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Davenport MH, Schaefer TL, Friedmann KJ, Fitzpatrick SE, Erickson CA. Pharmacotherapy for Fragile X Syndrome: Progress to Date. Drugs 2016; 76:431-45. [PMID: 26858239 DOI: 10.1007/s40265-016-0542-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
To date, no drug is approved for the treatment of Fragile X Syndrome (FXS) although many drugs are used to manage challenging behaviors from a symptomatic perspective in this population. While our understanding of FXS pathophysiology is expanding, efforts to devise targeted FXS-specific treatments have had limited success in placebo-controlled trials. Compounds aimed at rectifying excessive glutamate and deficient gamma-aminobutyric acid (GABA) neurotransmission, as well as other signaling pathways known to be affected by Fragile X Mental Retardation Protein (FMRP) are under various phases of development in FXS. With the failure of several metabotropic glutamate receptor subtype 5 (mGlur5) selective antagonists under clinical investigation, no clear single treatment appears to be greatly effective. These recent challenges call into question various aspects of clinical study design in FXS. More objective outcome measures are under development and validation. Future trials will likely be aimed at correcting multiple pathways known to be disrupted by the loss of FMRP. This review offers a brief summary of the prevalence, phenotypic characteristics, genetic causes and molecular functions of FMRP in the brain (as these have been extensively reviewed elsewhere), discusses the most recent finding in FXS drug development, and summarizes FXS trials utilizing symptomatic treatment.
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Affiliation(s)
- Matthew H Davenport
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229-3039, USA
- Department of Biomedical Engineering, College of Engineering and Applied Science, University of Cincinnati, Cincinnati, OH, 45221, USA
| | - Tori L Schaefer
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229-3039, USA
| | - Katherine J Friedmann
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229-3039, USA
| | | | - Craig A Erickson
- Division of Child and Adolescent Psychiatry (MLC 4002), Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave., Cincinnati, OH, 45229-3039, USA.
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52
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Lozano R, Azarang A, Wilaisakditipakorn T, Hagerman RJ. Fragile X syndrome: A review of clinical management. Intractable Rare Dis Res 2016; 5:145-57. [PMID: 27672537 PMCID: PMC4995426 DOI: 10.5582/irdr.2016.01048] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The fragile X mental retardation 1 gene, which codes for the fragile X mental retardation 1 protein, usually has 5 to 40 CGG repeats in the 5' untranslated promoter. The full mutation is the almost always the cause of fragile X syndrome (FXS). The prevalence of FXS is about 1 in 4,000 to 1 in 7,000 in the general population although the prevalence varies in different regions of the world. FXS is the most common inherited cause of intellectual disability and autism. The understanding of the neurobiology of FXS has led to many targeted treatments, but none have cured this disorder. The treatment of the medical problems and associated behaviors remain the most useful intervention for children with FXS. In this review, we focus on the non-pharmacological and pharmacological management of medical and behavioral problems associated with FXS as well as current recommendations for follow-up and surveillance.
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Affiliation(s)
- Reymundo Lozano
- Medical Investigation of Neurodevelopmental Disorders MIND Institute, UC Davis, CA, USA
- Department of Pediatrics, UC Davis, Sacramento, CA, USA
- Address correspondence to: Dr. Reymundo Lozano, Medical Investigation of Neurodevelopmental Disorders MIND Institute, UC Davis, CA, USA; Department of Pediatrics, UC Davis, Sacramento, CA, USA. E-mail:
| | - Atoosa Azarang
- Medical Investigation of Neurodevelopmental Disorders MIND Institute, UC Davis, CA, USA
- Department of Pediatrics, UC Davis, Sacramento, CA, USA
| | - Tanaporn Wilaisakditipakorn
- Medical Investigation of Neurodevelopmental Disorders MIND Institute, UC Davis, CA, USA
- Department of Pediatrics, UC Davis, Sacramento, CA, USA
| | - Randi J Hagerman
- Medical Investigation of Neurodevelopmental Disorders MIND Institute, UC Davis, CA, USA
- Department of Pediatrics, UC Davis, Sacramento, CA, USA
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53
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Characterization of ultrasonic vocalizations of Fragile X mice. Behav Brain Res 2016; 310:76-83. [PMID: 27142239 DOI: 10.1016/j.bbr.2016.04.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Revised: 04/07/2016] [Accepted: 04/10/2016] [Indexed: 11/20/2022]
Abstract
Fragile X Syndrome (FXS) is the leading form of inherited intellectual disability. It is caused by the transcriptional silencing of FMR1, the gene which codes for the Fragile X Mental Retardation Protein (FMRP). Patients who have FXS exhibit numerous behavioral and cognitive impairments, such as attention-deficit/hyperactivity disorder, obsessive compulsive disorder, and autistic-like behaviors. In addition to these behavioral abnormalities, FXS patients have also been shown to exhibit various deficits in communication such as abnormal sentence structures, increased utterances, repetition of sounds and words, and reduced articulation. These deficits can dramatically hinder communication for FXS patients, exacerbating learning and cognition impairments while decreasing their quality of life. To examine the biological underpinnings of these communication abnormalities, studies have used a mouse model of the Fragile X Syndrome; however, these vocalization studies have resulted in inconsistent findings that often do not correlate with abnormalities observed in FXS patients. Interestingly, a detailed examination of frequency modulated vocalizations that are believed to be a better assessment of rodent communication has never been conducted. The following study used courtship separation to conduct a detailed examination of frequency modulated ultrasonic vocalizations (USV) in FXS mice. Our analyses of frequency modulated USVs demonstrated that adult FXS mice exhibited longer phrases and more motifs. Phrases are vocalizations consisting of multiple frequency modulated ultrasonic vocalizations, while motifs are repeated frequency modulated USV patterns. Fragile X mice had a higher proportion of "u" syllables in all USVs and phrases while their wildtype counterparts preferred isolated "h" syllables. Although the specific importance of these syllables towards communication deficits still needs to be evaluated, these findings in production of USVs are consistent with the repetitive and perseverative speech patterns observed in FXS patients. This study demonstrates that FXS mice can be used to study the underlying biological mechanism(s) mediating FXS vocalization abnormalities.
