrum disorders.
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Affiliation(s)
- Sarah E Rotschafer
- Graduate Neuroscience Program, Department of Psychology, University of California, Riverside, CA USA
| | - Khaleel A Razak
- Graduate Neuroscience Program, Department of Psychology, University of California, Riverside, CA USA
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Molnár K, Kéri S. Bigger is better and worse: on the intricate relationship between hippocampal size and memory. Neuropsychologia 2014; 56:73-8. [PMID: 24423661 DOI: 10.1016/j.neuropsychologia.2014.01.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2013] [Revised: 12/14/2013] [Accepted: 01/03/2014] [Indexed: 10/25/2022]
Abstract
The structure-function relationship between the hippocampal region and memory is a debated topic in the literature. It has been suggested that larger hippocampi are associated with less effective memory performance in healthy young adults because of a partial synaptic pruning. Here, we tested this hypothesis in individuals with Fragile X Syndrome (FXS) with known abnormal pruning and IQ- and age-matched individuals with hypoxic brain injury, preterm birth, and obstetric complications. Results revealed larger normalized hippocampal volume in FXS compared with neurotypical controls, whereas individuals with hypoxic injury had smaller hippocampi. In neurotypical controls and individuals with hypoxic injury, better general memory, as indexed by the Wechsler Memory Scale-Revised, was associated with larger hippocampus. In contrast, in FXS we observed the opposite relationship: larger hippocampus was associated with worse general memory. Caudate volume did not correlate with memory in either group. These results suggest that incomplete pruning in young healthy adults may not contribute to less efficient memory capacity, and hippocampal size is positively associated with memory performance. However, abnormally large and poorly pruned hippocampus may indeed be less effective in FXS.
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Affiliation(s)
- Katalin Molnár
- Nyírő Gyula Hospital, National Institute of Psychiatry and Addictions, Budapest, Hungary; University of Szeged, Faculty of Medicine, Department of Physiology, Szeged, Hungary; Budapest University of Technology and Economics, Department of Cognitive Science, Budapest, Hungary
| | - Szabolcs Kéri
- Nyírő Gyula Hospital, National Institute of Psychiatry and Addictions, Budapest, Hungary; University of Szeged, Faculty of Medicine, Department of Physiology, Szeged, Hungary; Budapest University of Technology and Economics, Department of Cognitive Science, Budapest, Hungary.
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Tonnsen BL, Shinkareva SV, Deal SC, Hatton DD, Roberts JE. Biobehavioral indicators of social fear in young children with fragile X syndrome. AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES 2013; 118:447-59. [PMID: 24432858 PMCID: PMC4283795 DOI: 10.1352/1944-7558-118.6.447] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Anxiety is among the most impairing conditions associated with Fragile X syndrome (FXS) and is putatively linked to atypical physiological arousal. However, few studies have examined this association in young children with FXS. The authors examined whether patterns of arousal and behavior during an experimental stranger approach paradigm differ between a cross-sectional sample of 21 young children with FXS and 19 controls (12-58 months old). Groups did not differ in mean levels of behavioral fear. Unlike the control group, however, the FXS group demonstrated increased facial fear at older ages, as well as age-dependent changes in associations between heart activity and distress vocalizations. These findings may inform theoretical models of anxiety etiology in FXS and early detection efforts.
