Patients with the R133C mutation: is their phenotype different from patients with Rett syndrome with other mutations?

A proteomic approach to investigate the role of the MECP2 gene mutation in Rett syndrome redox regulatory pathways

Mutations in the X-linked methyl-CpG-binding 2 (MECP2) gene lead to Rett Syndrome (RTT; OMIM 312750), a devasting neurodevelopmental disorder. RTT clinical manifestations are complex and with different degrees of severity, going from autistic-like behavior to loss of acquired speech, motor skills and cardiac problems. Furthermore, the correlation between the type of MECP2 mutation and the clinical phenotype is still not fully understood. Contextually, different genotypes can differently affect the patient's phenotype and omics methodologies such as proteomics could be an important tool for a molecular characterization of genotype/phenotype correlation. The aim of our study was focused on evaluating RTT oxidative stress (OS) responses related to specific MECP2 gene mutations by using proteomics and bioinformatics approaches. Primary fibroblasts isolated from patients affected by R133C and R255× mutations were compared to healthy controls (HC). After clustering primary dermal fibroblasts based on their specific MECP2 mutations, fibroblast-derived protein samples were qualitative and quantitative analyzed, using a label free quantification (LFQ) analysis by mass spectrometry (MS), achieving a preliminary correlation for RTT genotype/phenotype. Among the identified proteins involved in redox regulation pathways, NAD(P)H:quinone acceptor oxidoreductase 1 (NQO1) was found to be absent in R255× cells, while it was present in R133C and in HC fibroblasts. Moreover, NQO1 aberrant gene regulation was also confirmed when cells were challenged with 100 μM hydrogen peroxide (H2O2). In conclusion, by employing a multidisciplinary approach encompassing proteomics and bioinformatics analyses, as well as molecular biology assays, the study uncovered phenotypic responses linked to specific MECP2 gene mutations. These findings contribute to a better understanding of the complexity of RTT molecular pathways, confirming the high heterogeneity among the patients.

Genotype and sleep independently predict mental health in Rett syndrome: an observational study

BACKGROUND

Rett syndrome is a genetically caused neurodevelopmental disorder associated with severe impairments and complex comorbidities. This study examined predictors of anxiety and depression in Rett syndrome, including genotype.

METHODS

The International Rett Syndrome Database, InterRett, was the data source for this observational study. Associations between genotype, functional abilities, comorbidities, anxiety and depression were estimated with univariate and multivariate regression models. An additional regression model for anxiety included use of an anxiety medication as a predictor variable.

RESULTS

The sample included 210 individuals aged 6-51 years of whom 54 (25.7%) were on psychotropic medication for anxiety or depression. Individuals with the p.Arg294* variant had the highest anxiety scores, as did those with insomnia or excessive daytime sleepiness, irrespective of anxiety medication use. Individuals with the p.Arg306Cys variant had the lowest depression scores, as did those with insomnia or excessive daytime sleepiness.

CONCLUSION

Findings indicated that genotype and sleep have implications for mental health in Rett syndrome, suggesting that anticipatory guidance and proactive management of poor sleep could improve mental health. More research is needed to understand the effects of psychometric medications, which cannot be inferred from this cross-sectional study.

State-of-the-art therapies for Rett syndrome

Rett syndrome (RTT) is an X-linked neurogenetic disorder caused by mutations of the MECP2 (methyl-CpG-binding protein 2) gene. Over two decades of work established MeCP2 as a protein with pivotal roles in the regulation of the epigenome, neuronal physiology, synaptic maintenance, and behaviour. Given the genetic aetiology of RTT and the proof of concept of its reversal in a mouse model, considerable efforts have been made to design therapeutic approaches to re-express MeCP2. By being at the forefront of the development of innovative gene therapies, research on RTT is of paramount importance for the treatment of monogenic neurological diseases. Here we discuss the recent advances and challenges of promising genetic strategies for the treatment of RTT including gene replacement therapies, gene/RNA editing strategies, and reactivation of the silenced X chromosome. WHAT THIS PAPER ADDS: Recent advances shed light on the promises of gene replacement therapy with new vectors designed to control the levels of MeCP2 expression. New developments in DNA/RNA editing approaches or reactivation of the silenced X chromosome open the possibility to re-express the native MeCP2 locus at endogenous levels. Current strategies still face limitations in transduction efficiency and future work is needed to improve brain delivery.

Repeat after Me(CP2)!

A motif of dinucleotide repeats in the genome may be associated with Rett syndrome

Profiling beneficial and potential adverse effects of MeCP2 overexpression in a hypomorphic Rett syndrome mouse model

De novo loss-of-function mutations in methyl-CpG-binding protein 2 (MeCP2) lead to the neurodevelopmental disorder Rett syndrome (RTT). Despite promising results from strategies aimed at increasing MeCP2 levels, additional studies exploring how hypomorphic MeCP2 mutations impact the therapeutic window are needed. Here, we investigated the consequences of genetically introducing a wild-type MECP2 transgene in the Mecp2 R133C mouse model of RTT. The MECP2 transgene reversed the majority of RTT-like phenotypes exhibited by male and female Mecp2 R133C mice. However, three core symptom domains were adversely affected in female Mecp2^R133C/+ animals; these phenotypes resemble those observed in disease contexts of excess MeCP2. Parallel control experiments in Mecp2^Null/+ mice linked these adverse effects to the hypomorphic R133C mutation. Collectively, these data provide evidence regarding the safety and efficacy of genetically overexpressing functional MeCP2 in Mecp2 R133C mice and suggest that personalized approaches may warrant consideration for the clinical assessment of MeCP2-targeted therapies.

Gross Motor, Physical Activity and Musculoskeletal Disorder Evaluation Tools for Rett Syndrome: A Systematic Review

In recent years, much attention has been paid to motor impairment of persons with Rett Syndrome (RTT), with increasing literature aimed to describe gross motor functioning and musculoskeletal disorders of the RTT population. The aim of this systematic review is to describe clinical evaluation tools used in the last decade to assess motor functioning and musculoskeletal abnormalities of patients with RTT. Thirty-four studies were reviewed and 20 tools were presented. Results showed that only two tools were used to measure functional change after rehabilitative or therapeutic interventions. This review underlies the lack of adequate evaluation tools to assess musculoskeletal abnormalities and deformities in RTT population. The absence of these assessments could be due to a statistical difficulty as it is challenging to build an evaluation tool that can score the entities of the abnormalities related to the amount of disability they cause.

Determinants of quality of life in Rett syndrome: new findings on associations with genotype

BACKGROUND

Rett syndrome is a genetically caused neurodevelopmental disorder associated with functional deficits and comorbidities. This study investigated relationships between genotype, functional abilities and comorbidities and quality of life in Rett syndrome.