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54
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Esbensen AJ, Schwichtenberg AJ. Sleep in Neurodevelopmental Disorders. INTERNATIONAL REVIEW OF RESEARCH IN DEVELOPMENTAL DISABILITIES 2016; 51:153-191. [PMID: 28503406 PMCID: PMC5424624 DOI: 10.1016/bs.irrdd.2016.07.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Individuals with intellectual and developmental disabilities (IDD) experience sleep problems at higher rates than the general population. Although individuals with IDD are a heterogeneous group, several sleep problems cluster within genetic syndromes or disorders. This review summarizes the prevalence of sleep problems experienced by individuals with Angelman syndrome, Cornelia de Lange syndrome, Cri du Chat syndrome, Down syndrome, fragile X syndrome, Prader-Willi syndrome, Smith-Magenis syndrome, Williams syndrome, autism spectrum disorder, and idiopathic IDD. Factors associated with sleep problems and the evidence for sleep treatments are reviewed for each neurodevelopmental disorder. Sleep research advancements in neurodevelopmental disorders are reviewed, including the need for consistency in defining and measuring sleep problems, considerations for research design and reporting of results, and considerations when evaluating sleep treatments.
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55
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Okray Z, de Esch CEF, Van Esch H, Devriendt K, Claeys A, Yan J, Verbeeck J, Froyen G, Willemsen R, de Vrij FMS, Hassan BA. A novel fragile X syndrome mutation reveals a conserved role for the carboxy-terminus in FMRP localization and function. EMBO Mol Med 2015; 7:423-37. [PMID: 25693964 PMCID: PMC4403044 DOI: 10.15252/emmm.201404576] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Loss of function of the FMR1 gene leads to fragile X syndrome (FXS), the most common form of intellectual disability. The loss of FMR1 function is usually caused by epigenetic silencing of the FMR1 promoter leading to expansion and subsequent methylation of a CGG repeat in the 5′ untranslated region. Very few coding sequence variations have been experimentally characterized and shown to be causal to the disease. Here, we describe a novel FMR1 mutation and reveal an unexpected nuclear export function for the C-terminus of FMRP. We screened a cohort of patients with typical FXS symptoms who tested negative for CGG repeat expansion in the FMR1 locus. In one patient, we identified a guanine insertion in FMR1 exon 15. This mutation alters the open reading frame creating a short novel C-terminal sequence, followed by a stop codon. We find that this novel peptide encodes a functional nuclear localization signal (NLS) targeting the patient FMRP to the nucleolus in human cells. We also reveal an evolutionarily conserved nuclear export function associated with the endogenous C-terminus of FMRP. In vivo analyses in Drosophila demonstrate that a patient-mimetic mutation alters the localization and function of Dfmrp in neurons, leading to neomorphic neuronal phenotypes.
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Affiliation(s)
- Zeynep Okray
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium Center for Human Genetics, University of Leuven School of Medicine and University Hospitals Leuven, Leuven, Belgium Program in Molecular and Developmental Genetics, Doctoral School of Biomedical Sciences, University of Leuven, Leuven, Belgium
| | - Celine E F de Esch
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Hilde Van Esch
- Center for Human Genetics, University of Leuven School of Medicine and University Hospitals Leuven, Leuven, Belgium
| | - Koen Devriendt
- Center for Human Genetics, University of Leuven School of Medicine and University Hospitals Leuven, Leuven, Belgium
| | - Annelies Claeys
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium Center for Human Genetics, University of Leuven School of Medicine and University Hospitals Leuven, Leuven, Belgium
| | - Jiekun Yan
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium Center for Human Genetics, University of Leuven School of Medicine and University Hospitals Leuven, Leuven, Belgium
| | - Jelle Verbeeck
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium Center for Human Genetics, University of Leuven School of Medicine and University Hospitals Leuven, Leuven, Belgium
| | - Guy Froyen
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium Center for Human Genetics, University of Leuven School of Medicine and University Hospitals Leuven, Leuven, Belgium
| | - Rob Willemsen
- Department of Clinical Genetics, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Femke M S de Vrij
- Department of Psychiatry, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Bassem A Hassan
- VIB Center for the Biology of Disease, VIB, Leuven, Belgium Center for Human Genetics, University of Leuven School of Medicine and University Hospitals Leuven, Leuven, Belgium Program in Molecular and Developmental Genetics, Doctoral School of Biomedical Sciences, University of Leuven, Leuven, Belgium
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56
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Abstract
Fragile X syndrome (FXS) results from a genetic mutation in a single gene yet produces a phenotypically complex disorder with a range of neurological and psychiatric problems. Efforts to decipher how perturbations in signaling pathways lead to the myriad alterations in synaptic and cellular functions have provided insights into the molecular underpinnings of this disorder. From this large body of data, the theme of circuit hyperexcitability has emerged as a potential explanation for many of the neurological and psychiatric symptoms in FXS. The mechanisms for hyperexcitability range from alterations in the expression or activity of ion channels to changes in neurotransmitters and receptors. Contributions of these processes are often brain region and cell type specific, resulting in complex effects on circuit function that manifest as altered excitability. Here, we review the current state of knowledge of the molecular, synaptic, and circuit-level mechanisms underlying hyperexcitability and their contributions to the FXS phenotypes.
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57
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Poisson A, Nicolas A, Cochat P, Sanlaville D, Rigard C, de Leersnyder H, Franco P, Des Portes V, Edery P, Demily C. Behavioral disturbance and treatment strategies in Smith-Magenis syndrome. Orphanet J Rare Dis 2015; 10:111. [PMID: 26336863 PMCID: PMC4559928 DOI: 10.1186/s13023-015-0330-x] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 08/27/2015] [Indexed: 11/10/2022] Open
Abstract
Background Smith-Magenis syndrome is a complex neurodevelopmental disorder that includes intellectual deficiency, speech delay, behavioral disturbance and typical sleep disorders. Ninety percent of the cases are due to a 17p11.2 deletion encompassing the RAI1 gene; other cases are linked to mutations of the same gene. Behavioral disorders often include outbursts, attention deficit/hyperactivity disorders, self-injury with onychotillomania and polyembolokoilamania (insertion of objects into body orifices), etc. Interestingly, the stronger the speech delay and sleep disorders, the more severe the behavioral issues. Sleep disturbances associate excessive daytime sleepiness with nighttime agitation. They are underpinned by an inversion of the melatonin secretion cycle. However, the combined intake of beta-blockers in the morning and melatonin in the evening may radically alleviate the circadian rhythm problems. Discussion Once sleep disorders are treated, the next challenge is finding an effective treatment for the remaining behavioral problems. Unfortunately, there is a lack of objective guidelines. A comprehensive evaluation of such disorders should include sleep disorders, potential causes of pain, neurocognitive level and environment (i.e. family and school). In any case, efforts should focus on improving communication skills, identifying and treating attention deficit/hyperactivity, aggressiveness and anxiety. Summary Treatment of Smith-Magenis syndrome is complex and requires a multidisciplinary team including, among others, geneticists, psychiatrists, neuropediatricians/neurologists, somnologists, developmental and behavioral pediatricians, and speech and language therapists.
