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The CRISPR-Cas9 technology has the potential to revolutionize the treatment of various diseases, including Rett syndrome, by enabling the correction of genes or mutations in human patient cells. However, several challenges need to be addressed before its widespread clinical application. These challenges include the low delivery efficiencies to target cells, the actual efficiency of the genome-editing process, and the precision with which the CRISPR-Cas system operates. Herein, the study presents a Magnetic Nanoparticle-Assisted Genome Editing (MAGE) platform, which significantly improves the transfection efficiency, biocompatibility, and genome-editing accuracy of CRISPR-Cas9 technology. To demonstrate the feasibility of the developed technology, MAGE is applied to correct the mutated MeCP2 gene in induced pluripotent stem cell-derived neural progenitor cells (iPSC-NPCs) from a Rett syndrome patient. By combining magnetofection and magnetic-activated cell sorting, MAGE achieves higher multi-plasmid delivery (99.3%) and repairing efficiencies (42.95%) with significantly shorter incubation times than conventional transfection agents without size limitations on plasmids. The repaired iPSC-NPCs showed similar characteristics as wild-type neurons when they differentiated into neurons, further validating MAGE and its potential for future clinical applications. In short, the developed nanobio-combined CRISPR-Cas9 technology offers the potential for various clinical applications, particularly in stem cell therapies targeting different genetic diseases.

Dominant X-linked diseases are uncommon due to female X chromosome inactivation (XCI). While random XCI usually protects females against X-linked mutations, Rett syndrome (RTT) is a female neurodevelopmental disorder caused by heterozygous MECP2 mutation. After 6-18 months of typical neurodevelopment, RTT girls undergo a poorly understood regression. We performed longitudinal snRNA-seq on cerebral cortex in a construct-relevant Mecp2e1 mutant mouse model of RTT, revealing transcriptional effects of cell type, mosaicism, and sex on progressive disease phenotypes. Across cell types, we observed sex differences in the number of differentially expressed genes (DEGs) with 6x more DEGs in mutant females than males. Unlike males, female DEGs emerged prior to symptoms, were enriched for homeostatic gene pathways in distinct cell types over time and correlated with disease phenotypes and human RTT cortical cell transcriptomes. Non-cell-autonomous effects were prominent and dynamic across disease progression of Mecp2e1 mutant females, indicating that wild-type-expressing cells normalize transcriptional homeostasis. These results advance our understanding of RTT progression and treatment.

To assess the age and MECP2 variants of recently identified males and set the stage for further study of clinical features in males. Genetic information on the specific MECP2 variant was acquired from the coordinator (K.F.) of the Parent Group for Males. Data were collected indicating whether these variants were de novo or transmitted from the mother and whether males who appeared to meet the diagnostic criteria for Rett syndrome had mosaicism for the MECP2 variant. Fifty-nine males were identified through the parent group. Their ages ranged from 2 to 28 years, with the median age being 7.0 years and the mean age being 10.8 years. Of these variants, 46 (78.0%) were de novo , nine (15.3%) were maternally inherited, and for four (6.8%) inheritance was not known. Eleven (18.6%) were mosaic, 10 with somatic mosaicism and one with Klinefelter syndrome (47XXY). Together with males reported previously from the US Natural History Study, the total group represents 85 males, of whom 27 are deceased. These data on males with MECP2 variants are important to caregivers, physicians, and researchers to begin to characterize their historical and clinical features, improve diagnostic recognition and overall care, and accelerate access to therapeutic studies including gene replacement strategies. Equal access to such therapies for males is critical. [ABSTRACT FROM AUTHOR]

This study aimed to explore the clinical utility of targeted MECP2 testing in a large cohort of females with neurodevelopmental delays. Our aim was to identify suitable candidates for testing based on prevailing diagnostic criteria. Eligible participants with global developmental delay/arrest or regression before age 36 months underwent MECP2 testing. MECP2 -positive patients were further categorized based on Rett syndrome (RTT) diagnostic criteria, including typical, atypical, possible, and unclassified, to assess disease typicality and progression with respect to age. Of the 683 patients, 162 (23.7%) were diagnosed with MECP2 -related RTT. Global developmental delay was the predominant initial symptom in approximately 75% of the cohort with developmental arrest/regression at testing. Symptoms emerged before age six months in 14 patients (8.6%). The average age at the time of MECP2 testing was 3.7 years, with 31.5% of the patients tested under two years. Of those under two years, 15 were initially categorized into the unclassified group; however, 12 were later reclassified into the typical/atypical RTT groups based on follow-up evaluation. Among the 119 patients monitored beyond age five years, 80% displayed typical RTT symptoms, 10 remained unclassified, and 9.8% had exonic deletions, posing challenges for detection using next-generation sequencing. Targeted MECP2 testing has emerged as a clinically valuable tool with a high diagnostic yield, including the identification of small deletions. Given that younger patients may not always meet the classic RTT criteria, this study recommends targeted MECP2 testing in younger patients without typical RTT features. [ABSTRACT FROM AUTHOR]

