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Lang S, Bartl-Pokorny KD, Pokorny FB, Garrido D, Mani N, Fox-Boyer AV, Zhang D, Marschik PB. Canonical Babbling: A Marker for Earlier Identification of Late Detected Developmental Disorders? CURRENT DEVELOPMENTAL DISORDERS REPORTS 2019; 6:111-118. [PMID: 31984204 PMCID: PMC6951805 DOI: 10.1007/s40474-019-00166-w] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Purpose of Review To summarize findings about the emergence and characteristics of canonical babbling in children with late detected developmental disorders (LDDDs), such as autism spectrum disorder, Rett syndrome, and fragile X syndrome. In particular, we ask whether infants’ vocal development in the first year of life contains any markers that may contribute to earlier detection of these disorders. Recent Findings Only a handful studies have investigated canonical babbling in infants with LDDDs. With divergent research paradigms and definitions applied, findings on the onset and characteristics of canonical babbling are inconsistent and difficult to compare. Infants with LDDDs showed reduced likelihood to produce canonical babbling vocalizations. If achieved, this milestone was more likely to be reached beyond the critical time window of 5–10 months. Summary Canonical babbling appears promising as a potential marker for early detection of infants at risk for developmental disorders. In-depth studies on babbling characteristics in LDDDs are warranted.
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Affiliation(s)
- Sigrun Lang
- 1iDN - interdisciplinary Developmental Neuroscience, Division of Phoniatrics, Medical University of Graz, Auenbruggerplatz 26, 8036 Graz, Austria
| | - Katrin D Bartl-Pokorny
- 1iDN - interdisciplinary Developmental Neuroscience, Division of Phoniatrics, Medical University of Graz, Auenbruggerplatz 26, 8036 Graz, Austria
| | - Florian B Pokorny
- 1iDN - interdisciplinary Developmental Neuroscience, Division of Phoniatrics, Medical University of Graz, Auenbruggerplatz 26, 8036 Graz, Austria.,2Machine Intelligence & Signal Processing group, Chair of Human-Machine Communication, Technical University of Munich, Munich, Germany
| | - Dunia Garrido
- 3Mind, Brain, and Behavior Research Center, University of Granada, Granada, Spain
| | - Nivedita Mani
- 4Psychology of Language Department, Georg-August University Göttingen, Göttingen, Germany.,Leibniz-ScienceCampus Primate Cognition, Göttingen, Germany
| | - Annette V Fox-Boyer
- 6Department of Human Communication Sciences, Sheffield University, Sheffield, Great Britain
| | - Dajie Zhang
- 1iDN - interdisciplinary Developmental Neuroscience, Division of Phoniatrics, Medical University of Graz, Auenbruggerplatz 26, 8036 Graz, Austria.,Leibniz-ScienceCampus Primate Cognition, Göttingen, Germany.,7Child and Adolescent Psychiatry and Psychotherapy, University Medical Center Göttingen, Göttingen, Germany
| | - Peter B Marschik
- 1iDN - interdisciplinary Developmental Neuroscience, Division of Phoniatrics, Medical University of Graz, Auenbruggerplatz 26, 8036 Graz, Austria.,Leibniz-ScienceCampus Primate Cognition, Göttingen, Germany.,7Child and Adolescent Psychiatry and Psychotherapy, University Medical Center Göttingen, Göttingen, Germany.,8Center of Neurodevelopmental Disorders (KIND), Center for Psychiatry Research, Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden
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Regression in Rett syndrome: Developmental pathways to its onset. Neurosci Biobehav Rev 2019; 98:320-332. [DOI: 10.1016/j.neubiorev.2019.01.028] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2018] [Revised: 01/24/2019] [Accepted: 01/29/2019] [Indexed: 11/18/2022]
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Are dopamine receptor and transporter changes in Rett syndrome reflected in Mecp2-deficient mice? Exp Neurol 2018; 307:74-81. [PMID: 29782864 DOI: 10.1016/j.expneurol.2018.05.019] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2017] [Revised: 04/27/2018] [Accepted: 05/17/2018] [Indexed: 11/20/2022]
Abstract
We tested the claim that the dopaminergic dysfunction of Rett Syndrome (RTT) also occurs in Mecp2-deficient mice that serve as a model of the syndrome. We used positron emission tomography (PET) to image dopamine D2 receptors (D2R) and transporters (DAT) in women with RTT and in Mecp2-deficient mice, and D1R and D2R density was measured in postmortem human tissue by autoradiography. Results showed 1) significantly reduced D2R density in the striatum of women with RTT compared to control subjects. 2) PET imaging of mouse striatum similarly demonstrated significant reductions in D2R density of 7-10 week-old hemizygous (Mecp2-null) and heterozygous (HET) mice compared to wild type (WT) mice. With age, the density of D2R declined in WT mice but not HET mice. 3) In contrast, postmortem autoradiography revealed no group differences in the density of D1R and D2R in the caudate and putamen of RTT versus normal control subjects. 4) In humans and in the mouse model, PET revealed only marginal group differences in DAT. The results confirm that dopaminergic dysfunction in RTT is also present in Mecp2-deficient mice and that reductions in D2R more likely explain the impaired ambulation and progressive rigidity observed rather than alterations in DAT.