METHODS

The International Rett Syndrome Database, InterRett, was used as a sampling frame for this observational study. Information was collected to describe functional abilities (walking and feeding), health (Sleep Disorder Scale for Children, the Rett Syndrome Behavioural Questionnaire), parental health (12-item Short Form Health Survey) sociodemographic factors (parental employment and education) and quality of life (Quality of Life Inventory-Disability) for 210 individuals with Rett syndrome. Univariate and multivariate regressions were used to analyse the relationships between the independent variables and quality of life.

RESULTS

Compared with individuals with the p.Arg270* mutation, those with the p.Arg294* mutation type had the poorest quality of life (coeff -12.81, 95% CI -23.49 to 2.12), despite this being recognised as a clinically milder genotype. Overall better walking and feeding skills and seizure parameters were more associated with better quality of life and poor sleep and behavioural difficulties with poorer quality of life.

CONCLUSIONS

These findings suggest that genotype, functioning and health each have implications for quality of life and should be considered when counselling families and planning clinical and support management strategies.

Methyl-CpG-binding protein 2 (MECP2) mutation type is associated with bone disease severity in Rett syndrome

Background

More than 95% of individuals with RTT have mutations in methyl-CpG-binding protein 2 (MECP2), whose protein product modulates gene transcription. The disorder is caused by mutations in a single gene and the disease severity in affected individuals can be quite variable. Specific MECP2 mutations may lead phenotypic variability and different degrees of disease severity. It is known that low bone mass is a frequent and early complication of subjects with Rett syndrome. As a consequence of the low bone mass Rett girls are at an increased risk of fragility fractures. This study aimed to investigate if specific MECP2 mutations may affects the degree of involvement of the bone status in Rett subjects.

Methods

In 232 women with Rett syndrome (mean age 13.8 ± 8.3 yrs) we measured bone mineral density at whole body and at femur (BMD-FN and BMD-TH) by using a DXA machine (Hologic QDR 4500). QUS parameters were assessed at phalanxes by Bone Profiler-IGEA (amplitude dependent speed of sound: AD-SoS and bone transmission time: BTT). Moreover, ambulation capacity (independent or assisted), fracture history and presence of scoliosis were assessed. We divided the subjects with the most common point mutations in two group based on genotype-phenotype severity; in particular, there has been consensus in recognising that the mutations R106T, R168X, R255X, R270X are considered more severe.

Results

As aspect, BMD-WB, BMD-FN and BMD-TH were lower in subjects with Rett syndrome that present the most severe mutations with respect to subjects with Rett syndrome with less severe mutations, but the difference was statistically significant only for BMD-FN and BMD-TH (p < 0.05). Also both AD-SoS and BTT values were lower in subjects that present the most severe mutations with respect to less severe mutations but the difference was not statistically significant. Moreover, subjects with Rett syndrome with more severe mutations present a higher prevalence of scoliosis (p < 0.05) and of inability to walk (p < 0.05).

Conclusion

This study confirms that MECP2 mutation type is a strong predictor of disease severity in subjects with Rett syndrome. In particular, the subjects with more severe mutation present a greater deterioration of bone status, and a higher prevalence of scoliosis and inability to walk.

Longitudinal effects of caregiving on parental well-being: the example of Rett syndrome, a severe neurological disorder

Little longitudinal research has examined parental well-being in those with a child with specific genetic developmental disorder although the associated severe neurological impairments and multiple physical comorbidities likely place substantial burden of caregiving on the parent. We aimed to examine longitudinally the well-being of parents of individuals included in the Australian Rett Syndrome Database over the period from 2002 to 2011 using the Short Form 12 Health Survey. Residential remoteness, the child being a teenager at baseline, having frequent sleep disturbances or behavioural problems, and the type of MECP2 gene mutation were each associated with later poorer parental physical well-being scores. Being a single parent or on a low income was also associated with later poorer physical well-being, while the child having enteral feeding was associated with later poorer emotional well-being. Both the physical and emotional well-being of the parent improved if the child was living in out-of-home care. Our findings suggest that some opportunities do exist for clinicians to help optimise parental well-being. Being alert to the possibility and need for management of a child's sleep or emotional disturbance is important as is awareness of the additional likely parental burden as the child moves through adolescence into early adulthood and their need for additional support at that time. However, the findings also highlight the complex nature of parental well-being over time in parents of children with a severe neurological disorder and how they may be affected by a range of inter-related family and child factors.

Quality of life related to clinical features in patients with Rett syndrome and their parents: a systematic review

Patients with a neurodevelopmental disorder such as Rett syndrome (RS), as well as their families, have complex needs that affect their quality of life (QoL). Therefore, both families and patients with RS must be provided with multidisciplinary health care that can identify the clinical features that most affect their QoL and mental health risks. The main objective of this paper is to provide a comprehensive overview of the QoL subdimensions of families affected by RS, including both the parents and children. We conducted a systematic review, following PRISMA criteria, of the data in the PubMed, PsycINFO, Cuiden, and LILACS databases. The results indicated that when considering the family as a whole, RS equally affects the physical and psychological QoL dimensions; the next most affected was the social dimension. According to parents' reports, seizures are one of the main factors that decreases their QoL. Thus, from a clinical point of view, controlling seizure activity of children with RS is the main way of improving the QoL of their parents. Interventions in patients affected by RS should be based on the improvement of visual contact and concentration, reducing somnolence, and increasing mobility. The subdimensions of QoL that were most affected in parents of girls with RS were those related to mental health and feelings of well-being.

From Function to Phenotype: Impaired DNA Binding and Clustering Correlates with Clinical Severity in Males with Missense Mutations in MECP2

Mutations in the MECP2 gene cause Rett syndrome (RTT). MeCP2 binds to chromocentric DNA through its methyl CpG-binding domain (MBD) to regulate gene expression. In heterozygous females the variable phenotypic severity is modulated by non-random X-inactivation, thus making genotype-phenotype comparisons unreliable. However, genotype-phenotype correlations in males with hemizygousMECP2 mutations can provide more accurate insights in to the true biological effect of specific mutations. Here, we compared chromatin organization and binding dynamics for twelve MeCP2 missense mutations (including two novel and the five most common MBD missense RTT mutations) and identifiedacorrelation with phenotype in hemizygous males. We observed impaired interaction of MeCP2-DNA for mutations around the MBD-DNA binding interface, and defective chromatin clustering for distal MBD mutations. Furthermore, binding and mobility dynamics show a gradient of impairment depending on the amino acid properties and tertiary structure within the MBD. Interestingly, a wide range of phenotypic/clinical severity, ranging from neonatal encephalopathy to mild psychiatric abnormalities were observed and all are consistent with our functional/molecular results. Overall, clinical severity showed a direct correlation with the functional impairment of MeCP2. These mechanistic and phenotypic correlations of MeCP2 mutations will enable improved and individualized diagnostics, and may lead to personalized therapeutic interventions.