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Affiliation(s)
- Alice Poisson
- Center for Screening and Treatment of Psychiatric Disorders of Genetic Origin, Vinatier Hospital, 95 Bd Pinel, 69678, Lyon, France. .,Cognitive Neuroscience Center, UMR 5229, French National Research Center (CNRS), Bron, France. .,Lyon 1 University, Lyon, France.
| | - Alain Nicolas
- Center for Screening and Treatment of Psychiatric Disorders of Genetic Origin, Vinatier Hospital, 95 Bd Pinel, 69678, Lyon, France.,Michel Jouvet Unite (sleep Medicine), Vinatier Hospital, Human chronobiology team INSERM 846, Bron, France
| | - Pierre Cochat
- Lyon 1 University, Lyon, France.,Pediatric Nephrology and Rhumatology Ward, Reference Center for Rare Kidney Diseases, Civil Hospices of Lyon, INSERM U820, Bron, France
| | - Damien Sanlaville
- Lyon 1 University, Lyon, France.,Department of Genetics, Reference Center for Developmental Anomalies and Malformation Syndromes, Civil Hospices of Lyon, Bron, France
| | - Caroline Rigard
- Center for Screening and Treatment of Psychiatric Disorders of Genetic Origin, Vinatier Hospital, 95 Bd Pinel, 69678, Lyon, France.,Cognitive Neuroscience Center, UMR 5229, French National Research Center (CNRS), Bron, France
| | | | - Patricia Franco
- Lyon 1 University, Lyon, France.,Hypnology Unit, Neuropediatric Ward, Civil Hospices of Lyon and INSERM U628, Lyon, France
| | - Vincent Des Portes
- Lyon 1 University, Lyon, France.,Pediatric Neurology Ward, Reference Center "Intellectual Deficiencies with Rare Causes", Civil Hospices of Lyon, Bron, France. CNRS UMR 5304, L2C2, Institute of Cognitive Sciences, 69675, Bron, France
| | - Patrick Edery
- Lyon 1 University, Lyon, France.,Department of Genetics, Reference Center for Developmental Anomalies and Malformation Syndromes, Civil Hospices of Lyon, Bron, France.,Neuroscience Research Center of Lyon, Inserm U1028, CNRS UMR 5292, UCBL, TIGER Team, Bron, France
| | - Caroline Demily
- Center for Screening and Treatment of Psychiatric Disorders of Genetic Origin, Vinatier Hospital, 95 Bd Pinel, 69678, Lyon, France.,Cognitive Neuroscience Center, UMR 5229, French National Research Center (CNRS), Bron, France.,Lyon 1 University, Lyon, France
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58
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Weisz ED, Monyak RE, Jongens TA. Deciphering discord: How Drosophila research has enhanced our understanding of the importance of FMRP in different spatial and temporal contexts. Exp Neurol 2015; 274:14-24. [PMID: 26026973 DOI: 10.1016/j.expneurol.2015.05.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 05/18/2015] [Accepted: 05/23/2015] [Indexed: 01/06/2023]
Abstract
Fragile X Syndrome (FXS) is the most common heritable form of intellectual impairment as well as the leading monogenetic cause of autism. In addition to its canonical definition as a neurodevelopmental disease, recent findings in the clinic suggest that FXS is a systemic disorder that is characterized by a variety of heterogeneous phenotypes. Efforts to study FXS pathogenesis have been aided by the development and characterization of animal models of the disease. Research efforts in Drosophila melanogaster have revealed key insights into the mechanistic underpinnings of FXS. While much remains unknown, it is increasingly apparent that FXS involves a myriad of spatially and temporally specific alterations in cellular function. Consequently, the literature is filled with numerous discordant findings. Researchers and clinicians alike must be cognizant of this dissonance, as it will likely be important for the design of preclinical studies to assess the efficacy of therapeutic strategies to improve the lives of FXS patients.
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Affiliation(s)
- Eliana D Weisz
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, United States
| | - Rachel E Monyak
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, United States
| | - Thomas A Jongens
- Department of Genetics, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA 19104, United States.
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59
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McDermott S, Hardin JW, Royer JA, Mann JR, Tong X, Ozturk OD, Ouyang L. Emergency department and inpatient hospitalizations for young people with fragile X syndrome. AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES 2015; 120:230-243. [PMID: 25928435 PMCID: PMC4491920 DOI: 10.1352/1944-7558-120.3.230] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We compared hospital encounters between adolescents and young adults with fragile X syndrome (FXS) to peers with intellectual disability (ID) from other causes, autism spectrum disorder (ASD), and a comparison group without these conditions matched by gender, age, and insurance coverage. Those with FXS, ASD, or ID were more likely to have had hospital encounters. In terms of age groups, we found mental illness hospitalizations decreased during adulthood as compared to adolescence for those with FXS, and we found that for conditions unrelated to FXS (e.g., respiratory, genitourinary, gastroenteritis, and pneumonia) adolescents had higher rates of hospitalization compared to their peers with FXS, ID, or ASD. We analyzed epilepsy, common among people with FXS and designated as an ambulatory care sensitive condition that can be treated outside the hospital, and found that people with FXS, ID, and ASD had higher odds of hospitalization due to epilepsy in both age groups than did the comparison group.
