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Genovese AC, Butler MG. Behavioral and Psychiatric Disorders in Syndromic Autism. Brain Sci 2024; 14:343. [PMID: 38671997 PMCID: PMC11048128 DOI: 10.3390/brainsci14040343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Revised: 03/25/2024] [Accepted: 03/28/2024] [Indexed: 04/28/2024] Open
Abstract
Syndromic autism refers to autism spectrum disorder diagnosed in the context of a known genetic syndrome. The specific manifestations of any one of these syndromic autisms are related to a clinically defined genetic syndrome that can be traced to certain genes and variants, genetic deletions, or duplications at the chromosome level. The genetic mutations or defects in single genes associated with these genetic disorders result in a significant elevation of risk for developing autism relative to the general population and are related to recurrence with inheritance patterns. Additionally, these syndromes are associated with typical behavioral characteristics or phenotypes as well as an increased risk for specific behavioral or psychiatric disorders and clinical findings. Knowledge of these associations helps guide clinicians in identifying potentially treatable conditions that can help to improve the lives of affected patients and their families.
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Affiliation(s)
- Ann C. Genovese
- Department of Psychiatry and Behavioral Sciences, University of Kansas Medical Center, Kansas City, KS 66160, USA;
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2
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Lopes AG, Loganathan SK, Caliaperumal J. Rett Syndrome and the Role of MECP2: Signaling to Clinical Trials. Brain Sci 2024; 14:120. [PMID: 38391695 PMCID: PMC10886956 DOI: 10.3390/brainsci14020120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2023] [Revised: 01/11/2024] [Accepted: 01/17/2024] [Indexed: 02/24/2024] Open
Abstract
Rett syndrome (RTT) is a neurological disorder that mostly affects females, with a frequency of 1 in 10,000 to 20,000 live birth cases. Symptoms include stereotyped hand movements; impaired learning, language, and communication skills; sudden loss of speech; reduced lifespan; retarded growth; disturbance of sleep and breathing; seizures; autism; and gait apraxia. Pneumonia is the most common cause of death for patients with Rett syndrome, with a survival rate of 77.8% at 25 years of age. Survival into the fifth decade is typical in Rett syndrome, and the leading cause of death is cardiorespiratory compromise. Rett syndrome progression has multiple stages; however, most phenotypes are associated with the nervous system and brain. In total, 95% of Rett syndrome cases are due to mutations in the MECP2 gene, an X-linked gene that encodes for the methyl CpG binding protein, a regulator of gene expression. In this review, we summarize the recent developments in the field of Rett syndrome and therapeutics targeting MECP2.
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Affiliation(s)
- Adele Gaspar Lopes
- Department of Pharmacology, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3G 2M1, Canada
- Cancer Research Program, Research Institute of the McGill University Health Centre, Montreal, QC H4A 3J1, Canada
| | - Sampath Kumar Loganathan
- Cancer Research Program, Research Institute of the McGill University Health Centre, Montreal, QC H4A 3J1, Canada
- Department of Biochemistry, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H4A 3J1, Canada
- Department of Otolaryngology, Head & Neck Surgery, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H4A 3J1, Canada
- Departments of Experimental Surgery and Experimental Medicine, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H4A 3J1, Canada
| | - Jayalakshmi Caliaperumal
- Ingram School of Nursing, Faculty of Medicine and Health Sciences, McGill University, Montreal, QC H3A 2M7, Canada
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Oberman LM, Leonard H, Downs J, Cianfaglione R, Stahlhut M, Larsen JL, Madden KV, Kaufmann WE. Rett Syndrome Behaviour Questionnaire in Children and Adults With Rett Syndrome: Psychometric Characterization and Revised Factor Structure. AMERICAN JOURNAL ON INTELLECTUAL AND DEVELOPMENTAL DISABILITIES 2023; 128:237-253. [PMID: 37104862 DOI: 10.1352/1944-7558-128.3.237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2021] [Accepted: 10/18/2022] [Indexed: 05/25/2023]
Abstract
Rett syndrome (RTT) is a severe neurodevelopmental disorder associated with multiple neurobehavioral abnormalities. The Rett Syndrome Behaviour Questionnaire (RSBQ) was developed for pediatric RTT observational studies. Because its application has expanded to adult and interventional studies, we evaluated the RSBQ's psychometric properties in six pediatric (n = 323) and five adult (n = 309) datasets. Total and General Mood subscale scores had good reliability. Clinical severity had no influence on RSBQ scores. Exploratory and confirmatory factor analyses yielded 6 pediatric and 7 adult clinically relevant and psychometrically strong factors including the original Breathing Problems and Fear/Anxiety subscales and the novel Emotional and Disruptive Behavior subscale composed of items from the original General Mood and Nighttime Behaviours subscales. The present findings support additional evaluations and improvements of an important RTT behavioral measure.
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Affiliation(s)
- Lindsay M Oberman
- Lindsay M. Oberman, Center for Neuroscience and Regenerative Medicine, Henry M. Jackson Foundation for the Advancement of Military Medicine, USA
| | - Helen Leonard
- Helen Leonard, Telethon Kids Institute, The University of Western Australia, Perth, Western Australia, Australia
| | - Jenny Downs
- Jenny Downs, Telethon Kids Institute, The University of Western Australia and School of Physiotherapy and Exercise Science, Curtin University, Perth, Western Australia, Australia
| | | | - Michelle Stahlhut
- Michelle Stahlhut, Center for Rett Syndrome, Rigshospitalet, Copenhagen, Denmark
| | - Jane L Larsen
- Jane L. Larsen, Center for Rett Syndrome, Rigshospitalet, Copenhagen, Denmark
| | | | - Walter E Kaufmann
- Walter E. Kaufmann, Anavex Life Sciences Corp. and Emory University School of Medicine, USA
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da Motta TP, Owens J, Abreu LG, Debossan SAT, Vargas-Ferreira F, Vettore MV. Malocclusion characteristics amongst individuals with autism spectrum disorder: a systematic review and meta-analysis. BMC Oral Health 2022; 22:341. [PMID: 35948958 PMCID: PMC9367144 DOI: 10.1186/s12903-022-02366-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Accepted: 07/22/2022] [Indexed: 11/17/2022] Open
Abstract
BACKGROUND To estimate the prevalence of malocclusion in individuals with autism spectrum disorders (ASD) and to assess the relationship between ASD and malocclusion. METHODS We searched electronic databases including PubMed, Scopus, Web of Science, Cochrane, Embase, SciELO LILACS, Proquest, OpenGrey and Google Scholar. There were no language or publication dates restrictions. Two researchers independently performed selection, data extraction and quality assessment. Quality assessment and risk of bias were evaluated through the Newcastle-Ottawa scale and ROBINS-E tool. Meta-analyses using random effect models were used to estimate pooled measures of prevalence of malocclusion characteristics in individuals with ASD and pooled odds ratio (OR) on the relationship between ASD and malocclusion characteristics. Subgroup meta-analyses were conducted according to children and adolescents, history of orthodontic treatment, and occurrence of other syndromes and medical conditions. RESULTS Searching identified 5549 papers with 238 were selected for full assessment. Eighteen cross-sectional studies were included according to inclusion criteria. Of them, eleven studies were considered of moderate quality. A judgement of critical risk of bias occurred for thirteen studies. The most prevalent malocclusion characteristics in individuals with ASD were crowding (33%; 95% CI 22 to 44%) and increased maxillary overjet (39%; 95% CI 23 to 54%). Individuals with ASD had higher odds of Angle's Class II (OR 1.92; 95% CI 1.36 to 2.72), Angle's Class III (OR 2.33; 95% CI 1.29 to 4.23), open bite (OR 1.96; 95% CI 1.21 to 3.16), and increased maxillary overjet (OR 1.53; 95% CI 1.06 to 2.21) than individuals without ASD. CONCLUSIONS Angle's Class II, Angle's Class III, anterior open bite and increased maxillary overjet were more prevalent in individuals with ASD than those without ASD. Further high-quality studies are needed.
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Affiliation(s)
- Thiago Peixoto da Motta
- Department of Social and Preventive Dentistry, School of Dentistry, Federal University of Minas Gerais, Av. Antônio Carlos, 6627 - Pampulha, Belo Horizonte, MG CEP 312270-901 Brazil
| | - Janine Owens
- NIHR Applied Research Collaborative, Greater Manchester (NIHR ARC GM), Faculty of Biology, Medicine and Health, Division of Nursing, Midwifery and Social Work, Jean McFarlane Building, University of Manchester, Oxford Road, Manchester, M13 9PL UK
| | - Lucas Guimarães Abreu
- Department of Child and Adolescent Oral Health, School of Dentistry, Federal University of Minas Gerais, Av. Antônio Carlos, 6627 - Pampulha, Belo Horizonte, MG CEP 312270-901 Brazil
| | - Suélen Alves Teixeira Debossan
- Department of Social and Preventive Dentistry, School of Dentistry, Federal University of Minas Gerais, Av. Antônio Carlos, 6627 - Pampulha, Belo Horizonte, MG CEP 312270-901 Brazil
| | - Fabiana Vargas-Ferreira
- Department of Social and Preventive Dentistry, School of Dentistry, Federal University of Minas Gerais, Av. Antônio Carlos, 6627 - Pampulha, Belo Horizonte, MG CEP 312270-901 Brazil
| | - Mario Vianna Vettore
- Department of Health and Nursing Sciences, Faculty of Health and Sports Sciences, University of Agder, Campus Kristiansand, Universitetsveien 25, 4630 Kristiansand, Norway
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Stafford CF, Sanchez-Lara PA. Impact of Genetic and Genomic Testing on the Clinical Management of Patients with Autism Spectrum Disorder. Genes (Basel) 2022; 13:genes13040585. [PMID: 35456390 PMCID: PMC9030515 DOI: 10.3390/genes13040585] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 03/21/2022] [Indexed: 02/06/2023] Open
Abstract
Research has shown that genetics play a key role in the development of autism spectrum disorder (ASD). ASD has been linked to many genes and is a prominent feature in numerous genetic disorders. A genetic evaluation should be offered to any patient who receives a diagnosis of ASD, including deep phenotyping and genetic testing when clinically indicated. When insurance does not cover genetic testing for ASD patients, the lack of medical utility is often cited as a reason for prior authorization request denial. However, ample evidence exists that genetic testing has the power to change clinical management in many of these patients. Genetic testing that results in a diagnosis guides clinicians to screen for associated medical conditions and can direct targeted medical interventions. Given the potential for clinically actionable results, it is important that genetic testing be available and accessible to all patients with ASD.