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Genes related to mitochondrial functions, protein degradation, and chromatin folding are differentially expressed in lymphomonocytes of Rett syndrome patients. Mediators Inflamm 2013; 2013:137629. [PMID: 24453408 PMCID: PMC3876710 DOI: 10.1155/2013/137629] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Accepted: 11/07/2013] [Indexed: 11/17/2022] Open
Abstract
Rett syndrome (RTT) is mainly caused by mutations in the X-linked methyl-CpG binding protein (MeCP2) gene. By binding to methylated promoters on CpG islands, MeCP2 protein is able to modulate several genes and important cellular pathways. Therefore, mutations in MeCP2 can seriously affect the cellular phenotype. Today, the pathways that MeCP2 mutations are able to affect in RTT are not clear yet. The aim of our study was to investigate the gene expression profiles in peripheral blood lymphomonocytes (PBMC) isolated from RTT patients to try to evidence new genes and new pathways that are involved in RTT pathophysiology. LIMMA (Linear Models for MicroArray) and SAM (Significance Analysis of Microarrays) analyses on microarray data from 12 RTT patients and 7 control subjects identified 482 genes modulated in RTT, of which 430 were upregulated and 52 were downregulated. Functional clustering of a total of 146 genes in RTT identified key biological pathways related to mitochondrial function and organization, cellular ubiquitination and proteosome degradation, RNA processing, and chromatin folding. Our microarray data reveal an overexpression of genes involved in ATP synthesis suggesting altered energy requirement that parallels with increased activities of protein degradation. In conclusion, these findings suggest that mitochondrial-ATP-proteasome functions are likely to be involved in RTT clinical features.
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Ricceri L, De Filippis B, Laviola G. Rett syndrome treatment in mouse models: searching for effective targets and strategies. Neuropharmacology 2012; 68:106-15. [PMID: 22940001 DOI: 10.1016/j.neuropharm.2012.08.010] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 08/08/2012] [Accepted: 08/13/2012] [Indexed: 11/24/2022]
Abstract
Rett syndrome (RTT) is a pervasive developmental disorder, primarily affecting girls with a prevalence of 1 in every 10,000 births; it represents the second most common cause of intellectual disability in females. Mutations in the gene encoding methyl-CpG-binding protein 2 (MECP2) have been identified as clear etiological factors in more than 90% of classical RTT cases. Whereas the mechanisms leading to the severe, progressive and specific neurological dysfunctions when this gene is mutated still remain to be elucidated, a series of different mouse models have been generated, bearing different Mecp2 mutation. Neurobehavioural analysis in these mouse lines have been carried out and phenotyping analysis can be now utilised to preclinically evaluate the effects of potential RTT treatments. This review summarizes the different results achieved in this research field taking into account different key targets identified to ameliorate RTT phenotype in mouse models, including those not directly downstream of MeCP2 and those limited to the early phases of postnatal development. This article is part of the Special Issue entitled 'Neurodevelopmental Disorders'.