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Affiliation(s)
| | | | | | | | - Jane E. Roberts
- University of South Carolina, 1512 Pendleton Street, Columbia SC 29201 ()
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Cohen S, Masyn K, Mastergeorge A, Hessl D. Psychophysiological responses to emotional stimuli in children and adolescents with autism and fragile X syndrome. JOURNAL OF CLINICAL CHILD AND ADOLESCENT PSYCHOLOGY 2013; 44:250-63. [PMID: 24156344 DOI: 10.1080/15374416.2013.843462] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Individuals with autism demonstrate atypical and variable responses to social and emotional stimuli, perhaps reflecting heterogeneity of the disorder. The goal of this study was to determine whether unique profiles of psychophysiological responses to such stimuli could be identified in individuals diagnosed with autism spectrum disorder (ASD), with fragile X syndrome (FXS), and with comorbid autism and fragile X syndrome (ASD + FXS), and in typically developing (TYP) individuals. This study included 52 boys (ages 10-17): idiopathic ASD (n = 12), FXS (n = 12), comorbid ASD + FXS (n = 17), and TYP (n = 11). Physiological responses, including potentiated startle, electrodermal response, heart rate variability, and vagal tone, were collected concurrently while participants viewed emotionally evocative pictures of human faces or nonsocial images. Although some of these measures have been utilized separately for investigations on these diagnostic groups, they have not been considered together. Results using Kruskal-Wallis one-way analysis of variance by ranks indicate statistically significant differences in distributions of autonomic regulation responses between groups. The most notable differences were between the ASD group and both the FXS groups on measures of sympathetic activity, with FXS groups evincing increased activity. Also, both the ASD and ASD + FXS groups showed significantly decreased parasympathetic activity compared with FXS and TYP groups. In addition, the ASD + FXS group demonstrated a unique distribution of startle potentiation and arousal modulation. This study provides evidence that autonomic arousal and regulation profiles could be useful for distinguishing subgroups of autism and shed light on the variability underlying emotional responsivity.
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Cook D, Nuro E, Murai KK. Increasing our understanding of human cognition through the study of Fragile X Syndrome. Dev Neurobiol 2013; 74:147-77. [PMID: 23723176 PMCID: PMC4216185 DOI: 10.1002/dneu.22096] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Accepted: 05/17/2013] [Indexed: 12/16/2022]
Abstract
Fragile X Syndrome (FXS) is considered the most common form of inherited intellectual disability. It is caused by reductions in the expression level or function of a single protein, the Fragile X Mental Retardation Protein (FMRP), a translational regulator which binds to approximately 4% of brain messenger RNAs. Accumulating evidence suggests that FXS is a complex disorder of cognition, involving interactions between genetic and environmental influences, leading to difficulties in acquiring key life skills including motor skills, language, and proper social behaviors. Since many FXS patients also present with one or more features of autism spectrum disorders (ASDs), insights gained from studying the monogenic basis of FXS could pave the way to a greater understanding of underlying features of multigenic ASDs. Here we present an overview of the FXS and FMRP field with the goal of demonstrating how loss of a single protein involved in translational control affects multiple stages of brain development and leads to debilitating consequences on human cognition. We also focus on studies which have rescued or improved FXS symptoms in mice using genetic or therapeutic approaches to reduce protein expression. We end with a brief description of how deficits in translational control are implicated in FXS and certain cases of ASDs, with many recent studies demonstrating that ASDs are likely caused by increases or decreases in the levels of certain key synaptic proteins. The study of FXS and its underlying single genetic cause offers an invaluable opportunity to study how a single gene influences brain development and behavior.
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Affiliation(s)
- Denise Cook
- Department of Neurology and Neurosurgery, Centre for Research in Neuroscience, The Research Institute of the McGill University Health Centre, Montreal General Hospital, Montreal, Quebec, Canada
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Tonnsen BL, Malone PS, Hatton DD, Roberts JE. Early negative affect predicts anxiety, not autism, in preschool boys with fragile X syndrome. JOURNAL OF ABNORMAL CHILD PSYCHOLOGY 2013; 41:267-80. [PMID: 23011214 DOI: 10.1007/s10802-012-9671-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Children with fragile X syndrome (FXS) face high risk for anxiety disorders, yet no studies have explored FXS as a high-risk sample for investigating early manifestations of anxiety outcomes. Negative affect is one of the most salient predictors of problem behaviors and has been associated with both anxiety and autistic outcomes in clinical and non-clinical pediatric samples. In light of the high comorbidity between autism and anxiety within FXS, the present study investigates the relationship between longitudinal trajectories of negative affect (between 8 and 71 months) and severity of anxiety and autistic outcomes in young males with FXS (n = 25). Multilevel models indicated associations between elevated anxiety and higher fear and sadness, lower soothability, and steeper longitudinal increases in approach. Autistic outcomes were unrelated to negative affect. These findings suggest early negative affect differentially predicts anxiety, not autistic symptoms, within FXS. Future research is warranted to determine the specificity of the relationship between negative affect and anxiety, as well as to explore potential moderators. Characterizing the relationship between early negative affect and anxiety within FXS may inform etiology and treatment considerations specific to children with FXS, as well as lend insight into precursors of anxiety disorders in other clinical groups and community samples.