An Exploration of the Use of Eye Gaze and Gestures in Females With Rett Syndrome

PURPOSE

This study investigated the communicative use of eye gaze and gestures in females with Rett syndrome.

METHOD

Data on 151 females with Rett syndrome participating in the Australian Rett Syndrome Database was used in this study. Items from the Communication and Symbolic Behavior Scales Developmental Profile Infant-Toddler Checklist (Wetherby & Prizant, 2002) were used to measure communication. Relationships between the use of eye gaze and gestures for communication were investigated using logistic regression. The influences of MECP2 mutation type, age, and level of motor abilities on the use of eye gaze and gestures were investigated using multivariate linear regression.

RESULTS

Both eye gaze and the use of gestures predicted the ability to make requests. Women aged 19 years or older had the lowest scores for eye gaze. Females with better gross motor abilities had higher scores for the use of eye gaze and gestures. The use of eye gaze did not vary across mutation groups, but those with a C-terminal deletion had the highest scores for use of gestures.

CONCLUSIONS

Eye gaze is used more frequently than gestures for communication, and this is related to age, MECP2 mutation type, and gross motor abilities.

Silent angels the genetic and clinical aspects of Rett syndrome

Rett syndrome is a neurodevelopmental genetic disorder and, because of some behavioral characteristics, individuals affected by the disease are known as silent angels. Girls with Rett syndrome perform stereotyped movements, they have learning difficulties, their reaction time is prolonged, and they seem alienated in the environment. These children require constant pediatric, neurological and orthopedic care. In the treatment of Rett syndrome physical therapy, music therapy, hydrotherapy, hippotherapy, behavioral methods, speech therapy and diet, are also used. In turn, psychological therapy of the syndrome is based on the sensory integration method, using two or more senses simultaneously. In 80% of cases, the syndrome is related to mutations of the MECP2 gene, located on chromosome X. The pathogenesis of Rett syndrome is caused by the occurrence of a non-functional MeCP2 protein, which is a transcription factor of many genes, i.e. Bdnf, mef2c, Sgk1, Uqcrc1. Abnormal expression of these genes reveals a characteristic disease phenotype. Clinical symptoms relate mainly to the nervous, respiratory, skeletal and gastrointestinal systems. Currently causal treatment is not possible. However, researchers are developing methods by which, perhaps in the near future, it will be possible to eliminate the mutations in the MECP2 gene, and this will give a chance to the patient for normal functioning.

The paper presents the etiology and pathogenesis of the disease, genetic, clinical, pharmacological aspects and other forms of Rett syndrome treatment.

Rett syndrome: a wide clinical and autonomic picture

Background

Rett Syndrome is a neurodevelopmental disorder almost exclusively affecting females, characterized by a broad clinical spectrum of signs and symptoms and a peculiar course. The disease affects different body systems: nervous, muscolo-skeletal, gastro-enteric. Moreover, part of the symptoms are related to the involvement of the autonomic nervous system.

In the Tuscany Rett Center at Versilia Hospital, we collected data from 151 subjects with a clinical diagnosis of classical or variant RTT syndrome. For each subject, we assessed the severity of the condition with clinical-rating scales (ISS, PBZ), we quantified the performance of the autonomic nervous system, and we performed genetic analysis. We used multivariate statistical analysis of the data to evaluate the relation between the different clinical RTT forms, the cardiorespiratory phenotype, the different genetic mutations and the severity of the clinical picture. Individuals were classified according to existing forms: Classical RTT and three atypical RTT: Z-RTT, Hanefeld, Congenital. A correlation between C-Terminal deletions and lower severity of the clinical manifestations was evident, in the previous literature, but, considering the analysis of autonomic behaviour, the original classification can be enriched with a more accurate subdivision of Rett subgroups, which may be useful for early diagnosis.

Results

Present data emphasize some differences, not entirely described in the literature, among RTT variants. In our cohort the Z-RTT variant cases show clinical features (communication, growth, epilepsy and development), well documented by specific ISS items, less severe, if compared to classical RTT and show autonomic disorders, previously not reported in the literature. In this form epilepsy is rarely present. In contrast, Hanefeld variant shows the constant presence of epilepsy which has an earlier onset In Hanefeld variant the frequency of apneas was rare and, among the cardiorespiratory phenotypes, the feeble type is lacking.

Conclusion

A quantitative analysis of the different autonomic components reveals differences across typical and atypical forms of RTT that leads to a more accurate classification of the groups. In our cohort of RTT individuals, the inclusion of autonomic parameter in the classification leads to an improved diagnosis at earlier stages of development.

Neurophysiology versus clinical genetics in Rett syndrome: A multicenter study

Many studies have attempted to establish the genotype-phenotype correlation in Rett syndrome (RTT). Cardiorespiratory measurements provide robust objective data, to correlate with each of the different clinical phenotypes. It has important implications for the management and treatment of this syndrome. The aim of this study was to correlate the genotype with the quantitative cardiorespiratory data obtained by neurophysiological measurement combined with a clinical severity score. This international multicenter study was conducted in four European countries from 1999 to 2012. The study cohort consisted of a group of 132 well-defined RTT females aged between 2 and 43 years with extended clinical, molecular, and neurophysiological assessments. Diagnosis of RTT was based on the consensus criteria for RTT and molecular confirmation. Genotype-phenotype analyses of clinical features and cardiorespiratory data were performed after grouping mutations by the same type and localization or having the same putative biological effect on the MeCP2 protein, and subsequently on eight single recurrent mutations. A less severe phenotype was seen in females with CTS, p.R133C, and p.R294X mutations. Autonomic disturbances were present in all females, and not restricted to nor influenced by one specific group or any single recurrent mutation. The objective information from non-invasive neurophysiological evaluation of the disturbed central autonomic control is of great importance in helping to organize the lifelong care for females with RTT. Further research is needed to provide insights into the pathogenesis of autonomic dysfunction, and to develop evidence-based management in RTT. © 2016 Wiley Periodicals, Inc.

Parental perspectives on the communication abilities of their daughters with Rett syndrome

OBJECTIVE

This study describes, from the perspective of parents, how females with Rett syndrome communicate in everyday life and the barriers and facilitators to successful communication.

METHODS

Sixteen interviews were conducted with parents with a daughter with Rett syndrome with a pathogenic mutation in the methyl-CpG-binding protein 2 gene. Interviews were recorded and transcribed verbatim. Transcripts were analysed using directed content analysis.