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60
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Schaefer TL, Davenport MH, Erickson CA. Emerging pharmacologic treatment options for fragile X syndrome. APPLICATION OF CLINICAL GENETICS 2015; 8:75-93. [PMID: 25897255 PMCID: PMC4396424 DOI: 10.2147/tacg.s35673] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Fragile X syndrome (FXS) is the most common single gene cause of intellectual disability and autism spectrum disorder. Caused by a silenced fragile X mental retardation 1 gene and the subsequent deficiency in fragile X mental retardation protein, patients with FXS experience a range of physical, behavioral, and intellectual debilitations. The FXS field, as a whole, has recently met with some challenges, as several targeted clinical trials with high expectations of success have failed to elucidate significant improvements in a variety of symptom domains. As new clinical trials in FXS are planned, there has been much discussion about the use of the commonly used clinical outcome measures, as well as study design considerations, patient stratification, and optimal age range for treatment. The evidence that modification of these drug targets and use of these failed compounds would prove to be efficacious in human clinical study were rooted in years of basic and translational research. There are questions arising as to the use of the mouse models for studying FXS treatment development. This issue is twofold: many of the symptom domains and molecular and biochemical changes assessed and indicative of efficacy in mouse model study are not easily amenable to clinical trials in people with FXS because of the intolerability of the testing paradigm or a lack of noninvasive techniques (prepulse inhibition, sensory hypersensitivity, startle reactivity, or electrophysiologic, biochemical, or structural changes in the brain); and capturing subtle yet meaningful changes in symptom domains such as sociability, anxiety, and hyperactivity in human FXS clinical trials is challenging with the currently used measures (typically parent/caregiver rating scales). Clinicians, researchers, and the pharmaceutical industry have all had to take a step back and critically evaluate the way we think about how to best optimize future investigations into pharmacologic FXS treatments. As new clinical trials are coming down the drug discovery pipeline, it is clear that the field is moving in a direction that values the development of molecular biomarkers, less subjective quantitative measures of symptom improvement, and rating scales developed specifically for use in FXS in conjunction with drug safety. While summarizing preclinical evidence, where applicable, and discussing challenges in FXS treatment development, this review details both completed clinical trials for the targeted and symptomatic treatment of FXS and introduces novel projects on the cusp of clinical trial investigation.
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Affiliation(s)
- Tori L Schaefer
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Matthew H Davenport
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
| | - Craig A Erickson
- Division of Child and Adolescent Psychiatry, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
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61
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Metabotropic glutamate receptor 5 as drug target for Fragile X syndrome. Curr Opin Pharmacol 2015; 20:124-34. [DOI: 10.1016/j.coph.2014.11.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 11/10/2014] [Accepted: 11/10/2014] [Indexed: 11/17/2022]
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62
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Lumaban JG, Nelson DL. The Fragile X proteins Fmrp and Fxr2p cooperate to regulate glucose metabolism in mice. Hum Mol Genet 2014; 24:2175-84. [PMID: 25552647 DOI: 10.1093/hmg/ddu737] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Fragile X syndrome results from loss of FMR1 expression. Individuals with the disorder exhibit not only intellectual disability, but also an array of physical and behavioral abnormalities, including sleep difficulties. Studies in mice demonstrated that Fmr1, along with its paralog Fxr2, regulate circadian behavior, and that their absence disrupts expression and cycling of essential clock mRNAs in the liver. Recent reports have identified circadian genes to be essential for normal metabolism. Here we describe the metabolic defects that arise in mice mutated for both Fmr1 and Fxr2. These mice have reduced fat deposits compared with age- and weight-matched controls. Several metabolic markers show either low levels in plasma or abnormal circadian cycling (or both). Insulin levels are consistently low regardless of light exposure and feeding conditions, and the animals are extremely sensitive to injected insulin. Glucose production from introduced pyruvate and glucagon is impaired and the mice quickly clear injected glucose. These mice also have higher food intake and higher VO2 and VCO2 levels. We analyzed liver expression of genes involved in glucose homeostasis and found several that are expressed differentially in the mutant mice. These results point to the involvement of Fmr1 and Fxr2 in maintaining the normal metabolic state in mice.
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Affiliation(s)
- Jeannette G Lumaban
- Department of Molecular and Human Genetics, Jan and Dan Duncan Neurological Research Institute, Baylor College of Medicine, 1250 Moursund Street, Houston, TX 77030, USA
| | - David L Nelson
- Department of Molecular and Human Genetics, Jan and Dan Duncan Neurological Research Institute, Baylor College of Medicine, 1250 Moursund Street, Houston, TX 77030, USA
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63
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Hanson AC, Hagerman RJ. Serotonin dysregulation in Fragile X Syndrome: implications for treatment. Intractable Rare Dis Res 2014; 3:110-7. [PMID: 25606361 PMCID: PMC4298641 DOI: 10.5582/irdr.2014.01027] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Accepted: 11/28/2014] [Indexed: 12/29/2022] Open
Abstract
Fragile X Syndrome (FXS) is a trinucleotide repeat disorder that results in the silencing of the Fragile X Mental Retardation 1 gene (FMR1), leading to a lack of the FMR1 protein (FMRP). FMRP is an mRNA-binding protein that regulates the translation of hundreds of mRNAs important for synaptic plasticity. Several of these pathways have been identified and have guided the development of targeted treatments for FXS. Here we present evidence that serotonin is dysregulated in FXS and treatment with the selective serotonin reuptake inhibitor (SSRI) sertraline may be beneficial for individuals with FXS, particularly in early childhood.
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Affiliation(s)
| | - Randi J Hagerman
- UC Davis MIND Institute and Department of Pediatrics, UC Davis Medical Center, Sacramento, CA, USA
- Address correspondence to: Dr. Randi J. Hagerman, UC Davis MIND Institute and Department of Pediatrics, UC Davis Medical Center, Sacramento, CA 95817, USA. E-mail:
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64
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Kidd SA, Lachiewicz A, Barbouth D, Blitz RK, Delahunty C, McBrien D, Visootsak J, Berry-Kravis E. Fragile X syndrome: a review of associated medical problems. Pediatrics 2014; 134:995-1005. [PMID: 25287458 DOI: 10.1542/peds.2013-4301] [Citation(s) in RCA: 148] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Fragile X syndrome (FXS) is the most common known genetic cause of inherited intellectual disability and the most common known single-gene cause of autism spectrum disorder. It has been reported that a spectrum of medical problems are commonly experienced by people with FXS, such as otitis media, seizures, and gastrointestinal problems. Previous studies examining the prevalence of medical problems related to FXS have been challenging to interpret because of their marked differences in population, setting, and sampling. Through this comprehensive review, we update the literature by reviewing studies that have reported on prominent medical problems associated with FXS. We then compare prevalence results from those studies with results from a large cross-sectional database consisting of data collected by fragile X clinics that specialize in the care of children with FXS and are part of the Fragile X Clinical and Research Consortium. It is vital for pediatricians and other clinicians to be familiar with the medical problems related to FXS so that affected patients may receive proper diagnosis and treatment; improved care may lead to better quality of life for these patients and their families.