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Affiliation(s)
| | - Pedro A. Sanchez-Lara
- Department of Pediatrics, Cedars-Sinai Medical Center, Los Angeles, CA 90048, USA
- David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA 90095, USA
- Correspondence:
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Reviewing Evidence for the Relationship of EEG Abnormalities and RTT Phenotype Paralleled by Insights from Animal Studies. Int J Mol Sci 2021; 22:ijms22105308. [PMID: 34069993 PMCID: PMC8157853 DOI: 10.3390/ijms22105308] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/09/2021] [Accepted: 05/12/2021] [Indexed: 12/29/2022] Open
Abstract
Rett syndrome (RTT) is a rare neurodevelopmental disorder that is usually caused by mutations of the MECP2 gene. Patients with RTT suffer from severe deficits in motor, perceptual and cognitive domains. Electroencephalogram (EEG) has provided useful information to clinicians and scientists, from the very first descriptions of RTT, and yet no reliable neurophysiological biomarkers related to the pathophysiology of the disorder or symptom severity have been identified to date. To identify consistently observed and potentially informative EEG characteristics of RTT pathophysiology, and ascertain areas most worthy of further systematic investigation, here we review the literature for EEG abnormalities reported in patients with RTT and in its disease models. While pointing to some promising potential EEG biomarkers of RTT, our review identify areas of need to realize the potential of EEG including (1) quantitative investigation of promising clinical-EEG observations in RTT, e.g., shift of mu rhythm frequency and EEG during sleep; (2) closer alignment of approaches between patients with RTT and its animal models to strengthen the translational significance of the work (e.g., EEG measurements and behavioral states); (3) establishment of large-scale consortium research, to provide adequate Ns to investigate age and genotype effects.
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Ozlu C, Bailey RM, Sinnett S, Goodspeed KD. Gene Transfer Therapy for Neurodevelopmental Disorders. Dev Neurosci 2021; 43:230-240. [PMID: 33882495 DOI: 10.1159/000515434] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/13/2021] [Indexed: 11/19/2022] Open
Abstract
Neurodevelopmental disorders (NDDs) include a broad spectrum of disorders that disrupt normal brain development. Though some NDDs are caused by acquired insults (i.e., toxic or infectious encephalopathy) or may be cryptogenic, many NDDs are caused by variants in a single gene or groups of genes that disrupt neuronal development or function. In this review, we will focus on those NDDs with a genetic etiology. The exact mechanism, timing, and progression of the molecular pathology are seldom well known; however, the abnormalities in development typically manifest in similar patterns such as delays or regression in motor function, social skills, and language or cognitive abilities. Severity of impairment can vary widely. At present, only symptomatic treatments are available to manage seizures and behavioral problems commonly seen in NDDs. In recent years, there has been a rapid expansion of research into gene therapy using adeno-associated viruses (AAVs). Using AAVs as vectors to replace the non- or dysfunctional gene in vivo is a relatively simple model which has created an unprecedented opportunity for the future of NDD treatment. Advances in this field are of paramount importance as NDDs lead to a massive lifelong burden of disease on the affected individuals and families. In this article, we review the unique advantages and challenges of AAV gene therapies. We then look at potential applications of gene therapy for 3 of the more common NDDs (Rett syndrome, fragile X syndrome, and Angelman syndrome), as well as 2 less common NDDs (SLC13A5 deficiency disorder and SLC6A1-related disorder). We will review the available natural history of each disease and current state of preclinical studies including a discussion on the application of AAV gene therapies for each disease.
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Affiliation(s)
- Can Ozlu
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Rachel M Bailey
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Center for Alzheimer's and Neurodegenerative Diseases, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Sarah Sinnett
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA.,Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Kimberly D Goodspeed
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
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Oberman LM, Kaufmann WE. Autism Spectrum Disorder Versus Autism Spectrum Disorders: Terminology, Concepts, and Clinical Practice. Front Psychiatry 2020; 11:484. [PMID: 32636765 PMCID: PMC7317665 DOI: 10.3389/fpsyt.2020.00484] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 05/12/2020] [Indexed: 11/17/2022] Open
Affiliation(s)
- Lindsay M Oberman
- Center for Neuroscience and Regenerative Medicine, Henry M. Jackson Foundation for the Advancement of Military Medicine, Rockville, MD, United States
| | - Walter E Kaufmann
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA, United States
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BUCHANAN C, STALLWORTH J, SCOTT A, GLAZE D, LANE J, SKINNER S, TIERNEY A, PERCY A, NEUL J, KAUFMANN W. Behavioral profiles in Rett syndrome: Data from the natural history study. Brain Dev 2019; 41:123-134. [PMID: 30217666 PMCID: PMC6392009 DOI: 10.1016/j.braindev.2018.08.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/13/2018] [Accepted: 08/21/2018] [Indexed: 11/15/2022]
Abstract
INTRODUCTION Rett syndrome (RTT) is a complex neurodevelopmental disorder with known behavioral abnormalities, both internalizing (e.g., anxiety, social withdrawal) and externalizing (e.g., aggression, self-abuse). However, a broad evaluation of behavioral abnormalities in a large cohort is lacking. OBJECTIVE In this report, we describe profiles of internalizing and externalizing behaviors in individuals evaluated in the multi-center U.S. Rett Natural History Study. METHODS Cross-sectional and longitudinal data were collected from 861 females with RTT and from 48 females who have MECP2 mutations without meeting criteria for RTT. Standard statistical methods including linear regression evaluated internalizing behavioral components from the Child Health Questionnaire (CHQ-PF50) and externalizing components from the Motor Behavioral Assessment (MBA). RESULTS We found mildly to moderately severe internalizing behaviors in nearly all individuals with RTT, while externalizing behaviors were mild and uncommon. Internalizing behavior in RTT was comparable to groups with psychiatric disorders. Participants with mixed (internalizing and externalizing) behaviors were younger and less affected overall, but showed prominent self-injury and worsening internalizing behaviors over time. CONCLUSIONS This study revealed that internalizing behaviors are common at a clinically significant level in RTT. Understanding clinical features associated with behavioral profiles could guide treatment strategies.
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Affiliation(s)
| | | | | | - Daniel GLAZE
- Baylor College of Medicine, Department of Pediatrics and Neurology, Texas, United States
| | - Jane LANE
- University of Alabama at Birmingham, Civitan International Research Center, Alabama, United States
| | | | - Aubin TIERNEY
- Greenwood Genetic Center, South Carolina, United States
| | - Alan PERCY
- University of Alabama at Birmingham, Department of Pediatrics, Civitan International Research Center, Alabama, United States
| | - Jeffrey NEUL
- Vanderbilt Kennedy Center, Vanderbilt University Medical Center, Tennessee, United States
| | - Walter KAUFMANN
- Greenwood Genetic Center, South Carolina, United States,University of South Carolina School of Medicine, Department of Pediatrics, South Carolina, United States,Emory University School of Medicine, Department of Human Genetics, Georgia, United States,Corresponding author: Walter Kaufmann, M.D., Ph.D., Greenwood Genetic Center; University of South Carolina School of Medicine, Department of Pediatrics; Emory University School of Medicine, Department of Human Genetics, 615 Michael St, Suite 301, Whitehead Building, Atlanta, GA 30322, USA, Tel: +1-864-678-7897, Fax: +1-864-250-9582,
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Fernandez BA, Scherer SW. Syndromic autism spectrum disorders: moving from a clinically defined to a molecularly defined approach. DIALOGUES IN CLINICAL NEUROSCIENCE 2018. [PMID: 29398931 PMCID: PMC5789213 DOI: 10.31887/dcns.2017.19.4/sscherer] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Autism spectrum disorder (ASD) encompasses a group of neurodevelopmental conditions diagnosed solely on the basis of behavioral assessments that reveal social deficits. Progress has been made in understanding its genetic underpinnings, but most ASD-associated genetic variants, which include copy number variants (CNVs) and mutations in ASD-risk genes, account for no more than 1 % of ASD cases. This high level of genetic heterogeneity leads to challenges obtaining and interpreting genetic testing in clinical settings. The traditional definition of syndromic ASD is a disorder with a clinically defined pattern of somatic abnormalities and a neurobehavioral phenotype that may include ASD. Most have a known genetic cause. Examples include fragile X syndrome and tuberous sclerosis complex. We propose dividing syndromic autism into the following two groups: (i) ASD that occurs in the context of a clinically defined syndrome-recognizing these disorders depends on the familiarity of the clinician with the features of the syndrome, and the diagnosis is typically confirmed by targeted genetic testing (eg, mutation screening of FMR1); (ii) ASD that occurs as a feature of a molecularly defined syndrome-for this group of patients, ASD-associated variants are identified by genome-wide testing that is not hypothesis driven (eg, microarray, whole exome sequencing). These ASD groups cannot be easily clinically defined because patients with a given variant have variable somatic abnormalities (dysmorphism and birth defects). In this article, we review common diagnoses from the above categories and suggest a testing strategy for patients, guided by determining whether the individual has essential or complex ASD; patients in the latter group have multiple morphologic anomalies on physical examination. Finally, we recommend that the syndromic versus nonsyndromic designation ultimately be replaced by classification of ASD according to its genetic etiology, which will inform about the associated spectrum and penetrance of neurobehavioral and somatic manifestations.