RESULTS

All parents reported their daughters were able to express discomfort and pleasure, and make requests and choices using a variety of modalities including vocalisations, body movements and eye gaze. Parents also reported their daughters understood most of what they said and that the level of functional abilities, such as mobility, and environmental factors, such as characteristics of the communication partner, influenced successful communication.

CONCLUSIONS

The perspectives of parents are integral to the assessment of communication abilities and have the potential to inform communication interventions for girls and women with Rett syndrome.

How can clinical ethics guide the management of comorbidities in the child with Rett syndrome?

Rett syndrome is a rare disorder caused by a mutation in the MECP2 gene. Those affected generally have severe functional impairments, and medical comorbidities such as scoliosis and poor growth are common. There is a paucity of information on the natural history of many rare disorders and an even greater deficit of evidence to guide best practice. The population-based and longitudinal Australian Rett Syndrome Database established in 1993 has supported investigations of the natural history of Rett syndrome and effectiveness of treatments. This paper reviews the disorder Rett syndrome and evidence for the management of scoliosis and poor growth within a clinical ethics framework. Compared with conservative management, we have shown that spinal fusion is associated with reduced mortality and better respiratory health. We have also shown that gastrostomy insertion is associated with subsequent weight gain. Family counselling for both procedures necessarily must include family perspectives and careful clinical attention to their needs and wishes. Vignettes describing family decision-making and experiences are presented to illustrate the principals of beneficence and autonomy in determining the best interests of the child and family. A blend of evidence-based practice with a strong clinical ethics framework has capacity to build existing strengths in families and reduce the negative impacts of disability and in so doing, optimise the health and wellbeing of those with Rett syndrome.

Experience of gastrostomy using a quality care framework: the example of rett syndrome

Rett syndrome is one of many severe neurodevelopmental disorders with feeding difficulties. In this study, associations between feeding difficulties, age, MECP2 genotype, and utilization of gastrostomy were investigated. Weight change and family satisfaction following gastrostomy were explored. Data from the longitudinal Australian Rett Syndrome Database whose parents provided data in the 2011 family questionnaire (n=229) were interrogated. We used logistic regression to model relationships between feeding difficulties, age group, and genotype. Content analysis was used to analyze data on satisfaction following gastrostomy. In those who had never had gastrostomy and who fed orally (n=166/229), parents of girls<7 years were more concerned about food intake compared with their adult peers (odds ratio [OR] 4.26; 95% confidence interval [CI] 1.29, 14.10). Those with a p.Arg168 mutation were often perceived as eating poorly with nearly a 6-fold increased odds of choking compared to the p.Arg133Cys mutation (OR 5.88; 95% CI 1.27, 27.24). Coughing, choking, or gagging during meals was associated with increased likelihood of later gastrostomy. Sixty-six females (28.8%) had a gastrostomy, and in those, large MECP2 deletions and p.Arg168 mutations were common. Weight-for-age z-scores increased by 0.86 (95% CI 0.41, 1.31) approximately 2 years after surgery. Families were satisfied with gastrostomy and felt less anxious about the care of their child. Mutation type provided some explanation for feeding difficulties. Gastrostomy assisted the management of feeding difficulties and poor weight gain, and was acceptable to families. Our findings are likely applicable to the broader community of children with severe disability.

Methyl-CpG-binding protein 2 (MECP2) mutation type is associated with disease severity in Rett syndrome

BACKGROUND

Rett syndrome (RTT), a neurodevelopmental disorder that primarily affects girls, is characterised by a period of apparently normal development until 6-18 months of age when motor and communication abilities regress. More than 95% of individuals with RTT have mutations in methyl-CpG-binding protein 2 (MECP2), whose protein product modulates gene transcription. Surprisingly, although the disorder is caused by mutations in a single gene, disease severity in affected individuals can be quite variable. To explore the source of this phenotypic variability, we propose that specific MECP2 mutations lead to different degrees of disease severity.

METHODS

Using a database of 1052 participants assessed over 4940 unique visits, the largest cohort of both typical and atypical RTT patients studied to date, we examined the relationship between MECP2 mutation status and various phenotypic measures over time.

RESULTS

In general agreement with previous studies, we found that particular mutations, such as p.Arg133Cys, p.Arg294X, p.Arg306Cys, 3° truncations and other point mutations, were relatively less severe in both typical and atypical RTT. In contrast, p.Arg106Trp, p.Arg168X, p.Arg255X, p.Arg270X, splice sites, deletions, insertions and deletions were significantly more severe. We also demonstrated that, for most mutation types, clinical severity increases with age. Furthermore, of the clinical features of RTT, ambulation, hand use and age at onset of stereotypies are strongly linked to overall disease severity.

CONCLUSIONS

We have confirmed that MECP2 mutation type is a strong predictor of disease severity. These data also indicate that clinical severity continues to become progressively worse regardless of initial severity. These findings will allow clinicians and families to anticipate and prepare better for the needs of individuals with RTT.

Methyl-CpG-binding protein 2 (MECP2) mutation type is associated with disease severity in Rett syndrome

BACKGROUND

Rett syndrome (RTT), a neurodevelopmental disorder that primarily affects girls, is characterised by a period of apparently normal development until 6-18 months of age when motor and communication abilities regress. More than 95% of individuals with RTT have mutations in methyl-CpG-binding protein 2 (MECP2), whose protein product modulates gene transcription. Surprisingly, although the disorder is caused by mutations in a single gene, disease severity in affected individuals can be quite variable. To explore the source of this phenotypic variability, we propose that specific MECP2 mutations lead to different degrees of disease severity.

METHODS

Using a database of 1052 participants assessed over 4940 unique visits, the largest cohort of both typical and atypical RTT patients studied to date, we examined the relationship between MECP2 mutation status and various phenotypic measures over time.

RESULTS

In general agreement with previous studies, we found that particular mutations, such as p.Arg133Cys, p.Arg294X, p.Arg306Cys, 3° truncations and other point mutations, were relatively less severe in both typical and atypical RTT. In contrast, p.Arg106Trp, p.Arg168X, p.Arg255X, p.Arg270X, splice sites, deletions, insertions and deletions were significantly more severe. We also demonstrated that, for most mutation types, clinical severity increases with age. Furthermore, of the clinical features of RTT, ambulation, hand use and age at onset of stereotypies are strongly linked to overall disease severity.

CONCLUSIONS

We have confirmed that MECP2 mutation type is a strong predictor of disease severity. These data also indicate that clinical severity continues to become progressively worse regardless of initial severity. These findings will allow clinicians and families to anticipate and prepare better for the needs of individuals with RTT.

