Profiling scoliosis in Rett syndrome

Effects of a Supervised-As-Needed Home Exercise Program on Scoliosis and Motor Function in Rett Syndrome: A Multiple-Baseline Study

Background/Objectives: Scoliosis is a prevalent comorbidity in Rett syndrome (RTT), often necessitating surgical intervention. This study investigated the impact of a 10-month individualized home exercise program (HEP) on scoliosis progression and gross motor function in girls aged six to 16 years with RTT. Methods: A multiple-baseline single-case design (AABA) was employed with 20 participants. A remotely supervised HEP, based on established principles focused on posture and physical activity, was implemented daily for at least one hour. The primary outcome was the rate of scoliosis progression assessed through the Cobb angle change measured via spinal radiographs at baseline, pre-intervention, and post-intervention. The secondary outcome was the gross motor function. Results: The HEP did not significantly reduce the rate of scoliosis progression. However, individual responses varied, with three participants showing scoliosis reduction. Significant improvements were observed in gross motor function, particularly in standing, walking, and stair-climbing abilities. Conclusions: The HEP did not significantly impact overall scoliosis progression, but a significant improvement was found in gross motor function. Further research into larger sample sizes is needed to confirm the effectiveness of exercise interventions in people with RTT.

Minimally Invasive Bipolar Technique for Scoliosis in Rett Syndrome-Results and Complications in a Series of 22 Cases

Background: This is a retrospective study. The aim of this study is to report the results of bipolar minimally invasive fusionless surgery for scoliosis in Rett syndrome with a minimum follow-up of 2 years. Conservative treatment is often not effective in Rett syndrome scoliosis. Posterior spinal fusion (PSF) has a high rate of complications; early surgery using traditional growing rods (TGRs) controls the deformity while preserving spinal and thoracic growth before arthrodesis. The need for surgical rod lengthening still has a high rate of complications and costs. Methods: We recorded the clinical and radiological outcomes of 22 consecutive patients with Rett scoliosis who underwent bipolar fusionless surgery with a mean follow-up of 56 months (24-99). We performed a bilateral construct with rods (with or without a self-sliding device) anchored proximally with four hook claws distally to the pelvis by ilio-sacral (IS) screws through a minimally invasive approach. Results: The Cobb angle was reduced from 74.4° initially to 28.9° postoperatively and to 25.7° at the last follow-up, which corresponds to a 65% correction of the initial deformity. The gain was maintained at the last follow-up. None of the patients required spinal fusion at skeletal maturity (55% of our patients reached skeletal maturity). There was a gain in body weight (27.97 kg at preoperative time and 33.04 kg at postoperative time). The surgical complication rate was 32%. Conclusions: We recorded the stable correction of deformities and weight gain over time using the bipolar minimally invasive fusionless technique with a reduced rate of complication compared to arthrodesis. The arthrodesis was not necessary at skeletal maturity, thanks to the delayed natural ankylosis of a fixed spine.

The Management of Bone Defects in Rett Syndrome

Rett syndrome (RS) is a rare neurodevelopmental disorder primarily caused by mutations in the X-linked methyl-CpG binding protein 2 (MECP2) gene, responsible for encoding MECP2 which plays a pivotal role in regulating gene expression. The neurological and non-neurological manifestations of RS vary widely in severity depending on the specific mutation type. Bone complications, mostly scoliosis but also osteoporosis, hip displacement, and a high rate of fractures, are among the most prevalent non-neurological comorbidities observed in girls with RS. Low bone mineral density (BMD) is primarily due to a slow rate of bone formation due to dysfunctional osteoblast activity. The use of anticonvulsants, immobilization, low physical activity, poor nutrition, and inadequate vitamin D intake all significantly hamper skeletal maturation and the accumulation of bone mass in RS girls, making them more susceptible to fragility fractures. In RS patients, the upper and lower limbs are the most common sites for fractures which are due to both a reduced BMD and a diminished bone size. This review summarizes the knowledge on risk factors for fragility fracture in patients with RS and proposes a potential diagnostic and therapeutic pathway to enhance low BMD and mitigate the risk of fragility fractures. In particular, this review focused on the importance of clinical and instrumental evaluation of bone status as a basis for adequate planning of nutritional, pharmacological, and surgical interventions to be undertaken. Additionally, the management of bone defects in individuals with RS should be customized to meet each person's specific needs, abilities, and general health.

Prevalence of orthopaedic conditions in Rett syndrome: a systematic review and meta-analysis

BACKGROUND

Rett syndrome (RTT), a developmental disorder primarily affecting girls and linked to methyl-CpG binding protein-2 (MECP2) gene mutations, presents musculoskeletal abnormalities with varying prevalence across studies and age groups. Our aim was to delineate the prevalence of orthopaedic conditions in individuals with RTT.

METHOD

Three databases were searched and independently screened by two reviewers to retrieve observational studies published after 2000 that recruited 10 or more patients diagnosed with RTT and reported the prevalence of any orthopaedic conditions (scoliosis, hip displacement, knee problems or foot deformities). A random-effects meta-analysis was performed to determine the pooled prevalence based on study weight.

RESULTS

Of 867 screened studies, 21 studies involving 9997 girls with RTT (mean age 14.1 years; range, 3-38.5) met the inclusion criteria. The pooled prevalence of scoliosis was 64.5% [95% confidence interval (CI) 55.4-73.6%; I2 = 99%; P < 0.01], of hip displacement was 29.6% (95% CI 8.9-50.2%; I2 = 97%; P < 0.01) and of foot deformities was 53% (95% CI 17.5-89.2%; I2 = 98%; P < 0.01). Knee problems were reported in only one study. Scoliosis prevalence increased in studies with a high percentage of genetic testing and MECP2 positivity [69.1% (95% CI 58.9-79.2%; I2 = 99%; P < 0.01)], those with a mean age over 13 years [73% (95% CI 59.1-87%; I2 = 100%; P < 0.01)], and studies combining both variables [80.13% (95% CI 70.8-89.4%; I2 = 81%; P < 0.01)].

CONCLUSIONS

This meta-analysis found that approximately two in three girls with RTT develop scoliosis, one in two exhibit foot deformities and one in three experience hip displacement. These findings enhance our understanding of the prevalence of orthopaedic conditions in RTT, which can guide the establishment of surveillance protocols, clinical guidelines and management strategies tailored to the needs of RTT patients.