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Affiliation(s)
- Bridgette L Tonnsen
- Department of Psychology, University of South Carolina, 1512 Pendleton St., Columbia, SC 29208, USA
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Abstract
Genetic disorders affecting the autonomic nervous system can result in abnormal development of the nervous system or they can be caused by neurotransmitter imbalance, an ion-channel disturbance or by storage of deleterious material. The symptoms indicating autonomic dysfunction, however, will depend upon whether the genetic lesion has disrupted peripheral or central autonomic centers or both. Because the autonomic nervous system is pervasive and affects every organ system in the body, autonomic dysfunction will result in impaired homeostasis and symptoms will vary. The possibility of genetic confirmation by molecular testing for specific diagnosis is increasing but treatments tend to remain only supportive and directed toward particular symptoms.
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Kim SY, Burris J, Bassal F, Koldewyn K, Chattarji S, Tassone F, Hessl D, Rivera SM. Fear-specific amygdala function in children and adolescents on the fragile x spectrum: a dosage response of the FMR1 gene. Cereb Cortex 2012; 24:600-13. [PMID: 23146966 DOI: 10.1093/cercor/bhs341] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mutations of the fragile X mental retardation 1 (FMR1) gene are the genetic cause of fragile X syndrome (FXS). The presence of significant socioemotional problems has been well documented in FXS although the brain basis of those deficits remains unspecified. Here, we investigated amygdala dysfunction and its relation to socioemotional deficits and FMR1 gene expression in children and adolescents on the FX spectrum (i.e., individuals whose trinucleotide CGG repeat expansion from 55 to over 200 places them somewhere within the fragile X diagnostic range from premutation to full mutation). Participants performed an fMRI task in which they viewed fearful, happy, and scrambled faces. Neuroimaging results demonstrated that FX participants revealed significantly attenuated amygdala activation in Fearful > Scrambled and Fearful > Happy contrasts compared with their neurotypical counterparts, while showing no differences in amygdala volume. Furthermore, we found significant relationships between FMR1 gene expression, anxiety/social dysfunction scores, and reduced amygdala activation in the FX group. In conclusion, we report novel evidence regarding a dosage response of the FMR1 gene on fear-specific functions of the amygdala, which is associated with socioemotional deficits in FXS.
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Affiliation(s)
- So-Yeon Kim
- Center for Mind and Brain, University of California, Davis, CA 95618, USA
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Trajectories of early brain volume development in fragile X syndrome and autism. J Am Acad Child Adolesc Psychiatry 2012; 51:921-33. [PMID: 22917205 PMCID: PMC3428739 DOI: 10.1016/j.jaac.2012.07.003] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2011] [Revised: 06/29/2012] [Accepted: 07/02/2012] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To examine patterns of early brain growth in young children with fragile X syndrome (FXS) compared with a comparison group (controls) and a group with idiopathic autism. METHOD The study included 53 boys 18 to 42 months of age with FXS, 68 boys with idiopathic autism (autism spectrum disorder), and a comparison group of 50 typically developing and developmentally delayed controls. Structural brain volumes were examined using magnetic resonance imaging across two time points, at 2 to 3 and again at 4 to 5 years of age, and total brain volumes and regional (lobar) tissue volumes were examined. In addition, a selected group of subcortical structures implicated in the behavioral features of FXS (e.g., basal ganglia, hippocampus, amygdala) was studied. RESULTS Children with FXS had larger global brain volumes compared with controls but were not different than children with idiopathic autism, and the rate of brain growth from 2 to 5 years of age paralleled that seen in controls. In contrast to children with idiopathic autism who had generalized cortical lobe enlargement, children with FXS showed specific enlargement in the temporal lobe white matter, cerebellar gray matter, and caudate nucleus, but a significantly smaller amygdala. CONCLUSIONS This structural longitudinal magnetic resonance imaging study of preschoolers with FXS observed generalized brain overgrowth in children with FXS compared with controls, evident at age 2 and maintained across ages 4 to 5. In addition, different patterns of brain growth that distinguished boys with FXS from boys with idiopathic autism were found.