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Affiliation(s)
- Bridget A Fernandez
- Disciplines of Genetics and Medicine, Faculty of Medicine, Memorial University of Newfoundland, St John's, NL Canada
| | - Stephen W Scherer
- The Center for Applied Genomics and Program in Genetics and Genomic Biology, The Hospital for Sick Children, Toronto, Ontario, Canada; McLaughlin Center and Department of Molecular Genetics, University of Toronto, Toronto, Ontario, Canada
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Tordjman S, Cohen D, Anderson G, Botbol M, Canitano R, Coulon N, Roubertoux P. Repint of “Reframing autism as a behavioral syndrome and not a specific mental disorder: Implications of genetic and phenotypic heterogeneity”. Neurosci Biobehav Rev 2018; 89:132-150. [DOI: 10.1016/j.neubiorev.2018.01.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 12/18/2016] [Accepted: 01/23/2017] [Indexed: 12/22/2022]
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Gold WA, Krishnarajy R, Ellaway C, Christodoulou J. Rett Syndrome: A Genetic Update and Clinical Review Focusing on Comorbidities. ACS Chem Neurosci 2018; 9:167-176. [PMID: 29185709 DOI: 10.1021/acschemneuro.7b00346] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Rett syndrome (RTT) is a unique neurodevelopmental disorder that primarily affects females resulting in severe cognitive and physical disabilities. Despite the commendable collective efforts of the research community to better understand the genetics and underlying biology of RTT, there is still no cure. However, in the past 50 years, since the first report of RTT, steady progress has been made in the accumulation of clinical and molecular information resulting in the identification of a number of genes associated with RTT and associated phenotypes, improved diagnostic criteria, natural history studies, curation of a number of databases capturing genotypic and phenotypic data, a number of promising clinical trials and exciting novel therapeutic options which are currently being tested in laboratory and clinical settings. This Review focuses on the current knowledge of the clinical aspects of RTT, with particular attention being paid to clinical trials and the comorbidities of the disorder as well as the genetic etiology and the recognition of new diseases genes.
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Affiliation(s)
- Wendy A Gold
- Genetic
Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
| | - Rahul Krishnarajy
- Genetic
Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
| | - Carolyn Ellaway
- Genetic
Metabolic Disorders Service, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
| | - John Christodoulou
- Genetic
Metabolic Disorders Research Unit, Western Sydney Genetics Program, The Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
- Neurodevelopmental
Genomics Research Group, Murdoch Children’s Research Institute,
and Department of Paediatrics, Melbourne Medical School, University of Melbourne, Melbourne, VIC 3010, Australia
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Fakhoury M. Imaging genetics in autism spectrum disorders: Linking genetics and brain imaging in the pursuit of the underlying neurobiological mechanisms. Prog Neuropsychopharmacol Biol Psychiatry 2018; 80:101-114. [PMID: 28322981 DOI: 10.1016/j.pnpbp.2017.02.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 02/22/2017] [Accepted: 02/22/2017] [Indexed: 01/08/2023]
Abstract
Autism spectrum disorders (ASD) include a wide range of heterogeneous neurodevelopmental conditions that affect an individual in several aspects of social communication and behavior. Recent advances in molecular genetic technologies have dramatically increased our understanding of ASD etiology through the identification of several autism risk genes, most of which serve important functions in synaptic plasticity and protein synthesis. However, despite significant progress in this field of research, the characterization of the neurobiological mechanisms by which common genetic risk variants might operate to give rise to ASD symptomatology has proven to be far more difficult than expected. The imaging genetics approach holds great promise for advancing our understanding of ASD etiology by bridging the gap between genetic variations and their resultant biological effects on the brain. This paper provides a conceptual overview of the contribution of genetics in ASD and discusses key findings from the emerging field of imaging genetics.
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Affiliation(s)
- Marc Fakhoury
- Department of Neurosciences, Faculty of Medicine, Université de Montréal, Montreal, Quebec H3C 3J7, Canada.
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Hamza M, Halayem S, Mrad R, Bourgou S, Charfi F, Belhadj A. Implication de l’épigénétique dans les troubles du spectre autistique : revue de la littérature. Encephale 2017; 43:374-381. [DOI: 10.1016/j.encep.2016.07.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 07/04/2016] [Accepted: 07/04/2016] [Indexed: 01/24/2023]
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15
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Martin P. Pain in Rett syndrome: peculiarities in pain processing and expression, liability to pain causing disorders and diseases, and specific aspects of pain assessment. ADVANCES IN AUTISM 2017. [DOI: 10.1108/aia-02-2017-0003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Peter Martin
- Epilepsiezentrum Kork, Seguin-Klinik, Kehl-Kork, Germany
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Robert C, Pasquier L, Cohen D, Fradin M, Canitano R, Damaj L, Odent S, Tordjman S. Role of Genetics in the Etiology of Autistic Spectrum Disorder: Towards a Hierarchical Diagnostic Strategy. Int J Mol Sci 2017; 18:E618. [PMID: 28287497 PMCID: PMC5372633 DOI: 10.3390/ijms18030618] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 02/17/2017] [Accepted: 02/20/2017] [Indexed: 12/27/2022] Open
Abstract
Progress in epidemiological, molecular and clinical genetics with the development of new techniques has improved knowledge on genetic syndromes associated with autism spectrum disorder (ASD). The objective of this article is to show the diversity of genetic disorders associated with ASD (based on an extensive review of single-gene disorders, copy number variants, and other chromosomal disorders), and consequently to propose a hierarchical diagnostic strategy with a stepwise evaluation, helping general practitioners/pediatricians and child psychiatrists to collaborate with geneticists and neuropediatricians, in order to search for genetic disorders associated with ASD. The first step is a clinical investigation involving: (i) a child psychiatric and psychological evaluation confirming autism diagnosis from different observational sources and assessing autism severity; (ii) a neuropediatric evaluation examining neurological symptoms and developmental milestones; and (iii) a genetic evaluation searching for dysmorphic features and malformations. The second step involves laboratory and if necessary neuroimaging and EEG studies oriented by clinical results based on clinical genetic and neuropediatric examinations. The identification of genetic disorders associated with ASD has practical implications for diagnostic strategies, early detection or prevention of co-morbidity, specific treatment and follow up, and genetic counseling.
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Affiliation(s)
- Cyrille Robert
- Pôle Hospitalo-Universitaire de Psychiatrie de l'Enfant et de l'Adolescent (PHUPEA), University of Rennes 1 and Centre Hospitalier Guillaume Régnier, 35200 Rennes, France.
- Service de Génétique Clinique, Centre de Référence Maladies Rares Anomalies du Développement (Centre Labellisé pour les Anomalies du Développement de l'Ouest: CLAD Ouest), Hôpital Sud, Centre Hospitalier Universitaire de Rennes, 35200 Rennes, France.
| | - Laurent Pasquier
- Service de Génétique Clinique, Centre de Référence Maladies Rares Anomalies du Développement (Centre Labellisé pour les Anomalies du Développement de l'Ouest: CLAD Ouest), Hôpital Sud, Centre Hospitalier Universitaire de Rennes, 35200 Rennes, France.
| | - David Cohen
- Hospital-University Department of Child and Adolescent Psychiatry, Pitié-Salpétrière Hospital, Paris 6 University, 75013 Paris, France.
| | - Mélanie Fradin
- Service de Génétique Clinique, Centre de Référence Maladies Rares Anomalies du Développement (Centre Labellisé pour les Anomalies du Développement de l'Ouest: CLAD Ouest), Hôpital Sud, Centre Hospitalier Universitaire de Rennes, 35200 Rennes, France.
| | - Roberto Canitano
- Division of Child and Adolescent Neuropsychiatry, University Hospital of Siena, 53100 Siena, Italy.
| | - Léna Damaj
- Service de Génétique Clinique, Centre de Référence Maladies Rares Anomalies du Développement (Centre Labellisé pour les Anomalies du Développement de l'Ouest: CLAD Ouest), Hôpital Sud, Centre Hospitalier Universitaire de Rennes, 35200 Rennes, France.
| | - Sylvie Odent
- Service de Génétique Clinique, Centre de Référence Maladies Rares Anomalies du Développement (Centre Labellisé pour les Anomalies du Développement de l'Ouest: CLAD Ouest), Hôpital Sud, Centre Hospitalier Universitaire de Rennes, 35200 Rennes, France.
| | - Sylvie Tordjman
- Pôle Hospitalo-Universitaire de Psychiatrie de l'Enfant et de l'Adolescent (PHUPEA), University of Rennes 1 and Centre Hospitalier Guillaume Régnier, 35200 Rennes, France.
- Laboratory of Psychology of Perception, University Paris Descartes, 75270 Paris, France.
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17
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Prevalence of four Mendelian disorders associated with autism in 2392 affected families. J Hum Genet 2017; 62:657-659. [PMID: 28250423 DOI: 10.1038/jhg.2017.16] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Revised: 01/17/2017] [Accepted: 01/19/2017] [Indexed: 11/09/2022]
Abstract
Autism spectrum disorder (ASD) is a neurobehavioral disorder with a heterogeneous genetic etiology. Based on the literature, several single-gene disorders, including Rett syndrome, Smith-Lemli-Opitz syndrome, PTEN hamartoma tumor syndrome and tuberous sclerosis, are associated with a high prevalence of ASD. We estimated the prevalence of these four conditions in a large cohort of patients using whole-exome sequencing data from 2392 families (1800 quads and 592 trios) with ASD from the National Database for Autism Research. Seven patients carried a pathogenic or likely pathogenic variant in either TSC1, TSC2, PTEN, DHCR7 or MECP2, with 6 out of 7 reportable variants occurring in PTEN (1 in 399).
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18
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Tordjman S, Cohen D, Coulon N, Anderson GM, Botbol M, Canitano R, Roubertoux PL. Reframing autism as a behavioral syndrome and not a specific mental disorder: Implications of genetic and phenotypic heterogeneity. Neurosci Biobehav Rev 2017; 80:210. [PMID: 28153685 DOI: 10.1016/j.neubiorev.2017.01.030] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Revised: 12/18/2016] [Accepted: 01/23/2017] [Indexed: 12/13/2022]
Abstract
Clinical and molecular genetics have advanced current knowledge on genetic disorders associated with autism. A review of diverse genetic disorders associated with autism is presented and for the first time discussed extensively with regard to possible common underlying mechanisms leading to a similar cognitive-behavioral phenotype of autism. The possible role of interactions between genetic and environmental factors, including epigenetic mechanisms, is in particular examined. Finally, the pertinence of distinguishing non-syndromic autism (isolated autism) from syndromic autism (autism associated with genetic disorders) will be reconsidered. Given the high genetic and etiological heterogeneity of autism, autism can be viewed as a behavioral syndrome related to known genetic disorders (syndromic autism) or currently unknown disorders (apparent non-syndromic autism), rather than a specific categorical mental disorder. It highlights the need to study autism phenotype and developmental trajectory through a multidimensional, non-categorical approach with multivariate analyses within autism spectrum disorder but also across mental disorders, and to conduct systematically clinical genetic examination searching for genetic disorders in all individuals (children but also adults) with autism.