Sleep problems are prevalent among individuals with Rett syndrome. We aimed to investigate sleep problems in individuals with Rett syndrome and their caregivers. A total of 29 participants diagnosed with Rett syndrome and their respective 29 caregivers were included. The Children Sleep Habits Questionnaire (CSHQ), the Pittsburgh Sleep Quality Index (PSQI), the Center for Epidemiologic Studies Depression Scale (CES-D), and the actigraphy data collected from Actiwatch 2 were used to investigate the change of sleep pattern. Based on the CSHQ questionnaire, 75.9% (22/29) of the patients reported sleep disturbances. The younger patients exhibited higher CSHQ scores. Actigraphy data revealed that both young and older patients had short total sleep duration, low sleep efficiency, long sleep-onset latency, long awaking duration, and fragmented sleep. The caregivers reported significantly higher PSQI scores, mildly declined sleep efficiency, and shorter total sleep duration in the actigraphy study. Associations were identified between smaller head circumference and shorter total sleep duration, more severe motor dysfunction and longer wake after sleep onset, worsen scoliosis and more awakenings per night. Sleep efficiency was inversely associated with epilepsy and positively associated with somatic growth. Sleep disturbances are common and should be investigated in individuals with Rett syndrome and their caregivers. Sleep problems are common and impactful among individuals with Rett syndrome (RTT) and their caregivers. We examined the sleep patterns of 29 RTT patients and their primary caregivers using various assessment tools. The study found that a majority of the patients experienced sleep disturbances, with younger patients showing more sleep difficulties. Caregivers also reported poor sleep quality. The findings emphasize the need to address sleep problems in RTT management, as improving sleep quality can positively impact the well-being of individuals with RTT and their caregivers. [ABSTRACT FROM AUTHOR]

This study tackles the question: how is literacy engagement enacted in the context of significant disability? We delve into the complex literacy practices of Kalika, a three-year-old child with Rett syndrome, a rare neurodevelopmental disorder, to elucidate how she engages with printed text. Rett syndrome leads to near total loss of verbal communication and limited functional hand use, making it particularly challenging to participate in traditionally recognized forms of literacy engagement. Using in-depth qualitative data from both in- and out-of-school settings, we conduct a micro-level analysis of Kalika's behaviours during story time rituals. In order to bring analytic coherence to the data, we classified her modalities of literacy engagement under two broad categories: 1) kinesics, which included a) corporal (entailing full body positioning and motion), b) oral (involving contact with mouth or expression), c) oculesics (relating to eye gaze), and d) haptic (relating to hands) elements as well as 2) vocalics (pertaining to vocal tone and vocalisation). Our analysis elucidates the sophisticated, complex multimodal practices that Kalika enacts to engage with texts. For far too long, students with significant disabilities have been viewed from deficit perspectives, neglected within the literature as well as in the classroom, and thought to require additional instruction to learn how to engage with texts. We suggest that perhaps it is a question, instead, of educators and scholars learning to expand their own frames of reference. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Rett syndrome (RTT) is an X-linked progressive neurodevelopmental disorder that involves mainly girls and is the second most frequent cause of genetic intellectual disability. RTT leads to neurological regression between 6 and 18 months of life and could be associated with a variable neurological impairment. However, RTT affects not only neurological function but also wide aspects of non-neurological organs. Recent data showed that the endocrine system is often involved in RTT patients, including disorders of growth, bone health, thyroid, puberty onset, and weight abnormalities However, systematic data on endocrinopathies in RTT are scarce and limited. Objective: This review aims to analyze the prevalence and type of endocrine comorbidities in RTT population, to allow a precocious diagnosis and appropriate endocrinological management. Methods: Systematic research was carried out from January 2000 to March 2024 through MEDLINE via PubMed, Scopus, and the Cochrane Library. Results: After the selection phase, a total of 22 studies (1090 screened) met the inclusion criteria and were reported in the present review. Five studies were observational-retrospective, four were cross-sectional and case report or series, three were survey, prospective, and case-control, and finally one study for descriptive-transversal and longitudinal population-based study. The sample population consisted of multiethnic groups or single ethnic groups. The main endocrinopathies reported were malnutrition, bone alterations, and alterations of puberty onset. Conclusions: Our analysis shows that endocrinopathies are not rare in RTT patients. Therefore, in the context of a multidisciplinary approach, accurate screening and monitoring for endocrinopathies should be recommended in all RTT patients, to improve clinical practice, healthcare management, and, finally, patients' quality of life. [ABSTRACT FROM AUTHOR]