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Losh M, Klusek J, Martin GE, Sideris J, Parlier M, Piven J. Defining genetically meaningful language and personality traits in relatives of individuals with fragile X syndrome and relatives of individuals with autism. Am J Med Genet B Neuropsychiatr Genet 2012; 159B:660-8. [PMID: 22693142 PMCID: PMC3740587 DOI: 10.1002/ajmg.b.32070] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2011] [Accepted: 05/02/2012] [Indexed: 12/17/2022]
Abstract
Substantial phenotypic overlap exists between fragile X syndrome (FXS) and autism, suggesting that FMR1 (the gene causing FXS) poses a significant risk for autism. Cross-population comparisons of FXS and autism therefore offer a potentially valuable method for refining the range of phenotypes associated with variation in FMR1. This study adopted a broader phenotype approach, focusing on parents who are at increased genetic liability for autism or FXS. Women who were carriers of FMR1 in its premutation state were compared with mothers of individuals with autism, and controls in an attempt to determine whether subtle features of the broad autism phenotype may express at elevated rates among FMR1 premutation carriers. The principal personality and language features comprising the broad autism phenotype (i.e., rigid and aloof personality, and particular patterns of pragmatic language use) were assessed among 49 premutation carriers who were mothers of individuals with FXS, 89 mothers of individuals with autism, and 23 mothers of typically developing individuals. Relative to controls, the autism and premutation parent groups showed elevated rates of certain personality and language characteristics of the broad autism phenotype. Findings suggest partially overlapping personality and language profiles among autism and premutation parent groups, with rigid personality style and patterns of pragmatic language use emerging as features most clearly shared between groups. These results provide further evidence for the overlap of autism and FXS, and may implicate FMR1 in some of the subtle features comprising the broad autism phenotype.
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Affiliation(s)
- Molly Losh
- Roxelyn and Richard Pepper Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.
| | - Jessica Klusek
- Division of Speech and Hearing Sciences, Department of Allied Health Sciences, University of North Carolina at Chapel Hill,Frank Porter Graham Child Development Institute, University of North Carolina at Chapel Hill
| | - Gary E. Martin
- Division of Speech and Hearing Sciences, Department of Allied Health Sciences, University of North Carolina at Chapel Hill,Frank Porter Graham Child Development Institute, University of North Carolina at Chapel Hill
| | - John Sideris
- Frank Porter Graham Child Development Institute, University of North Carolina at Chapel Hill
| | - Morgan Parlier
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill
| | - Joseph Piven
- Carolina Institute for Developmental Disabilities, University of North Carolina at Chapel Hill
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Small genomic rearrangements involving FMR1 support the importance of its gene dosage for normal neurocognitive function. Neurogenetics 2012; 13:333-9. [DOI: 10.1007/s10048-012-0340-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Accepted: 07/20/2012] [Indexed: 10/28/2022]
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Conceptualizing neurodevelopmental disorders through a mechanistic understanding of fragile X syndrome and Williams syndrome. Curr Opin Neurol 2012; 25:112-24. [PMID: 22395002 DOI: 10.1097/wco.0b013e328351823c] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
PURPOSE OF REVIEW The overarching goal of this review is to compare and contrast the cognitive-behavioral features of fragile X syndrome (FraX) and Williams syndrome and to review the putative neural and molecular underpinnings of these features. Information is presented in a framework that provides guiding principles for conceptualizing gene-brain-behavior associations in neurodevelopmental disorders. RECENT FINDINGS Abnormalities, in particular cognitive-behavioral domains with similarities in underlying neurodevelopmental correlates, occur in both FraX and Williams syndrome including aberrant frontostriatal pathways leading to executive function deficits, and magnocellular/dorsal visual stream, superior parietal lobe, inferior parietal lobe, and postcentral gyrus abnormalities contributing to deficits in visuospatial function. Compelling cognitive-behavioral and neurodevelopmental contrasts also exist in these two disorders, for example, aberrant amygdala and fusiform cortex structure and function occurring in the context of contrasting social behavioral phenotypes, and temporal cortical and cerebellar abnormalities potentially underlying differences in language function. Abnormal dendritic development is a shared neurodevelopmental morphologic feature between FraX and Williams syndrome. Commonalities in molecular machinery and processes across FraX and Williams syndrome occur as well - microRNAs involved in translational regulation of major synaptic proteins; scaffolding proteins in excitatory synapses; and proteins involved in axonal development. SUMMARY Although the genetic variations leading to FraX and Williams syndrome are different, important similarities and contrasts in the phenotype, neurocircuitry, molecular machinery, and cellular processes in these two disorders allow for a unique approach to conceptualizing gene-brain-behavior links occurring in neurodevelopmental disorders.