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Affiliation(s)
- Sharon A Kidd
- National Fragile X Foundation, Walnut Creek, California;
| | - Ave Lachiewicz
- Departments of Pediatrics, Psychiatry, and Behavioral Sciences, Duke University Medical Center, Durham, North Carolina
| | - Deborah Barbouth
- Department of Human Genetics, University of Miami Miller School of Medicine, Miami, Florida
| | - Robin K Blitz
- Developmental Pediatrics, Barrow Neurologic Institute at Phoenix Children's Hospital, Phoenix, Arizona; Department of Pediatrics, University of Arizona College of Medicine, Phoenix, Arizona
| | - Carol Delahunty
- Department of Developmental and Rehabilitation Pediatrics, Cleveland Clinic, Cleveland, Ohio
| | - Dianne McBrien
- Department of Pediatrics, University of Iowa Medical Center, Iowa City, Iowa
| | - Jeannie Visootsak
- Departments of Human Genetics, and Pediatrics, Emory University, Atlanta, Georgia; and
| | - Elizabeth Berry-Kravis
- Departments of Pediatrics, Neurologic Sciences, and Biochemistry, Rush University Medical Center, Chicago, Illinois
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65
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Illingworth JL, Watson P, Ring H. Why do seizures occur when they do? Situations perceived to be associated with increased or decreased seizure likelihood in people with epilepsy and intellectual disability. Epilepsy Behav 2014; 39:78-84. [PMID: 25218091 PMCID: PMC4274323 DOI: 10.1016/j.yebeh.2014.08.016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Revised: 07/30/2014] [Accepted: 08/07/2014] [Indexed: 11/01/2022]
Abstract
Seizure precipitants are commonly reported in the general population of people with epilepsy. However, there has been little research in this area in people with epilepsy and intellectual disability (ID). We conducted a survey of the situations associated with increased or decreased seizure likelihood in this population. The aim of the research was to identify situations of increased seizure likelihood (SISLs) and situations of decreased seizure likelihood (SDSLs) reported by carers of people with an ID and epilepsy. Three study groups were investigated: two groups comprising individuals with ID associated with a specific genetic diagnosis - Rett syndrome or fragile X syndrome - and one group consisting of individuals with a range of other etiologies. Responses relating to 100 people were received: 44 relating to people with Rett syndrome, 25 to people with fragile X syndrome, and 31 to people whose ID had some other etiologies. Ninety-eight percent of the respondents reported at least one SISL, and 60% reported at least one SDSL. Having more seizure types and greater seizure frequency were associated with a higher number of SISLs reported. The most commonly reported SISLs and SDSLs for each of the three groups are presented. The most common SISL overall was illness, which was reported as an SISL by 71% of the respondents. There was less consensus with regard to SDSLs. These findings provide a greater understanding of when seizures occur in those with ID and epilepsy, with possible implications for adjunctive behavioral management of seizures in those with treatment-refractory epilepsy.
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Affiliation(s)
- Josephine L. Illingworth
- Department of Psychiatry, University of Cambridge, Douglas House, 18d Trumpington Road, Cambridge CB2 8AH, UK,Corresponding author. Tel.: + 44 1223 746111.
| | - Peter Watson
- Medical Research Council Cognition and Brain Sciences Unit, 15 Chaucer Road, Cambridge CB2 7EF, UK
| | - Howard Ring
- Department of Psychiatry, University of Cambridge, Douglas House, 18d Trumpington Road, Cambridge CB2 8AH, UK,Cambridgeshire & Peterborough NHS Foundation Trust, Cambridge, UK,NIHR Collaboration for Leadership in Applied Health Research and Care (CLAHRC) East of England, Cambridge, UK
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Mullegama SV, Pugliesi L, Burns B, Shah Z, Tahir R, Gu Y, Nelson DL, Elsea SH. MBD5 haploinsufficiency is associated with sleep disturbance and disrupts circadian pathways common to Smith-Magenis and fragile X syndromes. Eur J Hum Genet 2014; 23:781-9. [PMID: 25271084 DOI: 10.1038/ejhg.2014.200] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 07/23/2014] [Accepted: 08/26/2014] [Indexed: 11/09/2022] Open
Abstract
Individuals with autism spectrum disorders (ASD) who have an identifiable single-gene neurodevelopmental disorder (NDD), such as fragile X syndrome (FXS, FMR1), Smith-Magenis syndrome (SMS, RAI1), or 2q23.1 deletion syndrome (del 2q23.1, MBD5) share phenotypic features, including a high prevalence of sleep disturbance. We describe the circadian deficits in del 2q23.1 through caregiver surveys in which we identify several frequent sleep anomalies, including night/early awakenings, coughing/snoring loudly, and difficulty falling asleep. We couple these findings with studies on the molecular analysis of the circadian deficits associated with haploinsufficiency of MBD5 in which circadian gene mRNA levels of NR1D2, PER1, PER2, and PER3 were altered in del 2q23.1 lymphoblastoid cell lines (LCLs), signifying that haploinsufficiency of MBD5 can result in dysregulation of circadian rhythm gene expression. These findings were further supported by expression microarrays of MBD5 siRNA knockdown cells that showed significantly altered expression of additional circadian rhythm signaling pathway genes. Based on the common sleep phenotypes observed in del 2q23.1, SMS, and FXS patients, we explored the possibility that MBD5, RAI1, and FMR1 function in overlapping circadian rhythm pathways. Bioinformatic analysis identified conserved putative E boxes in MBD5 and RAI1, and expression levels of NR1D2 and CRY2 were significantly reduced in patient LCLs. Circadian and mTOR signaling pathways, both associated with sleep disturbance, were altered in both MBD5 and RAI1 knockdown microarray data, overlapping with findings associated with FMR1. These data support phenotypic and molecular overlaps across these syndromes that may be exploited to provide therapeutic intervention for multiple disorders.
