1
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Jeon SJ, Gonzales EL, Mabunga DFN, Valencia ST, Kim DG, Kim Y, Adil KJL, Shin D, Park D, Shin CY. Sex-specific Behavioral Features of Rodent Models of Autism Spectrum Disorder. Exp Neurobiol 2018; 27:321-343. [PMID: 30429643 PMCID: PMC6221834 DOI: 10.5607/en.2018.27.5.321] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Revised: 10/08/2018] [Accepted: 10/10/2018] [Indexed: 12/13/2022] Open
Abstract
Sex is an important factor in understanding the clinical presentation, management, and developmental trajectory of children with neuropsychiatric disorders. While much is known about the clinical and neurobehavioral profiles of males with neuropsychiatric disorders, surprisingly little is known about females in this respect. Animal models may provide detailed mechanistic information about sex differences in autism spectrum disorder (ASD) in terms of manifestation, disease progression, and development of therapeutic options. This review aims to widen our understanding of the role of sex in autism spectrum disorder, by summarizing and comparing behavioral characteristics of animal models. Our current understanding of how differences emerge in boys and girls with neuropsychiatric disorders is limited: Information derived from animal studies will stimulate future research on the role of biological maturation rates, sex hormones, sex-selective protective (or aggravating) factors and psychosocial factors, which are essential to devise sex precision medicine and to improve diagnostic accuracy. Moreover, there is a strong need of novel strategies to elucidate the major mechanisms leading to sex-specific autism features, as well as novel models or methods to examine these sex differences.
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Affiliation(s)
- Se Jin Jeon
- Center for Neuroscience, Korea Institute of Science & Technology, Seoul 02792, Korea.,Department of Pharmacology and Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul 05029, Korea
| | - Edson Luck Gonzales
- Department of Pharmacology and Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul 05029, Korea.,Department of Neuroscience, School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul 05029, Korea
| | - Darine Froy N Mabunga
- Department of Pharmacology and Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul 05029, Korea.,Department of Neuroscience, School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul 05029, Korea
| | - Schley T Valencia
- Department of Pharmacology and Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul 05029, Korea.,Department of Neuroscience, School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul 05029, Korea
| | - Do Gyeong Kim
- Department of Pharmacology and Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul 05029, Korea.,Department of Neuroscience, School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul 05029, Korea
| | - Yujeong Kim
- Department of Pharmacology and Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul 05029, Korea.,Department of Neuroscience, School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul 05029, Korea
| | - Keremkleroo Jym L Adil
- Department of Pharmacology and Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul 05029, Korea.,Department of Neuroscience, School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul 05029, Korea
| | - Dongpil Shin
- Department of Pharmacology and Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul 05029, Korea.,Department of Neuroscience, School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul 05029, Korea
| | - Donghyun Park
- Department of Pharmacology and Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul 05029, Korea.,Department of Neuroscience, School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul 05029, Korea
| | - Chan Young Shin
- Department of Pharmacology and Advanced Translational Medicine, School of Medicine, Konkuk University, Seoul 05029, Korea.,Department of Neuroscience, School of Medicine and Center for Neuroscience Research, Konkuk University, Seoul 05029, Korea.,KU Open Innovation Center, Konkuk University, Seoul 05029, Korea
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2
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Curie A, Lesca G, Bussy G, Manificat S, Arnaud V, Gonzalez S, Revol O, Calender A, Gérard D, des Portes V. Asperger syndrome and early-onset schizophrenia associated with a novel MECP2 deleterious missense variant. Psychiatr Genet 2018; 27:105-109. [PMID: 28230711 DOI: 10.1097/ypg.0000000000000165] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Methyl-CpG-binding protein 2 (MECP2) deleterious variants, which are responsible for Rett syndrome in girls, are involved in a wide spectrum of developmental disabilities in males. A neuropsychiatric phenotype without intellectual disability is uncommon in patients with MECP2 deleterious variants. We report on two dizygotic twins with an MECP2-related psychiatric disorder without intellectual disability. Neuropsychological and psychiatric phenotype assessments were performed, and a genetic analysis was carried out. Both patients fulfilled the Pervasive Developmental Disorder criteria on Autism Diagnostic Observation Schedule and Asperger syndrome criteria on Diagnostic and Statistical Manual of Mental Disorders, 4th ed. (DSM-IV). One patient developed early-onset schizophrenia (DSM-IV criteria) with two acute psychotic episodes, the latest one following corticosteroids and sodium valproate intake, with major hyperammonemia. A novel MECP2 gene transversion c.491 G>T [p.(Ser164Ile)] was found in both twins. Pathogenicity of this variant was considered on the basis of strong clinical and molecular data. The underlying molecular basis of neuropsychiatric disorders may have important consequences on genetic counseling and therapeutic strategies.
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Affiliation(s)
- Aurore Curie
- aClaude Bernard Lyon 1 University bInstitute of Cognitive Science, CNRS UMR 5304 cFrench National Reference Center for Rare Diseases with Intellectual Disability dReference Center on Learning Disabilities, Pediatric Functional Rehabilitation Department, Escale, Women Mothers and Children Hospital eDepartment of Child Psychiatry, Neurological Hospital fDepartment of Medical Genetics, Lyon University Hospital gCNRS UMR 5292, INSERM U1028, CNRL hDepartment of Child Psychiatry, Saint Jean de Dieu Hospital, Lyon, France
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3
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Zhang X, Yang J, Li Y, Ma X, Li R. Sex chromosome abnormalities and psychiatric diseases. Oncotarget 2018; 8:3969-3979. [PMID: 27992373 PMCID: PMC5354807 DOI: 10.18632/oncotarget.13962] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 12/07/2016] [Indexed: 12/02/2022] Open
Abstract
Excesses of sex chromosome abnormalities in patients with psychiatric diseases have recently been observed. It remains unclear whether sex chromosome abnormalities are related to sex differences in some psychiatric diseases. While studies showed evidence of susceptibility loci over many sex chromosomal regions related to various mental diseases, others demonstrated that the sex chromosome aneuploidies may be the key to exploring the pathogenesis of psychiatric disease. In this review, we will outline the current evidence on the interaction of sex chromosome abnormalities with schizophrenia, autism, ADHD and mood disorders.