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Hall SS, Lightbody AA, McCarthy BE, Parker KJ, Reiss AL. Effects of intranasal oxytocin on social anxiety in males with fragile X syndrome. Psychoneuroendocrinology 2012; 37:509-18. [PMID: 21862226 PMCID: PMC3353652 DOI: 10.1016/j.psyneuen.2011.07.020] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Revised: 06/17/2011] [Accepted: 07/29/2011] [Indexed: 10/17/2022]
Abstract
Fragile X syndrome (FXS) is a rare inherited genetic disorder causing severe intellectual disability and autistic-like symptoms. Individuals with FXS, males in particular, often exhibit extreme eye gaze avoidance and hyperarousal when they encounter stressful social situations. We investigated whether oxytocin (OT), a hormone with prosocial and anxiolytic effects, could alleviate symptoms of social anxiety in this population. A randomized double-blind placebo-controlled single-dose trial was performed with intranasal administration of placebo, 24 IU OT and 48 IU OT. Measures of eye gaze frequency, heart rate, respiratory sinus arrhythmia (RSA), heart rate variability (HRV) and salivary cortisol were obtained during a structured social challenge conducted 50 min following OT administration. Ten low-functioning males with FXS (aged 13-28 years) traveled to Stanford for the initial visit: 8 completed the study. Eye gaze frequency improved significantly in response to the 24 IU OT dose and salivary cortisol levels decreased significantly in response to the 48 IU OT dose. There was no effect of OT on heart rate, RSA or HRV although individual plots of the heart rate data suggested that OT increased heart rate in some participants and decreased heart rate in others. These findings suggest that intranasal administration of OT may ameliorate some symptoms of social anxiety in patients with FXS. Further double-blind placebo-controlled studies of OT, conducted in combination with behavioral treatment programs, may be warranted.
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Affiliation(s)
- Scott S. Hall
- Corresponding author. Tel.: +1 650 498 4799. (S.S. Hall)
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Hunsaker MR. Comprehensive neurocognitive endophenotyping strategies for mouse models of genetic disorders. Prog Neurobiol 2012; 96:220-41. [PMID: 22266125 PMCID: PMC3289520 DOI: 10.1016/j.pneurobio.2011.12.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 12/06/2011] [Accepted: 12/20/2011] [Indexed: 01/21/2023]
Abstract
There is a need for refinement of the current behavioral phenotyping methods for mouse models of genetic disorders. The current approach is to perform a behavioral screen using standardized tasks to define a broad phenotype of the model. This phenotype is then compared to what is known concerning the disorder being modeled. The weakness inherent in this approach is twofold: First, the tasks that make up these standard behavioral screens do not model specific behaviors associated with a given genetic mutation but rather phenotypes affected in various genetic disorders; secondly, these behavioral tasks are insufficiently sensitive to identify subtle phenotypes. An alternate phenotyping strategy is to determine the core behavioral phenotypes of the genetic disorder being studied and develop behavioral tasks to evaluate specific hypotheses concerning the behavioral consequences of the genetic mutation. This approach emphasizes direct comparisons between the mouse and human that facilitate the development of neurobehavioral biomarkers or quantitative outcome measures for studies of genetic disorders across species.