Rett Syndrome: The Emerging Landscape of Treatment Strategies

Rett syndrome (RTT) has enjoyed remarkable progress in achieving specific therapies. RTT, a unique neurodevelopmental disorder first described in 1966, progressed slowly until the landmark paper of Hagberg and colleagues in 1983. Thereafter, rapid advances were achieved including the development of specific diagnostic criteria and the active search for a genetic etiology, resulting 16 years later in identification of variants in the methyl-CpG-binding protein (MECP2) gene located at Xq28. Shortly thereafter, the NIH Office of Rare Diseases funded the RTT Natural History Study (NHS) in 2003, initiating the acquisition of natural history data on clinical features from a large population of individuals with RTT. This information was essential for advancement of clinical trials to provide specific therapies for this disorder. In the process, the International Rett Syndrome Association (IRSA) was formed (now the International Rett Syndrome Foundation-IRSF), which participated directly in encouraging and expanding enrollment in the NHS and, subsequently, in developing the SCOUT program to facilitate testing of potential therapeutic agents in a mouse model of RTT. The overall objective was to review clinical characteristics developed from the NHS and to discuss the status of specific therapies for this progressive neurodevelopmental disorder. The NHS study provided critical information on RTT: growth, anthropometrics, longevity, key comorbidities including epilepsy, breath abnormalities, gastroesophageal dysfunction, scoliosis and other orthopedic issues, puberty, behavior and anxiety, and progressive motor deterioration including the appearance of parkinsonian features. Phenotype-genotype correlations were noted including the role of X chromosome inactivation. Development of clinical severity and quality of life measures also proved critical for subsequent clinical trials. Further, development of biochemical and neurophysiologic biomarkers offered further endpoints for clinical trials. Initial clinical trials prior to the NHS were ineffective, but advances resulting from the NHS and other studies worldwide promoted significant interest from pharmaceutical firms resulting in several clinical trials. While some of these have been unrewarding such as sarizotan, others have been quite promising including the approval of trofinetide by the FDA in 2023 as the first agent available for specific treatment of RTT. Blarcamesine has been trialed in phase 3 trials, 14 agents have been studied in phase 2 trials, and 7 agents are being evaluated in preclinical/translational studies. A landmark study in 2007 by Guy et al. demonstrated that activation of a normal MECP2 gene in a null mouse model resulted in significant improvement. Gene replacement therapy has advanced through translational studies to two current phase 1/2 clinical trials (Taysha102 and Neurogene-401). Additional genetic therapies are also under study including gene editing, RNA editing, and X-chromosome reactivation. Taken together, progress in understanding and treating RTT over the past 40 years has been remarkable. This suggests that further advances can be expected.

Comprehensive High-Depth Proteomic Analysis of Plasma Extracellular Vesicles Containing Preparations in Rett Syndrome

Backgroud: Rett syndrome is a neurodevelopmental disorder that affects 1 in 10,000 females. Various treatments have been explored; however, no effective treatments have been reported to date, except for trofinetide, a synthetic analog of glycine-proline-glutamic acid, which was approved by the FDA in 2023. Serological biomarkers that correlate with the disease status of RTT are needed to promote early diagnosis and to develop novel agents. Methods: In this study, we performed a high-depth proteomic analysis of extracellular vesicles containing preparations extracted from patient plasma samples to identify novel biomarkers. Results: We identified 33 upregulated and 17 downregulated candidate proteins among a total of 4273 proteins in RTT compared to the healthy controls. Among these, UBE3B was predominantly increased in patients with Rett syndrome and exhibited a strong correlation with the clinical severity score, indicating the severity of the disease. Conclusions: We demonstrated that the proteomics of high-depth extracellular vesicles containing preparations in rare diseases could be valuable in identifying new disease biomarkers and understanding their pathophysiology.

Burden of illness in Rett syndrome: initial evaluation of a disorder-specific caregiver survey

BACKGROUND

Rett syndrome (RTT) is a severe X-linked neurodevelopmental disorder associated with multiple neurologic impairments. Previous studies have shown challenges to the quality of life of individuals with RTT and their caregivers. However, instruments applied to quantify disease burden have not adequately captured the impact of these impairments on affected individuals and their families. Consequently, an international collaboration of stakeholders aimed at evaluating Burden of Illness (BOI) in RTT was organized.

METHODS

Based on literature reviews and qualitative interviews with parents of children and adults with RTT, a caregiver questionnaire was constructed to evaluate 22 problems (inclusive of core characteristics, functional impairments, and comorbidities) often experienced with RTT, rated mainly with a 5-level Likert scale. The questionnaire was administered anonymously online to an international sample of 756 caregivers (predominantly parents) of girls and women with RTT. Descriptive statistics were used to identify problems of high frequency and impact on affected individuals and caregivers. Chi-square tests characterized the relationship between problem severity and impact responses, while nonparametric ANOVAs of raw and z-score adjusted scores identified agreement between severity and impact on individual and caregiver. Secondary inferential tests were used to determine the roles of age, clinical type, and country of residence on BOI in RTT.

RESULTS

There was variability in reported frequency of problems, with the most prevalent, severe and impactful being those related to the core features of RTT (i.e., communication and fine and gross motor impairments). Chi-square analyses demonstrated interdependence between severity and impact responses, while ANOVAs showed that many problems had disproportionately greater impact than severity, either on affected individuals (e.g., hand stereotypies) or their caregivers (e.g., sleep difficulties, seizures, pain, and behavioral abnormalities). With certain exceptions (e.g., breath-holding, seizures), age, clinical type, or country of residence did not influence these BOI profiles.

CONCLUSIONS

Our data demonstrate that core features and related impairments are particularly impactful in RTT. However, problems with mild severity can also have disproportionate impact on affected individuals and, particularly, on their caregivers. Future analyses will examine the role of factors such as treatment outcomes, healthcare services, and healthcare provider's perspectives, in these BOI profiles.

Orthopedic Conditions and Interplay with Functional Abilities and MECP2 Variant Subtype in Rett Syndrome Patients

PURPOSE

Rett syndrome (RTT) is a rare multi-systemic disorder primarily linked to mutations in MECP2 gene. This study aims to describe the prevalence of orthopedic conditions in RTT patients, and examine their intricate interplay with functional capabilities, and MECP2 variant subtypes.

METHODS

Conducted as a cross-sectional retrospective observational study, the research encompassed 55 patients meeting clinical RTT criteria and holding MECP2 mutations. A review of clinical records was performed to gather demographic data, mutation subtypes, orthopedic conditions, management strategies, and assessments of function.

RESULTS

Mean age of the participants was 10.22 ± 4.64 years (range, 2.9-19.41). Prevalence rates of orthopedic conditions were as follows: kyphoscoliosis 63.6%, hip displacement 14.6%, knee problems 40%, and foot deformities 75.5%. Significant relationship emerged between spinal (p < 0.01) and knee deformities (p < 0.01) with reduced motor function across various domains. Hip displacement significantly affected sitting ability (p = 0.002), and foot deformities impacted standing and walking capabilities (p = 0.049). Mutation clusters analysis revealed significant correlations with spinal (p = 0.022) and knee deformities (p = 0.002). Linear models highlighted the critical importance of mutation clusters, spine deformities, age, and hip management concerning functional variables.

CONCLUSIONS

In this study, foot deformities were the most frequent orthopedic manifestation, followed by spinal, knee, and hip deformities; and unveiled their relationships with functional status and groups of mutations in RTT patients.

LEVEL OF EVIDENCE

Level IV, Case series.

Paediatric syndromic scoliosis: proceedings of the half-day course at the 57th annual meeting of the Scoliosis Research Society

There are some syndromes that present with unique manifestations pertaining to the spinal column. A good working understanding of these common syndromes is useful for the spinal deformity surgeons and related healthcare providers. This review attempts to encompass these unique features and discuss them in three broad groups: hypermobility syndromes, muscle pathology-related syndromes, and syndromes related to poor bone quality. This review explores the features of these syndromes underpinning the aspects of surgical and medical management. This review represents the proceedings of the Paediatric Half-Day Course at the 57th Annual Meeting of the Scoliosis Research Society.

Identification of Predictors for Progression of Scoliosis in Rett Syndrome

Rett syndrome is a neurodevelopmental disorder in which scoliosis is a common orthopedic complication. This explorative study aims to identify predictors for rapid progression of scoliosis in Rett syndrome to enable variable selection for future prediction model development. A univariable logistic regression model was used to identify variables that discriminate between individuals with and without rapid progression of scoliosis (>10  ∘ Cobb angle/6 months) based on multi-center data. Predictors were identified using univariable logistic regression with OR (95% CI) and AUC (95% CI). Age at inclusion, Cobb angle at baseline and epilepsy have the highest discriminative ability for rapid progression of scoliosis in Rett syndrome.