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Affiliation(s)
- Laura Ricceri
- Section of Neurotoxicology and Neuroendocrinology, Dept. Cell Biology and Neurosciences, Istituto Superiore di Sanità, Viale Regina Elena, 299, I-00161 Roma, Italy
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Riise R, Brox JI, Sorensen R, Skjeldal OH. Spinal deformity and disability in patients with Rett syndrome. Dev Med Child Neurol 2011; 53:653-7. [PMID: 21501153 DOI: 10.1111/j.1469-8749.2011.03935.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
AIM Rett syndrome is a neurodevelopmental disorder starting in early childhood with devastating consequences both on the brain and on systemic neurons. Scoliosis is a common complication in most of these patients. The aim of the study was to describe the prevalence of scoliosis, classify spinal deformity, and evaluate the association between disability and scoliosis in patients with Rett syndrome. METHOD Twenty-nine female patients, mean age 14 years 8 months (range 4 y 10 mo-33 y) were included. Outcome parameters were the Barthel Index for evaluation of function, pain, analgesics, and radiological evaluation of the spine including curve size (Cobb's method) and curve type. None of the patients had surgery before assessment. RESULTS Twenty-five (87%) patients had radiographically verified scoliosis. The median curve was 41° (range 15-77). The curve was classified as C-shaped (neuromuscular) in 16 patients and double curve-shaped in nine. Function was poorer in patients with C-shaped curve (p<0.01). Walking on a level surface (r=0.9) and the ability to ascend or descend stairs (r=0.8) were highly correlated with the Barthel Index. Curve size was moderately correlated with function (r=0.5). INTERPRETATION Function level in females with Rett syndrome measured according to the Barthel Index showed significant correlation to scoliosis curve type. A low score was associated with a C-shaped curve involving all of the spine and pelvis.
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Affiliation(s)
- Rolf Riise
- Department of Orthopedic Surgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
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Carter JC, Lanham DC, Pham D, Bibat G, Naidu S, Kaufmann WE. Selective cerebral volume reduction in Rett syndrome: a multiple-approach MR imaging study. AJNR Am J Neuroradiol 2008; 29:436-41. [PMID: 18065507 DOI: 10.3174/ajnr.a0857] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Previous studies have examined volumetric abnormalities in Rett syndrome (RTT), using MR imaging and focusing on selective changes. However, these studies preceded the identification of MECP2 as the gene mutated in most RTT cases. We studied regional brain volume changes as noted by MR imaging in girls with RTT who had mutations in the MECP2 gene and more or less severe clinical outcomes to further characterize the neuroanatomy of RTT and its correlations with clinical severity. MATERIALS AND METHODS Complementary semiautomated Talairach- and voxel-based approaches were used to study spoiled gradient-recalled acquisition sequence MR imaging scans from 23 girls with MECP2 mutations/RTT, including a pair of discordant monozygotic twins and 25 age-matched control girls. Both absolute and relative volumetric changes were examined to account for the well-documented global reduction in brain volume seen in RTT. RESULTS Absolute volumetric reductions were observed throughout the brain in RTT. Selective/relative decreases in parietal lobe gray matter, particularly in the dorsal parietal region, and mild, diffuse reductions in cortical white matter were observed in the RTT group compared with control subjects. In girls with RTT and a more severe phenotype, anterior frontal lobe volumes were relatively more reduced. Twin comparisons revealed selective preservation of the occipital cortex. CONCLUSION Selective reductions of dorsal parietal gray matter and preservation of the occipital cortex seem to be basic neuroanatomic features of RTT, whereas preferential reduction of the anterior frontal lobe appears to be a correlate of clinical severity in this disorder. The most affected brain regions include those that may underlie key functional deficits observed in RTT.