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Affiliation(s)
- S Tordjman
- Pôle Hospitalo-Universitaire de Psychiatrie de l'Enfant et de l'Adolescent, Université de Rennes 1 and Centre Hospitalier Guillaume Régnier, 154 rue de Châtillon, 35200 Rennes, France; Laboratoire Psychologie de la Perception, Université Paris Descartes and CNRS UMR 8158, Paris, France.
| | - D Cohen
- Department of Child and Adolescent Psychiatry, AP-HP, GH Pitié-Salpétrière, CNRS FRE 2987, Université Pierre et Marie Curie, Paris, France
| | - N Coulon
- Laboratoire Psychologie de la Perception, Université Paris Descartes and CNRS UMR 8158, Paris, France
| | - G M Anderson
- Child Study Center, Yale University School of Medicine, New Haven, CT, USA
| | - M Botbol
- Departement Hospitalo-Universitaire de Psychiatrie de l'Enfant et de l'Adolescent, Université de Bretagne Occidentale, Brest, France
| | - R Canitano
- Division of Child and Adolescent Neuropsychiatry, University Hospital of Siena, Siena, Italy
| | - P L Roubertoux
- Aix Marseille Université, GMGF, Inserm, UMR_S 910, 13385, Marseille, France
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19
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Ma M, Adams HR, Seltzer LE, Dobyns WB, Paciorkowski AR. Phenotype Differentiation of FOXG1 and MECP2 Disorders: A New Method for Characterization of Developmental Encephalopathies. J Pediatr 2016; 178:233-240.e10. [PMID: 27640358 PMCID: PMC5873956 DOI: 10.1016/j.jpeds.2016.08.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 06/14/2016] [Accepted: 08/09/2016] [Indexed: 01/07/2023]
Abstract
OBJECTIVE To differentiate developmental encephalopathies by creating a novel quantitative phenotyping tool. STUDY DESIGN We created the Developmental Encephalopathy Inventory (DEI) to differentiate disorders with complex multisystem neurodevelopmental symptoms. We then used the DEI to study the phenotype features of 20 subjects with FOXG1 disorder and 11 subjects with MECP2 disorder. RESULTS The DEI identified core domains of fine motor and expressive language that were severely impaired in both disorders. Individuals with FOXG1 disorder were overall more severely impaired. Subjects with FOXG1 disorder were less able to walk, had worse fine motor skills, more disability in receptive language and reciprocity, and had more disordered sleep than did subjects with MECP2 disorder (P <.05). Covariance, cluster, and principal component analysis confirmed a relationship between impaired awareness, reciprocity, and language in both disorders. In addition, abnormal ambulation was a first principal component for FOXG1 but not for MECP2 disorder, suggesting that impaired ambulation is a strong differentiating factor clinically between the 2 disorders. CONCLUSIONS We have developed a novel quantitative developmental assessment tool for developmental encephalopathies and propose this tool as a method to identify and illustrate core common and differential domains of disability in these complex disorders. These findings demonstrate clear phenotype differences between FOXG1 and MECP2 disorders.
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Affiliation(s)
- Mandy Ma
- University of Buffalo School of Medicine, Buffalo, NY
| | - Heather R. Adams
- Department of Neurology, University of Rochester Medical Center, Rochester, NY
| | - Laurie E. Seltzer
- Department of Neurology, University of Rochester Medical Center, Rochester, NY,Strong Epilepsy Center, University of Rochester Medical Center, Rochester, NY
| | - William B. Dobyns
- Department of Neurology, University of Washington, Seattle, WA,Division of Medical Genetics, Department of Pediatrics, University of Washington, Seattle, WA,Center for Integrative Brain Research, Seattle Children’s Research Institute, Seattle, WA
| | - Alex R. Paciorkowski
- Department of Neurology, University of Rochester Medical Center, Rochester, NY,Departments of Pediatrics and Biomedical Genetics, University of Rochester Medical Center, Rochester, NY,Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, NY
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20
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Kaufmann WE, Stallworth JL, Everman DB, Skinner SA. Neurobiologically-based treatments in Rett syndrome: opportunities and challenges. Expert Opin Orphan Drugs 2016; 4:1043-1055. [PMID: 28163986 PMCID: PMC5214376 DOI: 10.1080/21678707.2016.1229181] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Accepted: 08/23/2016] [Indexed: 12/14/2022]
Abstract
Introduction: Rett syndrome (RTT) is an X-linked neurodevelopmental disorder that primarily affects females, typically resulting in a period of developmental regression in early childhood followed by stabilization and severe chronic cognitive, behavioral, and physical disability. No known treatment exists beyond symptomatic management, and while insights into the genetic cause, pathophysiology, neurobiology, and natural history of RTT have been gained, many challenges remain. Areas covered: Based on a comprehensive survey of the primary literature on RTT, this article describes and comments upon the general and unique features of the disorder, genetic and neurobiological bases of drug development, and the history of clinical trials in RTT, with an emphasis on drug trial design, outcome measures, and implementation. Expert opinion: Neurobiologically based drug trials are the ultimate goal in RTT, and due to the complexity and global nature of the disorder, drugs targeting both general mechanisms (e.g., growth factors) and specific systems (e.g., glutamate modulators) could be effective. Trial design should optimize data on safety and efficacy, but selection of outcome measures with adequate measurement properties, as well as innovative strategies, such as those enhancing synaptic plasticity and use of biomarkers, are essential for progress in RTT and other neurodevelopmental disorders.
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Affiliation(s)
- Walter E Kaufmann
- Center for Translational Research, Greenwood Genetic Center, Greenwood, SC, USA; Department of Neurology, Boston Children's Hospital, Boston, MA, USA
| | | | - David B Everman
- Center for Translational Research, Greenwood Genetic Center , Greenwood , SC , USA
| | - Steven A Skinner
- Center for Translational Research, Greenwood Genetic Center , Greenwood , SC , USA
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21
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Is it possible to diagnose Rett syndrome before classical symptoms become obvious? Review of 24 Danish cases born between 2003 and 2012. Eur J Paediatr Neurol 2015; 19:679-87. [PMID: 26228846 DOI: 10.1016/j.ejpn.2015.07.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/22/2015] [Revised: 07/01/2015] [Accepted: 07/02/2015] [Indexed: 11/21/2022]
Abstract
BACKGROUND/PURPOSE Rett syndrome (RTT) is a neurodevelopmental disorder that affects mainly females; it results in multiple disabilities and carries a risk of medical comorbidities. Early diagnosis is important to help establish the best treatment opportunities and preventive care in order to slow down the progression of symptoms. We wanted to test our hypothesis that it is possible to diagnose RTT before the classical symptoms become obvious. METHODS We analysed development and symptoms before and at the time of the RTT diagnosis, as well as the symptoms that triggered MECP2 mutation analysis, in a cohort of girls with RTT born in Denmark between 2003 and 2012. RESULTS Twenty-four girls were included, and 87.5% of these girls were diagnosed when the classical RTT symptoms were recognized. However, parents were concerned about their daughters between 3 and 58 months prior to the RTT diagnosis, and they felt that the professionals did not share their concern in the beginning. When reviewing medical files and questionnaires, we noted that the majority of girls did have combinations of concerning symptoms such as developmental delay and a collection of subtle signs such as autistic traits, placidity, floppiness with suspicion of muscular or mitochondrial diseases, hair pulling, teeth grinding, development of incontinence and problems with initiating movements. CONCLUSION We conclude that many individuals with MECP2 mutation exhibit characteristics that should raise suspicion for RTT, prior to evolution of the core clinical criteria. As RTT is a rare disease, it is of importance to constantly educate clinicians for heightened awareness of RTT.
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22
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Lee BH, Smith T, Paciorkowski AR. Autism spectrum disorder and epilepsy: Disorders with a shared biology. Epilepsy Behav 2015; 47:191-201. [PMID: 25900226 PMCID: PMC4475437 DOI: 10.1016/j.yebeh.2015.03.017] [Citation(s) in RCA: 103] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/06/2015] [Accepted: 03/13/2015] [Indexed: 12/17/2022]
Abstract
There is an increasing recognition of clinical overlap in patients presenting with epilepsy and autism spectrum disorder (ASD), and a great deal of new information regarding the genetic causes of both disorders is available. Several biological pathways appear to be involved in both disease processes, including gene transcription regulation, cellular growth, synaptic channel function, and maintenance of synaptic structure. We review several genetic disorders where ASD and epilepsy frequently co-occur, and we discuss the screening tools available for practicing neurologists and epileptologists to help determine which patients should be referred for formal ASD diagnostic evaluation. Finally, we make recommendations regarding the workflow of genetic diagnostic testing available for children with both ASD and epilepsy. This article is part of a Special Issue entitled "Autism and Epilepsy".
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Affiliation(s)
- Bo Hoon Lee
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Tristram Smith
- Division of Neurodevelopmental and Behavioral Pediatrics, Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA
| | - Alex R Paciorkowski
- Department of Pediatrics, University of Rochester Medical Center, Rochester, NY, USA; Department of Neurology, University of Rochester Medical Center, Rochester, NY, USA; Department of Biomedical Genetics, University of Rochester Medical Center, Rochester, NY, USA; Center for Neural Development and Disease, University of Rochester Medical Center, Rochester, NY, USA.
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23
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Abstract
Mutations in Methyl-CpG-Binding protein 2 (MECP2) are commonly associated with the neurodevelopmental disorder Rett syndrome (RTT). However, some people with RTT do not have mutations in MECP2, and interestingly there have been people identified with MECP2 mutations that do not have the clinical features of RTT. In this report we present four people with neurodevelopmental abnormalities and clear RTT-disease causing MECP2 mutation but lacking the characteristic clinical features of RTT. One patient's symptoms suggest an extension of the known spectrum of MECP2 associated phenotypes to include global developmental delay with obsessive compulsive disorder and attention deficit hyperactivity disorder. These results reemphasize that RTT should remain a clinical diagnosis, based on the recent consensus criteria.