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Affiliation(s)
- Xinzhu Zhang
- Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China
| | - Jian Yang
- Beijing Key Laboratory of Mental Disorders, Beijing Anding Hospital, Beijing, China
| | - Yuhong Li
- Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Mental Disorders, Beijing Anding Hospital, Beijing, China
| | - Xin Ma
- Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Mental Disorders, Beijing Anding Hospital, Beijing, China
| | - Rena Li
- Beijing Institute for Brain Disorders, Capital Medical University, Beijing, China.,Beijing Key Laboratory of Mental Disorders, Beijing Anding Hospital, Beijing, China.,Center for Hormone Advanced Science and Education, Roskamp Institute, Sarasota, FL, USA
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4
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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: 190] [Impact Index Per Article: 17.3] [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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5
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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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6
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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: 312] [Impact Index Per Article: 28.4] [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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7
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Carter MT, Scherer SW. Autism spectrum disorder in the genetics clinic: a review. Clin Genet 2013; 83:399-407. [PMID: 23425232 DOI: 10.1111/cge.12101] [Citation(s) in RCA: 118] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 01/14/2013] [Accepted: 01/14/2013] [Indexed: 01/08/2023]
Abstract
Autism spectrum disorders (ASDs) are a heterogeneous group of neurodevelopmental disorders affecting social communication, language and behavior. The underlying cause(s) in a given individual is often elusive, with the exception of clinically recognizable genetic syndromes with readily available molecular diagnosis, such as fragile X syndrome. Clinical geneticists approach patients with ASDs by ruling out known genetic and genomic syndromes, leaving more than 80% of families without a definitive diagnosis and an uncertain risk of recurrence. Advances in microarray technology and next-generation sequencing are revealing rare variants in genes with important roles in synapse formation, function and maintenance. This review will focus on the clinical approach to ASDs, given the current state of knowledge about their complex genetic architecture.
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Affiliation(s)
- M T Carter
- Division of Clinical and Metabolic Genetics, The Hospital for Sick Children, Toronto, ON, Canada.
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8
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Xi CY, Lu Y, Tan YH, Hua TY, Zhao YJ, Liu XM, Gao H. Analysis of MECP2 gene copy number in boys with autism. J Child Neurol 2011; 26:570-3. [PMID: 21531908 DOI: 10.1177/0883073810387138] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Autism is a severe neurodevelopmental disorder with a strong genetic basis.The methyl-CpG binding protein 2 gene (MECP2) is a dosage-sensitive gene in brain development and has been implicated as a candidate gene for autism. Duplication of the MECP2 gene has been reported in a few boys with autistic features. To further investigate the association of MECP2 duplication with autism, the authors performed real-time quantitative polymerase chain reaction (PCR) to detect copy number variations of the MECP2 gene in 82 autistic boys. No copy number variation was found in these patients, indicating that duplication of the MECP2 gene is not frequent in autistic patients. The authors consider that duplication of the MECP2 gene has no major effect on the susceptibility to autism. Replication of studies in a large-sized sample and a well-characterized subgroup of autism are warranted to further identify the association of MECP2 gene duplication with autism.
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Affiliation(s)
- Chun-Yan Xi
- Department of Developmental Pediatrics, Shengjing Hospital, China Medical University, Shenyang, China.
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9
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Markram K, Markram H. The intense world theory - a unifying theory of the neurobiology of autism. Front Hum Neurosci 2010; 4:224. [PMID: 21191475 PMCID: PMC3010743 DOI: 10.3389/fnhum.2010.00224] [Citation(s) in RCA: 270] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Accepted: 11/19/2010] [Indexed: 12/19/2022] Open
Abstract
Autism covers a wide spectrum of disorders for which there are many views, hypotheses and theories. Here we propose a unifying theory of autism, the Intense World Theory. The proposed neuropathology is hyper-functioning of local neural microcircuits, best characterized by hyper-reactivity and hyper-plasticity. Such hyper-functional microcircuits are speculated to become autonomous and memory trapped leading to the core cognitive consequences of hyper-perception, hyper-attention, hyper-memory and hyper-emotionality. The theory is centered on the neocortex and the amygdala, but could potentially be applied to all brain regions. The severity on each axis depends on the severity of the molecular syndrome expressed in different brain regions, which could uniquely shape the repertoire of symptoms of an autistic child. The progression of the disorder is proposed to be driven by overly strong reactions to experiences that drive the brain to a hyper-preference and overly selective state, which becomes more extreme with each new experience and may be particularly accelerated by emotionally charged experiences and trauma. This may lead to obsessively detailed information processing of fragments of the world and an involuntarily and systematic decoupling of the autist from what becomes a painfully intense world. The autistic is proposed to become trapped in a limited, but highly secure internal world with minimal extremes and surprises. We present the key studies that support this theory of autism, show how this theory can better explain past findings, and how it could resolve apparently conflicting data and interpretations. The theory also makes further predictions from the molecular to the behavioral levels, provides a treatment strategy and presents its own falsifying hypothesis.