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Affiliation(s)
- Michael R Hunsaker
- Department of Neurological Surgery, University of California, Davis, Davis, CA 95616, USA.
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Van der Molen MJW, Van der Molen MW, Ridderinkhof KR, Hamel BCJ, Curfs LMG, Ramakers GJA. Attentional set-shifting in fragile X syndrome. Brain Cogn 2012; 78:206-17. [PMID: 22261226 DOI: 10.1016/j.bandc.2011.12.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2011] [Revised: 12/17/2011] [Accepted: 12/20/2011] [Indexed: 01/18/2023]
Abstract
The ability to flexibly adapt to the changing demands of the environment is often reported as a core deficit in fragile X syndrome (FXS). However, the cognitive processes that determine this attentional set-shifting deficit remain elusive. The present study investigated attentional set-shifting ability in fragile X syndrome males with the well-validated intra/extra dimensional set-shifting paradigm (IED) which offers detailed assessment of rule learning, reversal learning, and attentional set-shifting ability within and between stimulus dimensions. A novel scoring method for IED stage errors was employed to interpret set-shifting failure in terms of repetitive decision-making, distraction to irrelevance, and set-maintenance failure. Performance of FXS males was compared to typically developing children matched on mental age, adults matched on chronological age, and individuals with Down syndrome matched on both mental and chronological age. Results revealed that a significant proportion of FXS males already failed prior to the intra-dimensional set-shift stage, whereas all control participants successfully completed the stages up to the crucial extra-dimensional set-shift. FXS males showed a specific weakness in reversal learning, which was characterized by repetitive decision-making during the reversal of newly acquired stimulus-response associations in the face of simple stimulus configurations. In contrast, when stimulus configurations became more complex, FXS males displayed increased distraction to irrelevant stimuli. These findings are interpreted in terms of the cognitive demands imposed by the stages of the IED in relation to the alleged neural deficits in FXS.
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Cellular Mechanisms for the Biogenesis and Transport of Synaptic and Dense-Core Vesicles. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2012; 299:27-115. [DOI: 10.1016/b978-0-12-394310-1.00002-3] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Molecular and genetic analysis of the Drosophila model of fragile X syndrome. Results Probl Cell Differ 2012; 54:119-56. [PMID: 22009350 DOI: 10.1007/978-3-642-21649-7_7] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The Drosophila genome contains most genes known to be involved in heritable disease. The extraordinary genetic malleability of Drosophila, coupled to sophisticated imaging, electrophysiology, and behavioral paradigms, has paved the way for insightful mechanistic studies on the causes of developmental and neurological disease as well as many possible interventions. Here, we focus on one of the most advanced examples of Drosophila genetic disease modeling, the Drosophila model of Fragile X Syndrome, which for the past decade has provided key advances into the molecular, cellular, and behavioral defects underlying this devastating disorder. We discuss the multitude of RNAs and proteins that interact with the disease-causing FMR1 gene product, whose function is conserved from Drosophila to human. In turn, we consider FMR1 mechanistic relationships in non-neuronal tissues (germ cells and embryos), peripheral motor and sensory circuits, and central brain circuits involved in circadian clock activity and learning/memory.
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Casten KS, Gray AC, Burwell RD. Discrimination learning and attentional set formation in a mouse model of Fragile X. Behav Neurosci 2011; 125:473-9. [PMID: 21517146 DOI: 10.1037/a0023561] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Fragile X Syndrome is the most prevalent genetic cause of mental retardation. Selective deficits in executive function, including inhibitory control and attention, are core features of the disorder. In humans, Fragile X results from a trinucleotide repeat in the Fmr1 gene that renders it functionally silent and has been modeled in mice by targeted deletion of the Fmr1 gene. Fmr1 knockout (KO) mice recapitulate many features of Fragile X syndrome, but evidence for deficits in executive function is inconsistent. To address this issue, we trained wild-type and Fmr1 KO mice on an experimental paradigm that assesses attentional set-shifting. Mice learned to discriminate between stimuli differing in two of three perceptual dimensions. Successful discrimination required attending only to the relevant dimension, while ignoring irrelevant dimensions. Mice were trained on three discriminations in the same perceptual dimension, each followed by a reversal. This procedure normally results in the formation of an attentional set to the relevant dimension. Mice were then required to shift attention and discriminate based on a previously irrelevant perceptual dimension. Wild-type mice exhibited the increase in trials to criterion expected when shifting attention from one perceptual dimension to another. In contrast, the Fmr1 KO group failed to show the expected increase, suggesting impairment in forming an attentional set. Fmr1 KO mice also exhibited a general impairment in learning discriminations and reversals. This is the first demonstration that Fmr1 KO mice show a deficit in attentional set formation.