Rett Syndrome-Associated Scoliosis: Analysis of National Trends and Treatment Patterns of a Rare Indication for Posterior Instrumented Fusion

STUDY DESIGN

Retrospective database cohort study.

OBJECTIVE

To evaluate U.S. treatment trends and inpatient outcomes for children undergoing posterior spinal fusion (PSF) for Rett syndrome (RTT)-associated scoliosis (RAS).

SUMMARY OF BACKGROUND DATA

RTT is a rare, sporadic neurodevelopmental disorder presenting in childhood with developmental regression, ataxia, and seizures. RAS occurs in 50% to 80% of cases of RTT, but little is known about the case volume and perioperative experience for children undergoing PSF.

MATERIALS AND METHODS

Using the International Classification of Diseases Ninth and 10th revision codes in the national Kids' Inpatient Database, we identified children with RTT who underwent PSF from 2000 to 2019. Annual case volumes were analyzed. Clinical characteristics and outcomes were compared with those of a cohort of patients with neuromuscular scoliosis (NMS).

RESULTS

Among 220 patients with RAS, 216 (98.2%) were females (mean age at surgery: 12.3±3.3 yr). Surgical case incidence steadily increased over 19 years, with more RAS admissions in the South (31.4%). Overall, patients with RAS demonstrated a higher mean Elixhauser Comorbidity Index score (2 vs . 1, P < 0.001) and had more perioperative complications (41.4% vs . 18%, P < 0.001) than patients with NMS. RTT diagnosis independently predicted higher odds of any complications (odds ratio: 1.98, P < 0.001) and increased length of stay (odds ratio: 1.18, P = 0.009) for admissions for PSF.

CONCLUSIONS

Surgical treatment for RAS is rare but increased over a 19-year period. Cases appear to be clustering by region, with the highest proportion in the South. The higher Elixhauser Comorbidity Index in RAS patients predicted higher costs, longer hospital stays, more complications (particularly respiratory), and more nonroutine discharge disposition than in other patients with NMS. RTT was independently associated with higher odds of complications and longer length of stay. Because RAS cases appear to be increasing in number, future studies should emphasize methods to reduce morbidity and investigate deformity-specific metrics to help better understand this population.

Clinical and genetic correlations of scoliosis in Rett syndrome

AIM

To identify the clinical features correlating with the presence and severity of scoliosis in girls with Rett syndrome (RTT).

METHOD

Seventy-five girls with a clinical and genetically determined diagnosis of RTT participated in this cross-sectional study. Clinical scales administered included the Rett assessment rating scale, the modified Ashworth scale, the Rett syndrome motor evaluation scale, the PainAD, and the scale of evaluation of purposeful hand function. Multivariable analyses, such as ordinal logistic regression and ANCOVA, were used to assess the correlation between these scales and a clinical score of scoliosis.

RESULTS

About 60% of patients had scoliosis, in general mild or moderate. The severity of scoliosis correlated with age and important neurological factors such as muscular hypertonus and hyperreflexia, standing, walking (level walking and on stairs), and postural transitions. No association was found with global disease severity, hand function, pain, or type of genetic mutation.

INTERPRETATION

Scoliosis is a relevant problem in RTT. It should be carefully monitored along the life span, especially in conjunction with (loco-)motor impairment in these patients.

Intensive Postural and Motor Activity Program Reduces Scoliosis Progression in People with Rett Syndrome

Background: A scoliosis prevalence of 94% was reported in the population with Rett syndrome (RTT), with an annual progression rate of 14 to 21° Cobb which may result in pain, loss of sitting balance, deterioration of motor skills, and lung disfunction. This paper describes the efficacy of an intensive conservative individualized physical and postural activity program in preventing scoliosis curvature progression in patients with RTT. Methods: Twenty subjects diagnosed with RTT and scoliosis were recruited, and an individualized intensive daily physical activity program was developed for each participant. Each program was conducted for six months by participants’ primary caregivers in their daily living environment. Fortnightly remote supervision of the program implementation was provided by an expert therapist. Pre- and post-intervention radiographs and motor functioning were analyzed. Results: An averaged progression of +1.7° ± 8.7° Cobb, over one year (12.3 ± 3.5 months) was observed in our group, together with motor function improvements. A relation between curve progression and motor skill improvement was observed. Conclusions: The intervention prevented scoliosis progression in our group. The achievement of functional motor improvements could enable better body segment control and muscle balancing, with a protective effect on scoliosis progression. The intervention was effective for individuals with RTT across various ages and severity levels. Individual characteristics of each participant and the details of their activity program are described.

Enablers and barriers in dental attendance in Rett syndrome: an international observational study

AIMS

Intellectual and developmental disabilities are heterogeneous in aetiology and presentation, and one cannot make assumptions about the oral health barriers of those with Rett syndrome (RTT) based on findings from generic studies. This study investigated caregivers' perceptions regarding access to dental care for those with (RTT), and associations of dental treatments received by those with RTT with their caregivers' perceived value of oral health and perception of their own as well as their daughter's dental anxiety.

METHODS AND RESULTS

Retrospective observational data of a subset of individuals with confirmed MECP2 mutations in the InterRett database (n = 216) were used to explore caregiver-related factors and their relationships with longitudinal data on dental service utilisation, using negative binomial regression. The main reported barriers to dental care access for individuals with RTT were primarily dentist-related in nature, regardless of dental service history. Those with reported dental nonattendance were of older age. Increasing levels of caregiver-reported dental fear were associated with less frequent dental check-ups or for any appointments for affected individuals.

CONCLUSIONS

Dentist-related barriers and caregiver-reported anxiety may both adversely affect dental attendance for those with RTT. Future research should explore caregivers' beliefs and oral health literacy.

Rett syndrome: think outside the (skull) box

Rett syndrome (RTT) is a severe X-linked neurodevelopmental disorder characterized by neurodevelopmental regression between 6 and 18 months of life and associated with multi-system comorbidities. Caused mainly by pathogenic variants in the MECP2 (methyl CpG binding protein 2) gene, it is the second leading genetic cause of intellectual disability in girls after Down syndrome. RTT affects not only neurological function but also a wide array of non-neurological organs. RTT-related disorders involve abnormalities of the respiratory, cardiovascular, digestive, metabolic, skeletal, endocrine, muscular, and urinary systems and immune response. Here, we review the different aspects of RTT affecting the main peripheral groups of organs and sometimes occurring independently of nervous system defects.

Altered Bone Status in Rett Syndrome

Rett syndrome (RTT) is a monogenic neurodevelopmental disorder primarily caused by mutations in X-linked MECP2 gene, encoding for methyl-CpG binding protein 2 (MeCP2), a multifaceted modulator of gene expression and chromatin organization. Based on the type of mutation, RTT patients exhibit a broad spectrum of clinical phenotypes with various degrees of severity. In addition, as a complex multisystem disease, RTT shows several clinical manifestations ranging from neurological to non-neurological symptoms. The most common non-neurological comorbidities include, among others, orthopedic complications, mainly scoliosis but also early osteopenia/osteoporosis and a high frequency of fractures. A characteristic low bone mineral density dependent on a slow rate of bone formation due to dysfunctional osteoblast activity rather than an increase in bone resorption is at the root of these complications. Evidence from human and animal studies supports the idea that MECP2 mutation could be associated with altered epigenetic regulation of bone-related factors and signaling pathways, including SFRP4/WNT/β-catenin axis and RANKL/RANK/OPG system. More research is needed to better understand the role of MeCP2 in bone homeostasis. Indeed, uncovering the molecular mechanisms underlying RTT bone problems could reveal new potential pharmacological targets for the treatment of these complications that adversely affect the quality of life of RTT patients for whom the only therapeutic approaches currently available include bisphosphonates, dietary supplements, and physical activity.