Loss-of-function mutations in MECP2 are associated to Rett syndrome (RTT), a severe neurodevelopmental disease. Mainly working as a transcriptional regulator, MeCP2 absence leads to gene expression perturbations resulting in deficits of synaptic function and neuronal activity. In addition, RTT patients and mouse models suffer from a complex metabolic syndrome, suggesting that related cellular pathways might contribute to neuropathogenesis. Along this line, autophagy is critical in sustaining developing neuron homeostasis by breaking down dysfunctional proteins, lipids, and organelles. Here, we investigated the autophagic pathway in RTT and found reduced content of autophagic vacuoles in Mecp2 knock-out neurons. This correlates with defective lipidation of LC3B, probably caused by a deficiency of the autophagic membrane lipid phosphatidylethanolamine. The administration of the autophagy inducer trehalose recovers LC3B lipidation, autophagosomes content in knock-out neurons, and ameliorates their morphology, neuronal activity and synaptic ultrastructure. Moreover, we provide evidence for attenuation of motor and exploratory impairment in Mecp2 knock-out mice upon trehalose administration. Overall, our findings open new perspectives for neurodevelopmental disorders therapies based on the concept of autophagy modulation. Synopsis: Autophagosome biogenesis is impaired in Rett syndrome, a complex neurodevelopmental disorder caused by loss of function mutations in MECP2. Autophagy enhancement restores defects in neurons lacking Mecp2, suggesting a possible contribution of this pathway in the pathogenesis of Rett. LC3B-II lipidation, which is essential for autophagosome biogenesis, is defective in Mecp2 KO cells, probably due to the reduced availability of phosphatidylethanolamine (PE). The natural disaccharide and autophagy inducer trehalose restores the amount of PE and improves dendritic complexity and synaptic ultrastructure in Mecp2 KO neurons. In vivo administration of trehalose ameliorates exploratory and locomotor skills of Mecp2 KO male mice. Autophagosome biogenesis is impaired in Rett syndrome, a complex neurodevelopmental disorder caused by loss of function mutations in MECP2. Autophagy enhancement restores defects in neurons lacking Mecp2, suggesting a possible contribution of this pathway in the pathogenesis of Rett. [ABSTRACT FROM AUTHOR]

Rett syndrome (RTT) is a severe neurodevelopmental disorder primarily caused by mutations in the methyl-CpG binding protein 2 (MECP2) gene. Despite advancements in research, no cure exists due to an incomplete understanding of the molecular effects of MeCP2 deficiency. Previous studies have identified impaired tropomyosin receptor kinase (Trk) neurotrophin (NTP) signaling and mitochondrial redox imbalances as key drivers of the pathology. Moreover, altered glycosphingolipid metabolism has been reported in RTT. GM1 ganglioside is a known regulator of the nervous system, and growing evidence indicates its importance in maintaining neuronal homeostasis via its oligosaccharide chain, coded as GM1-OS. GM1-OS directly interacts with the Trk receptors on the cell surface, triggering neurotrophic and neuroprotective pathways in neurons. In this study, we demonstrate that GM1-OS ameliorates RTT deficits in the Mecp2-null model. GM1-OS restored synaptogenesis and reduced mitochondrial oxidative stress of Mecp2-knock-out (ko) cortical neurons. When administered in vivo, GM1-OS mitigated RTT-like symptoms. Our findings indicate that GM1-OS effects were mediated by Trk receptor activation on the neuron's plasma membrane. Overall, our results highlight GM1-OS as a promising candidate for RTT treatment. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Background: Rett syndrome (RTT) is an early-onset neurological disorder primarily affecting females, leading to severe cognitive and physical disabilities. Recent studies indicate that an imbalance of redox homeostasis and exacerbated inflammatory responses are key players in the clinical manifestations of the disease. Emerging evidence highlights that the p75 neurotrophin receptor (p75NTR) is implicated in the regulation of oxidative stress (OS) and inflammation. Thus, this study is aimed at investigating the effects of p75NTR modulation by LM11A-31 on fibroblasts derived from RTT donors. Methods: RTT cells were treated with 0.1 µM of LM11A-31 for 24 h, and results were obtained using qPCR, immunofluorescence, ELISA, and Western blot techniques. Results: Our findings demonstrate that LM11A-31 reduces OS markers in RTT fibroblasts. Specifically, p75NTR modulation by LM11A-31 restores protein glutathionylation and reduces the expression of the pro-oxidant enzyme NOX4. Additionally, LM11A-31 significantly decreases the expression of the pro-inflammatory mediators interleukin-6 and interleukin-8. Additionally, LM11A-31 normalizes the expression levels of transcription factors involved in the regulation of the antioxidant response and inflammation. Conclusions: Collectively, these data suggest that p75NTR modulation may represent an effective therapeutic target to improve redox balance and reduce inflammation in RTT. [ABSTRACT FROM AUTHOR]