Normal reactions to orthostatic stress in Rett syndrome

The aim of this study was to investigate orthostatic reactions in females with Rett syndrome (RTT), and also whether the severity of the syndrome had an impact on autonomic reactions. Based on signs of impaired function of the central autonomic system found in RTT, it could be suspected that orthostatic reactions were affected. The orthostatic reactions in 21 females with RTT and 14 normally developed females matched by age were investigated when they rose from a sitting position, and during standing for 3 min. Reactions of the heart, the blood pressure and the time for recovery of systolic blood pressure, were studied in real time, heartbeat by heartbeat, simultaneously. There was no difference between participants with RTT and the normally developed controls regarding general orthostatic reactions (heart rate, systolic and diastolic blood pressure, and mean arterial pressure) when getting up from a sitting position, and when standing erect for 3 min. In the specific immediate response by the heart to standing up, the 30:15 ratio, significantly lower values were found for females with RTT. In the RTT group, the maximum fall of systolic blood pressure showed a tendency to a larger decrease, and the initial decrease in systolic blood pressure was significantly faster. The time for recovery of systolic blood pressure from standing erect did not differ between groups. At baseline the females with RTT had significantly lower systolic blood pressure and a tendency to a higher heart rate. The results do not indicate any autonomic limitations for people with RTT in getting up from a sitting position and standing. The participants with RTT had normal orthostatic reactions indicated by the heart and blood pressure responses when standing erect for 3min. A faster initial drop in systolic blood pressure in people with RTT was notable.

The experiences of mothers of young adults with an intellectual disability transitioning from secondary school to adult life

BACKGROUND

The transition from school to adulthood for young adults with an intellectual disability involves movement from a generally secure and supported school environment to an emerging adult life that may be characterised by a wide variation in adoption of adult roles related to employment, independent living, friendships, and day activities.

METHOD

In this study, we investigated the perspectives of 18 mothers of young adults with either Down syndrome or Rett syndrome through qualitative semistructured interviews. The International Classification of Functioning, Disability and Health (ICF) framework was used as a conceptual basis.

RESULTS

Themes that emerged included adult roles assumed during the day, accommodation, quality of life, living a "good" life, and family impact.

CONCLUSIONS

In contrast with Rett syndrome, mothers of young adults with Down syndrome described more difficult pathways to attaining stability in adult roles. Environmental facilitators and barriers emerged in the area of support, relationships, services, systems, and policies.

Mutational analysis of methyl-CpG binding protein 2 (MECP2) gene in Indian cases of Rett syndrome

Rett syndrome (RTT) is an X-linked postnatal neurological disorder, primarily affecting females and characterized by regression, epilepsy, stereotypical hand movements, and motor abnormalities. Its prevalence is about 1 in 10,000 female births. RTT is caused by mutations within methyl CpG-binding protein 2 (MECP2) gene. Over 200 individual nucleotide changes in the gene, which cause pathogenic mutations, have been reported; however, eight most commonly occurring missense and nonsense mutations account for almost 70% of all mutations. RTT cases have also been reported from India. The phenotype (classical and atypical inclusive) has many differentials. However, a genetically based confirmed diagnosis would help in management and counseling. In this pilot study we have analyzed MECP2 mutations in ten Indian sporadic patients diagnosed clinically as having RTT. Two mutations and one novel variant in MECP2 have been detected. Missense mutations p.R133C and c.806delG have been detected. The missence mutation p.R133C was the part of eight hotspots reported in Rett patients. This patient met all the essential criteria except delayed onset of regression. The other c.806delG mutation positive patient also fulfilled all the obligatory criteria of classical RTT. Another clinically atypical Rett patient showed a novel mutation p.C339S in MECP2 gene. The preliminary result necessitates a large-scale study of RTT patients to determine more precisely the influence of MECP2 mutations in Indian patients and their correlation with clinical phenotypes.

The role of oxidative stress in Rett syndrome: an overview

The main cause of Rett syndrome (RTT), a pervasive development disorder almost exclusively affecting females, is a mutation in the methyl-CpG binding protein 2 (MeCP2) gene. To date, no cure for RTT exists, although disease reversibility has been demonstrated in animal models. Emerging evidence from our and other laboratories indicates a potential role of oxidative stress (OS) in RTT. This review examines the current state of the knowledge on the role of OS in explaining the natural history, genotype-phenotype correlation, and clinical heterogeneity of the human disease. Biochemical evidence of OS appears to be related to neurological symptom severity, mutation type, and clinical presentation. These findings pave the way for potential new genetic downstream therapeutic strategies aimed at improving patient quality of life. Further efforts in the near future are needed for investigating the yet unexplored "black box" between the MeCP2 gene mutation and subsequent OS derangement.

Genotype-phenotype relationships as prognosticators in Rett syndrome should be handled with care in clinical practice

Rett syndrome (RTT; OMIM 312750) is an X-linked dominant neurodevelopmental disorder leading to cognitive and motor impairment, epilepsy, and autonomic dysfunction in females. Since the discovery that RTT is caused by mutations in MECP2, large retrospective genotype-phenotype correlation studies have been performed. A number of general genotype-phenotype relationships were confirmed and specific disorder profiles were described. Nevertheless, conflicting results are still under discussion, partly due to the variability in classification of mutations, assessment tools, and structure of the data sets. The aim of this study was to investigate relationships between genotype and specific clinical data collected by the same experienced physician in a well-documented RTT cohort, and evaluate its prognostic value in counseling young parents with a newly diagnosed RTT girl regarding her future outcome. The Maastricht-Leuven Rett Syndrome Database is a register of 137 molecularly confirmed clinical RTT cases, containing both molecular and clinical data on examination and follow up by the same experienced physician. Although the general genotype-phenotype relationships were confirmed, the clinical severity was still found to be very variable. We therefore recommend caution in using genotype-phenotype data in the prognosis of outcome for children in Rett syndrome. Early diagnosis, early intervention, and preventive management are imperative for better outcomes and better quality of daily life for RTT females and their families.

F₄-neuroprostanes mediate neurological severity in Rett syndrome

BACKGROUND

Rett syndrome (RTT) is a pervasive development disorder, mainly caused by mutations in the methyl-CpG binding protein 2 (MeCP2) gene. No reliable biochemical markers of the disease are available. Here we assess F₄-neuroprostanes (F₄-NeuroPs), lipid peroxidation products of the docosahexaenoic acid, as a novel disease marker in RTT and correlate it with clinical presentation, MeCP2 mutation type, and disease progression. In addition, we investigate on the impact of ω-3 polyunsaturated fatty acids (ω-3 PUFAs) supplementation on F₄-NeuroPs levels.

METHODS

A case-control study design was used. A cohort of RTT patients (n=144) exhibiting different clinical presentations, disease stages, and MeCP2 gene mutations were evaluated. F₄-NeuroPs were measured in free form using a GC/NICI-MS/MS technique. Plasma F₄-NeuroPs levels in patients were compared to healthy controls and related to RTT forms, disease progression, and response to ω-3 PUFAs supplementation.

