Genotype-phenotype correlation in Brazillian Rett syndrome patients

BACKGROUND: Rett syndrome (RS) is a severe neurodevelopmental X-linked dominant disorder caused by mutations in the MECP2 gene. PURPOSE: To search for point mutations on the MECP2 gene and to establish a correlation between the main point mutations found and the phenotype. METHOD: Clinical evaluation of 105 patients, following a standard protocol. Detection of point mutations on the MECP2 gene was performed on peripheral blood DNA by sequencing the coding region of the gene. RESULTS: Classical RS was seen in 68% of the patients. Pathogenic point mutations were found in 64.1% of all patients and in 70.42% of those with the classical phenotype. Four new sequence variations were found, and their nature suggests patogenicity. Genotype-phenotype correlations were performed. CONCLUSION: Detailed clinical descriptions and identification of the underlying genetic alterations of this Brazilian RS population add to our knowledge of genotype/phenotype correlations, guiding the implementation of mutation searching programs.

Variant Rett Syndrome in a Girl with a Pericentric X-Chromosome Inversion Leading to Epigenetic Changes and Overexpression of the MECP2 Gene

Rett syndrome is a neurodevelopmental disorder caused by mutations in the MECP2 gene. We investigated the genetic basis of disease in a female patient with a Rett-like clinical. Karyotype analysis revealed a pericentric inversion in the X chromosome -46,X,inv(X)(p22.1q28), with breakpoints in the cytobands where the MECP2 and CDKL5 genes are located. FISH analysis revealed that the MECP2 gene is not dislocated by the inversion. However, and in spite of a balanced pattern of X inactivation, this patient displayed hypomethylation and an overexpression of the MECP2 gene at the mRNA level in the lymphocytes (mean fold change: 2.55±0.38) in comparison to a group of control individuals; the expression of the CDKL5 gene was similar to that of controls (mean fold change: 0.98±0.10). No gains or losses were detected in the breakpoint regions encompassing known or suspected transcription regulatory elements. We propose that the de-regulation of MECP2 expression in this patient may be due to alterations in long-range genomic interactions caused by the inversion and hypothesize that this type of epigenetic de-regulation of the MECP2 may be present in other RTT-like patients.

Rett Syndrome With and Without Detected MECP2 Mutations: an Attempt to Redefine Phenotypes

Background: The diagnosis of Rett syndrome (RTT) is based on a set of clinical criteria, irrespective of mutation status. The aims of this study were (1) to define the clinical differences existing between patients with Rett syndrome with (Group I) and without a MECP2 mutation (Group II), and (2) to characterize the phenotypes associated with the more common MECP2 mutations. Patients and Methods: We analyzed 87 patients fulfilling the clinical criteria for RTT. All were observed and videotaped by the same paediatric neurologist. Seven common mutations were considered separately, and associated clinical features analysed. Results: Comparing Group I and II, we found differences concerning psychomotor development prior to onset, acquisition of propositive manipulation and language, and evolving autistic traits. Based on age at observation, we found differences in eye pointing, microcephaly, growth, number of stereotypies, rigidity, ataxia and ataxic-rigid gait, and severity score. Patients with truncating differed from those with missense mutations regarding acquisition of propositive words and independent gait, before the beginning of the disease, and microcephaly, growth, foot length, dystonia, rigidity and severity score, at the time of observation. Patients with the R168X mutation had a more severe phenotype, whereas those with R133C showed a less severe one. Patients with R294X had a hyperactive behaviour, and those with T158M seemed to be particularly ataxic and rigid. Conclusion: A clear regressive period (with loss of prehension and language, deceleration of growth) and the presence of more than three different stereotypies, rigidity and ataxic-rigid gait seemed to be very helpful in differentiating Group I from Group II.

Analysis of Highly Conserved Regions of the 3'UTR of MECP2 Gene in Patients with Clinical Diagnosis of Rett Syndrome and Other Disorders Associated with Mental Retardation

In this work we explored the role of the 3'UTR of the MECP2 gene in patients with clinical diagnosis of RTT and mental retardation; focusing on regions of the 3'UTR with almost 100% conservation at the nucleotide level among mouse and human. By mutation scanning (DOVAM-S technique) the MECP2 3'UTR of a total of 66 affected females were studied. Five3'UTR variants in the MECP2 were found (c.1461+9G>A, c.1461+98insA, c.2595G>A, c.9961C>G and c.9964delC) in our group of patients. None of the variants found is located in putative protein-binding sites nor predicted to have a pathogenic role. Our data suggest that mutations in this region do not account for a large proportion of the RTT cases without a genetic explanation.

Mutations in the MECP2 Gene Are Not a Major Cause of Rett Syndrome-Like or Related Neurodevelopmental Phenotype in Male Patients

Rett syndrome is a genetic neurodevelopmental disorder that affects mainly girls, but mutations in the causative MECP2 gene have also been identified in boys with classic Rett syndrome and Rett syndrome-like phenotypes. We have studied a group of 28 boys with a neurodevelopmental disorder, 13 of which with a Rett syndrome-like phenotype; the patients had diverse clinical presentations that included perturbations of the autistic spectrum, microcephaly, mental retardation, manual stereotypies, and epilepsy. We analyzed the complete coding region of the MECP2 gene, including the detection of large rearrangements, and we did not detect any pathogenic mutations in the MECP2 gene in these patients, in whom the genetic basis of disease remained unidentified. Thus, additional genes should be screened in this group of patients.