Correcting Scoliosis in Rett Syndrome

Objectives Rett syndrome is a rare disorder characterised by severe scoliosis in 80% of cases. In this retrospective case series, we analysed the radiographic, clinical, and functional outcomes of consecutive patients treated for scoliosis associated with Rett syndrome. We sought to understand the results of the treatment of scoliosis in Rett syndrome and evaluate the need to fuse to the pelvis. Methods A retrospective case series was used to analyse the radiographic, clinical, and functional outcomes of consecutive patients treated for Rett syndrome scoliosis between the ages of 10 and 8 years in a single tertiary paediatric spinal unit. Cases were identified through departmental and neurophysiological records, and patients were excluded if the diagnosis of Rett syndrome was not confirmed. Results Seven eligible cases were identified. At presentation, the mean coronal Cobb angle was 90.9°, mean sagittal Cobb 72.0°, and pelvic obliquity 24.5°. The mean post-operative improvement in coronal Cobb was 53.2° and pelvic obliquity reduced to 5.8°. These did not change during a mean follow up of 3.5 years. None showed any post-operative complications. Three patients with a mean 16.1° pelvic obliquity underwent a fusion to L5. The postoperative result in those cases remained stable at 3.5 years mean follow-up and full skeletal maturity. Conclusion Our data suggests that with modern technology, severe curves can be safely treated. Fusion to the pelvis is not necessary in patients with mild, flexible pelvic obliquity.

Oral health care and service utilisation in individuals with Rett syndrome: an international cross-sectional study

BACKGROUND

There is a dearth of literature available on the comparative oral health status of those with Rett syndrome (RTT) despite diurnal bruxism being a supportive diagnostic criterion for the disorder. This study was designed to investigate the dental experiences of individuals with RTT in terms of perceived at-home and professional dental care.

METHODS

Using data in the InterRett database, provided by English-speaking families of individuals with a confirmed MECP2 genetic mutation, the study investigated relationships between dental problems, oral care, child factors including bruxism and use of gastrostomy, and socioeconomic indicators. The study also explored relationships between dental presentations and socioeconomic, child, and family-related factors.

RESULTS

Individuals with RTT exhibiting bruxism were more likely to access dental treatment. Those who had full oral feeding had a higher incidence rate of dental treatment than those with full tube feeding. A conservative (under) estimation of the overall dental caries progression rate revealed that this may be similar to that of the normal population.

CONCLUSIONS

Drivers for dental treatment in RTT include bruxism as well as dental caries. Those who have full oral feeding experience more dental treatment than those with full tube feeding. A higher maternal education level may confer a protective effect for oral health outcomes in those with RTT. Nevertheless, families generally tended to value the importance of oral health despite reported difficulties in day-to-day mouth care.

Multisystem comorbidities in classic Rett syndrome: a scoping review

BACKGROUND

Rett syndrome (RTT) is a severe, progressive neurodevelopmental disorder with multisystem comorbidities that evolve across a patient's lifespan requiring attentive coordination of subspecialty care by primary care providers. A comprehensive, up-to-date synthesis of medical comorbidities in RTT would aid care coordination and anticipatory guidance efforts by healthcare providers. Our objective was to review and summarise published evidence regarding prevalence of RTT medical comorbidities across all relevant organ systems.

METHODS

Search of PubMed from January 2000 to July 2019 was performed using the search terms (Rett and MECP2 AND patient) OR (Rett and MECP2 AND cohort). Articles reporting the prevalence of clinical findings in RTT were assessed with respect to the size and nature of the cohorts interrogated and their relevance to clinical care.

RESULTS

After review of over 800 records, the multisystem comorbidities of RTT were summarised quantitatively from 18 records comprising both retrospective and prospective cohorts (31-983 subjects). Neurological comorbidities had the highest prevalence, occurring in nearly all individuals with gastrointestinal and orthopaedic concerns almost as prevalent as neurological. With the exception of low bone mineral content which was relatively common, endocrine comorbidities were seen in only around one-third of patients. Although more prevalent compared with the general population, cardiac conduction abnormalities were the least common comorbidity in RTT.

CONCLUSIONS

Effective care coordination for RTT requires knowledge of and attention to multiple comorbidities across multiple unrelated organ systems. Many issues common to RTT can potentially be managed by a primary care provider but the need for sub-specialist referral can be anticipated. Since the median life expectancy extends into the sixth decade with evolving subspecialty requirements throughout this time, paediatric providers may be tasked with continued coordination of these comorbidities or transitioning to adult medicine and specialists with experience managing individuals with complex medical needs.

Parenting girls with Rett syndrome: An investigation on self-perceived levels of stress

BACKGROUND

Although lives of parents of girls with Rett syndrome (RTT) are centred on the process of care, in the current literature their perceived levels of stress have been rarely investigated.

METHODS

We analysed levels of stress in a sample of 79 fathers and mothers parenting girls with RTT, who were required to compile the Parenting Stress Index (PSI) questionnaire.

RESULTS

We found clinical levels of stress in about 39% of fathers, as compared with 44% of the mothers. Severity of RTT, but not other factors such as the genetic domain, presence of epilepsy or scoliosis, predicted Total Stress scores in both fathers' subsample and mothers' subsample. A cumulative effect of caring, that is association of higher levels of stress with longer process of care, did also emerge from estimation of smoothing splines.

CONCLUSIONS

Fathers' resources should be taken more into account, especially in the rehabilitation and socialization process of adults with RTT.

Consensus guidelines on managing Rett syndrome across the lifespan

BACKGROUND

Rett syndrome (RTT) is a severe neurodevelopmental disorder with complex medical comorbidities extending beyond the nervous system requiring the attention of health professionals. There is no peer-reviewed, consensus-based therapeutic guidance to care in RTT. The objective was to provide consensus on guidance of best practice for addressing these concerns.

METHODS

Informed by the literature and using a modified Delphi approach, a consensus process was used to develop guidance for care in RTT by health professionals.

RESULTS

Typical RTT presents early in childhood in a clinically recognisable fashion. Multisystem comorbidities evolve throughout the lifespan requiring coordination of care between primary care and often multiple subspecialty providers. To assist health professionals and families in seeking best practice, a checklist and detailed references for guidance were developed by consensus.

CONCLUSIONS

The overall multisystem issues of RTT require primary care providers and other health professionals to manage complex medical comorbidities within the context of the whole individual and family. Given the median life expectancy well into the sixth decade, guidance is provided to health professionals to achieve current best possible outcomes for these special-needs individuals.