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Affiliation(s)
- Kamila Markram
- Laboratory of Neural Microcircuits, Brain Mind Institute, Ecole Polytechnique Fédérale de LausanneLausanne, Switzerland
| | - Henry Markram
- Laboratory of Neural Microcircuits, Brain Mind Institute, Ecole Polytechnique Fédérale de LausanneLausanne, Switzerland
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10
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Abstract
In this review, we detail the history, molecular diagnosis, epidemiology, and clinical features of the MECP2 duplication syndrome, including considerations for the care of patients with this X-linked neurodevelopmental disorder. MECP2 duplication syndrome is 100% penetrant in affected males and is associated with infantile hypotonia, severe to profound mental retardation, autism or autistic features, poor speech development, recurrent infections, epilepsy, progressive spasticity, and, in some cases, developmental regression. Most of the reported cases are inherited, however, de novo cases have been documented. While carrier females have been reported to be unaffected, more recent research demonstrates that despite normal intelligence, female carriers display a range of neuropsychiatric phenotypes that pre-date the birth of an affected son. Given what we know of the syndrome to date, we propose that genetic testing is warranted in cases of males with infantile hypotonia and in cases of boys with mental retardation and autistic features with or without recurrent infections, progressive spasticity, epilepsy, or developmental regression. We discuss recommendations for clinical management and surveillance as well as the need for further clinical, genotype-phenotype, and molecular studies to assist the patients and their families who are affected by this syndrome.
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Affiliation(s)
- Melissa B Ramocki
- Department of Pediatrics, Baylor College of Medicine, Texas Children's Hospital, Houston, TX 77030, USA.
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11
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Loat CS, Curran S, Lewis CM, Duvall J, Geschwind D, Bolton P, Craig IW. Methyl-CpG-binding protein 2 polymorphisms and vulnerability to autism. GENES, BRAIN, AND BEHAVIOR 2008; 7:754-60. [PMID: 19125863 PMCID: PMC3645848 DOI: 10.1111/j.1601-183x.2008.00414.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The methyl-binding protein gene, MECP2, is a candidate for involvement in autism through its implication as a major causative factor in Rett syndrome that has similarities to autism. Rare mutations in MECP2 have also been identified in autistic individuals. We have examined the possible broader involvement of MECP2 as a predisposing factor in the disorder. Analysis of polymorphic markers spanning the gene and comprising both microsatellites and single nucleotide polymorphisms (SNPs) by the transmission disequilibrium test in two collections of families (219 in total), one in the USA and one in the UK, has provided evidence for significant association (P = 0.009) for a three-marker SNP haplotype of MECP2 with autism/autism spectrum disorders. This association is supported by association of both Single Sequence Repeat (SSR) and SNP single markers located at the 3' end of the MECP2 locus and flanking sequence, the most significant being that of an indel marker located in intron 2 (P = 0.001 - Bonferroni corrected P = 0.006). This suggests that one or more functional variants of MECP2 existing at significant frequencies in the population may confer increased risk of autism/autism spectrum disorders and warrants further investigation in additional independent samples.
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Affiliation(s)
- C. S. Loat
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King’s College London
| | - S. Curran
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King’s College London
| | - C. M. Lewis
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King’s College London
- Statistical Genetics Unit, Department of Medical and Molecular Genetics, King’s College London School of Medicine, Guy’s Hospital, London, United Kingdom
| | - J. Duvall
- Department of Neurology, UCLA, Los Angeles, CA, USA
| | - D. Geschwind
- Department of Neurology, UCLA, Los Angeles, CA, USA
| | - P. Bolton
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King’s College London
| | - I. W. Craig
- Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, King’s College London
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12
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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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13
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Young DJ, Bebbington A, Anderson A, Ravine D, Ellaway C, Kulkarni A, de Klerk N, Kaufmann WE, Leonard H. The diagnosis of autism in a female: could it be Rett syndrome? Eur J Pediatr 2008; 167:661-9. [PMID: 17684768 DOI: 10.1007/s00431-007-0569-x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Accepted: 07/02/2007] [Indexed: 10/23/2022]
Abstract
The overlap between autism and Rett syndrome clinical features has led to many cases of Rett syndrome being initially diagnosed with infantile autism or as having some autistic features. Both conditions seriously disrupt social and language development and are often accompanied by repetitive, nonpurposeful stereotypic hand movements. The aims of this study were to compare the early and subsequent clinical courses of female subjects with Rett syndrome categorised by whether or not a diagnosis of autism had been proposed before Rett syndrome had been diagnosed and compare the spectrum of methyl-CpG binding protein 2 (MECP2) mutations identified among the two groups. This study made use of a total of 313 cases recorded in two databases: the Australian Rett Syndrome Database (ARSD) and the International Rett Syndrome Phenotype Database (InterRett). Cases with an initial diagnosis of autism had significantly milder Rett syndrome symptoms and were more likely to remain ambulant, to have some functional hand use and not to have developed a scoliosis. Females with the p.R306C or p.T158M mutations in the MECP2 gene were more likely to have an initial diagnosis of autism, and the specific Rett syndrome symptoms were noted at a later age. We recommend that females who are initially considered to have autism be carefully monitored for the evolution of the signs and symptoms of Rett syndrome.
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Affiliation(s)
- Deidra J Young
- Centre for Child Health Research, Telethon Institute for Child Health Research, University of Western Australia, Perth, WA, Australia.