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Affiliation(s)
- Sureni V Mullegama
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Loren Pugliesi
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Brooke Burns
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Zalak Shah
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Raiha Tahir
- Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
| | - Yanghong Gu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - David L Nelson
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Sarah H Elsea
- 1] Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA [2] Department of Human and Molecular Genetics, Virginia Commonwealth University School of Medicine, Richmond, VA, USA
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Gadoth N, Oksenberg A. Sleep and sleep disorders in rare hereditary diseases: a reminder for the pediatrician, pediatric and adult neurologist, general practitioner, and sleep specialist. Front Neurol 2014; 5:133. [PMID: 25101051 PMCID: PMC4101612 DOI: 10.3389/fneur.2014.00133] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/03/2014] [Indexed: 12/11/2022] Open
Abstract
Although sleep abnormalities in general and sleep-related breathing disorders (SBD) in particular are quite common in healthy children; their presence is notably under-recognized. Impaired sleep is a frequent problem in subjects with inborn errors of metabolism as well as in a variety of genetic disorders; however, they are commonly either missed or underestimated. Moreover, the complex clinical presentation and the frequently life-threatening symptoms are so overwhelming that sleep and its quality may be easily dismissed. Even centers, which specialize in rare genetic-metabolic disorders, are expected to see only few patients with a particular syndrome, a fact that significantly contributes to the under-diagnosis and treatment of impaired sleep in this particular population. Many of those patients suffer from reduced life quality associated with a variable degree of cognitive impairment, which may be worsened by poor sleep and abnormal ventilation during sleep, abnormalities which can be alleviated by proper treatment. Even when such problems are detected, there is a paucity of publications on sleep and breathing characteristics of such patients that the treating physician can refer to. In the present paper, we provide an overview of sleep and breathing characteristics in a number of rare genetic–metabolic disorders with the hope that it will serve as a reminder for the medical professional to look for possible impaired sleep and SBD in their patients and when present to apply the appropriate evaluation and treatment options.
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Affiliation(s)
- Natan Gadoth
- Sleep Disorders Unit, Loewenstein Rehabilitation Center , Raanana , Israel ; Department of Neurology, Mayanei Hayeshua Medical Center , Bnei Barak , Israel ; Sackler Faculty of Medicine, Tel-Aviv University , Tel-Aviv , Israel
| | - Arie Oksenberg
- Sleep Disorders Unit, Loewenstein Rehabilitation Center , Raanana , Israel
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Picchioni D, Reith RM, Nadel JL, Smith CB. Sleep, plasticity and the pathophysiology of neurodevelopmental disorders: the potential roles of protein synthesis and other cellular processes. Brain Sci 2014; 4:150-201. [PMID: 24839550 PMCID: PMC4020186 DOI: 10.3390/brainsci4010150] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2013] [Revised: 02/26/2014] [Accepted: 03/07/2014] [Indexed: 12/28/2022] Open
Abstract
Sleep is important for neural plasticity, and plasticity underlies sleep-dependent memory consolidation. It is widely appreciated that protein synthesis plays an essential role in neural plasticity. Studies of sleep-dependent memory and sleep-dependent plasticity have begun to examine alterations in these functions in populations with neurological and psychiatric disorders. Such an approach acknowledges that disordered sleep may have functional consequences during wakefulness. Although neurodevelopmental disorders are not considered to be sleep disorders per se, recent data has revealed that sleep abnormalities are among the most prevalent and common symptoms and may contribute to the progression of these disorders. The main goal of this review is to highlight the role of disordered sleep in the pathology of neurodevelopmental disorders and to examine some potential mechanisms by which sleep-dependent plasticity may be altered. We will also briefly attempt to extend the same logic to the other end of the developmental spectrum and describe a potential role of disordered sleep in the pathology of neurodegenerative diseases. We conclude by discussing ongoing studies that might provide a more integrative approach to the study of sleep, plasticity, and neurodevelopmental disorders.
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Affiliation(s)
- Dante Picchioni
- Behavioral Biology Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; E-Mail:
- Advanced MRI Section, National Institute of Neurological Disorders and Stroke, Bethesda, MD 20892, USA
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD 20892, USA; E-Mails: (R.M.R.); (J.L.N.)
| | - R. Michelle Reith
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD 20892, USA; E-Mails: (R.M.R.); (J.L.N.)
| | - Jeffrey L. Nadel
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD 20892, USA; E-Mails: (R.M.R.); (J.L.N.)
| | - Carolyn B. Smith
- Section on Neuroadaptation and Protein Metabolism, National Institute of Mental Health, Bethesda, MD 20892, USA; E-Mails: (R.M.R.); (J.L.N.)
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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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Gonçalves JT, Anstey JE, Golshani P, Portera-Cailliau C. Circuit level defects in the developing neocortex of Fragile X mice. Nat Neurosci 2013; 16:903-9. [PMID: 23727819 PMCID: PMC3695061 DOI: 10.1038/nn.3415] [Citation(s) in RCA: 208] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 04/30/2013] [Indexed: 12/20/2022]
Abstract
Subtle alterations in how cortical network dynamics are modulated by different behavioral states could disrupt normal brain function and underlie symptoms of neuropsychiatric disorders, including Fragile X syndrome (FXS). Using two-photon calcium imaging and electrophysiology, we recorded spontaneous neuronal ensemble activity in mouse somatosensory cortex. Unanesthetized Fmr1(-/-) mice exhibited abnormally high synchrony of neocortical network activity, especially during the first two postnatal weeks. Neuronal firing rates were threefold higher in Fmr1(-/-) mice than in wild-type mice during whole-cell recordings manifesting Up/Down states (slow-wave sleep, quiet wakefulness), probably as a result of a higher firing probability during Up states. Combined electroencephalography and calcium imaging experiments confirmed that neurons in mutant mice had abnormally high firing and synchrony during sleep. We conclude that cortical networks in FXS are hyperexcitable in a brain state-dependent manner during a critical period for experience-dependent plasticity. These state-dependent network defects could explain the intellectual, sleep and sensory integration dysfunctions associated with FXS.