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24
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Kirkovski M, Enticott PG, Fitzgerald PB. A review of the role of female gender in autism spectrum disorders. J Autism Dev Disord 2014; 43:2584-603. [PMID: 23525974 DOI: 10.1007/s10803-013-1811-1] [Citation(s) in RCA: 209] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
This paper reviews the literature exploring gender differences associated with the clinical presentation of autism spectrum disorders (ASD). The potentially mediating effect of comorbid psychopathology, biological and neurodevelopmental implications on these gender differences is also discussed. A vastly heterogeneous condition, while females on the lower-functioning end of the spectrum appear to be more severely affected, an altered clinical manifestation of the disorder among high-functioning females may consequently result in many being un- or mis-diagnosed. To date, there is strong bias in the literature towards the clinical presentation of ASD in males. It is imperative that future research explores gender differences across the autism spectrum, in order to improve researchers', clinicians' and the public's understanding of this debilitating disorder.
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Affiliation(s)
- Melissa Kirkovski
- Monash Alfred Psychiatry Research Centre, The Alfred and Central Clinical School, Monash University, Level 4, 607 St Kilda Rd, Melbourne, VIC, 3004, Australia,
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25
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Tordjman S, Somogyi E, Coulon N, Kermarrec S, Cohen D, Bronsard G, Bonnot O, Weismann-Arcache C, Botbol M, Lauth B, Ginchat V, Roubertoux P, Barburoth M, Kovess V, Geoffray MM, Xavier J. Gene × Environment interactions in autism spectrum disorders: role of epigenetic mechanisms. Front Psychiatry 2014; 5:53. [PMID: 25136320 PMCID: PMC4120683 DOI: 10.3389/fpsyt.2014.00053] [Citation(s) in RCA: 165] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 05/02/2014] [Indexed: 01/03/2023] Open
Abstract
Several studies support currently the hypothesis that autism etiology is based on a polygenic and epistatic model. However, despite advances in epidemiological, molecular and clinical genetics, the genetic risk factors remain difficult to identify, with the exception of a few chromosomal disorders and several single gene disorders associated with an increased risk for autism. Furthermore, several studies suggest a role of environmental factors in autism spectrum disorders (ASD). First, arguments for a genetic contribution to autism, based on updated family and twin studies, are examined. Second, a review of possible prenatal, perinatal, and postnatal environmental risk factors for ASD are presented. Then, the hypotheses are discussed concerning the underlying mechanisms related to a role of environmental factors in the development of ASD in association with genetic factors. In particular, epigenetics as a candidate biological mechanism for gene × environment interactions is considered and the possible role of epigenetic mechanisms reported in genetic disorders associated with ASD is discussed. Furthermore, the example of in utero exposure to valproate provides a good illustration of epigenetic mechanisms involved in ASD and innovative therapeutic strategies. Epigenetic remodeling by environmental factors opens new perspectives for a better understanding, prevention, and early therapeutic intervention of ASD.
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Affiliation(s)
- Sylvie Tordjman
- Laboratoire Psychologie de la Perception, Université Paris Descartes, CNRS UMR 8158, Paris, France
- Pôle Hospitalo-Universitaire de Psychiatrie de l’Enfant et de l’Adolescent, Université de Rennes 1, Centre Hospitalier Guillaume Régnier, Rennes, France
| | - Eszter Somogyi
- Laboratoire Psychologie de la Perception, Université Paris Descartes, CNRS UMR 8158, Paris, France
| | - Nathalie Coulon
- Laboratoire Psychologie de la Perception, Université Paris Descartes, CNRS UMR 8158, Paris, France
| | - Solenn Kermarrec
- Laboratoire Psychologie de la Perception, Université Paris Descartes, CNRS UMR 8158, Paris, France
- Pôle Hospitalo-Universitaire de Psychiatrie de l’Enfant et de l’Adolescent, Université de Rennes 1, Centre Hospitalier Guillaume Régnier, Rennes, France
| | - David Cohen
- Department of Child and Adolescent Psychiatry, AP-HP, GH Pitié-Salpétrière, CNRS FRE 2987, University Pierre and Marie Curie, Paris, France
| | - Guillaume Bronsard
- Laboratoire de Santé Publique (EA3279), School of Medicine of La Timone, Marseille, France
| | - Olivier Bonnot
- Laboratoire Psychologie de la Perception, Université Paris Descartes, CNRS UMR 8158, Paris, France
| | - Catherine Weismann-Arcache
- Laboratoire Psychologie et Neurosciences de la Cognition et de l’Affectivité, Université de Rouen, Mont Saint Aignan, France
| | - Michel Botbol
- Laboratoire Psychologie de la Perception, Université Paris Descartes, CNRS UMR 8158, Paris, France
- Service Hospitalo-Universitaire de Psychiatrie de l’Enfant et de l’Adolescent, Université de Bretagne Occidentale, CHU de Brest, Brest, France
| | - Bertrand Lauth
- Department of Child and Adolescent Psychiatry, Landspitali University Hospital, University of Iceland, Reykjavik, Iceland
| | - Vincent Ginchat
- Department of Child and Adolescent Psychiatry, AP-HP, GH Pitié-Salpétrière, CNRS FRE 2987, University Pierre and Marie Curie, Paris, France
| | - Pierre Roubertoux
- Laboratoire de Génétique Médicale, Génomique Fonctionnelle, INSERM U 910, Université d’Aix-Marseille 2, Marseille, France
| | - Marianne Barburoth
- Laboratoire Psychologie de la Perception, Université Paris Descartes, CNRS UMR 8158, Paris, France
| | - Viviane Kovess
- Department of Epidemiology and Biostatistics, EHESP School for Public Health, EA 4057 University Paris Descartes, Paris, France
| | - Marie-Maude Geoffray
- Service Universitaire de Psychiatrie de l’Enfant et de l’Adolescent Hospitalier Le Vinatier, Bron, France
| | - Jean Xavier
- Department of Child and Adolescent Psychiatry, AP-HP, GH Pitié-Salpétrière, CNRS FRE 2987, University Pierre and Marie Curie, Paris, France
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26
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Seltzer LE, Paciorkowski AR. Genetic disorders associated with postnatal microcephaly. AMERICAN JOURNAL OF MEDICAL GENETICS PART C-SEMINARS IN MEDICAL GENETICS 2014; 166C:140-55. [PMID: 24839169 DOI: 10.1002/ajmg.c.31400] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Several genetic disorders are characterized by normal head size at birth, followed by deceleration in head growth resulting in postnatal microcephaly. Among these are classic disorders such as Angelman syndrome and MECP2-related disorder (formerly Rett syndrome), as well as more recently described clinical entities associated with mutations in CASK, CDKL5, CREBBP, and EP300 (Rubinstein-Taybi syndrome), FOXG1, SLC9A6 (Christianson syndrome), and TCF4 (Pitt-Hopkins syndrome). These disorders can be identified clinically by phenotyping across multiple neurodevelopmental and neurobehavioral realms, and enough data are available to recognize these postnatal microcephaly disorders as separate diagnostic entities in their own right. A second diagnostic grouping, comprised of Warburg MICRO syndrome, Cockayne syndrome, and Cerebral-oculo-facial skeletal syndrome, share similar features of somatic growth failure, ophthalmologic, and dysmorphologic features. Many postnatal microcephaly syndromes are caused by mutations in genes important in the regulation of gene expression in the developing forebrain and hindbrain, although important synaptic structural genes also play a role. This is an emerging group of disorders with a fascinating combination of brain malformations, specific epilepsies, movement disorders, and other complex neurobehavioral abnormalities.
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27
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Abstract
Rett syndrome (RTT) is a severe and progressive neurological disorder, which mainly affects young females. Mutations of the methyl-CpG binding protein 2 (MECP2) gene are the most prevalent cause of classical RTT cases. MECP2 mutations or altered expression are also associated with a spectrum of neurodevelopmental disorders such as autism spectrum disorders with recent links to fetal alcohol spectrum disorders. Collectively, MeCP2 relation to these neurodevelopmental disorders highlights the importance of understanding the molecular mechanisms by which MeCP2 impacts brain development, mental conditions, and compromised brain function. Since MECP2 mutations were discovered to be the primary cause of RTT, a significant progress has been made in the MeCP2 research, with respect to the expression, function and regulation of MeCP2 in the brain and its contribution in RTT pathogenesis. To date, there have been intensive efforts in designing effective therapeutic strategies for RTT benefiting from mouse models and cells collected from RTT patients. Despite significant progress in MeCP2 research over the last few decades, there is still a knowledge gap between the in vitro and in vivo research findings and translating these findings into effective therapeutic interventions in human RTT patients. In this review, we will provide a synopsis of Rett syndrome as a severe neurological disorder and will discuss the role of MeCP2 in RTT pathophysiology.
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28
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Rosti RO, Sadek AA, Vaux KK, Gleeson JG. The genetic landscape of autism spectrum disorders. Dev Med Child Neurol 2014; 56:12-8. [PMID: 24116704 DOI: 10.1111/dmcn.12278] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/22/2013] [Indexed: 12/13/2022]
Abstract
Autism spectrum disorders (ASDs) are a group of heterogeneous neurodevelopmental disorders that show impaired communication and socialization, restricted interests, and stereotypical behavioral patterns. Recent advances in molecular medicine and high throughput screenings, such as array comparative genomic hybridization (CGH) and exome and whole genome sequencing, have revealed both novel insights and new questions about the nature of this spectrum of disorders. What has emerged is a better understanding about the genetic architecture of various genetic subtypes of ASD and correlations of genetic mutations with specific autism subtypes. Based on this new information, we outline a strategy for advancing diagnosis, prognosis, and counseling for patients and families.