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Affiliation(s)
- J C Carter
- Center for Genetic Disorders of Cognition and Behavior, Kennedy Krieger Institute, Baltimore, MD 21211, USA
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Leonard H, Moore H, Carey M, Fyfe S, Hall S, Robertson L, Wu XR, Bao X, Pan H, Christodoulou J, Williamson S, Klerk ND. Genotype and early development in Rett syndrome: the value of international data. Brain Dev 2005; 27 Suppl 1:S59-S68. [PMID: 16182492 DOI: 10.1016/j.braindev.2005.03.023] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2004] [Revised: 10/01/2004] [Accepted: 03/05/2005] [Indexed: 11/18/2022]
Abstract
BACKGROUND Rett syndrome is a neurodevelopmental disorder mostly affecting females and caused by mutations in the MECP2 gene. Originally the syndrome was characterised as having a normal prenatal and perinatal period with later regression. Previous work has speculated that the girl with Rett syndrome may not be normal at birth. AIMS to examine whether early development between birth and ten months varies by genotype in Rett syndrome. METHODS cases were sourced from two databases, the Australian Rett Syndrome Database (est. 1993) and the newly formed InterRett - IRSA Rett Phenotype Database. Data available on 320 cases included information provided by parents on perinatal problems, early developmental behaviour and mobility. Problem scores, mobility scores and a total composite score for each mutation were generated and compared. RESULTS overall, 58% of respondents noted unusual behaviour during the first six months and 70.6% from the period between 6 and 10 months of life. Statistically significant differences were detected between some of the common mutations. Infants with R294X (P=0.05) and R133C (P=0.03) were less likely than those with R255X to have problems in the perinatal period. The most severe profile overall for early development was associated with mutations R255X and R270X. CONCLUSION This is the largest study to date examining the effects of individual mutations in Rett syndrome. With the ongoing case ascertainment and expansion of InterRett, sample size will increase rapidly and provide improved statistical power for future analyses. Results from this study will contribute to understanding the mechanism of early development in Rett syndrome and determining if and at which time(s) early intervention might be feasible.
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Affiliation(s)
- Helen Leonard
- Telethon Institute for Child Health Research, Centre for Child Health Research, The University of Western Australia, Perth, Western Australia.
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Pozzi CM, Rosemberg S. Rett syndrome: clinical and epidemiological aspects in a Brazilian institution. ARQUIVOS DE NEURO-PSIQUIATRIA 2003; 61:909-15. [PMID: 14762589 DOI: 10.1590/s0004-282x2003000600004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Rett syndrome (RS) is a neurodevelopmental disorder, preferentially found in females and specifically involving the functions on which intelligence and its expression depend - learning, hand use and speech - leaving many others intact. Mutations have been identified at Xq28 on the MECP2 gene (methyl-CpG 2), which selectively silences the expression of other genes whose location is still unknown. This is a study on clinical, diagnostic and epidemiological aspects of RS in a Brazilian sample. It included 33 female patients with chronic encephalopathy without known etiology. RS was diagnosed in 24 patients (72.7%): 17 (70.8%) had classical RS; 5 (20.8%), atypical RS and 2 (8.4%), potential RS. In 9 girls clinical data and/or laboratory studies excluded diagnosis of RS. Among the atypical RS patients, 4 were form fruste and one, congenital form. Among the girls with other encephalopathies, cerebral malformation was the most frequent finding.
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Affiliation(s)
- Cristina M Pozzi
- Neurology Division Department of Paediatrics, Santa Casa Medical School, Sao Paulo, SP, Brazil.
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Ronnett GV, Leopold D, Cai X, Hoffbuhr KC, Moses L, Hoffman EP, Naidu S. Olfactory biopsies demonstrate a defect in neuronal development in Rett's syndrome. Ann Neurol 2003; 54:206-18. [PMID: 12891673 DOI: 10.1002/ana.10633] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Rett's Syndrome (RTT) is a neurodevelopmental disorder resulting from mutation in the mecp2 gene that encodes methyl CpG binding protein 2, a transcriptional repressor. Because this disease primarily affects neurons, tissue is not available during active disease. We used the olfactory system as a model to investigate abnormalities in neuronal development in RTT, because olfactory receptor neurons (ORNs) are replaced throughout life by ongoing postnatal neurogenesis. Thus, even in the adult, the olfactory epithelium contains neurons at various developmental stages. We obtained biopsies of nasal epithelium containing ORNs from RTT patients and age-matched controls to study the status of the neuronal population using antibodies to stage-specific developmental markers. There were no postprocedure complications. Compared with age-matched controls, there were far fewer mature ORNs, as defined by olfactory marker protein expression, and significantly greater numbers of immature neuron-specific tubulin-positive ORNs present. In RTT biopsies, olfactory marker protein-positive neurons displayed abnormal structure. These results suggest that dysfunction of MeCP2 results in decreased survival of mature ORNs with a compensatory increase in neurogenesis, or a failure of immature neurons to mature. Our study indicates that olfactory biopsies provide a method to study neuronal developmental diseases in adults and children.