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14
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Nagarajan RP, Hogart AR, Gwye Y, Martin MR, LaSalle JM. Reduced MeCP2 expression is frequent in autism frontal cortex and correlates with aberrant MECP2 promoter methylation. Epigenetics 2008; 1:e1-11. [PMID: 17486179 PMCID: PMC1866172 DOI: 10.4161/epi.1.4.3514] [Citation(s) in RCA: 276] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Mutations in MECP2, encoding methyl CpG binding protein 2 (MeCP2), cause most cases of Rett syndrome (RTT), an X-linked neurodevelopmental disorder. Both RTT and autism are "pervasive developmental disorders" and share a loss of social, cognitive and language skills and a gain in repetitive stereotyped behavior, following apparently normal perinatal development. Although MECP2 coding mutations are a rare cause of autism, MeCP2 expression defects were previously found in autism brain. To further study the role of MeCP2 in autism spectrum disorders (ASDs), we determined the frequency of MeCP2 expression defects in brain samples from autism and other ASDs. We also tested the hypotheses that MECP2 promoter mutations or aberrant promoter methylation correlate with reduced expression in cases of idiopathic autism. MeCP2 immunofluorescence in autism and other neurodevelopmental disorders was quantified by laser scanning cytometry and compared with control postmortem cerebral cortex samples on a large tissue microarray. A significant reduction in MeCP2 expression compared to age-matched controls was found in 11/14 autism (79%), 9/9 RTT (100%), 4/4 Angelman syndrome (100%), 3/4 Prader-Willi syndrome (75%), 3/5 Down syndrome (60%), and 2/2 attention deficit hyperactivity disorder (100%) frontal cortex samples. One autism female was heterozygous for a rare MECP2 promoter variant that correlated with reduced MeCP2 expression. A more frequent occurrence was significantly increased MECP2 promoter methylation in autism male frontal cortex compared to controls. Furthermore, percent promoter methylation of MECP2 significantly correlated with reduced MeCP2 protein expression. These results suggest that both genetic and epigenetic defects lead to reduced MeCP2 expression and may be important in the complex etiology of autism.
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Affiliation(s)
| | | | | | | | - Janine M. LaSalle
- * Address correspondence to: Janine M. LaSalle, Medical Microbiology and Immunology, One Shields Ave., Davis, CA 95616, (530) 754-7598 (phone), (530) 752-8692, (fax)
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15
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Xi CY, Ma HW, Lu Y, Zhao YJ, Hua TY, Zhao Y, Ji YH. MeCP2 gene mutation analysis in autistic boys with developmental regression. Psychiatr Genet 2007; 17:113-6. [PMID: 17413451 DOI: 10.1097/ypg.0b013e3280114a5c] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Autism and Rett syndrome are both pervasive developmental disorders and share many characteristics in common. One of these features is developmental regression with loss of social, cognitive and language skills after a period of apparently normal development during the first 1-2 years of life, which raises the question of whether there is a common pathway underlying regression in these two disorders. The Rett syndrome gene was identified as MeCP2 gene on Xq28, a powerful transcriptional repressor. To explore its possible role in the etiology of autism and involvement in regression, we searched for MeCP2 gene mutations in a well characterized sample of 31 autistic boys with developmental regression by direct sequencing. One sequence variant in 3' untranslated region was observed. The patient inherited the variant from his unaffected mother, so it may be a rare polymorphism. No coding sequence variant was found in any of the patients tested. We conclude that mutations in the coding sequence of MeCP2 are not a frequent cause of regression in autism. The long 3' untranslated region of MeCP2 is highly conserved across species, suggesting that they are important for the post-transcriptional regulation of MeCP2 gene. It may be worthwhile extending the mutation screening, with a larger sample of strictly defined phenotype, to regulatory elements and untranslated regions of this gene, to explore to what degree MeCP2 gene is involved in the etiology of autism and its possible role in the regression of autism.
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Affiliation(s)
- Chun-Yan Xi
- Department of Developmental Pediatrics, The 2nd Hospital, China Medical University, Shenyang, China.
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16
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Abstract
Rett syndrome (RS) is an X-linked neurodevelopmental disorder and the second most common cause of genetic mental retardation in females. Different mutations in MECP2 are found in up to 95% of typical cases of RS. This mainly neuronal expressed gene functions as a major transcription repressor. Extensive studies on girls who have RS and mouse models are aimed at finding main gene targets for MeCP2 protein and defining neuropathologic changes caused by its defects. Studies comparing autistic features in RS with idiopathic autism and mentally retarded patients are presented. Decreased dendritic arborization is common to RS and autism, leading to further research on similarities in pathogenesis, including MeCP2 protein levels in autistic brains and MeCP2 effects on genes connected to autism, like DLX5 and genes on 15q11-13 region. This area also is involved in Angelman syndrome, which has many similarities to RS. Despite these connections, MECP2 mutations in nonspecific autistic and mentally retarded populations are rare.
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Affiliation(s)
- Bruria Ben Zeev Ghidoni
- Pediatric Neurology Unit, Safra Pediatric Hospital, Sheba Medical Center, Ramat-Gan, Israel.
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17
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Moog U, Van Roozendaal K, Smeets E, Tserpelis D, Devriendt K, Buggenhout GV, Frijns JP, Schrander-Stumpel C. MECP2 mutations are an infrequent cause of mental retardation associated with neurological problems in male patients. Brain Dev 2006; 28:305-10. [PMID: 16376510 DOI: 10.1016/j.braindev.2005.10.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 09/04/2005] [Accepted: 10/14/2005] [Indexed: 02/04/2023]
Abstract
Mutations in the methyl-CpG-binding protein 2 (MECP2) gene located on Xq28, cause Rett syndrome (RTT) in female patients. Meanwhile, nonmosaic MECP2 mutations unknown in girls have been found in an increasing number of male patients with a normal 46, XY karyotype. They can cause a broad spectrum of neurodevelopmental disorders which often show a combination of mental retardation (MR) with neurological symptoms. We present the results of MECP2 analysis in a group of 72 male patients with an unexplained combination of MR and neurological features, and review the mutational reports published on male patients since the discovery of the MECP2 gene. Analysis included sequencing of exon 1 which thus far was mostly omitted from DNA screening. One pathogenic mutation has been found in a patient with Rett variant, in addition to an unclassified variant and a series of nonpathogenic changes. No changes have been found in exon 1. Criteria for testing of male patients are classic RTT, severe neonatal encephalopathy, and RTT variant which may be clinically underrecognized. Testing can also be considered in males with a combination of unexplained MR and (progressive) neurological manifestations although the yield of MECP2 analysis is probably low in this situation. Based on the literature, MECP2 testing in males with MR only is debatable.