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Affiliation(s)
- Rasim O Rosti
- Department of Neurosciences and Pediatrics, Howard Hughes Medical Institute, University of California, San Diego, CA, USA
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29
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Liao HM, Gau SSF, Tsai WC, Fang JS, Su YC, Chou MC, Liu SK, Chou WJ, Wu YY, Chen CH. Chromosomal abnormalities in patients with autism spectrum disorders from Taiwan. Am J Med Genet B Neuropsychiatr Genet 2013; 162B:734-41. [PMID: 24132905 DOI: 10.1002/ajmg.b.32153] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Accepted: 03/05/2013] [Indexed: 12/12/2022]
Abstract
Autism spectrum disorders (ASD) are childhood-onset neurodevelopmental disorders characterized by verbal communication impairments, social reciprocity deficits, and the presence of restricted interests and stereotyped behaviors. Genetic factors contribute to the incidence of ASD evidently. However, the genetic spectrum of ASD is highly heterogeneous. Chromosomal abnormalities contribute significantly to the genetic deficits of syndromic and non-syndromic ASD. In this study, we conducted karyotyping analysis in a sample of 500 patients (447 males, 53 females) with ASD from Taiwan, the largest cohort in Asia, to the best of our knowledge. We found three patients having sex chromosome aneuploidy, including two cases of 47, XXY and one case of 47, XYY. In addition, we detected a novel reciprocal chromosomal translocation between long arms of chromosomes 4 and 14, designated t(4;14)(q31.3;q24.1), in a patient with Asperger's disorder. This translocation was inherited from his unaffected father, suggesting it might not be pathogenic or it needs further hits to become pathogenic. In line with other studies, our study revealed that subjects with sex chromosomal aneuploidy are liable to neurodevelopmental disorders, including ASD, and conventional karyotyping analysis is still a useful tool in detecting chromosomal translocation in patients with ASD, given that array-based comparative genomic hybridization technology can provide better resolution in detecting copy number variations of genomic DNA.
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Affiliation(s)
- Hsiao-Mei Liao
- Department of Psychiatry, National Taiwan University College of Medicine, Taipei, Taiwan
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30
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Persico AM, Napolioni V. Autism genetics. Behav Brain Res 2013; 251:95-112. [PMID: 23769996 DOI: 10.1016/j.bbr.2013.06.012] [Citation(s) in RCA: 173] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 06/03/2013] [Accepted: 06/04/2013] [Indexed: 12/22/2022]
Abstract
Autism spectrum disorder (ASD) is a severe neuropsychiatric disease with strong genetic underpinnings. However, genetic contributions to autism are extremely heterogeneous, with many different loci underlying the disease to a different extent in different individuals. Moreover, the phenotypic expression (i.e., "penetrance") of these genetic components is also highly variable, ranging from fully penetrant point mutations to polygenic forms with multiple gene-gene and gene-environment interactions. Furthermore, many genes involved in ASD are also involved in intellectual disability, further underscoring their lack of specificity in phenotypic expression. We shall hereby review current knowledge on the genetic basis of ASD, spanning genetic/genomic syndromes associated with autism, monogenic forms due to copy number variants (CNVs) or rare point mutations, mitochondrial forms, and polygenic autisms. Finally, the recent contributions of genome-wide association and whole exome sequencing studies will be highlighted.
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Affiliation(s)
- Antonio M Persico
- Child and Adolescent Neuropsychiatry Unit, University Campus Bio-Medico, Rome, Italy.
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31
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Abstract
Rett syndrome (RTT, MIM#312750) is a neurodevelopmental disorder that is classified as an autism spectrum disorder. Clinically, RTT is characterized by psychomotor regression with loss of volitional hand use and spoken language, the development of repetitive hand stereotypies, and gait impairment. The majority of people with RTT have mutations in Methyl-CpG-binding Protein 2 (MECP2), a transcriptional regulator. Interestingly, alterations in the function of the protein product produced by MECP2, MeCP2, have been identified in a number of other clinical conditions. The many clinical features found in RTT and the various clinical problems that result from alteration in MeCP2 function have led to the belief that understanding RTT will provide insight into a number of other neurological disorders. Excitingly, RTT is reversible in a mouse model, providing inspiration and hope that such a goal may be achieved for RTT and potentially for many neurodevelopmental disorders.
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Affiliation(s)
- Jeffrey Lorenz Neul
- Neurological Research Institute, 1250 Moursund Street, Suite 1250.18, Houston, TX 77030, USA.
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Schaefer GB, Mendelsohn NJ. Clinical genetics evaluation in identifying the etiology of autism spectrum disorders: 2013 guideline revisions. Genet Med 2013; 15:399-407. [PMID: 23519317 DOI: 10.1038/gim.2013.32] [Citation(s) in RCA: 321] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The autism spectrum disorders are a collective of conditions that have in common impaired socialization and communication in association with stereotypic behaviors. The reported incidence of autism spectrum disorders has increased dramatically over the past two decades. In addition, increased attention has been paid to these conditions by both lay and professional groups. These trends have resulted in an increase in the number of referrals to clinical geneticist for the evaluation of persons with autism spectrum disorders. The primary roles of the geneticist in this process are to define etiology when possible, to provide genetic counseling, and to contribute to case management. In deciding on the appropriate evaluation for a particular patient, the geneticist will consider a host of factors: (i) ensuring an accurate diagnosis of autism before proceeding with any investigation; (ii) discussing testing options, diagnostic yields, and family investment before proceeding with an evaluation; (iii) communicating and coordinating with the patient-centered medical home (PCMH); (iv) assessing the continuously expanding and evolving list of available laboratory-testing modalities in light of the published literature; (v) recognizing the expanded phenotypes of well-described syndromic and metabolic conditions that overlap with autism spectrum disorders; and (vi) defining an individualized evaluation plan based on the unique history and clinical features of a given patient. The guidelines in this paper have been developed to assist the clinician in the consideration of these factors. It updates the original publication from 2008.Genet Med 2013:15(5):399-407.
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Affiliation(s)
- G Bradley Schaefer
- Department of Genetics and Pediatrics, University of Arkansas for Medical Sciences, Little Rock, AR, USA.
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Lee JYL, Leonard H, Piek JP, Downs J. Early development and regression in Rett syndrome. Clin Genet 2013; 84:572-6. [DOI: 10.1111/cge.12110] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2012] [Revised: 01/21/2013] [Accepted: 01/21/2013] [Indexed: 11/30/2022]
Affiliation(s)
- JYL Lee
- School of Psychology and Speech Pathology and Curtin Health Innovation Research Institute; Curtin University; Perth Australia
| | - H Leonard
- Telethon Institute for Child Health Research, Centre for Child Health Research; University of Western Australia; Perth Australia
| | - JP Piek
- School of Psychology and Speech Pathology and Curtin Health Innovation Research Institute; Curtin University; Perth Australia
| | - J Downs
- Telethon Institute for Child Health Research, Centre for Child Health Research; University of Western Australia; Perth Australia
- School of Physiotherapy and Curtin Health Innovation Research Institute; Curtin University; Perth Australia
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Marschik PB, Kaufmann WE, Einspieler C, Bartl-Pokorny KD, Wolin T, Pini G, Budimirovic DB, Zappella M, Sigafoos J. Profiling early socio-communicative development in five young girls with the preserved speech variant of Rett syndrome. RESEARCH IN DEVELOPMENTAL DISABILITIES 2012; 33:1749-56. [PMID: 22699249 PMCID: PMC3445809 DOI: 10.1016/j.ridd.2012.04.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 04/18/2012] [Indexed: 05/12/2023]
Abstract
Rett syndrome (RTT) is a developmental disorder characterized by regression of purposeful hand skills and spoken language, although some affected children retain some ability to speech. We assessed the communicative abilities of five young girls, who were later diagnosed with the preserved speech variant of RTT, during the pre-regression period (aged 12-24 months). Videotapes, obtained by parents during routine family situations and celebrations, were analyzed to identify communicative forms and functions used by these toddlers. Non-verbal communicative forms dominated over verbal-communicative forms for six of the eight identified communication functions. Although the girls used various non-verbal forms to make requests, for example, none of the individuals were observed to make choices or request information. Early peculiarities in the speech-language domain during the first year of life became more prominent and evident during the second year of life as general differences between typical development and atypical development become more obvious in RTT. These findings highlight the importance of assessing socio-communicative forms and functions at early age in children with RTT. The results suggest that speech-language functions did not appear to play a major role in the children's communicative attempts. We conclude that, even among children with the preserved speech variant, socio-communicative deficits are present before regression and persist after this period.
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Affiliation(s)
- Peter B. Marschik
- Institute of Physiology (Developmental Physiology and Developmental Neuroscience; IN:spired), Center for Physiological Medicine, Medical University of Graz, Austria
- Center for Genetic Disorders of Cognition and Behavior, Fragile X Clinic, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Walter E. Kaufmann
- Children's Hospital Boston, Harvard Medical School, Boston, MA, USA
- Center for Genetic Disorders of Cognition and Behavior, Fragile X Clinic, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Christa Einspieler
- Institute of Physiology (Developmental Physiology and Developmental Neuroscience; IN:spired), Center for Physiological Medicine, Medical University of Graz, Austria
- Corresponding author at: Institute of Physiology, Center for Physiological Medicine, Medical University of Graz, Harrachgasse 21/5, 8010 Graz, Austria. Tel.: +43 316 380 4266; fax: +43 316 380 9630.
| | - Katrin D. Bartl-Pokorny
- Institute of Physiology (Developmental Physiology and Developmental Neuroscience; IN:spired), Center for Physiological Medicine, Medical University of Graz, Austria
| | - Thomas Wolin
- Institute of Physiology (Developmental Physiology and Developmental Neuroscience; IN:spired), Center for Physiological Medicine, Medical University of Graz, Austria
| | - Giorgio Pini
- Tuscany Rett Centre Versilia Hospital, Lido di Camaiore, Italy
| | - Dejan B. Budimirovic
- Center for Genetic Disorders of Cognition and Behavior, Fragile X Clinic, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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Gürkan CK, Hagerman RJ. TARGETED TREATMENTS IN AUTISM AND FRAGILE X SYNDROME. RESEARCH IN AUTISM SPECTRUM DISORDERS 2012; 6:1311-1320. [PMID: 23162607 PMCID: PMC3498468 DOI: 10.1016/j.rasd.2012.05.007] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Autism is a neurodevelopmental disorder consisting of a constellation of symptoms that sometimes occur as part of a complex disorder characterized by impairments in social interaction, communication and behavioral domains. It is a highly disabling disorder and there is a need for treatment targeting the core symptoms. Although autism is accepted as highly heritable, there is no genetic cure at this time. Autism is shown to be linked to several genes and is a feature of some complex genetic disorders, including fragile X syndrome (FXS), fragile X premutation involvement, tuberous sclerosis and Rett syndrome. The term autism spectrum disorders (ASDs) covers autism, Asperger syndrome and pervasive developmental disorders (PDD-NOS) and the etiologies are heterogeneous. In recent years, targeted treatments have been developed for several disorders that have a known specific genetic cause leading to autism. Since there are significant molecular and neurobiological overlaps among disorders, targeted treatments developed for a specific disorder may be helpful in ASD of unknown etiology. Examples of this are two drug classes developed to treat FXS, Arbaclofen, a GABA(B) agonist, and mGluR5 antagonists, and both may be helpful in autism without FXS. The mGluR5 antagonists are also likely to have a benefit in the aging problems of fragile X premutation carriers, the fragile X -associated tremor ataxia syndrome (FXTAS) and the Parkinsonism that can occur in aging patients with fragile X syndrome. Targeted treatments in FXS which has a well known genetic etiology may lead to new targeted treatments in autism.