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Affiliation(s)
- Gabriele V Ronnett
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
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Colvin L, Fyfe S, Leonard S, Schiavello T, Ellaway C, De Klerk N, Christodoulou J, Msall M, Leonard H. Describing the phenotype in Rett syndrome using a population database. Arch Dis Child 2003; 88:38-43. [PMID: 12495959 PMCID: PMC1719276 DOI: 10.1136/adc.88.1.38] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Mutations in the MECP2 gene have been recently identified as the cause of Rett syndrome, prompting research into genotype-phenotype relations. However, despite these genetic advances there has been little descriptive epidemiology of the full range of phenotypes. AIMS To describe the variation in phenotype in Rett syndrome using four different scales, by means of a population database. METHODS Using multiple sources of ascertainment including the Australian Paediatric Surveillance Unit, the development of an Australian cohort of Rett syndrome cases born since 1976 has provided the first genetically characterised population based study of Rett syndrome. Follow up questionnaires were administered in 2000 to families and used to provide responses for items in four different severity scales. RESULTS A total of 199 verified cases of Rett syndrome were reported between January 1993 and July 2000; 152 families provided information for the follow up study. The mean score using the Kerr scale was 22.9 (SD 4.8) and ranged from 20.5 in those under 7 years to 24.2 in those over 17 years. The mean Percy score was 24.9 (SD 6.6) and also increased with age group from 23.0 to 26.9. The mean Pineda score was 16.3 (SD 4.5) and did not differ by age group. The mean WeeFIM was 29.0 (SD 11.9), indicating extreme dependence, and ranged from 18 to 75. CONCLUSION We have expanded on the descriptive epidemiology of Rett syndrome and shown different patterns according to the severity scale selected. Although all affected children are severely functionally dependent, it is still possible to identify some variation in ability, even in children with identified MECP2 mutations.
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Affiliation(s)
- L Colvin
- Centre for Child Health Research, The University of Western Australia, Telethon Institute for Child Health Research, Perth, Western Australia
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Charman T, Cass H, Owen L, Wigram T, Slonims V, Weeks L, Wisbeach A, Reilly S. Regression in individuals with Rett syndrome. Brain Dev 2002; 24:281-3. [PMID: 12142064 DOI: 10.1016/s0387-7604(02)00058-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Data on features of regression and pre-regression developmental history in a case series of 53 girls and women with Rett syndrome are presented. Consistent with the diagnostic criteria, hand skills and verbal or non-verbal communication skills were the most common skills lost during regression. Play and motor skills were also lost in half the cases. Regression most commonly occurred between 12 and 18 months of age but was noted in a few cases before 6 months or after 36 months. Pre-regression developmental delays or abnormalities were noted in over two-thirds of cases, increasing to 85% of the youngest cases where parental reporting was likely to be more accurate. Age at regression was not associated with severity of physical and growth symptoms, and thus did not appear to be an index of neurological severity. There is a continuing need to further elucidate the pre- and post-regression features of Rett syndrome in order to aid early identification, diagnosis and referral for genotype mutation analysis.
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Affiliation(s)
- Tony Charman
- Behavioural and Brain Sciences Unit, Institute of Child Health, 30 Guildford St, WC1N 1EH London, UK.
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Abstract
Development and retention of speech is reported in 265 people with Rett syndrome: 30% (80) never gained real words, 55% (145) gained real words and lost them, 15%(40) retained some words and 6% of the total (16/265) continued to use phrases appropriately. Morphological studies of the cytoarchitecture of the speech areas in 14 cases indicate the existence of interhemispheric differences which form part of the infrastructure for speech processing. Ten adults with Rett syndrome and with meaningful speech are compared to age matched adults without speech. The profile of mind and strategies for coping with its problems are described by a family. Although the range in severity is wide the mental profile is remarkably consistent across the severity range with regard to both positive and negative aspects.