RESULTS

Plasma F₄-NeuroPs levels were i) higher in RTT than in controls; ii) increased with the severity of neurological symptoms; iii) significantly elevated during the typical disease progression; iv) higher in MeCP2-nonsense as compared to missense mutation carriers; v) higher in typical RTT as compared to RTT variants; and vi) decreased in response to 12 months ω-3 PUFAs oral supplementation.

CONCLUSIONS

Quantification of plasma F₄-NeuroPs provides a novel RTT marker, related to neurological symptoms severity, mutation type and clinical presentation.

Longitudinal hand function in Rett syndrome

Loss of hand function is a core feature of Rett syndrome. This article describes longitudinal hand function at 3 time points for 72 subjects participating in the Australian Rett Syndrome Database. Approximately 40% of subjects with some grasping abilities lost skill over the 3- to 4-year period between video assessments. In these subjects, a decrease in hand function was seen less frequently in girls 13 to 19 years old than in those younger than 8 years, in subjects with some mobility compared with those who were wheelchair bound, and in those who had previously been able to finger feed. Relationships with the magnitude of change reflected these findings. Change in hand function did not vary with clinical severity. The results for all subjects were similar to results obtained when analysis was restricted to those with a pathogenic mutation. Variability in the longitudinal course of hand function in Rett syndrome was observed.

The relationship between MECP2 mutation type and health status and service use trajectories over time in a Rett syndrome population

This study aimed to investigate the trajectories over time of health status and health service use in Rett syndrome by mutation type. Data were obtained from questionnaires administered over six years to 256 participants from the Australian Rett Syndrome Database. Health status (episodes of illness and medication load) and health service use (general practitioner and specialist visits and hospital stays) were summarized into composite scores with Principal Component Analysis. Linear and mixed regression models examined effects of mutation type and other variables on these scores over time. For some mutations (such as p.R255X, p.R168X) health status was poorer at a younger age and improved over time, while for p.R133C it was better at a younger age and deteriorated with time. For those with p.R133C health service use was lowest at a younger age and highest at 25 years. With other mutations, such as p.R255X, p.R270X, p.R294X, C terminal and p.R306C, health service use was higher at a younger age, but dropped off considerably by 25 years of age. Health service use generally declined in parallel with deterioration in health status, although this pattern differed by mutation type, demonstrating important variability in the course of Rett syndrome.

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.

Atypical presentations and specific genotypes are associated with a delay in diagnosis in females with Rett syndrome

There is often delay between onset of Rett syndrome symptoms and its diagnosis, possibly related to symptom presentation or socio-demographic factors. We hypothesized that girls with an atypical presentation or whose family had a lower socio-economic status would receive a later diagnosis. Female subjects with a confirmed diagnosis of Rett syndrome were sourced from the Australian Rett Syndrome and InterRett Databases. Variables analyzed included timing and development of symptoms; MECP2 mutation type; parental occupation and education; maternal age and birth order. Residential location and socio-economic status were also analyzed for the Australian cases. Linear regression was used to determine relationships between these factors and age at diagnosis. A total of 909 cases were included. An older age of diagnosis was associated with later loss of hand function and speech, later onset of hand stereotypies and the presence of the p.R133C or p.R294X MECP2 mutation. Socio-economic factors did not predict age of diagnosis for Australian families. For families participating in the InterRett database, a younger age of diagnosis was associated with higher levels of parental education or occupation. A clinical picture consistent with the classic presentation of Rett syndrome is associated with an earlier diagnosis. Clinicians need to be alerted to the variable presentation of Rett syndrome including the milder phenotypes of cases with the p.R133C or p.R294X mutation. Educational resources to assist this understanding including guidance on when to request genetic testing could be useful to streamline the process of diagnosis in Rett syndrome.

Updating the profile of C-terminal MECP2 deletions in Rett syndrome

OBJECTIVES

This study aimed to compare the phenotype of Rett syndrome cases with C-terminal deletions to that of cases with different MECP2 mutations and to examine the phenotypic variation within C-terminal deletions.

METHODS

Cases were selected from InterRett, an international database and from the population-based Australian Rett Syndrome Database. Cases (n=832) were included if they had a pathogenic MECP2 mutation in which the nature of the amino acid change was known. Three severity scale systems were used, and individual aspects of the phenotype were also compared.

RESULTS

Lower severity was associated with C-terminal deletions (n=79) compared to all other MECP2 mutations (e.g. Pineda scale C-terminals mean 15.0 (95% CI 14.0-16.0) vs 16.2 (15.9-16.5). Cases with C-terminal deletions were more likely to have a normal head circumference (odds ratio 3.22, 95% CI 1.53 - 6.79) and weight (odds ratio 2.97, 95% CI 1.25-5.76). Onset of stereotypies tended to be later (median age 2.5 years vs 2 years, p<0.001 from survival analysis), and age of learning to walk tended to be earlier (median age 1.6 years vs 2 years, p=0.002 from survival analysis). Those with C-terminal deletions occurring later in the region had lower average severity scores than those occurring earlier in the region.

CONCLUSION

In terms of overall severity C-terminal deletion cases would appear to be in the middle of the range. In terms of individual aspects of phenotype growth and ability to ambulate appear to be particular strengths. By pooling data internationally this study has achieved the case numbers to provide a phenotypic profile of C-terminal deletions in Rett syndrome.

InterRett, a model for international data collection in a rare genetic disorder

Rett syndrome (RTT) is a rare genetic disorder within the autistic spectrum. This study compared socio-demographic, clinical and genetic characteristics of the international database, InterRett, and the population based Australian Rett syndrome database (ARSD). It also explored the strengths and limitations of InterRett in comparison with other studies. A literature review compared InterRett with RTT population-based and case-based studies of thirty or more cases that investigated genotype and/or phenotype relationships. Questionnaire data were used to determine case status and to investigate the comparability of InterRett and ARSD. Twenty four case series, five population based studies and a MECP2 mutation database were identified of which twenty one (70%) collected phenotype and genotype data. Only three studies were representative of their underlying case population and many had low numbers. Of one thousand one hundred and fourteen InterRett subjects, nine hundred and thirty five born after 1976 could be verified as Rett cases and compared with the two hundred and ninety five ARSD subjects. Although more InterRett families had higher education and occupation levels and their children were marginally less severe, the distribution of MECP2 mutation types was similar. The InterRett can be used with confidence to investigate genotype phenotype associations and clinical variation in RTT and provides an exemplary international model for other rare disorders.