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Affiliation(s)
- C. Kağan Gürkan
- Department of Pediatrics and the MIND Institute, UC Davis Medical Center, Adress: MIND Institute at UC Davis Medical Center, 2825 50th Street, Sacramento, California 95817
| | - Randi J. Hagerman
- Department of Pediatrics and the MIND Institute, UC Davis Medical Center, Adress: MIND Institute at UC Davis Medical Center, 2825 50th Street, Sacramento, California 95817
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Kaufmann WE, Tierney E, Rohde CA, Suarez-Pedraza MC, Clarke MA, Salorio CF, Bibat G, Bukelis I, Naram D, Lanham DC, Naidu S. Social impairments in Rett syndrome: characteristics and relationship with clinical severity. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2012; 56:233-247. [PMID: 21385260 DOI: 10.1111/j.1365-2788.2011.01404.x] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
BACKGROUND While behavioural abnormalities are fundamental features of Rett syndrome (RTT), few studies have examined the RTT behavioural phenotype. Most of these reports have focused on autistic features, linked to the early regressive phase of the disorder, and few studies have applied standardised behavioural measures. We used a battery of standardised measures of behaviour and functioning to test the following hypotheses: (1) autistic behaviour is prominent throughout childhood in RTT; (2) autistic features are more salient in individuals with milder presentation; (3) severity of autistic behaviour is associated with a wider range of behavioural problems; and (4) specific MECP2 mutations are linked to more severe autistic behaviour. METHODS Eighty MECP2 mutation-positive girls with RTT (aged 1.6-14.9 years) were administered: (1) the Screen for Social Interaction (SSI), a measure of autistic behaviour suited for individuals with severe communication and motor impairment; (2) the Rett Syndrome Behaviour Questionnaire (RSBQ), covering a wide range of abnormal behaviours in RTT; (3) the Vineland Adaptive Behavior Scales (VABS); and (4) a modified version of the Rett Syndrome Severity Scale (RSSS). Regression analyses examined the predictive value of age and RSSS on autistic behaviour and other behavioural abnormalities. T-tests further characterised the behavioural phenotype of individual MECP2 mutations. RESULTS While age had no significant effect on SSI or RSBQ total scores in RTT, VABS Socialization and Composite scores decreased over time. Clinical severity (i.e. RSSS) also increased with age. Surprisingly, SSI performance was not related to either RSSS or VABS Composite scores. Autistic behaviour was weakly linked with the RSBQ Hand behaviour factor scores, but not with the RSBQ Fear/Anxiety factor. Clinical (neurological) severity did not predict RSBQ scores, as evidenced by the analysis of individual MECP2 mutations (e.g. p.R106W, p.R270X and p.R294X). CONCLUSIONS Our data suggest that in RTT, autistic behaviour persists after the period of regression. It also demonstrated that neurological and behavioural impairments, including autistic features, are relatively independent of one another. Consistent with previous reports of the RTT phenotype, individual MECP2 mutations demonstrate complex associations with autistic features. Evidence of persistent autistic behaviour throughout childhood, and of a link between hand function and social skills, has important implications not only for research on the RTT behavioural phenotype, but also for the clinical management of the disorder.
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Affiliation(s)
- W E Kaufmann
- Center for Genetic Disorders of Cognition and Behavior, Kennedy Krieger Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA.
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Abstract
Epidemiologic data gathered over the last 40 years report that the conservative estimate of autistic spectrum disorder prevalence is 27.5 per 10,000 individuals; however, the prevalence estimate based on newer surveys is 60 per 10,000 individuals. Several factors are considered in various epidemiologic surveys of autism, especially the evolution of the concept of autism and changing criteria for diagnosis. This article reviews the incidence, prevalence, and risk factors for autism.
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Affiliation(s)
- Erin Duchan
- Department of Pediatrics and Human Development, Michigan State University College of Human Medicine and Kalamazoo Center for Medical Studies, 1000 Oakland Drive, Kalamazoo, MI 49008, USA
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Liao W, Gandal MJ, Ehrlichman RS, Siegel SJ, Carlson GC. MeCP2+/- mouse model of RTT reproduces auditory phenotypes associated with Rett syndrome and replicate select EEG endophenotypes of autism spectrum disorder. Neurobiol Dis 2012; 46:88-92. [PMID: 22249109 DOI: 10.1016/j.nbd.2011.12.048] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Revised: 12/16/2011] [Accepted: 12/31/2011] [Indexed: 10/14/2022] Open
Abstract
Impairments in cortical sensory processing have been demonstrated in Rett syndrome (RTT) and Autism Spectrum Disorders (ASD) and are thought to contribute to high-order phenotypic deficits. However, underlying pathophysiological mechanisms for these abnormalities are unknown. This study investigated auditory sensory processing in a mouse model of RTT with a heterozygous loss of MeCP2 function. Cortical abnormalities in a number of neuropsychiatric disorders, including ASD are reflected in auditory evoked potentials and fields measured by EEG and MEG. One of these abnormalities, increased latency of cortically sourced components, is associated with language and developmental delay in autism. Additionally, gamma-band abnormalities have recently been identified as an endophenotype of idiopathic autism. Both of these cortical abnormalities are potential clinical endpoints for assessing treatment. While ascribing similar mechanisms of idiopathic ASD to Rett syndrome (RTT) has been controversial, we sought to determine if mouse models of RTT replicate these intermediate phenotypes. Mice heterozygous for the null mutations of the gene MeCP2, were implanted for EEG. In response to auditory stimulation, these mice recapitulated specific latency differences as well as select gamma and beta band abnormalities associated with ASD. MeCP2 disruption is the predominant cause of RTT, and reductions in MeCP2 expression predominate in ASD. This work further suggests a common cortical pathophysiology for RTT and ASD, and indicates that the MeCP2+/- model may be useful for preclinical development targeting specific cortical processing abnormalities in RTT with potential relevance to ASD.
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Affiliation(s)
- Wenlin Liao
- Department of Psychiatry, University of Pennsylvania, Philadelphia, PA 19104, USA
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Lim F, Downs J, Li J, Bao XH, Leonard H. Barriers to diagnosis of a rare neurological disorder in China-Lived experiences of Rett syndrome families. Am J Med Genet A 2011; 158A:1-9. [DOI: 10.1002/ajmg.a.34351] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Accepted: 08/05/2011] [Indexed: 11/12/2022]
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Abstract
Autism is an etiologically and clinically heterogeneous group of disorders, diagnosed solely by the complex behavioral phenotype. On the basis of the high-heritability index, geneticists are confident that autism will be the first behavioral disorder for which the genetic basis can be well established. Although it was initially assumed that major genome-wide and candidate gene association studies would lead most directly to common autism genes, progress has been slow. Rather, most discoveries have come from studies of known genetic disorders associated with the behavioral phenotype. New technology, especially array chromosomal genomic hybridization, has both increased the identification of putative autism genes and raised to approximately 25%, the percentage of children for whom an autism-related genetic change can be identified. Incorporating clinical geneticists into the diagnostic and autism research arenas is vital to the field. Interpreting this new technology and deciphering autism's genetic montage require the skill set of the clinical geneticist including knowing how to acquire and interpret family pedigrees, how to analyze complex morphologic, neurologic, and medical phenotypes, sorting out heterogeneity, developing rational genetic models, and designing studies. The current emphasis on deciphering autism spectrum disorders has accelerated the field of neuroscience and demonstrated the necessity of multidisciplinary research that must include clinical geneticists both in the clinics and in the design and implementation of basic, clinical, and translational research.
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Young D, Bebbington A, de Klerk N, Bower C, Nagarajan L, Leonard H. The relationship between MECP2 mutation type and health status and service use trajectories over time in a Rett syndrome population. RESEARCH IN AUTISM SPECTRUM DISORDERS 2011; 5:442-449. [PMID: 21057653 PMCID: PMC2968739 DOI: 10.1016/j.rasd.2010.06.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
This study aimed to investigate the trajectories over time of health status and health service use in Rett syndrome by mutation type. Data were obtained from questionnaires administered over six years to 256 participants from the Australian Rett Syndrome Database. Health status (episodes of illness and medication load) and health service use (general practitioner and specialist visits and hospital stays) were summarized into composite scores with Principal Component Analysis. Linear and mixed regression models examined effects of mutation type and other variables on these scores over time. For some mutations (such as p.R255X, p.R168X) health status was poorer at a younger age and improved over time, while for p.R133C it was better at a younger age and deteriorated with time. For those with p.R133C health service use was lowest at a younger age and highest at 25 years. With other mutations, such as p.R255X, p.R270X, p.R294X, C terminal and p.R306C, health service use was higher at a younger age, but dropped off considerably by 25 years of age. Health service use generally declined in parallel with deterioration in health status, although this pattern differed by mutation type, demonstrating important variability in the course of Rett syndrome.