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Affiliation(s)
- A M Kerr
- Department of Psychological Medicine, University of Glasgow, Gartnavel Royal Hospital, 1055 Great Western Road, G21 0XH, Glasgow, UK.
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Abstract
The Rett syndrome (RS) is a peculiar, sporadic, atrophic disorder, almost entirely confined to females. After the first six months of life there is developmental slowing with reduced communication and head growth for about one year. This is followed by a rapid destructive stage with severe dementia and loss of hand skills (with frequent hand wringing), apraxia and ataxia, autistic features and irregular breathing with hyperventilation. Seizures often supervene. Subsequently there is some stabilization in a pseudo-stationary stage during the preschool to school years, associated with more emotional contact but also abnormalities of the autonomic and skeletal systems. After the age of 15-20 years, a late motor deterioration occurs with dystonia and frequent spasticity but seizures become milder. RS has generally been considered an X-linked disorder in which affected females represent a new mutation, with male lethality. Linkage studies suggested a critical region at Xq28. In 1999, mutations in the gene MECP2 encoding X-linked methyl cytosine-binding protein 2 (MeCP2) were found in a proportion of Rett girls. This protein can bind methylated DNA. Analyses are leading to much further investigation of mutants and their effects on genes. Neuropathological and electrophysiological studies of RS are described. Description of neurometabolic factors includes reduced levels of dopamine, serotonin, noradrenaline and choline acetyltransferase (ChAT) in brain, also estimation of nerve growth factors, endorphin, substance P, glutamate and other amino acids and their receptor levels. The results of neuroimaging are surveyed, including volumetric magnetic resonance imaging (MRI) and positron emission tomography (PET).
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Affiliation(s)
- H G Dunn
- Division of Neurology, British Columbia's Children's Hospital, Vancouver, BC, Canada
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Ellaway C, Buchholz T, Smith A, Leonard H, Christodoulou J. Rett syndrome: significant clinical overlap with Angelman syndrome but not with methylation status. J Child Neurol 1998; 13:448-51. [PMID: 9733292 DOI: 10.1177/088307389801300907] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Rett syndrome and Angelman syndrome are neurodevelopmental disorders characterized by severe intellectual disability, microcephaly, speech disturbance, movement disorders with gait and/or truncal ataxia, and occasionally a similar facial appearance. Both conditions can be difficult to diagnose in girls early in their clinical course and can be difficult to distinguish from each other. Genomic imprinting is a known association in Angelman syndrome and previously has been suggested in Rett syndrome. Our aim was to evaluate the methylation status in a cohort of classical patients with Rett syndrome, using a methylation system for chromosome 15q11-13. Methylation analysis of chromosome 15 has not been previously reported in Rett syndrome. Furthermore, we document the clinical features of 31 girls with classical Rett syndrome and confirm the phenotypic similarities between Rett syndrome and Angelman syndrome. The methylation studies in these girls with Rett syndrome were normal. This excludes an imprinting error of the Angelman syndrome critical region on chromosome 15 (15q11-13) as an association with Rett syndrome, and indicates that methylation studies may be useful in distinguishing Rett syndrome from Angelman syndrome in young patients with an overlapping clinical phenotype. A normal methylation pattern, however, does not exclude the diagnosis of Angelman syndrome and clear distinction between the two syndromes will evolve over time.
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Affiliation(s)
- C Ellaway
- Department of Paediatrics and Child Health, University of Sydney, New South Wales, Australia
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Abstract
Rett syndrome (RS) is a neurological disorder that mainly, and possibly exclusively, affects girls. After its description in 1966 by Andreas Rett in the Wiener Klinische Wochenschrift, awareness and interest in RS were enhanced by the 1983 report of Hagberg et al. in the Annals of Neurology. Diagnosis, and indeed the hypothesis that it exists, continue to be based upon a consistent constellation of clinical features observed in thousands of female patients world-wide. A diagnostic marker has not been identified. Notwithstanding this serious limitation, it is generally agreed that RS is a distinct entity and that it is genetically determined. Although it is associated with devastating loss of function between infancy and the fifth year of life, its course becomes relatively static thereafter, setting it apart from most of the genetic neurodegenerative disorders of childhood. Neuropathological and neurochemical studies call attention to RS as a neurodevelopmental disorder. Clarification of its pathogenesis may provide new insight into normal brain development. This report summarizes existing information and concepts about RS, and presents recent advances.