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Affiliation(s)
- J Tiago Gonçalves
- Department of Neurology, David Geffen School of Medicine, University of California, Los Angeles, California, USA
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Abstract
PURPOSE OF REVIEW Sleep disorders in children and adolescents often present with various medical comorbidities. The aim of this review is to present the recent literature findings on this issue. RECENT FINDINGS The major medical comorbid conditions that accompany insomnia or short sleep duration in children and adolescents are obesity and metabolic syndrome, growth hormone deficiency, allergic conditions, various disorders accompanied by chronic pain, neoplasms and blood malignancies, and genetic and congenital disorders. Hypersomnia is mainly related to malignancies. Children and adolescents with obstructive sleep apnoea syndrome or sleep-disordered breathing may suffer from obesity and metabolic syndrome, polycystic ovaries, hypothyroidism, asthma, epilepsy, various ear nose throat disorders, congenital malformations or genetic conditions. Parasomnias may be comorbid with some medical conditions, but the main challenge in their evaluation is the differential diagnosis from nocturnal epileptic seizures. SUMMARY The co-occurrence of sleep disorders and medical conditions in childhood and adolescence is quite frequent and has an impact on general health and quality of life.
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Gervan P, Gombos F, Kovacs I. Perceptual learning in Williams syndrome: looking beyond averages. PLoS One 2012; 7:e40282. [PMID: 22792262 PMCID: PMC3390366 DOI: 10.1371/journal.pone.0040282] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 06/04/2012] [Indexed: 11/18/2022] Open
Abstract
Williams Syndrome is a genetically determined neurodevelopmental disorder characterized by an uneven cognitive profile and surprisingly large neurobehavioral differences among individuals. Previous studies have already shown different forms of memory deficiencies and learning difficulties in WS. Here we studied the capacity of WS subjects to improve their performance in a basic visual task. We employed a contour integration paradigm that addresses occipital visual function, and analyzed the initial (i.e. baseline) and after-learning performance of WS individuals. Instead of pooling the very inhomogeneous results of WS subjects together, we evaluated individual performance by expressing it in terms of the deviation from the average performance of the group of typically developing subjects of similar age. This approach helped us to reveal information about the possible origins of poor performance of WS subjects in contour integration. Although the majority of WS individuals showed both reduced baseline and reduced learning performance, individual analysis also revealed a dissociation between baseline and learning capacity in several WS subjects. In spite of impaired initial contour integration performance, some WS individuals presented learning capacity comparable to learning in the typically developing population, and vice versa, poor learning was also observed in subjects with high initial performance levels. These data indicate a dissociation between factors determining initial performance and perceptual learning.
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Affiliation(s)
- Patricia Gervan
- Department of Cognitive Science, Budapest University of Technology and Economics, Budapest, Hungary.
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Weselake SV, Wevrick R. Co-morbidity of complex genetic disorders and hypersomnias of central origin: lessons from the underlying neurobiology of wake and sleep. Clin Genet 2012; 82:379-87. [PMID: 22533571 DOI: 10.1111/j.1399-0004.2012.01886.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Appropriate wake and sleep cycles are important to physical well-being, and are modulated by neuronal networks in the brain. A variety of medical conditions can disrupt sleep or cause excessive daytime sleepiness. Clinical diagnostic classification schemes have historically lumped genetic disorders together into a category that considers the sleep dysfunction to be secondary to a medical condition. The unique nature of sleep endophenotypes that occur more frequently in particular genetic disorders has been underappreciated. Increased understanding of the pathophysiology of wake/sleep dysfunction in rare genetic disorders could inform studies of the neurological mechanisms that underlie more common forms of wake and sleep dysfunction. In this review, we highlight genetic developmental disorders in which sleep endophenotypes have been described, and then consider genetic neurodegenerative disorders with sleep characteristics that set them apart from the disruptions to sleep that are typically associated with aging and dementia.
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Affiliation(s)
- S V Weselake
- Department of Medical Genetics, University of Alberta, Edmonton, Alberta, Canada T6G 2H7
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Medication utilization for targeted symptoms in children and adults with fragile X syndrome: US survey. J Dev Behav Pediatr 2012; 33:62-9. [PMID: 22064563 DOI: 10.1097/dbp.0b013e318236c0e1] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVE To identify the most common neurological and behavioral symptoms treated by medications in individuals with fragile X syndrome (FXS), factors associated with treatment variability, and difficulty in swallowing a pill. METHOD A total of 1019 caregivers provided information about 1064 sons and 299 daughters with FXS in a US national survey. Caregivers reported (a) current use of medications for attention, anxiety, hyperactivity, mood swings, anger, depression, seizures, self-injury, or sleep; (b) perceived efficacy; and (c) difficulty in swallowing a pill. RESULTS Sixty-one percent of males and 38% of females were currently taking medication for at least 1 symptom. The most common symptoms were anxiety, attention, and hyperactivity. Treatments for attention and hyperactivity were common in childhood but declined substantially after the age of 18 years; anxiety treatment remained high in adults. Children perceived to be more impaired and children diagnosed or treated for autism were more likely to be taking medications. Caregivers considered most medications somewhat effective, but less than one-third rated current medication as "a lot" effective. Many children had difficulty swallowing a pill, but only 11% of adult males and 2% of adult females had a lot of difficulty. CONCLUSION Symptom-based medication use is common in FXS, although response is incomplete and there is clearly an unmet need for medications with improved efficacy. The persistent use of medications to treat anxiety, mood, and behavior problems throughout adolescence and into the adult years suggests important outcomes when evaluating the efficacy of new medications.
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Hagerman R, Lauterborn J, Au J, Berry-Kravis E. Fragile X syndrome and targeted treatment trials. Results Probl Cell Differ 2012; 54:297-335. [PMID: 22009360 PMCID: PMC4114775 DOI: 10.1007/978-3-642-21649-7_17] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Work in recent years has revealed an abundance of possible new treatment targets for fragile X syndrome (FXS). The use of animal models, including the fragile X knockout mouse which manifests a phenotype very similar to FXS in humans, has resulted in great strides in this direction of research. The lack of Fragile X Mental Retardation Protein (FMRP) in FXS causes dysregulation and usually overexpression of a number of its target genes, which can cause imbalances of neurotransmission and deficits in synaptic plasticity. The use of metabotropic glutamate receptor (mGluR) blockers and gamma amino-butyric acid (GABA) agonists have been shown to be efficacious in reversing cellular and behavioral phenotypes, and restoring proper brain connectivity in the mouse and fly models. Proposed new pharmacological treatments and educational interventions are discussed in this chapter. In combination, these various targeted treatments show promising preliminary results in mitigating or even reversing the neurobiological abnormalities caused by loss of FMRP, with possible translational applications to other neurodevelopmental disorders including autism.
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Affiliation(s)
- Randi Hagerman
- Department of Pediatrics, University of California, Sacramento, CA, USA.