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Affiliation(s)
- Ute Moog
- Department of Clinical Genetics, University Hospital Maastricht, P.O. Box 5800, 6202 AZ Maastricht, The Netherlands.
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18
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Kaufmann WE, Johnston MV, Blue ME. MeCP2 expression and function during brain development: implications for Rett syndrome's pathogenesis and clinical evolution. Brain Dev 2005; 27 Suppl 1:S77-S87. [PMID: 16182491 DOI: 10.1016/j.braindev.2004.10.008] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2004] [Accepted: 10/15/2004] [Indexed: 02/06/2023]
Abstract
Most cases of Rett syndrome (RTT) are associated with mutations of the transcriptional regulator MeCP2. On the basis of molecular structure, ontogeny, and subcellular and regional distribution, MeCP2 appears to be a link between synaptic activity and neuronal transcription. Integrating data on MeCP2 neurobiology, RTT neurobiology, MeCP2 mutational patterns in RTT and other disorders, histone profiles of relevance to RTT, and genotype-phenotype correlations in RTT, we update here our synaptic hypothesis of RTT. We postulate that MeCP2 dysfunction leads to abnormal brain development through maladjustment of neuronal gene expression to synaptic and other extra-cellular signals, mainly during the critical period of synaptic maturation. RTT phenotype will develop, only if severe MeCP2 dysfunction is present during early neuronal differentiation. Two models are proposed for explaining general and regional neuronal abnormalities in RTT and the phenotypical outcome of MeCP2 dysfunction, respectively.
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Affiliation(s)
- Walter E Kaufmann
- Center for Genetic Disorders of Cognition and Behavior, Kennedy Krieger Institute and Johns Hopkins University School of Medicine, Baltimore, MD 21211, USA.
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19
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Abstract
Mutations in the X-linked gene encoding the methyl-CpG binding protein MeCP2 are the primary cause of classic and atypical Rett syndrome and have recently been shown to contribute to other neurodevelopmental disorders of varying severity. To determine whether there are molecular correlates to the phenotypic heterogeneity, numerous groups have performed genotype-phenotype correlation studies. These studies have yielded conflicting results, in part because they used different criteria for determining severity and classifying mutations. Evolution of the phenotype with age and variable expressivity arising from individual variability in X-chromosome inactivation patterns are among other reasons the findings varied. Nonetheless, evidence of differences in the phenotypic consequences of specific types of mutations is emerging. This review analyzes the available literature and makes recommendations for future studies.
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Affiliation(s)
- Andrea L Ham
- Department of Biological Sciences, University of Delaware, Newark, DE, USA
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20
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Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder occurring almost exclusively in females. Regression is a defining feature of RTT. During the regression stage, RTT girls display many autistic features, such as loss of communication and social skills, poor eye contact, and lack of interest, and initially may be given the diagnosis of autism. The discovery of the genetic cause of RTT, mutations in the MECP2 gene, a transcriptional repressor, has promoted the early diagnosis of RTT and development of mouse models. The phenotype of one mouse model includes features such as regression and abnormal behavioral and social interactions. The timing of the period of regression in RTT--during ages 1 to 2 years--parallels the period of intense synaptic development. The effects of the MECP2 mutation also increases concomitantly with peak synaptogenesis. Neuropathological findings in Rett include the selective reduction of dendritric spines in the pyramidal cells of RTT brains; this feature has also been reported in autism. Studies have observed that MECP influences the expression of brain-derived neurotrophic factor and thus may influence synaptic plasticity. Abnormalities in synapse maintenance and modulation may contribute to regression in RTT and autism. Studies of the clinical aspects of the regression period and of the mouse model may be useful in understanding the pathophysiology of RTT and other neurodevelopmental disorders such as autism. A recent study observed abnormal expression of MeCP2 in RTT and other neurodevelopmental disorders such as autism. Although the genetic background and certain clinical features differ in RTT and autism, a similar mechanism involving MeCP2 regulation and expression may contribute to regression.
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Affiliation(s)
- Daniel G Glaze
- The Blue Bird Circle Rett Center, Baylor College of Medicine, Houston, Texas 77030, USA.
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21
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Cohen D, Pichard N, Tordjman S, Baumann C, Burglen L, Excoffier E, Lazar G, Mazet P, Pinquier C, Verloes A, Héron D. Specific Genetic Disorders and Autism: Clinical Contribution Towards their Identification. J Autism Dev Disord 2005; 35:103-16. [PMID: 15796126 DOI: 10.1007/s10803-004-1038-2] [Citation(s) in RCA: 173] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Autism is a heterogeneous disorder that can reveal a specific genetic disease. This paper describes several genetic diseases consistently associated with autism (fragile X, tuberous sclerosis, Angelman syndrome, duplication of 15q11-q13, Down syndrome, San Filippo syndrome, MECP2 related disorders, phenylketonuria, Smith-Magenis syndrome, 22q13 deletion, adenylosuccinate lyase deficiency, Cohen syndrome, and Smith-Lemli-Opitz syndrome) and proposes a consensual and economic diagnostic strategy to help practitioners to identify them. A rigorous initial clinical screening is presented to avoid unnecessary laboratory and imaging studies. Regarding psychiatric nosography, the concept of "syndromal autism"--autism associated with other clinical signs should be promoted because it may help to distinguish patients who warrant a multidisciplinary approach and further investigation.