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Olmos-Serrano JL, Corbin JG. Amygdala regulation of fear and emotionality in fragile X syndrome. Dev Neurosci 2011; 33:365-78. [PMID: 21893939 PMCID: PMC3254036 DOI: 10.1159/000329424] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Accepted: 05/01/2011] [Indexed: 11/19/2022] Open
Abstract
Fear is a universal response to a threat to one's body or social status. Disruption in the detection and response of the brain's fear system is commonly observed in a variety of neurodevelopmental disorders, including fragile X syndrome (FXS), a brain disorder characterized by variable cognitive impairment and behavioral disturbances such as social avoidance and anxiety. The amygdala is highly involved in mediating fear processing, and increasing evidence supports the idea that inhibitory circuits play a key role in regulating the flow of information associated with fear conditioning in the amygdala. Here, we review the known and potential importance of amygdala fear circuits in FXS, and how developmental studies are critical to understand the formation and function of neuronal circuits that modulate amygdala-based behaviors.
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Affiliation(s)
| | - Joshua G. Corbin
- Center for Neuroscience Research, Children's Research Institute, Children's National Medical Center, Washington, D.C.,USA
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Gatto CL, Broadie K. Fragile X mental retardation protein is required for programmed cell death and clearance of developmentally-transient peptidergic neurons. Dev Biol 2011; 356:291-307. [PMID: 21596027 PMCID: PMC3143227 DOI: 10.1016/j.ydbio.2011.05.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2011] [Revised: 04/22/2011] [Accepted: 05/03/2011] [Indexed: 01/19/2023]
Abstract
Fragile X syndrome (FXS), caused by loss of fragile X mental retardation 1 (FMR1) gene function, is the most common heritable cause of intellectual disability and autism spectrum disorders. The FMR1 product (FMRP) is an RNA-binding protein best established to function in activity-dependent modulation of synaptic connections. In the Drosophila FXS disease model, loss of functionally-conserved dFMRP causes synaptic overgrowth and overelaboration in pigment dispersing factor (PDF) peptidergic neurons in the adult brain. Here, we identify a very different component of PDF neuron misregulation in dfmr1 mutants: the aberrant retention of normally developmentally-transient PDF tritocerebral (PDF-TRI) neurons. In wild-type animals, PDF-TRI neurons in the central brain undergo programmed cell death and complete, processive clearance within days of eclosion. In the absence of dFMRP, a defective apoptotic program leads to constitutive maintenance of these peptidergic neurons. We tested whether this apoptotic defect is circuit-specific by examining crustacean cardioactive peptide (CCAP) and bursicon circuits, which are similarly developmentally-transient and normally eliminated immediately post-eclosion. In dfmr1 null mutants, CCAP/bursicon neurons also exhibit significantly delayed clearance dynamics, but are subsequently eliminated from the nervous system, in contrast to the fully persistent PDF-TRI neurons. Thus, the requirement of dFMRP for the retention of transitory peptidergic neurons shows evident circuit specificity. The novel defect of impaired apoptosis and aberrant neuron persistence in the Drosophila FXS model suggests an entirely new level of "pruning" dysfunction may contribute to the FXS disease state.