Diagnostic criteria for the Zappella variant of Rett syndrome (the preserved speech variant)

The preserved speech variant is the milder form of Rett syndrome: affected girls show the same stages of this condition and by the second half of the first decade are making slow progress in manual and verbal abilities. They walk without help, and may be able to make simple drawings and write a few words. Most of them can speak in sentences. Autistic behavior can often be observed. We previously described several cases in the pre-molecular era and subsequently reported a survey of 12 cases with MECP2 mutations. Seventeen new patients with the preserved speech variant and a proven MECP2 mutation have been clinically evaluated. Additional clinical data of our previously described cases are reported. These 29 preserved speech variant cases were compared with 129 classic Rett patients using a clinical severity score system including 22 different signs. There was both statistical and clinical evidence of the existence of this variant. On the basis of their abilities these girls can be distinguished as low-, intermediate- and high-functioning. Girls of the last two groups show a greater homogeneity: they speak in sentences, use their hands more easily, have normal somatic features, mild neurovegetative abnormalities, with autistic behavior in 76%, epilepsy in 30%, while girls of the first group are closer to classic Rett syndrome. The majority of patients carries either missense mutations (especially the p.R133C change) or late truncating mutations in the MECP2 gene. These results confirm the existence of this variant of Rett syndrome (Zappella variant), a clear example of progress of manual and verbal abilities, and not of a "preserved speech" and suggest corresponding diagnostic criteria.

Gross motor profile in rett syndrome as determined by video analysis

Movement impairment is a fundamental but variable component of the Rett syndrome phenotype. This study used video supplemented by parent report data to describe the gross motor profile in females with Rett syndrome (n=99) and to investigate the impact of age, genotype, scoliosis and hand stereotypies. Factor analysis enabled the calculation of general and complex gross motor skills scores. Most subjects were able to sit, slightly less than half were able to walk and a minority were able to transfer without assistance. General gross motor skills declined with age and were poorer in those who had surgically treated scoliosis but not conservatively managed scoliosis. Complex gross motor skills did not decline with age and were better in those without scoliosis. Those with a p.R133C, p.R294X, or a p.R255X mutation appear to have better motor skills overall than those with a p.R270X or large deletion mutation. Motor scores were not related to the frequency of hand stereotypies. This information is useful for the clinician and family when planning support strategies and interventions.

The diagnosis of autism in a female: could it be Rett syndrome?

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.

Specific mutations in methyl-CpG-binding protein 2 confer different severity in Rett syndrome

OBJECTIVE

To determine if a relationship exists between the clinical features of Rett syndrome, an X-linked dominant neurodevelopmental disorder, and specific mutations in MECP2.

METHOD

Cross-sectional study of 245 girls and women with typical Rett syndrome seen between 1990 and 2004 in tertiary academic outpatient specialty clinics and who had complete MECP2 mutation analysis. A structured clinical evaluation was completed for each participant. The results were grouped by MECP2 mutation and compared.

RESULTS

Participants with the R133C mutation are less severely affected than those with R168X or large DNA deletions (p < 0.05). Likewise, individuals with the R168X mutation are more severely affected than those with R294X and late carboxy-terminal truncating mutations (p < 0.05). Clinical differences are notable in ambulation, hand use, and language (p < 0.004), three cardinal features of Rett syndrome. Individuals with R168X are less likely to walk (p = 0.008), retain hand use (p = 0.002), or use words (p = 0.001). In contrast, those with carboxy-terminal truncations are more likely to walk (p = 0.007) and use words (p < 0.001). The R306C mutation, previously found to confer milder features, adversely affects only one clinical feature, language (p < 0.05).

CONCLUSIONS

Specific mutations in MECP2 confer different severity. These results allow the design of therapies targeted toward the amelioration of expected problems. Furthermore, the distinct effects of MECP2 mutations on clinical severity must be considered in clinical intervention trials.

Analysis of protein domains and Rett syndrome mutations indicate that multiple regions influence chromatin-binding dynamics of the chromatin-associated protein MECP2 in vivo

The methyl-CpG-binding protein 2 (MECP2) serves both organizational and transcriptional functions in the nucleus, with two well-characterized domains integrally related to these functions. The recognition of methylated CpG dinucleotides is accomplished by the methyl-binding domain (MBD), and the transcriptional repression domain (TRD) facilitates protein-protein interactions with chromatin remodeling proteins. For each known function of MECP2, chromatin binding is a crucial activity. Here, we apply photobleaching strategies within the nucleus using domain-deleted MECP2 proteins as well as naturally occurring point mutations identified in individuals with the neurodevelopmental disorder Rett syndrome (RTT). These studies reveal that MECP2 is transiently associated with chromatin in vivo and confirm a central role for the MBD in directing the protein to heterochromatin. In addition, we report for the first time that the small region between the MBD and the TRD, known as the interdomain region (ID), stabilizes chromatin binding by MECP2 independently of the MBD. The TRD of MECP2 also contributes towards chromatin binding, whereas the N- and C-termini do not. Some common RTT missense and nonsense mutations significantly affect binding kinetics, suggesting that alterations in chromatin binding can result in protein dysfunction and hence a disease phenotype.

Early determinants of fractures in Rett syndrome

OBJECTIVES

The goals were to compare the fracture incidence in Rett syndrome with that in the general population and to investigate the impact of genotype, epilepsy, and early motor skills on subsequent fracture incidence in girls and young women with Rett syndrome.

METHODS

The Australian Rett syndrome study, a population-based study operating since 1993, investigated Australian subjects with Rett syndrome born since 1976. The 234 (81.2%) of 288 verified cases in the Australian Rett syndrome database in 2004 whose families had completed follow-up questionnaires and provided information about fracture history were included in the analyses. The main outcomes were fracture incidence in the Rett syndrome population and fracture risk according to genotype, presence of epilepsy, and early motor profile.

RESULTS

Fracture incidence in this cohort was 43.3 episodes per 1000 person-years, nearly 4 times greater than the population rate. Risk was increased specifically in cases with p.R270X mutations and in cases with p.R168X mutations. Having epilepsy also increased fracture risk, even after adjustment for genotype.

CONCLUSIONS

Girls and young women with Rett syndrome are at increased risk of fracture. Those with mutations found previously to be more severe and those with epilepsy have an increased propensity toward fractures. Improved understanding of the risk factors for fracture could contribute to better targeting of interventions to decrease fracture incidence in this vulnerable population.

The story of Rett syndrome: from clinic to neurobiology

The postnatal neurodevelopmental disorder Rett syndrome (RTT) is caused by mutations in the gene encoding methyl-CpG binding protein 2 (MeCP2), a transcriptional repressor involved in chromatin remodeling and the modulation of RNA splicing. MECP2 aberrations result in a constellation of neuropsychiatric abnormalities, whereby both loss of function and gain in MECP2 dosage lead to similar neurological phenotypes. Recent studies demonstrate disease reversibility in RTT mouse models, suggesting that the neurological defects in MECP2 disorders are not permanent. To investigate the potential for restoring neuronal function in RTT patients, it is essential to identify MeCP2 targets or modifiers of the phenotype that can be therapeutically modulated. Moreover, deciphering the molecular underpinnings of RTT is likely to contribute to the understanding of the pathogenesis of a broader class of neuropsychiatric disorders.