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Affiliation(s)
- David Cohen
- Service de Psychiatrie de l'Enfant et de l'Adolescent, Groupe Hospitalier Pitié-Salpétrière, Paris.
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22
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LaSalle JM, Hogart A, Thatcher KN. Rett Syndrome: A Rosetta Stone for Understanding the Molecular Pathogenesis of Autism. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2005; 71:131-65. [PMID: 16512349 DOI: 10.1016/s0074-7742(05)71006-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Affiliation(s)
- Janine M LaSalle
- Medical Microbiology and Immunology and Rowe Program in Human Genetics, School of Medicine, University of California, Davis 95616, USA
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23
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Abstract
Autism spectrum disorders (ASD) are among the most heritable of all neuropsychiatric disorders. Discovery of autism susceptibility genes has been the focus of intense research efforts over the last 10 years, and current estimates suggest that 10 to 20 different interacting genes are involved. Evidence from twin and family studies demonstrates increased risk in family members not only for autistic disorder, but also for a milder constellation of similar symptoms referred to as the broader phenotype. In addition, several genetic syndromes and chromosomal anomalies have been associated with ASD. Large family studies using linkage-analysis techniques have demonstrated several chromosomal regions thought to harbor genes related to the disorder. Finally, specific candidate genes based on function and location have been explored; these studies are reviewed here.
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Affiliation(s)
- Sarah J Spence
- UCLA Center for Autism Research and Treatment, UCLA Neuropsychiatric Institute, and Mattel Children's Hospital at UCLA, David Geffen School of Medicine, Los Angeles, CA, USA
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24
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Shibayama A, Cook EH, Feng J, Glanzmann C, Yan J, Craddock N, Jones IR, Goldman D, Heston LL, Sommer SS. MECP2 structural and 3'-UTR variants in schizophrenia, autism and other psychiatric diseases: a possible association with autism. Am J Med Genet B Neuropsychiatr Genet 2004; 128B:50-3. [PMID: 15211631 DOI: 10.1002/ajmg.b.30016] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Mutations in the gene coding for methyl-CpG-binding protein 2 (MECP2) cause Rett syndrome (RTT) and have also been reported in a number of X-linked mental retardation syndromes. Furthermore, putative mutations recently have been described in a few autistic patients and a boy with language disorder and schizophrenia. In this study, DNA samples from individuals with schizophrenia and other psychiatric diseases were scanned in order to explore whether the phenotypic spectrum of mutations in the MECP2 gene can extend beyond the traditional diagnoses of RTT in females and severe neonatal encephalopathy in males. The coding regions, adjacent splicing junctions, and highly conserved segments of the 3'-untranslated region (3'-UTR) were examined in 214 patients, including 106 with schizophrenia, 24 with autism, and 84 patients with other psychiatric diseases by detection of virtually all mutations-single strand conformation polymorphism (SSCP) (DOVAM-S). To our knowledge, this is the first analysis of variants in conserved regions of the 3'-UTR of this gene. A total of 5.2 kb per haploid gene was analyzed (1.5 Mb for 214 patients). A higher frequency of missense and 3'-UTR variants was found in autism. One missense and two 3'-UTR variants were found in 24 patients with autism versus one patient with a missense change in 144 ethnically similar individuals without autism (P = 0.009). These mutations suggest that a possible association between MECP2 mutations and autism may warrant further study.
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Affiliation(s)
- Akane Shibayama
- Department of Molecular Genetics and Diagnosis, City of Hope National Medical Center, 1500 East Duarte Road, Duarte, CA 91010-3000, USA.
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25
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Abstract
Rett syndrome, one of the leading causes of mental retardation and developmental regression in girls, is the first pervasive developmental disorder with a known genetic cause. The majority of cases of sporadic Rett syndrome are caused by mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2). MeCP2 binds methylated DNA and likely regulates gene expression and chromatin structure. Genotype/phenotype analysis revealed that the phenotypic spectrum of MECP2 mutations in humans is broader than initially suspected: Mutations have been discovered in Rett syndrome variants, mentally retarded males, and autistic children. A variety of in vivo and in vitro models has been developed that allow analysis of MeCP2 function and pathogenic studies of Rett syndrome. Because the neuropathology of Rett syndrome shares certain features with other neurodevelopmental disorders, a common pathogenic process may underlie these disorders. Thus, Rett syndrome is a prototype for the genetic, molecular, and neurobiological analysis of neurodevelopmental disorders.
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Affiliation(s)
- Jeffrey L Neul
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
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26
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Affiliation(s)
- Janine M LaSalle
- Medical Microbiology and Immunology and Rowe Program in Human Genetics, School of Medicine, University of California, Davis, California 95616, USA
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27
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Hammer S, Dorrani N, Hartiala J, Stein S, Schanen NC. Rett syndrome in a 47,XXX patient with a de novo MECP2 mutation. Am J Med Genet A 2003; 122A:223-6. [PMID: 12966522 DOI: 10.1002/ajmg.a.20320] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Rett syndrome is caused by mutation in MECP2, a gene located on Xq28 and subject to X-inactivation. MECP2 encodes methyl CpG-binding protein 2, a widely expressed transcriptional repressor of methylated DNA. Mutations in MECP2 are primarily de novo events in the male germ line and thus lead to an excess of affected females. Here we report the identification of a unique 47,XXX girl with relatively mild atypical Rett syndrome leading initially to a diagnosis of infantile autism with regression. Mutation analysis of the MECP2 gene identified a de novo MECP2 mutation, L100V. Examination of a panel of X-linked microsatellite markers indicated that her supernumerary X chromosome is maternally derived. X-inactivation patterns were determined by analysis of methylation of the androgen receptor locus, and indicated preferential inactivation of her paternal allele. The parental origin of her MECP2 mutation could not be determined because she was uninformative for intronic polymorphisms flanking her mutation. This is the first reported case of sex chromosome trisomy and MECP2 mutation in a female, and it illustrates the importance of allele dosage on the severity of Rett syndrome phenotype.