Variation in novel exons (RACEfrags) of the MECP2 gene in Rett syndrome patients and controls.

The study of transcription using genomic tiling arrays has lead to the identification of numerous additional exons. One example is the MECP2 gene on the X chromosome; using 5'RACE and RT-PCR in human tissues and cell lines, we have found more than 70 novel exons (RACEfrags) connecting to at least one annotated exon.. We sequenced all MECP2-connected exons and flanking sequences in 3 groups: 46 patients with the Rett syndrome and without mutations in the currently annotated exons of the MECP2 and CDKL5 genes; 32 patients with the Rett syndrome and identified mutations in the MECP2 gene; 100 control individuals from the same geoethnic group. Approximately 13 kb were sequenced per sample, (2.4 Mb of DNA resequencing). A total of 75 individuals had novel rare variants (mostly private variants) but no statistically significant difference was found among the 3 groups. These results suggest that variants in the newly discovered exons may not contribute to Rett syndrome. Interestingly however, there are about twice more variants in the novel exons than in the flanking sequences (44 vs. 21 for approximately 1.3 Mb sequenced for each class of sequences, p=0.0025). Thus the evolutionary forces that shape these novel exons may be different than those of neighboring sequences.

Quantification of functional abilities in Rett syndrome: a comparison between stages III and IV

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Facilitating communication in children with multiple disabilities: three case studies of girls with Rett syndrome

Purpose: To investigate the effect of cueing on communicative responses of children with multiple disabilities in an educational setting. It was hypothesized that differences would exist in teacher interactional styles and the use of orienting cues would increase the communicative responses of the participants. Method: A naturalistic observation research method was employed in order to examine the interaction of three student-teacher dyads in three special schools. Three different activity types were videotaped from which interactions were coded and analysed. Results: Multi-modal cueing facilitated communicative responses of children with Rett syndrome. However, increased communication opportunities provided by caregivers did not elicit increased responses from the girls. Conclusion: There is a difference in cueing by teachers in their interactions with children with multiple disabilities. Also, more frequent communicative interactions did not necessarily lead to increased student responses. It is suggested that amount and type of cueing may need to be considered to be effective in generating student responses. The small number of participants, however, means findings should be viewed cautiously and that more research is indicated.

Behaviour state analysis in Rett syndrome: Continuous data reliability measurement

Awareness of optimal behaviour states of children with profound intellectual disability has been reported in the literature as a potentially useful tool for planning intervention within this population. Some arguments have been raised, however, which question the reliability and validity of previously published work on behaviour state analysis. This article sheds light on the debate by presenting two stages of a study of behaviour state analysis for eight girls with Rett syndrome. The results support Mudford, Hogg, and Roberts' (1997, 1999) concerns with the pooling of participant data. The results of Stage 2 also suggest, however, that most categories of behaviour state can be reliably distinguished once definitions of behaviours for each state are clearly defined.

Rett syndrome

Rett syndrome is one of the most common causes of complex disability in girls. It is characterized by early neurological regression that severely affects motor, cognitive and communication skills, by autonomic dysfunction and often a seizure disorder. It is a monogenic X-linked dominant neurodevelopmental disorder related to mutation in MECP2, which encodes the methyl-CpG-binding protein MeCP2. There are several mouse models either based on conditional knocking out of the Mecp2 gene or on a truncating mutation. We discuss the clinical aspects with special emphasis on the behavioral phenotype and we review current perspectives in clinical management alongside with perspectives in altering gene expression. Copyright © 2012 S. Karger AG, Basel.

Síndrome de Rett: estudo retrospectivo e prospectivo de 28 pacientes

From November 1982 to May 1999, 28 children with Rett syndrome were followed-up for a medium period of 6 years and 2 months. Regression of developmental milestones started at the age between 5 and 20 months. Nineteen cases of typical Rett syndrome had uneventful pre and perinatal periods, loss of previously acquired purposeful hand skills, mental and motor regression and developed hand stereotypies; sixteen had head growth deceleration and 12 gait apraxia. Nine patients were atypical cases, 2 formes frustres, 2 congenital, 3 with early seizure onset, 1 preserved speech and 1 male. Epilepsy was present in 21 patients, predominantly partial seizures and the drug of choise was carbamazepine (15 patients). In the initial evaluation most patients were distributed on Stages II and III and on follow-up on Stages III and IV. Three children died.