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Gross C, Berry-Kravis EM, Bassell GJ. Therapeutic strategies in fragile X syndrome: dysregulated mGluR signaling and beyond. Neuropsychopharmacology 2012; 37:178-95. [PMID: 21796106 PMCID: PMC3238060 DOI: 10.1038/npp.2011.137] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Revised: 06/17/2011] [Accepted: 06/17/2011] [Indexed: 01/11/2023]
Abstract
Fragile X syndrome (FXS) is an inherited neurodevelopmental disease caused by loss of function of the fragile X mental retardation protein (FMRP). In the absence of FMRP, signaling through group 1 metabotropic glutamate receptors is elevated and insensitive to stimulation, which may underlie many of the neurological and neuropsychiatric features of FXS. Treatment of FXS animal models with negative allosteric modulators of these receptors and preliminary clinical trials in human patients support the hypothesis that metabotropic glutamate receptor signaling is a valuable therapeutic target in FXS. However, recent research has also shown that FMRP may regulate diverse aspects of neuronal signaling downstream of several cell surface receptors, suggesting a possible new route to more direct disease-targeted therapies. Here, we summarize promising recent advances in basic research identifying and testing novel therapeutic strategies in FXS models, and evaluate their potential therapeutic benefits. We provide an overview of recent and ongoing clinical trials motivated by some of these findings, and discuss the challenges for both basic science and clinical applications in the continued development of effective disease mechanism-targeted therapies for FXS.
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Affiliation(s)
- Christina Gross
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
| | - Elizabeth M Berry-Kravis
- Departments of Pediatrics, Neurology, and Biochemistry, Rush University Medical Center, Chicago, IL, USA
| | - Gary J Bassell
- Department of Cell Biology, Emory University School of Medicine, Atlanta, GA, USA
- Department of Neurology, Emory University School of Medicine, Atlanta, GA, USA
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Altered neocortical rhythmic activity states in Fmr1 KO mice are due to enhanced mGluR5 signaling and involve changes in excitatory circuitry. J Neurosci 2011; 31:14223-34. [PMID: 21976507 DOI: 10.1523/jneurosci.3157-11.2011] [Citation(s) in RCA: 125] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Despite the pronounced neurological deficits associated with mental retardation and autism, the degree to which neocortical circuit function is altered remains unknown. Here, we study changes in neocortical network function in the form of persistent activity states in the mouse model of fragile X syndrome--the Fmr1 knock-out (KO). Persistent activity states, or UP states, in the neocortex underlie the slow oscillation which occurs predominantly during slow-wave sleep, but may also play a role during awake states. We show that spontaneously occurring UP states in the primary somatosensory cortex are 38-67% longer in Fmr1 KO slices. In vivo, UP states reoccur with a clear rhythmic component consistent with that of the slow oscillation and are similarly longer in the Fmr1 KO. Changes in neocortical excitatory circuitry likely play the major role in this alteration as supported by three findings: (1) longer UP states occur in slices of isolated neocortex, (2) pharmacologically isolated excitatory circuits in Fmr1 KO neocortical slices display prolonged bursting states, and (3) selective deletion of Fmr1 in cortical excitatory neurons is sufficient to cause prolonged UP states whereas deletion in inhibitory neurons has no effect. Excess signaling mediated by the group 1 glutamate metabotropic receptor, mGluR5, contributes to the longer UP states. Genetic reduction or pharmacological blockade of mGluR5 rescues the prolonged UP state phenotype. Our results reveal an alteration in network function in a mouse model of intellectual disability and autism which may impact both slow-wave sleep and information processing during waking states.
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McLennan Y, Polussa J, Tassone F, Hagerman R. Fragile x syndrome. Curr Genomics 2011; 12:216-24. [PMID: 22043169 PMCID: PMC3137006 DOI: 10.2174/138920211795677886] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2011] [Revised: 03/30/2011] [Accepted: 03/31/2011] [Indexed: 02/03/2023] Open
Abstract
Recent data from a national survey highlighted a significant difference in obesity rates in young fragile X males (31%) compared to age matched controls (18%). Fragile X syndrome (FXS) is the most common cause of intellectual disability in males and the most common single gene cause of autism. This X-linked disorder is caused by an expansion of a trinucleotide CGG repeat (>200) on the promotor region of the fragile X mental retardation 1 gene (FMR1). As a result, the promotor region often becomes methylated which leads to a deficiency or absence of the FMR1 protein (FMRP). Common characteristics of FXS include mild to severe cognitive impairments in males but less severe cognitive impairment in females. Physical features of FXS include an elongated face, prominent ears, and post-pubertal macroorchidism. Severe obesity in full mutation males is often associated with the Prader-Willi phenotype (PWP) which includes hyperphagia, lack of satiation after meals, and hypogonadism or delayed puberty; however, there is no deletion at 15q11-q13 nor uniparental maternal disomy. Herein, we discuss the molecular mechanisms leading to FXS and the Prader-Willi phenotype with an emphasis on mouse FMR1 knockout studies that have shown the reversal of weight increase through mGluR antagonists. Finally, we review the current medications used in treatment of FXS including the atypical antipsychotics that can lead to weight gain and the research regarding the use of targeted treatments in FXS that will hopefully have a significantly beneficial effect on cognition and behavior without weight gain.
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Affiliation(s)
- Yingratana McLennan
- Medical Investigation of Neurodevelopmental Disorders (M.I.N.D.) Institute, University of California Davis Health System, Sacramento, California, USA
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Bailey DB, Raspa M, Olmsted MG. Using a parent survey to advance knowledge about the nature and consequences of fragile X syndrome. AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES 2010; 115:447-460. [PMID: 20945998 DOI: 10.1352/1944-7558-115.6.447] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Understanding the nature and consequences of intellectual and developmental disabilities is challenging, especially when the condition is rare, affected individuals are geographically dispersed, and/or resource constraints limit large-scale studies involving direct assessment. Surveys provide an alternative methodology for gathering information but must be carefully designed and interpreted in light of obvious limitations. In this paper we discuss the potential of surveys in understanding a disabling condition; delineate characteristics of successful survey research; describe a survey of families of individuals with fragile X syndrome; and synthesize major findings. The survey has provided new information about the nature and consequences of fragile X syndrome in a cost-effective fashion, suggesting that survey methodology has a useful place in creating new knowledge about intellectual and developmental disabilities.
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