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Affiliation(s)
- Cheryl L Gatto
- Departments of Biological Sciences and Cell and Developmental Biology, Kennedy Center for Research on Human Development, Vanderbilt University, Nashville, TN 37232, USA
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47
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Hall SS, Walter E, Sherman E, Hoeft F, Reiss AL. The neural basis of auditory temporal discrimination in girls with fragile X syndrome. J Neurodev Disord 2011; 1:91-9. [PMID: 19890439 PMCID: PMC2772079 DOI: 10.1007/s11689-009-9007-x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Fragile X syndrome (FXS) is a common genetic disorder in which temporal processing may be impaired. To our knowledge however, no studies have examined the neural basis of temporal discrimination in individuals with FXS using functional magnetic resonance imaging (fMRI). Ten girls with fragile X syndrome and ten developmental age-matched typically developing controls performed an auditory temporal discrimination task in a 3T scanner. Girls with FXS showed significantly greater brain activation in a left-lateralized network, comprising left medial frontal gyrus, left superior and middle temporal gyrus, left cerebellum, and left brainstem (pons), when compared to a developmental age-matched typically developing group of subjects who had similar in-scanner task performance. There were no regions that showed significantly greater brain activation in the control group compared to individuals with FXS. These data indicate that networks of brain regions involved in auditory temporal processing may be dysfunctional in FXS. In particular, it is possible that girls with FXS employ left hemispheric resources to overcompensate for relative right hemispheric dysfunction.
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Affiliation(s)
- Scott S Hall
- Department of Psychiatry and Behavioral Sciences, School of Medicine, Stanford University, 401 Quarry Road, Stanford, CA 94305-5795, USA
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Pirozzi F, Tabolacci E, Neri G. The FRAXopathies: definition, overview, and update. Am J Med Genet A 2011; 155A:1803-16. [PMID: 21739597 DOI: 10.1002/ajmg.a.34113] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Accepted: 04/22/2011] [Indexed: 01/12/2023]
Abstract
The fragile X syndrome, fragile X tremor ataxia syndrome, and premature ovarian insufficiency are conditions related to the X chromosome folate-sensitive fragile site FRAXA. Therefore, we propose that they are considered as a family of disorders under the general designation of FRAXopathies. The present review will outline the main clinical and molecular features of these disorders, with special emphasis on the pathogenic mechanisms that lead to distinct phenotypes, starting from related mutations. The understanding of these mechanisms is already generating promising therapeutic approaches.
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Lo-Castro A, D'Agati E, Curatolo P. ADHD and genetic syndromes. Brain Dev 2011; 33:456-61. [PMID: 20573461 DOI: 10.1016/j.braindev.2010.05.011] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2010] [Revised: 05/26/2010] [Accepted: 05/27/2010] [Indexed: 11/28/2022]
Abstract
A high rate of Attention Deficit/Hyperactivity Disorder (ADHD)-like characteristics has been reported in a wide variety of disorders including syndromes with known genetic causes. In this article, we review the genetic and the neurobiological links between ADHD symptoms and some genetic syndromes such as: Fragile X Syndrome, Neurofibromatosis 1, DiGeorge Syndrome, Tuberous Sclerosis Complex, Turner Syndrome, Williams Syndrome and Klinefelter Syndrome. Although each syndrome may arise from different genetic abnormalities with multiple molecular functions, the effects of these abnormalities may give rise to common effects downstream in the biological pathways or neural circuits, resulting in the presentation of ADHD symptoms. Early diagnosis of ADHD allows for earlier treatment, and has the potential for a better outcome in children with genetic syndromes.
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Affiliation(s)
- Adriana Lo-Castro
- Department of Neuroscience, Paediatric Neurology Unit, "Tor Vergata" University of Rome, Italy.
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Abstract
The purpose of this review was to understand the types of memory impairments that are associated with intellectual disability (ID, formerly called mental retardation) and the implications of these impairments for reading development. Specifically, studies on working memory, delayed memory and learning, and semantic/conceptual memory in Down syndrome, Williams syndrome, and fragile X syndrome were examined. A distinct memory profile emerged for each of the 3 etiologies of ID. Memory profiles are discussed in relation to strengths and weaknesses in reading skills in these three etiologies. We suggest that reading instruction be designed to capitalize on relatively stronger memory skills while providing extra support for especially challenging aspects of reading.
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