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Affiliation(s)
- Sara Hammer
- Department of Human Genetics, UCLA School of Medicine, Los Angeles, California, USA
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28
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Abstract
The association of Rett syndrome with pathogenic mutations of the methyl-CpG binding protein 2 (MECP2) gene was first made in 1999. Since that time, it has been found that the clinical phenotype can, at least in part, be explained in terms of the type and location of the MECP2 mutation and epigenetic factors such as skewing of X-chromosome inactivation. In addition, MECP2 mutations may be associated with non-Rett syndrome clinical phenotypes, including nonsyndromic and syndromic X-linked mental retardation and Angelman-like phenotypes. Intense research efforts are currently focused on understanding the pathogenesis of Rett syndrome, using sophisticated techniques such as microarray analysis, and the development of mouse models, with an ultimate aim being the development of targeted therapies that could ameliorate or even prevent the devastating consequences of this enigmatic neurodevelopmental disorder.
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Affiliation(s)
- John Christodoulou
- Western Sydney Genetics Program, The Children's Hospital at Westmead, NSW, Australia.
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29
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Mount RH, Charman T, Hastings RP, Reilly S, Cass H. Features of autism in Rett syndrome and severe mental retardation. J Autism Dev Disord 2003; 33:435-42. [PMID: 12959422 DOI: 10.1023/a:1025066913283] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
It has long been recognized that there is phenotypic overlap between Rett syndrome (RS) and autism. Advances in our clinical and genetic understanding of RS over the past decade have made clear that the cause and course of RS and autism are distinct (except perhaps in a few cases). Despite this, further delineation of the phenotypic overlap between RS and autism is warranted to enhance clinical decision-making and to further understanding of neuropathological development in both disorders. The present study measured autistic symptoms using the Autism Behavior Checklist (ABC) in a sample of girls with RS and a comparison group of girls with severe and profound mental retardation (SMR). Controlling for developmental level and motor ability, girls with RS scored more highly than those with SMR on the Sensory and Relating subscales. In contrast, there were no group differences on the Body and Object use, Language and Social and Self-help subscales. Further work on the characterisation of the behavioral phenotype of genetic disorders such as RS and autism may aid in identifying the neuropathogenic processes that lead from gene-to-brain-to-behavior.
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Affiliation(s)
- Rebecca H Mount
- Behavioural and Brain Sciences Unit, Institute of Child Health, University College London, UK
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30
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Zappella M, Meloni I, Longo I, Canitano R, Hayek G, Rosaia L, Mari F, Renieri A. Study of MECP2 gene in Rett syndrome variants and autistic girls. Am J Med Genet B Neuropsychiatr Genet 2003; 119B:102-7. [PMID: 12707946 DOI: 10.1002/ajmg.b.10070] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Mutations in MECP2 gene account for approximately 80% of cases of Rett syndrome (RTT), an X-linked severe developmental disorder affecting young girls, as well as for most cases of Preserved Speech Variant (PSV), a mild RTT variant in which autistic behavior is common. The aim of this study is to determine whether MECP2 mutations are responsible for PSV only or may cause other forms of autistic disorders. We screened for mutations by SSCP 19 girls with a clinical diagnosis of autism, two of them fulfilling the PSV criteria. A pathogenic mutation was found only in the latter two cases (R133C and R453X). A long follow-up of these two girls revealed a unique clinical course. They initially developed the first three stages of RTT, they were severely retarded and had autistic behavior. Over the years their abilities increased progressively and by early adolescence they lost autistic behavior, becoming adequately accustomed to people and reaching an IQ close to 45. These results confirm previous clinical studies suggesting that a wide spectrum of RTT exists including girls with mental abilities considerably higher than in classic RTT. We conclude that MECP2 mutations (missense or late truncating) can be found in girls with an IQ close to 45 and a clinical history of PSV of Rett syndrome. Furthermore, MECP2 mutations are not found in patients in which autism remains stable over the years.
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Affiliation(s)
- Michele Zappella
- Department of Child Neuropsychiatry, Azienda Ospedaliera Senese, Siena, Italy
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31
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Abstract
OBJECTIVE We reevaluated 49 girls with either Rett syndrome (RTT) or features of RTT who had negative test results for mutations in the MECP2 gene and compared them with 49 girls who had positive test results. The girls with MECP2-positive results included 2 girls with forme fruste and 2 with congenital RTT. Study design Based on the original diagnostic criteria for RTT, we developed a 10-item checklist with a score ranging from 0 to 12. RESULTS If only girls with a score of 8 or more had been tested, 46% of the girls without mutations would have been excluded from testing without missing a single girl with MECP2-positive results. CONCLUSIONS This checklist provides a simple aid for deciding whether or not a genetic test for RTT should be performed with only a minimal risk of missing girls with MECP2-positive results.
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Affiliation(s)
- Peter Huppke
- Neuropediatric Department and Department of Genetic Epidemiology, Institute of Human Genetics, Georg-August-Universität Göttingen, Göttingen, Germany.