Exclusive expression of MeCP2 in the nervous system distinguishes between brain and peripheral Rett syndrome-like phenotypes

Rett syndrome (RTT) is a severe genetic disorder resulting from mutations in the X-linked MECP2 gene. MeCP2 protein is highly expressed in the nervous system and deficiency in the mouse central nervous system alone recapitulates many features of the disorder. This suggests that RTT is primarily a neurological disorder, although the protein is reportedly widely expressed throughout the body. To determine whether aspects of the RTT phenotype that originate in non-neuronal tissues might have been overlooked, we generated mice in which Mecp2 remains at near normal levels in the nervous system, but is severely depleted elsewhere. Comparison of these mice with wild type and globally MeCP2-deficient mice showed that the majority of RTT-associated behavioural, sensorimotor, gait and autonomic (respiratory and cardiac) phenotypes are absent. Specific peripheral phenotypes were observed, however, most notably hypo-activity, exercise fatigue and bone abnormalities. Our results confirm that the brain should be the primary target for potential RTT therapies, but also strongly suggest that some less extreme but clinically significant aspects of the disorder arise independently of defects in the nervous system.

Rett Syndrome: A Genetic Update and Clinical Review Focusing on Comorbidities

Rett syndrome (RTT) is a unique neurodevelopmental disorder that primarily affects females resulting in severe cognitive and physical disabilities. Despite the commendable collective efforts of the research community to better understand the genetics and underlying biology of RTT, there is still no cure. However, in the past 50 years, since the first report of RTT, steady progress has been made in the accumulation of clinical and molecular information resulting in the identification of a number of genes associated with RTT and associated phenotypes, improved diagnostic criteria, natural history studies, curation of a number of databases capturing genotypic and phenotypic data, a number of promising clinical trials and exciting novel therapeutic options which are currently being tested in laboratory and clinical settings. This Review focuses on the current knowledge of the clinical aspects of RTT, with particular attention being paid to clinical trials and the comorbidities of the disorder as well as the genetic etiology and the recognition of new diseases genes.

Abnormal Foot Position and Standing and Walking Ability in Rett Syndrome: an Exploratory Study

This study aimed to determine whether there is a relationship between abnormal foot position and standing and walking ability in individuals with Rett syndrome (RTT), a rare neurological condition primarily affecting females, often accompanied by impaired gross motor function and musculoskeletal deformities. Through means of an online survey, physiotherapists were asked to share information about their work and experience with individuals with RTT. They were asked about their clients' scores on the Rett Syndrome Gross Motor Scale and measures of their foot deformity, passive range of motion of dorsiflexion of the foot, use of supportive footwear, pressure load on the foot, and symmetry in weight bearing. 45 physiotherapists gave answers relating to 67 individuals with RTT who ranged in age from 2 to over 50 years. Almost 80% had an abnormal foot position which required support of special shoes or orthoses. Approximately 55% experienced abnormal pressure load on the foot and 65% demonstrated asymmetrical weight-bearing; 22% could sit independently and 17% were able to stand and walk independently. Of all the variables investigated, only abnormal distribution of pressure on the foot and asymmetry in weight bearing through the legs were found to be (negatively) correlated with standing and walking ability. Physiotherapists can use this information to give advice on othopedic support for the feet of individuals with RTT.

Early Life Epilepsies are a Comorbidity of Developmental Brain Disorders

Early-life epilepsies are a series of disorders frequently accompanied by a broad range of morbidities that include cognitive, behavioral, neuromuscular, and sleep disturbances; enteric and other forms of autonomic dysfunction; sensory processing difficulties; and other issues. Usually these morbidities cluster together in a single patient. Rather than these being separate conditions, all, including the seizures, are manifestations or coexpressions of developmental brain disorders. Instead of viewing epilepsy as the disease and the other features as comorbidities, approaching early-life epilepsies as part of the spectrum of developmental brain disorders could have implications for multidisciplinary care models, anticipatory guidance, and counseling of parents, as well as the design of randomized trials and targeting important outcomes. Ultimately, such an approach could improve understanding and help optimize outcomes in these difficult to treat disorders of early childhood.

Assessment of Caregiver Inventory for Rett Syndrome

Rett syndrome (RTT) requires total caregiver attention and leads to potential difficulties throughout life. The Caregiver Burden Inventory, designed for Alzheimer disease, was modified to a RTT Caregiver Inventory Assessment (RTT CIA). Reliability and face, construct, and concurrent validity were assessed in caregivers of individuals with RTT. Chi square or Fisher's exact test for categorical variables and t tests or Wilcoxon two-sample tests for continuous variables were utilized. Survey completed by 198 caregivers; 70 caregivers completed follow-up assessment. Exploratory factor analysis revealed good agreement for physical burden, emotional burden, and social burden. Internal reliability was high (Cronbach's alpha 0.898). RTT CIA represents a reliable and valid measure, providing a needed metric of caregiver burden in this disorder.

Scoliosis in Rett Syndrome: Progression, Comorbidities, and Predictors

BACKGROUND

Scoliosis is prominent in Rett syndrome (RTT). Following the prior report from the US Natural History Study, the onset and progression of severe scoliosis (≥40° Cobb angle) and surgery were examined regarding functional capabilities and specific genotypes, addressing the hypothesis that abnormal muscle tone, poor oral feeding, puberty, and delays or absence of sitting balance and ambulation may be responsible for greater risk in RTT.

METHODS

The multicenter RTT Natural History Study gathered longitudinal data for classic RTT, including mutation type, scoliosis, muscle tone, sitting, ambulation, hand function, and feeding. Cox regression models were used to examine the association between scoliosis and functional characteristics. All analyses utilized SAS 9.4; two-sided P values of <0.05 were considered significant.

RESULTS

A total of 913 females with classic RTT were included. Scoliosis frequency and severity increased with age. Severe scoliosis was found in 251 participants (27%), 113 of whom developed severe scoliosis during the follow-up assessments; 168 (18%) had surgical correction. Severe MECP2 mutations (R106W, R168X, R255X, R270X, and large deletions) showed a higher proportion of scoliosis. Individuals developing severe scoliosis or requiring surgery were less likely to sit, ambulate, or use their hands and were more likely to have begun puberty. Significant differences were absent for epilepsy rates, sleep problems, or constipation.

DISCUSSION

Scoliosis requires vigilance regarding the risk factors noted, particularly specific mutations and the role of puberty and motor abilities. Bracing is recommended for moderate curves and surgery for severe curves in accordance with published guidelines for scoliosis management.

Clinical and biological progress over 50 years in Rett syndrome

In the 50 years since Andreas Rett first described the syndrome that came to bear his name, and is now known to be caused by a mutation in the methyl-CpG-binding protein 2 (MECP2) gene, a compelling blend of astute clinical observations and clinical and laboratory research has substantially enhanced our understanding of this rare disorder. Here, we document the contributions of the early pioneers in Rett syndrome (RTT) research, and describe the evolution of knowledge in terms of diagnostic criteria, clinical variation, and the interplay with other Rett-related disorders. We provide a synthesis of what is known about the neurobiology of MeCP2, considering the lessons learned from both cell and animal models, and how they might inform future clinical trials. With a focus on the core criteria, we examine the relationships between genotype and clinical severity. We review current knowledge about the many comorbidities that occur in RTT, and how genotype may modify their presentation. We also acknowledge the important drivers that are accelerating this research programme, including the roles of research infrastructure, international collaboration and advocacy groups. Finally, we highlight the major milestones since 1966, and what they mean for the day-to-day lives of individuals with RTT and their families.