MECP2 mutations in Serbian Rett syndrome patients

BACKGROUND

Rett syndrome is a severe neurodevelopmental X-linked dominant disorder affecting 1/15,000 girls worldwide. Eight years ago, the MECP2 gene was associated with the devastating clinical features observed in Rett syndrome patients.

OBJECTIVES

To investigate the spectrum and the frequency of MECP2 mutations in Serbian Rett syndrome patients.

PATIENTS AND METHODS

We screened the MECP2 coding region by conventional mutational screening (single-strand conformation polymorphism/sequencing) in 24 patients of Serbian origin and in their 41 unaffected family members. In search for gene dosage alterations in seemingly mutation-negative girls, we developed a new, specific quantitative PCR method.

RESULTS

Nineteen patients (79%) carried MECP2 mutations, five of which were novel (one nonsense mutation, one duplication and three deletions). Fourteen previously described disease-causing sequence changes and one polymorphism were also detected. Detailed case reports are given for the carriers of the novel mutations. Large MECP2 rearrangements cause Rett syndrome in a significant number of girls without 'classic' mutations in this gene. Therefore, we developed a specific quantitative PCR method, covering MECP2 exons 3 and 4, which previously has not been used for screening. No dosage alterations of the two exons were found in the four tested mutation-negative girls.

CONCLUSIONS

This is the first genetic study of Rett syndrome in Serbian patients describing the MECP2 mutational and phenotypic spectrum in this population. Detailed clinical descriptions of this ethnically homogeneous patient population add to our knowledge of genotype/phenotype correlations in this severe condition.

Sleep problems in Rett syndrome

Rett syndrome (RTT) is a severe neurological disorder, affecting mainly females. It is generally caused by mutations in the MECP2 gene. Sleep problems are thought to occur commonly in Rett syndrome, but there has been little research on prevalence or natural history. An Australian population-based registry of cases born since 1976 has been operating since 1993, with current ascertainment at 300. The Australian Rett Syndrome Database (ARSD) consists of information about Rett syndrome cases including their functional ability, behaviour, sleep patterns, medical conditions and genotype. The cases range in age from 2 to 29 years. The aim of this study was to investigate the type and frequency of sleep problems, relationships with age and MECP2 mutation type and to evaluate changes over time. Parents or carers of the subjects with Rett syndrome were asked to complete a questionnaire about sleep problems on three separate occasions (2000, 2002 and 2004). Regression modelling was used to investigate the relationships between sleep problems, age and mutation type. Sleep problems were identified in over 80% of cases. The prevalence of night-time laughter decreased with age and the prevalence of reported night-time seizures and daytime napping increased with age. The prevalence of sleep problems was highest in cases with a large deletion of the MECP2 gene and in those with the p.R294X or p.R306C mutations. Sleep problems are common in Rett syndrome and there is some variation with age and mutation type.

Development of a Video-based Evaluation Tool in Rett Syndrome

This paper describes the development of a video-based evaluation tool for use in Rett syndrome (RTT). Components include a parent-report checklist, and video filming and coding protocols that contain items on eating, drinking, communication, hand function and movements, personal care and mobility. Ninety-seven of the 169 families who initially agreed to participate returned a videotape within 8 months of the first request. Subjects whose videos were returned had a similar age profile to those who did not provide a video but were more likely to have classical than atypical RTT. Evidence of the content and social validity and inter-rater reliability on 11 videos is provided. Video may provide detailed, objective assessment of function and behaviour in RTT.

Multiple modes of interaction between the methylated DNA binding protein MeCP2 and chromatin

Mutations of the methylated DNA binding protein MeCP2, a multifunctional protein that is thought to transmit epigenetic information encoded as methylated CpG dinucleotides to the transcriptional machinery, give rise to the debilitating neurodevelopmental disease Rett syndrome (RTT). In this in vitro study, the methylation-dependent and -independent interactions of wild-type and mutant human MeCP2 with defined DNA and chromatin substrates were investigated. A combination of electrophoretic mobility shift assays and visualization by electron microscopy made it possible to understand the different conformational changes underlying the gel shifts. MeCP2 is shown to have, in addition to its well-established methylated DNA binding domain, a methylation-independent DNA binding site (or sites) in the first 294 residues, while the C-terminal portion of MeCP2 (residues 295 to 486) contains one or more essential chromatin interaction regions. All of the RTT-inducing mutants tested were quantitatively bound to chromatin under our conditions, but those that tend to be associated with the more severe RTT symptoms failed to induce the extensive compaction observed with wild-type MeCP2. Two modes of MeCP2-driven compaction were observed, one promoting nucleosome clustering and the other forming DNA-MeCP2-DNA complexes. MeCP2 binding to DNA and chromatin involves a number of different molecular interactions, some of which result in compaction and oligomerization. The multifunctional roles of MeCP2 may be reflected in these different interactions.

Physical and mental health of mothers caring for a child with Rett syndrome

OBJECTIVES

Our goal was to investigate the physical and mental health of mothers who care for a child with Rett syndrome.

METHODS

We assessed maternal physical and mental health by using the SF-12 version 1 physical component summary and mental component summary scores as the outcome measures of interest. Mothers (n = 135) of children with Rett syndrome completed the SF-12 measure as part of the Australian Rett Syndrome Study in 2002. The analysis investigated linear relationships between physical and mental health scores and maternal, family, and child characteristics.

RESULTS

Mothers ranged in age from 21 to 60 years and their children from 3 to 27 years. Nearly half of these mothers (47.4%) indicated that they worked full-time or part-time outside the home, and 41% had a combined family (gross) income of <40,000 Australian dollars. The resultant model for physical health demonstrated that the following factors were positively associated with better maternal physical health: the mother working full-time or part-time outside the home, having some high school education, having private health insurance, the child not having breathing problems in the last 2 years, the child not having home-based structured therapy, and high scores on the Family Resource Scale (indicating adequacy of time resources for basic and family needs). The resultant model for mental health demonstrated that the following factors were positively associated with better maternal mental health: the mother working full-time or part-time outside the home, the child not having a fracture in the last 2 years, lesser reporting of facial stereotypes and involuntary facial movements, being in a well-adjusted marriage, and having low stress scores.

CONCLUSIONS

Our study suggests that the most important predictors of maternal physical and emotional health are child behavior, caregiver demands, and family function.