Methylation, a key epigenetic modification, is essential for regulating gene expression and protein function without altering the DNA sequence, contributing to various biological processes, including gene transcription, embryonic development, and cellular functions. Methylation encompasses DNA methylation, RNA methylation and histone modification. Recent research indicates that DNA methylation is vital for establishing and maintaining normal brain functions by modulating the high-order structure of DNA. Alterations in the patterns of DNA methylation can exert significant impacts on both gene expression and cellular function, playing a role in the development of numerous diseases, such as neurological disorders, cardiovascular diseases as well as cancer. Our current understanding of the etiology of neurological diseases emphasizes a multifaceted process that includes neurodegenerative, neuroinflammatory, and neurovascular events. Epigenetic modifications, especially DNA methylation, are fundamental in the control of gene expression and are critical in the onset and progression of neurological disorders. Furthermore, we comprehensively overview the role and mechanism of DNA methylation in in various biological processes and gene regulation in neurological diseases. Understanding the mechanisms and dynamics of DNA methylation in neural development can provide valuable insights into human biology and potentially lead to novel therapies for various neurological diseases. [ABSTRACT FROM AUTHOR]

Introduction: Rett syndrome (RTT) is a rare neurodevelopmental disorder with developmental impairments, comorbidities, and abnormal behaviours such as hand stereotypies and emotional features. The Rett Syndrome Behaviour Questionnaire (RSBQ) was developed to describe the behavioural and emotional features of RTT. Little is known how RSBQ scores are associated with genetic and clinical characteristics in RTT. This study investigated relationships between genotype, age, walking, hand function, sleep, and RSBQ total and subscale scores in RTT. Methods: This is a cross-sectional analysis of data collected in the Australian Rett Syndrome Database and the International Rett Syndrome Phenotype Database. Parent caregivers completed the RSBQ and Sleep Disturbance Scale for Children [subscales for disorders of initiating and maintaining sleep (DIMS), disorders of excessive somnolence (DOES)], and provided information on age, variant type, functional abilities (mobility, hand function), seizure frequency and gastrointestinal problems. Associations between the RSBQ scores and the independent variables were modelled using linear regression. Results: Data were available for 365 individuals with RTT [median (range) age 17.8 (2.9–51.9) years, 2 males]. Compared to adults, 2- to 12-year-old children had higher mean Total, Night-time Behaviour and Fear/Anxiety scores. Compared to individuals with a C-terminal deletion, individuals with the p.Arg255* variant had higher mean Total and Night-time Behaviours scores, whereas the p.Arg294* variant had higher mean Mood scores. Individuals with intermediate mobility and hand function abilities had a higher mean Total score. Total RSBQ and subscale scores were similar across categories for seizures, constipation, and reflux, but were higher with abnormal DIMS and abnormal DOES scores. Conclusion: Except for associations with sleep, the RSBQ measures the behavioural phenotype rather than clinical severity in RTT, as traditionally conceptualised in terms of functional abilities and comorbidities. When designing clinical trials, the RSBQ needs to be complemented by other outcome measures to assess specific core functions and associated comorbidities in RTT. [ABSTRACT FROM AUTHOR]