Neurobiologically-based treatments in Rett syndrome: opportunities and challenges

Introduction: Rett syndrome (RTT) is an X-linked neurodevelopmental disorder that primarily affects females, typically resulting in a period of developmental regression in early childhood followed by stabilization and severe chronic cognitive, behavioral, and physical disability. No known treatment exists beyond symptomatic management, and while insights into the genetic cause, pathophysiology, neurobiology, and natural history of RTT have been gained, many challenges remain. Areas covered: Based on a comprehensive survey of the primary literature on RTT, this article describes and comments upon the general and unique features of the disorder, genetic and neurobiological bases of drug development, and the history of clinical trials in RTT, with an emphasis on drug trial design, outcome measures, and implementation. Expert opinion: Neurobiologically based drug trials are the ultimate goal in RTT, and due to the complexity and global nature of the disorder, drugs targeting both general mechanisms (e.g., growth factors) and specific systems (e.g., glutamate modulators) could be effective. Trial design should optimize data on safety and efficacy, but selection of outcome measures with adequate measurement properties, as well as innovative strategies, such as those enhancing synaptic plasticity and use of biomarkers, are essential for progress in RTT and other neurodevelopmental disorders.

Family satisfaction following spinal fusion in Rett syndrome

PURPOSE

We evaluated family satisfaction following spinal fusion in girls with Rett syndrome.

METHODS

Families participating in the population-based and longitudinal Australian Rett Syndrome Database whose daughter had undergone spinal fusion provided data on satisfaction overall, care processes and expected changes in health and function. Content analysis of responses to open-ended questions was conducted.

RESULTS

Families reported high levels of overall satisfaction and consistently high ratings in relation to surgical and ICU care. Outstanding clinical care and the development of strong partnerships with clinical staff were much appreciated by families, whereas poor information exchange and inconsistent care caused concerns.

CONCLUSIONS

Family satisfaction is an important outcome within a patient-centred quality of care framework. Our findings suggest strategies to inform the delivery of care in relation to spinal fusion for Rett syndrome and could also inform the hospital care of other children with disability and a high risk of hospitalization.

Progress in Rett Syndrome: from discovery to clinical trials

Fifty years ago, Andreas Rett described a disorder in 22 females featuring prominent regression of fine motor and communication skills, cognitive impairment, stereotypic movements, periodic breathing, and gait abnormalities. This disorder became known as Rett syndrome (RTT) following the report of Hagberg et al. in 1983. Although RTT was scarcely recognized at that time in the United States, here the efforts of Rett and Hagberg led to rapid progress in recognition and diagnosis, a clearer understanding of its clinical and pathological underpinnings, and, ultimately, identification of mutations in the methyl-CpG-binding protein 2 (MECP2) gene as the primary cause of this unique and challenging neurodevelopmental disorder. Thereafter, a natural history study and critical translational research in animal models paved the way for potential disease-modifying agents to be assessed in human clinical trials. To be successful, the energies of the international community at all levels, including researchers in clinical and basic science, funding agencies, pharmaceutical companies, patient advocates, and, above all, parents and their children are essential. Otherwise, hopes for effective treatment, if not, a cure, will remain unfulfilled.

MeCP2 deficiency results in robust Rett-like behavioural and motor deficits in male and female rats

Since the identification of MECP2 as the causative gene in the majority of Rett Syndrome (RTT) cases, transgenic mouse models have played a critical role in our understanding of this disease. The use of additional mammalian RTT models offers the promise of further elucidating critical early mechanisms of disease as well as providing new avenues for translational studies. We have identified significant abnormalities in growth as well as motor and behavioural function in a novel zinc-finger nuclease model of RTT utilizing both male and female rats throughout development. Male rats lacking MeCP2 (Mecp2^ZFN/y) were noticeably symptomatic as early as postnatal day 21, with most dying by postnatal day 55, while females lacking one copy of Mecp2 (Mecp2^ZFN/+) displayed a more protracted disease course. Brain weights of Mecp2^ZFN/y and Mecp2^ZFN/+rats were significantly reduced by postnatal day 14 and 21, respectively. Early motor and breathing abnormalities were apparent in Mecp2^ZFN/y rats, whereas Mecp2^ZFN/+rats displayed functional irregularities later in development. The large size of this species will provide profound advantages in the identification of early disease mechanisms and the development of appropriately timed therapeutics. The current study establishes a foundational basis for the continued utilization of this rat model in future RTT research.

The Natural History of Scoliosis in Females With Rett Syndrome

STUDY DESIGN

Population-based longitudinal observational study.

OBJECTIVE

To describe the prevalence of scoliosis in Rett syndrome, structural characteristics and progression, taking into account the influences of age, genotype, and ambulatory status.

SUMMARY OF BACKGROUND DATA

Scoliosis is the most common orthopedic comorbidity in Rett syndrome yet very little is known about its natural history and influencing factors such as age, genotype, and ambulatory status.

METHODS

The infrastructure of the Australian Rett Syndrome Database was used to identify all cases with confirmed Rett syndrome in Australia and collect data on genotype and walking status. We identified radiological records and described the Cobb angle of each curve. Time to event analysis was used to estimate the median age of onset of scoliosis and the log-rank test to compare by mutation type. Latent class group analysis was used to identify groups for the trajectory of walking status over time and a multilevel linear model used to assess trajectories of scoliosis development by mutation type and walking status. We used a logistic regression model to estimate the probability of developing a scoliosis with a Cobb angle >60° at 16 years in relation to Cobb angle and walking status at 10 years of age.

RESULTS

The median age of scoliosis onset was 11 years with earliest onset in those with a p.Arg255 mutation or large deletion. Scoliosis was progressive for all mutation types except for those with the p.Arg306Cys mutation. Scoliosis progression was reduced when there was capacity to walk independently or with assistance. Cobb angle and walking ability at age 10 can be reliably used to identify those who will develop a very severe scoliosis by age 16.

CONCLUSION

These data on prognosis of scoliosis inform clinical decision making about the likelihood of progression to very severe scoliosis and the need for surgical management.

LEVEL OF EVIDENCE

4.

Clinical Guidelines for Management of Bone Health in Rett Syndrome Based on Expert Consensus and Available Evidence

OBJECTIVES

We developed clinical guidelines for the management of bone health in Rett syndrome through evidence review and the consensus of an expert panel of clinicians.

METHODS

An initial guidelines draft was created which included statements based upon literature review and 11 open-ended questions where literature was lacking. The international expert panel reviewed the draft online using a 2-stage Delphi process to reach consensus agreement. Items describe the clinical assessment of bone health, bone mineral density assessment and technique, and pharmacological and non-pharmacological interventions.

RESULTS

Agreement was reached on 39 statements which were formulated from 41 statements and 11 questions. When assessing bone health in Rett syndrome a comprehensive assessment of fracture history, mutation type, prescribed medication, pubertal development, mobility level, dietary intake and biochemical bone markers is recommended. A baseline densitometry assessment should be performed with accommodations made for size, with the frequency of surveillance determined according to individual risk. Lateral spine x-rays are also suggested. Increasing physical activity and initiating calcium and vitamin D supplementation when low are the first approaches to optimizing bone health in Rett syndrome. If individuals with Rett syndrome meet the ISCD criterion for osteoporosis in children, the use of bisphosphonates is recommended.

CONCLUSION

A clinically significant history of fracture in combination with low bone densitometry findings is necessary for a diagnosis of osteoporosis. These evidence and consensus-based guidelines have the potential to improve bone health in those with Rett syndrome, reduce the frequency of fractures, and stimulate further research that aims to ameliorate the impacts of this serious comorbidity.