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Affiliation(s)
- Deidra Young
- Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Perth, Western Australia
| | - Ami Bebbington
- Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Perth, Western Australia
| | - Nick de Klerk
- Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Perth, Western Australia
| | - Carol Bower
- Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Perth, Western Australia
| | - Lakshmi Nagarajan
- Department of Neurology, Princess Margaret Hospital for Children, Subiaco, Western Australia
| | - Helen Leonard
- Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Perth, Western Australia
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Fehr S, Downs J, Bebbington A, Leonard H. Atypical presentations and specific genotypes are associated with a delay in diagnosis in females with Rett syndrome. Am J Med Genet A 2010; 152A:2535-42. [PMID: 20815036 DOI: 10.1002/ajmg.a.33640] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
There is often delay between onset of Rett syndrome symptoms and its diagnosis, possibly related to symptom presentation or socio-demographic factors. We hypothesized that girls with an atypical presentation or whose family had a lower socio-economic status would receive a later diagnosis. Female subjects with a confirmed diagnosis of Rett syndrome were sourced from the Australian Rett Syndrome and InterRett Databases. Variables analyzed included timing and development of symptoms; MECP2 mutation type; parental occupation and education; maternal age and birth order. Residential location and socio-economic status were also analyzed for the Australian cases. Linear regression was used to determine relationships between these factors and age at diagnosis. A total of 909 cases were included. An older age of diagnosis was associated with later loss of hand function and speech, later onset of hand stereotypies and the presence of the p.R133C or p.R294X MECP2 mutation. Socio-economic factors did not predict age of diagnosis for Australian families. For families participating in the InterRett database, a younger age of diagnosis was associated with higher levels of parental education or occupation. A clinical picture consistent with the classic presentation of Rett syndrome is associated with an earlier diagnosis. Clinicians need to be alerted to the variable presentation of Rett syndrome including the milder phenotypes of cases with the p.R133C or p.R294X mutation. Educational resources to assist this understanding including guidance on when to request genetic testing could be useful to streamline the process of diagnosis in Rett syndrome.
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Affiliation(s)
- Stephanie Fehr
- The Telethon Institute for Child Health Research, Centre for Child Health Research, University of Western Australia, Perth, Western Australia, Australia
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Moss J, Howlin P. Autism spectrum disorders in genetic syndromes: implications for diagnosis, intervention and understanding the wider autism spectrum disorder population. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2009; 53:852-873. [PMID: 19708861 DOI: 10.1111/j.1365-2788.2009.01197.x] [Citation(s) in RCA: 175] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
BACKGROUND An emerging literature on behavioural phenotypes has highlighted apparent associations between autism spectrum disorders (ASDs) or ASD-related phenomenology and a number of different genetically determined syndromes. METHOD A systematic review of the current literature regarding the association with ASD and ASD characteristics was conducted in the following syndrome groups: Fragile X, Rett, Tuberous Sclerosis Complex, Down, Angelman, CHARGE and Phenylketonuria. Specific consideration was given to the role of intellectual disability in assessing the association between ASD and these syndrome groups. RESULTS The review highlights that while formal diagnostic assessments may indicate an association between ASD and specific syndrome groups, detailed investigation has revealed subtle but qualitative differences in the presentation of ASD-like phenomenology in particular syndrome groups. The degree of ID of the individual clearly has a role to play with regard to the development and presentation of ASD-like characteristics, and caution should be taken when assessing ASD symptomatology in genetically determined syndromes associated with severe ID. However, degree of ID cannot solely account for the heightened prevalence of ASD characteristics in some specific syndrome groups. CONCLUSIONS There is a need for caution in interpreting the significance of superficial similarities between ASD and the behavioural phenotypes of certain genetically determined syndromes. However, recognition of ASD-like characteristics (even where a true diagnosis of ASD may not be relevant) in individuals with genetic syndromes is crucial in ensuring that individuals receive appropriate behavioural management and educational placement. Further research in this field requires fine-grained investigation of behavioural phenomenology within individual syndrome groups.
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Affiliation(s)
- J Moss
- Department of Psychology, Institute of Psychiatry, King's College, London, UK.
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Zeev BB, Bebbington A, Ho G, Leonard H, de Klerk N, Gak E, Vecsler M, Vecksler M, Christodoulou J. The common BDNF polymorphism may be a modifier of disease severity in Rett syndrome. Neurology 2009; 72:1242-7. [PMID: 19349604 DOI: 10.1212/01.wnl.0000345664.72220.6a] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
BACKGROUND Rett syndrome (RTT) is caused by mutations in the transcriptional repressor methyl CpG-binding protein 2 (MECP2). Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor playing a major role in neuronal survival, neurogenesis, and plasticity, and it has been shown that BDNF expression is regulated by MeCP2 through a complex interaction. A common polymorphism of BDNF (Val66Met [p.V66M]) has been found to correlate with severity and course of several neuropsychiatric disorders. METHODS We examined the association between disease severity score, assessed by the modified Percy score, and BDNF polymorphism, using regression methods, in 125 mutation-positive patients with RTT from the Australian Rett Syndrome Database and an Israeli cohort. RESULTS Those who were heterozygous (Val/Met) had slightly more severe disease than those who were homozygous for the wild-type (Val/Val) BDNF polymorphism (increased severity score 2.1, p = 0.09). In those with p.R168X, a commonly occurring MECP2 mutation in RTT, there was a 6-point increase in severity score for those who were heterozygous for the BDNF polymorphism, both unadjusted (p = 0.02) and adjusted for age (p = 0.03). Individuals with the p.R168X mutation and heterozygous for the BDNF polymorphism were also at an increased risk of seizure onset (hazard ratio 5.3, 95% confidence interval 1.6-17.7) compared with those homozygous for the wild-type BDNF allele. CONCLUSIONS In addition to mutation type and degree of X-chromosome skewing, the common brain-derived neurotrophic factor (BDNF) polymorphism appears to be another genetic modifier of Rett syndrome (RTT) severity. This suggests that BDNF function may play a significant role in the pathogenesis of RTT.
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Affiliation(s)
- B Ben Zeev
- Pediatric Neurology Unit, Safra Pediatric Hospital, Sheba Medical Center, Ramat-Gan, Israel
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46
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Trends in autism spectrum disorder diagnoses: 1994-2007. J Autism Dev Disord 2009; 39:1099-111. [PMID: 19294498 DOI: 10.1007/s10803-009-0723-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Accepted: 02/26/2009] [Indexed: 12/15/2022]
Abstract
We analyzed predictors of parent-reported initial diagnosis (autistic disorder [AD], pervasive developmental disorder-not otherwise specified [PDD-NOS], pervasive developmental disorder ['PDD'] and autism spectrum disorder ['ASD'], and Asperger syndrome [AS]), among 6,176 individuals with autism spectrum disorders diagnosed from 1994 through 2007. Overall, distribution of diagnoses was influenced by a secular time trend factor; other significant factors included ethnicity, white race, geographic location, urbanicity, and initial evaluator. Since 2001, most initial diagnoses of AD and AS have remained steady while 'PDD' and PDD-NOS have decreased. 'ASD' diagnoses have increased, especially among school-based teams; AS diagnoses also increased uniquely among these evaluators. Findings from this study suggest that current diagnostic guidelines may not be meeting all community evaluator needs.
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Hughes JR. A review of recent reports on autism: 1000 studies published in 2007. Epilepsy Behav 2008; 13:425-37. [PMID: 18627794 DOI: 10.1016/j.yebeh.2008.06.015] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/06/2008] [Revised: 06/24/2008] [Accepted: 06/27/2008] [Indexed: 01/28/2023]
Abstract
From 1000 studies published in 2007 on all aspects of autism, those that reached clear conclusions or included quantitative data were selected for this review. Possible etiologies include elemental metals, especially the inconsistent evidence regarding mercury from the vaccine preservative thimerosal, not used after 2001, and chromosomes and genes with the conclusion that autism has a complex genetic architecture. Also, various parental conditions are considered, as are many different abnormalities in the central nervous system, especially underconnectivity within the cortex. Furthermore, deficiencies in mirror neurons have been proposed, leading to the "theory of mind" explanation that autistic children tend to disregard others. In addition, various global deficiencies, like an increase in inhibitory synaptic transmission, are proposed. Characteristics of these children include selective (inward) attention; underresponsiveness; stereotyped repetitive motor behavior; increased head size, weight, and height; various cognitive and communicative disorders; and also epilepsy. Therapy has emphasized risperidone, but some atypical antipsychotic medications have been helpful, as have robotic aids, massage, hyperbaric oxygen, and music. Nearly every conceivable problem that a child could have can be observed in these unfortunate children.
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Affiliation(s)
- John R Hughes
- Department of Neurology, University of Illinois Medical Center (M/C 796), 912 South Wood Street, Chicago, IL 60612, USA
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Lintas C, Persico AM. Autistic phenotypes and genetic testing: state-of-the-art for the clinical geneticist. J Med Genet 2008; 46:1-8. [PMID: 18728070 PMCID: PMC2603481 DOI: 10.1136/jmg.2008.060871] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Autism spectrum disorders represent a group of developmental disorders with strong genetic underpinnings. Several cytogenetic abnormalities or de novo mutations able to cause autism have recently been uncovered. In this study, the literature was reviewed to highlight genotype-phenotype correlations between causal gene mutations or cytogenetic abnormalities and behavioural or morphological phenotypes. Based on this information, a set of practical guidelines is proposed to help clinical geneticists pursue targeted genetic testing for patients with autism whose clinical phenotype is suggestive of a specific genetic or genomic aetiology.
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Affiliation(s)
- C Lintas
- Laboratory of Molecular Psychiatry and Neurogenetics, University Campus Bio-Medico, Via Alvaro del Portillo 21, I-00128 Rome, Italy
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Kaufmann WE, Capone GT, Clarke M, Budimirovic DB. Autism in Genetic Intellectual Disability. AUTISM : THE INTERNATIONAL JOURNAL OF RESEARCH AND PRACTICE 2008. [DOI: 10.1007/978-1-60327-489-0_4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
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