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Affiliation(s)
- S B Naidu
- Kennedy Krieger Institute, Baltimore, MD.
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Affiliation(s)
- S Naidu
- Kennedy Krieger Institute, Johns Hopkins Medical Institutions, Baltimore, Maryland 21205, USA
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Abstract
Rett syndrome (RS) is a progressive disorder that is predominant in females. It is associated with cortical atrophy, stereotyped hand movements mimicking hand-washing, severe mental deficiency, and cortical and extrapyramidal dysfunction. The cause of RS is unknown; no consistent genetic abnormalities, at either the cellular or mitochondrial levels, have been identified. The diagnosis still depends solely upon clinical evidence. The clinical progression of RS is consistent with an arrested neuronal development that may be due to either impaired cellular differentiation or the lack of appropriate trophic factors. Neuropathological studies have confirmed (1) a generalized brain atrophy involving the cerebrum and cerebellum; (2) a decrease in neuronal cell size and increased cell packing density throughout the brain; (3) a reduction in the number of basal forebrain cholinergic neurons; (4) a reduction in the concentration of melanin-containing neurons in the substantia nigra. Biochemical studies have identified (1) a decrease in cholinergic markers in the neocortex, hippocampus, thalamus and basal ganglia; (2) inconsistent and variable changes in biogenic amine biomarkers in post-mortem tissues and cerebrospinal fluid (CSF); (3) an elevation of beta-endorphin levels in the thalamus and glutamate levels in the CSF; (4) no evidence for mitochondrial dysfunction. These data suggest that there is a primary deficit in cholinergic function that might underlie some of the higher cognitive impairments and extrapyramidal dysfunction. Overall, the clinical, biochemical and neuropathological data suggest that RS is a neurodevelopmental disorder that has its greatest effects upon a limited number of neural systems during the first few years of postnatal life.
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Affiliation(s)
- G L Wenk
- Department of Psychology, University of Arizona, Tucson 85724, USA.
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Kaufmann WE, Worley PF, Taylor CV, Bremer M, Isakson PC. Cyclooxygenase-2 expression during rat neocortical development and in Rett syndrome. Brain Dev 1997; 19:25-34. [PMID: 9071487 DOI: 10.1016/s0387-7604(96)00047-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Cyclooxygenase or prostaglandin endoperoxide H synthase-2 (PGHS-2) is the first enzyme in the prostanoid biosynthetic pathways and, in brain, it is regulated as an immediate-early gene (IEG). PGHS-2 mRNA and protein are rapidly induced by physiological synaptic activity, and high basal expression in cerebral cortex appears to be maintained by the natural synaptic activity. In contrast to other IEGs, PGHS-2 is a dendritic protein that is enriched in dendritic spines and is, therefore, likely to play a direct role in synaptic physiology. Consistent with a signaling function in mature dendritic spines, PGHS-2 expression is strongly regulated during normal postnatal development in the rat, with peak expression during the third and fourth weeks. Here we use immunocytochemical approaches to compare the developmental expression of PGHS-2 in rat neocortex with that of other well characterized markers of dendritic maturation. PGHS-2 immunoreactivity (ir) follows histogenetic gradients and expression in secondary or more distal dendrites postdates that of even the most delayed dendritic proteins. This developmental pattern parallels the critical period for somatosensory and visual cortex development. Accordingly, PGHS-2-ir may be a useful marker of the final activity-dependent stages of cortical development. Consistent with the potential histochemical utility, we demonstrate that the normal laminar pattern of PGHS-2-ir in human cortex is altered in patients with Rett syndrome, a form of mental retardation with known alterations of dendritic maturation. Further studies of the developmental expression of PGHS-2 in human cortical development may permit analyses of dendritic abnormalities, in syndromes associated with disturbances of activity-dependent development, as well as provide an anatomic basis for understanding the role of prostaglandin signaling in cortical development.
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Affiliation(s)
- W E Kaufmann
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21287-6417, USA.
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