Evaluation of CSF Neurotransmitters and Folate in 25 Patients with Rett Disorder and Effects of Treatment

Background: Rett disorder (RD) is a progressive neurodevelopmental entity caused by mutations in the MECP2 gene. It has been postulated that there are alterations in the levels of certain neurotransmitters and folate in the pathogenesis of this disease. Here we re-evaluated this hypothesis. Patients and Methods: We evaluated CSF folate, biogenic amines and pterines in 25 RD patients. Treatment with oral folinic acid was started in those cases with low folate. Patients were clinically evaluated and videotaped up to 6 months after therapy. Results: CSF folate was below the reference values in 32% of the patients. Six months after treatment no clinical improvement was observed. Three of the four patients with the R294X mutation had increased levels of a dopamine metabolite associated to a particular phenotype. Three patients had low levels of a serotonin metabolite. Two of them were treated with fluoxetine and one showed clinical improvement. No association was observed between CSF folate and these metabolites, after adjusting for the patients age and neopterin levels. Conclusion: Our results support that folinic acid supplementation has no significant effects on the course of the disease. We report discrete and novel neurotransmitter abnormalities that may contribute to the pathogenesis of RD highlighting the need for further studies on CSF neurotransmitters in clinically and genetically well characterized patients.

Equinoterapia en niñas con síndrome de Rett

El presente estudio tiene como objetivo principal la valoración de los beneficios que la equinoterapia tiene en niñas afectadas con síndrome de Rett, y se llevará a cabo en un centro hípico que reúna las condiciones e instalaciones necesarias para poder realizar las sesiones de tratamiento. Será un estudio cualitativo y transversal, en el que participarán tanto fisioterapeutas expertos en el ámbito de la equinoterapia como niñas con síndrome de Rett que estén siendo tratadas con ella. Mediante entrevistas semiestructuradas de respuesta abierta a los profesionales y a los familiares cercanos de las niñas, se podrá recopilar la información necesaria para la elaboración de los resultados finales. La utilización de la equinoterapia debería ser una útil herramienta más de la que pudiera disponer la medicina y, concretamente, la fisioterapia para el tratamiento de los trastornos neurológicos o de muchos otros. Las posibles limitaciones de este estudio pueden ser la falta de niñas que cumplan los requisitos necesarios para participar en el proyecto, debido a que el síndrome de Rett es una enfermedad minoritaria.

Sindrome de Rett

Neste Projecto de Investigação proponho abordar questões relacionadas com o Síndrome de Rett, pois é uma temática pouco estudada e consequentemente, a bibliografia é escassa. Tendo um grande interesse pela Deficiência Mental e sabendo que há muitas coisas, e algumas muito boas, pretendo com este estudo saber mais acerca das necessidades e das competências da criança com Síndrome de Rett. A experiência profissional, por opção própria e consciente, relaciona-se com crianças portadoras de deficiências. Os profissionais que trabalham nesta área gostam do que fazem, do qual os professores de Ensino Especial e, por isso, há o intuito de ter possibilidades em compreender todas as vontades e desejos, alegrias e tristezas, conforto e desconforto que as nossas crianças nos comunicam, muitas vezes com um simples olhar. Sabemos que podemos trabalhar juntos, de mãos dadas, para que isso aconteça, como dizia Carl Sandburg: "Enquanto há vida, há esperança". É emocionante quando nos encontramos a caminho de novas descobertas que nos tragam respostas às nossas questões e à esperança de tratamentos que ajudarão as crianças com Síndrome de Rett. Nas palavras de Eleanor Roosevelt, “nunca duvide que o comprometimento de um pequeno grupo de pessoas dedicadas possa mudar o mundo. Na verdade é a única coisa que pode”. Flocos de neve são uma das coisas mais frágeis da natureza... mas veja só o que eles podem fazer quando se juntam! Por outro lado pretende-se planear Programas de Intervenção apropriados. Com base nestes pressupostos aceitei o desafio e encaro o tema pelo que tem de novidade e, aprofundar os conhecimentos na área da deficiência mental. O Projecto encontra-se organizado em duas partes. Na primeira parte, proceder-se-á à análise da literatura onde se fará a apresentação da problemática e dos conceitos fundamentais do trabalho. Tentar-se-á fazer uma abordagem a vários aspectos que se consideram de grande importância para a compreensão desta deficiência. Assim, nesta parte I caracterizar-se-á o Síndrome de Rett, analisar-se-ão as suas causas, o diagnóstico e medidas de intervenção médica, terapêutica, educativa, pedagógica, psicológica e social. Parte II, apresentar-se-á o objecto de estudo, de acordo com a pergunta de partida. Especificar-se-ão as hipóteses teóricas que estão na base desta pesquisa e as respectivas variáveis dependentes e independentes que visarão estabelecer elos de ligação causa e efeito. Apresentar-se-á os instrumentos de pesquisa e os aspectos metodológicos respeitantes ao estudo de uma criança com Síndrome de Rett sobre a qual serão colhidos dados para a elaboração deste trabalho. Surgem as considerações finais e conclusão onde se colocarão questões e pistas sobre a importância do conhecimento das dificuldades e competências adquiridas pela criança para a elaboração de um Projecto de Intervenção. Faz-se também referência à bibliografia consultada para recolha de dados necessários à realização deste estudo. Os anexos constarão de um glossário.