Spinal Fusion for Scoliosis in Rett Syndrome With an Emphasis on Respiratory Failure and Opioid Usage

Our objective was to characterize our experience with 8 patients with Rett syndrome undergoing scoliosis surgery in regard to rates of respiratory failure and rates of ventilator-acquired pneumonia in comparison to patients with neurologic scoliosis and adolescent idiopathic scoliosis. This study was a retrospective chart review of patients undergoing scoliosis surgery at a tertiary children's hospital. Patients were divided into 3 groups: (1) adolescent idiopathic scoliosis, (2) neurologic scoliosis, and (3) Rett syndrome. There were 133 patients with adolescent idiopathic scoliosis, 48 patients with neurologic scoliosis, and 8 patients with Rett syndrome. We found that patients with Rett syndrome undergoing scoliosis surgery have higher rates of respiratory failure and longer ventilation times in the postoperative period when compared with both adolescent idiopathic scoliosis and neurologic scoliosis patients. There is insufficient evidence to suggest a difference in the incidence of ventilator-acquired pneumonia between the Rett syndrome and the neurologic scoliosis group. We believe our findings are the first in the literature to show a statistically significant difference between these 3 groups in regard to incidence of respiratory failure.

The Changing Face of Survival in Rett Syndrome and MECP2-Related Disorders

PURPOSE

Survival in Rett syndrome remains unclear. Although early estimates were grim, more recent data suggest that survival into adulthood is typical. We aimed to define survival in Rett syndrome more clearly and identify risk factors for early death.

METHODS

Participants with clinical Rett Syndrome or methyl-CpG-binding protein 2 mutations without clinical RTT were recruited through the Rett Syndrome Natural History study from 2006 to 2015. Clinical details were collected, and survival was determined using the Kaplan-Meier estimator. Risk factors were assessed using Cox proportional hazards models.

RESULTS

Among 1189 valid participants, 51 died (range 3.9-66.6 years) during the 9-year follow-up period. Those who died included 36 (3.9%) classic Rett syndrome females, 5 (5.9%) atypical severe Rett syndrome females, 1 (2.4%) non-Rett syndrome female, the single atypical severe male, 6 (30%) non-Rett syndrome males, and 2 (7.1%) methyl-CpG-binding protein 2 duplication syndrome males. All atypical mild Rett syndrome females, methyl-CpG-binding protein 2 duplication syndrome females, and the single classic Rett syndrome male remain alive. Most deaths were due to cardiorespiratory issues. Only one died from severe malnutrition, scoliosis, and extreme frailty. Survival for classic and atypical Rett syndrome was greater than 70% at 45 years. Overall severity and several modifiable risk factors, including ambulation, weight, and seizures, were associated with mortality in classic Rett syndrome.

CONCLUSIONS

Survival into the fifth decade is typical in Rett syndrome, and death due to extreme frailty has become rare. Although the leading cause of death remains cardiorespiratory compromise, many risk factors for early death are modifiable. Intense therapeutic interventions could further improve the prognosis for individuals with Rett syndrome.

Improving Treatment Trial Outcomes for Rett Syndrome: The Development of Rett-specific Anchors for the Clinical Global Impression Scale

Rett syndrome is a genetically based neurodevelopmental disorder. Although the clinical consequences of Rett syndrome are profound and lifelong, currently no approved drug treatments are available specifically targeted to Rett symptoms. High quality outcome measures, specific to the core symptoms of a disorder are a critical component of well-designed clinical trials for individuals with neurodevelopmental disorders. The Clinical Global Impression Scale is a measure of global clinical change with strong face validity that has been widely used as an outcome measure in clinical trials of central nervous system disorders. Despite its favorable assay sensitivity in clinical trials, as a global measure, the Clinical Global Impression Scale is not specific to the signs and symptoms of the disorder under study. Development of key anchors for the scale, specific to the disorder being assessed, holds promise for enhancing the validity and reliability of the measure for disorders such as Rett syndrome.

MeCP2 in the regulation of neural activity: Rett syndrome pathophysiological perspectives

Rett syndrome (RTT), an X-linked neurodevelopment disorder, occurs in approximately one out of 10,000 females. Individuals afflicted by RTT display a constellation of signs and symptoms, affecting nearly every organ system. Most striking are the neurological manifestations, including regression of language and motor skills, increased seizure activity, autonomic dysfunction, and aberrant regulation of breathing patterns. The majority of girls with RTT have mutations in the gene encoding for methyl-CpG binding protein 2 (MeCP2). Since the discovery of this genetic cause of RTT in 1999, there has been an accelerated pace of research seeking to understand the role of MeCP2 in the brain in the hope of developing a disease-modifying therapy for RTT. In this study, we review the clinical features of RTT and then explore the latest mechanistic studies in order to explain how a mutation in MeCP2 leads to these unique features. We cover in detail studies examining the role of MeCP2 in neuronal physiology, as well as recent evidence that implicates a key role for glia in the pathogenesis of RTT. In the past 20 years, these basic and clinical studies have yielded an extraordinary understanding of RTT; as such, we end this narrative review considering the translation of these studies into clinical trials for the treatment of RTT.

Rett Syndrome: Reaching for Clinical Trials

Rett syndrome (RTT) is a syndromic autism spectrum disorder caused by loss-of-function mutations in MECP2. The methyl CpG binding protein 2 binds methylcytosine and 5-hydroxymethycytosine at CpG sites in promoter regions of target genes, controlling their transcription by recruiting co-repressors and co-activators. Several preclinical studies in mouse models have identified rational molecular targets for drug therapies aimed at correcting the underlying neural dysfunction. These targeted therapies are increasingly translating into human clinical trials. In this review, we present an overview of RTT and describe the current state of preclinical studies in methyl CpG binding protein 2-based mouse models, as well as current clinical trials in individuals with RTT.

Biomechanical properties of bone in a mouse model of Rett syndrome

Rett syndrome (RTT) is an X-linked genetic disorder and a major cause of intellectual disability in girls. Mutations in the methyl-CpG binding protein 2 (MECP2) gene are the primary cause of the disorder. Despite the dominant neurological phenotypes, MECP2 is expressed ubiquitously throughout the body and a number of peripheral phenotypes such as scoliosis, reduced bone mineral density and skeletal fractures are also common and important clinical features of the disorder. In order to explore whether MeCP2 protein deficiency results in altered structural and functional properties of bone and to test the potential reversibility of any defects, we have conducted a series of histological, imaging and biomechanical tests of bone in a functional knockout mouse model of RTT. Both hemizygous Mecp2(stop/y) male mice in which Mecp2 is silenced in all cells and female Mecp2(stop/+) mice in which Mecp2 is silenced in ~50% of cells as a consequence of random X-chromosome inactivation, revealed significant reductions in cortical bone stiffness, microhardness and tensile modulus. Microstructural analysis also revealed alterations in both cortical and cancellous femoral bone between wild-type and MeCP2-deficient mice. Furthermore, unsilencing of Mecp2 in adult mice cre-mediated stop cassette deletion resulted in a restoration of biomechanical properties (stiffness, microhardness) towards wild-type levels. These results show that MeCP2-deficiency results in overt, but potentially reversible, alterations in the biomechanical integrity of bone and highlights the importance of targeting skeletal phenotypes in considering the development of pharmacological and gene-based therapies.

Rett Syndrome: Coming to Terms with Treatment

Rett syndrome (RTT) has experienced remarkable progress over the past three decades since emerging as a disorder of worldwide proportions, particularly with discovery of the linkage of RTT to MECP2 mutations. The advances in clinical research and the increasing pace of basic science investigations have accelerated the pattern of discovery and understanding. Clinical trials are ongoing and others are planned. A review of these events and the prospects for continued success are highlighted below. The girls and women encountered today with RTT are, overall, in better general, neurologic, and behavioral health than those encountered earlier. This represents important progress worldwide from the concerted efforts of a broadly based and diverse clinical and basic research consortium as well as the efforts of parents, family, and friends.