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32
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Carney RM, Wolpert CM, Ravan SA, Shahbazian M, Ashley-Koch A, Cuccaro ML, Vance JM, Pericak-Vance MA. Identification of MeCP2 mutations in a series of females with autistic disorder. Pediatr Neurol 2003; 28:205-11. [PMID: 12770674 DOI: 10.1016/s0887-8994(02)00624-0] [Citation(s) in RCA: 164] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Rett disorder and autistic disorder are both pervasive developmental disorders. Recent studies indicate that at least 80% of Rett Disorder cases are caused by mutations in the methyl-CpG-binding protein 2 (MeCP2) gene. Since there is some phenotypic overlap between autistic disorder and Rett disorder, we analyzed 69 females clinically diagnosed with autistic disorder for the presence of mutations in the MeCP2 gene. Two autistic disorder females were found to have de novo mutations in the MeCP2 gene. These data provide additional evidence of variable expression in the Rett disorder phenotype and suggest MeCP2 testing may be warranted for females presenting with autistic disorder.
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Affiliation(s)
- Regina M Carney
- Department of Medicine and the Center for Human Genetics, Duke University Medical Center, Durham, North Carolina 27710, USA
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33
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Weiss LA, Escayg A, Kearney JA, Trudeau M, MacDonald BT, Mori M, Reichert J, Buxbaum JD, Meisler MH. Sodium channels SCN1A, SCN2A and SCN3A in familial autism. Mol Psychiatry 2003; 8:186-94. [PMID: 12610651 DOI: 10.1038/sj.mp.4001241] [Citation(s) in RCA: 225] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Autism is a psychiatric disorder with estimated heritability of 90%. One-third of autistic individuals experience seizures. A susceptibility locus for autism was mapped near a cluster of voltage-gated sodium channel genes on chromosome 2. Mutations in two of these genes, SCN1A and SCN2A, result in the seizure disorder GEFS+. To evaluate these sodium channel genes as candidates for the autism susceptibility locus, we screened for variation in coding exons and splice sites in 117 multiplex autism families. A total of 27 kb of coding sequence and 3 kb of intron sequence were screened. Only six families carried variants with potential effects on sodium channel function. Five coding variants and one lariat branchpoint mutation were each observed in a single family, but were not present in controls. The variant R1902C in SCN2A is located in the calmodulin binding site and was found to reduce binding affinity for calcium-bound calmodulin. R542Q in SCN1A was observed in one autism family and had previously been identified in a patient with juvenile myoclonic epilepsy. The effect of the lariat branchpoint mutation was tested in cultured lymphoblasts. Additional population studies and functional tests will be required to evaluate pathogenicity of the coding and lariat site variants. SNP density was 1/kb in the genomic sequence screened. We report 38 sodium channel SNPs that will be useful in future association and linkage studies.
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Affiliation(s)
- L A Weiss
- Department of Human Genetics, University of Michigan, 4708 Medical Science II, Ann Arbor, MI 48109-0618, USA
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34
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Lobo-Menendez F, Sossey-Alaoui K, Bell JM, Copeland-Yates SA, Plank SM, Sanford SO, Skinner C, Simensen RJ, Schroer RJ, Michaelis RC. Absence of MeCP2 mutations in patients from the South Carolina autism project. Am J Med Genet B Neuropsychiatr Genet 2003; 117B:97-101. [PMID: 12555243 DOI: 10.1002/ajmg.b.10016] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The methyl-CpG binding protein 2 (MeCP2) gene has recently been identified as the gene responsible for Rett syndrome (RS), a pervasive developmental disorder considered by many to be one of the autism spectrum disorders. Most female patients with MeCP2 mutations exhibit the classic features of RS, including autistic behaviors. Most male patients with MeCP2 mutations exhibit moderate to severe developmental delay/mental retardation. Ninety nine patients from the South Carolina autism project (SCAP) were screened for MeCP2 mutations, including all 41 female patients from whom DNA samples were available plus the 58 male patients with the lowest scores on standard IQ tests and/or the Vineland Adaptive Behavior Scale. No pathogenic mutations were observed in these patients. One patient had the C582T variant, previously reported in the unaffected father of an RS patient. Two other patients had single nucleotide polymorphisms in the 3' UTR of the gene, G1470A and C1516G. These variants were seen in 12/82 and 1/178 phenotypically normal male controls, respectively. The findings from this and other studies suggest that mutations in the coding sequence of the MeCP2 gene are not a significant etiological factor in autism.
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35
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Moog U, Smeets EEJ, van Roozendaal KEP, Schoenmakers S, Herbergs J, Schoonbrood-Lenssen AMJ, Schrander-Stumpel CTRM. Neurodevelopmental disorders in males related to the gene causing Rett syndrome in females (MECP2). Eur J Paediatr Neurol 2003; 7:5-12. [PMID: 12615169 DOI: 10.1016/s1090-3798(02)00134-4] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mutations in the MECP2 (methyl-CpG-binding protein 2) gene are known to cause Rett syndrome, a well-known and clinically defined neurodevelopmental disorder. Rett syndrome occurs almost exclusively in females and for a long time was thought to be an X-linked dominant condition lethal in hemizygous males. Since the discovery of the MECP2 gene as the cause of Rett syndrome in 1999, MECP2 mutations have, however, also been reported in males. These males phenotypically have classical Rett syndrome when the mutation arises as somatic mosaicism or when they have an extra X chromosome. In all other cases, males with MECP2 mutations show diverse phenotypes different from classical Rett syndrome. The spectrum ranges from severe congenital encephalopathy, mental retardation with various neurological symptoms, occasionally in association with psychiatric illness, to mild mental retardation only. We present a 21-year-old male with severe mental retardation, spastic tetraplegia, dystonia, apraxia and neurogenic scoliosis. A history of early hypotonia evolving into severe spasticity, slowing of head growth, breathing irregularities and good visual interactive behaviour were highly suggestive of Rett syndrome. He has a de novo missense mutation in exon 3 of the MECP2 gene (P225L). The clinical spectrum and molecular findings in males with MECP2 mutations are reviewed.
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Affiliation(s)
- Ute Moog
- Department of Clinical Genetics, University Hospital, Maastricht, The Netherlands
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