MeCP2 reinforces STAT3 signaling and the generation of effector CD4+ T cells by promoting miR-124-mediated suppression of SOCS5

Methyl CpG binding protein 2 (MeCP2) is an X-linked, multifunctional epigenetic regulator that is best known for its role in the neurological disorder Rett syndrome; however, it is also linked to multiple autoimmune disorders. We examined a potential role for MeCP2 in regulating the responses of CD4+ T cells to stimulation with antigen. MeCP2 was indispensable for the differentiation of naïve CD4+ T cells into T helper type 1 (T(H)1) and T(H)17 cells and for T(H)1- or T(H)17-mediated pathologies in vitro and in vivo. Loss of MeCP2 in CD4+ T cells impaired the expression of the microRNA (miR) miR-124 and consequently relieved miR-124-mediated repression of the translation of suppressor of cytokine signaling 5 (Socs5) mRNA. The resulting accumulation of SOCS5 inhibited the cytokine-dependent activation of signal transducer and activator of transcription 1 (STAT1) and STAT3, which are necessary for the differentiation of T(H)1 and T(H)17 cells, respectively. Upon silencing of MeCP2, primary neurons and astrocytes also failed to respond properly to STAT3-dependent signaling stimulated by neurotrophic factors. Together, these findings suggest that the regulation of STAT3 signaling may represent a common etiology underpinning the roles of MeCP2 in both the nervous and immune systems.

Gastrointestinal dysmotility in Rett syndrome

OBJECTIVES

Through evidence review and the consensus of an expert panel, we developed recommendations for the clinical management of gastroesophageal reflux disease, constipation, and abdominal bloating in Rett syndrome.

METHODS

Based on review of the literature and family concerns expressed on RettNet, initial draft recommendations were created. Wherein the literature was lacking, 25 open-ended questions were included. Input from an international, multidisciplinary panel of clinicians was sought using a 2-stage modified Delphi process to reach consensus agreement. Items related to the clinical assessment and management of gastroesophageal reflux disease, constipation, and abdominal bloating.

RESULTS

Consensus was achieved on 78 of 85 statements. A comprehensive approach to the assessment of gastroesophageal reflux and reflux disease, constipation, and abdominal bloating was recommended, taking into account impairment of communication skills in Rett syndrome. A stepwise approach to the management was identified with initial use of conservative strategies, escalating to pharmacological measures and surgery, if necessary.

CONCLUSIONS

Gastrointestinal dysmotility occurs commonly in Rett syndrome. These evidence- and consensus-based recommendations have the potential to improve care of dysmotility issues in a rare condition and stimulate research to improve the present limited evidence base.

Preclinical research in Rett syndrome: setting the foundation for translational success

In September of 2011, the National Institute of Neurological Disorders and Stroke (NINDS), the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), the International Rett Syndrome Foundation (IRSF) and the Rett Syndrome Research Trust (RSRT) convened a workshop involving a broad cross-section of basic scientists, clinicians and representatives from the National Institutes of Health (NIH), the US Food and Drug Administration (FDA), the pharmaceutical industry and private foundations to assess the state of the art in animal studies of Rett syndrome (RTT). The aim of the workshop was to identify crucial knowledge gaps and to suggest scientific priorities and best practices for the use of animal models in preclinical evaluation of potential new RTT therapeutics. This review summarizes outcomes from the workshop and extensive follow-up discussions among participants, and includes: (1) a comprehensive summary of the physiological and behavioral phenotypes of RTT mouse models to date, and areas in which further phenotypic analyses are required to enhance the utility of these models for translational studies; (2) discussion of the impact of genetic differences among mouse models, and methodological differences among laboratories, on the expression and analysis, respectively, of phenotypic traits; and (3) definitions of the standards that the community of RTT researchers can implement for rigorous preclinical study design and transparent reporting to ensure that decisions to initiate costly clinical trials are grounded in reliable preclinical data.

Clinical characteristics of children with rett syndrome

Objective

To identify the clinical characteristics and investigate function related aspects of Korean children with Rett syndrome.

Method

A total of 26 patients diagnosed as Rett syndrome were clinically observed until the age of five or over. We surveyed past history, developmental history, and presence of typical clinical features of Rett syndrome. Furthermore, we investigated differences in clinical characteristics according to functional status and changes in clinical features related to growth.

Results

There were no problems related to gestational, perinatal or neonatal history. Only 12 patients had an ultimate head circumference of less than 3 percentile. Developmental regression was definite in all patients. At final assessment, only 14 patients were able to walk. Twenty patients had an epileptic history requiring medication. Sixteen patients with scoliosis showed progression during serial follow-up. The percentage of patients who were able to walk before 16 months was higher in the high function group than the low function group. The age of regression was 5.4 and 4.0 years in the high and low function group respectively, but the difference was not statistically significant. Scoliosis was more severe and seizure onset age was younger in the low function group.

Conclusion

We investigated 26 clinical characteristics in Korean children with Rett syndrome. Their clinical features change according to age, and we believe such knowledge could be utilized in rehabilitation to minimize their disabilities.

The phenotype associated with a large deletion on MECP2

Multiplex ligation-dependent Probe Amplification (MLPA) has become available for the detection of a large deletion on the MECP2 gene allowing genetic confirmation of previously unconfirmed cases of clinical Rett syndrome. This study describes the phenotype of those with a large deletion and compares with those with other pathogenic MECP2 mutations. Individuals were ascertained from the Australian Rett Syndrome and InterRett databases with data sourced from family and clinician questionnaires, and two case studies were constructed from the longitudinal Australian data. Regression and survival analysis were used to compare severity and age of onset of symptoms in those with and without a large deletion. Data were available for 974 individuals including 51 with a large deletion and ages ranged from 1 year 4 months to 49 years (median 9 years). Those with a large deletion were more severely affected than those with other mutation types. Specifically, individuals with large deletions were less likely to have learned to walk (OR 0.42, 95% CI: 0.22-0.79, P=0.007) and to be currently walking (OR 0.53, 95% CI: 0.26-1.10, P=0.089), and were at higher odds of being in the most severe category of gross motor function (OR 1.84, 95% CI: 0.98-3.48, P=0.057) and epilepsy (OR 2.72, 95% CI: 1.38-5.37, P=0.004). They also developed epilepsy, scoliosis, hand stereotypies and abnormal breathing patterns at an earlier age. We have described the disorder profile associated with a large deletion from the largest sample to date and have found that the phenotype is severe with motor skills particularly affected.

Rett syndrome: exploring the autism link

The presence of autism in individuals with neurodevelopmental disorders, whether transient as in Rett syndrome (RTT) or enduring as in fragile X syndrome or Down syndrome, suggests the possibility of common neurobiologic mechanisms whose elucidation could fundamentally advance our understanding. This review explores the commonalities and differences between autism and RTT at clinical and molecular levels with respect to current status and challenges for each, highlights recent findings from the Rare Disease Network Natural History study on RTT, and summarizes the broad range of phenotypes resulting from mutations in the methyl-CpG-binding protein 2 gene (MECP2), which is responsible for RTT in 95% of individuals with the disorder. For RTT, animal models have been critical resources for advancing pathobiologic discovery and promise to be important test beds for evaluating new therapies. Fundamental understanding of autism based on unique genetic mechanism(s) must await similar advances.