Methyl‐CpG binding protein 2 (MeCP2) is an important X‐linked DNA methylation reader and a key heterochromatin organizer. The expression level of MeCP2 is crucial, as indicated by the observation that loss‐of‐function mutations of MECP2 cause Rett syndrome, whereas an extra copy spanning the MECP2 locus results in MECP2 duplication syndrome, both being progressive neurodevelopmental disorders. Our previous study demonstrated that MeCP2 protein expression is rapidly induced by renal ischemia–reperfusion injury (IRI) and protects the kidney from IRI through transcriptionally repressing the interleukin‐6 (IL‐6)/signal transducer and activator of transcription 3 signaling pathway. However, the mechanisms underlying the upregulation of MeCP2 have remained elusive. Here, by using two hypoxia cell models, hypoxia and reoxygenation and cobalt chloride stimulation, we confirmed that the removal of lysine 48‐linked ubiquitination from MeCP2 prevented its proteasome‐dependent degradation under hypoxic conditions. Through unbiased screening based on a deubiquitinating enzymes library, we identified ubiquitin‐specific protease 15 (USP15) as a stabilizer of MeCP2. Further studies revealed that USP15 could attenuate hypoxia‐induced MeCP2 degradation by cleaving lysine 48‐linked ubiquitin chains from MeCP2, primarily targeting its C‐terminal domain. Consistently, USP15 inhibited hypoxia‐induced signal transducer and activator of transcription 3 activation, resulting in reduced transcription of IL‐6 downstream genes. In summary, our study reveals an important role for USP15 in the maintenance of MeCP2 stability and the regulation of IL‐6 signaling. [ABSTRACT FROM AUTHOR]

Pathognomonic EEG patterns have been described in genetic conditions such as Angelman and Rett syndromes. EEG patterns along the ictal-interictal continuum have been increasingly recognized with the greater availability of continuous EEG monitoring; however, treatment decisions may be difficult with unpredictable clinical implications. Rhythmic High-Amplitude Delta Activity with Superimposed (Poly) Spikes (RHADS) has been described as a particular EEG pattern in POLG1 Alpers Syndrome. The balance between treating subclinical seizures and managing encephalopathy in these patients is challenging. [ABSTRACT FROM AUTHOR]

Motor deficit is a core symptom of Rett syndrome, a rare neurological disease caused in most cases by mutations of the methyl-CpG-binding protein2 (MECP2) gene. Serotonin reuptake inhibitors improve motor coordination in Mecp2 heterozygous (Het) mice and serotonin depletion prevented this effect. Here, we assess alterations in indole levels in various brain regions and whether boosting brain serotonin synthesis with the serotonin precursors tryptophan, 5-hydroxytryptophan and α-lactalbumin rescued motor coordination deficit of Mecp2 Het mice. Motor coordination was assessed in the accelerated rotarod during and after systemic administration of serotonin precursors for 2–3 weeks. Since no data are available, the effect of α-lactalbumin on tryptophan, serotonin and 5-hydroxyindoleacetic acid levels was evaluated in various brain regions in order to identify the dose of ALAC to evaluate on motor coordination. As compared to WT, Mecp2 Het mice show reduced levels of serotonin in the whole brain, hippocampus, brainstem and cerebral cortex, but not the striatum. Reduced levels of 5-hydroxyindoleacetic acid were observed in the hippocampus and brainstem. Doses of serotonin precursors increasing brain tryptophan and/or serotonin production and metabolism had no effect on motor coordination. The results indicate that boosting serotonin synthesis is not sufficient to improve motor coordination of Mecp2 Het mice. [ABSTRACT FROM AUTHOR]

Background: Rett syndrome (RTT) is an uncommon inherited neurodevelopmental disorder that affects brain development, mostly in females. It results from mutation in MECP2 gene in the long arm (q) of the X chromosome. Objective: Trofinetide is a recently developed drug that has a neuroprotective effect on neurons, and it is our aim in this meta-analysis to evaluate its efficacy and safety in treating Rett syndrome patients. Methods: We searched 5 databases (PubMed, Scopus, Embase, Web of Science, and Cochrane Library databases) to identify randomized controlled trials (RCTs) comparing Trofinetide and placebo in patients with Rett syndrome until August 13, 2023.Our primary outcomes were the Clinical Global Impression-Improvement (CGI) and the Rett syndrome Behavior Questionnaire (RSBQ). We used Risk of Bias Assessment tool-2 (ROB2) to assess the methodological quality of the included randomized controlled trials. Results: Three RCTs with a total of 325 patients were included with a follow-up duration ranging from one month to three months. 186 patients received the intervention drug (Trofinetide) and 138 received the placebo. Trofinetide was found to reduce CGI and RSBQ significantly more than placebo (MD = -0.35, 95% CI [-0.52 to -0.18], P 0.0001), (MD = -3.40, 95% CI [-3.69 to -3.12], P 0.00001) respectively. Most adverse events did not show any statistical difference between Trofinetide and the placebo. Conclusion: Trofinetide offers promise as a potential effective and safe therapeutic opportunity for a population without many available treatments, with improvements seen on both CGI and RSBQ assessments and no severe adverse effects reported. [ABSTRACT FROM AUTHOR]

Typical (or classic) Rett syndrome (RTT) is an X‐linked neurodevelopmental disorder characterized by a period of regression, partial or complete loss of purposeful hand movements, and acquired speech, impaired gait, and stereotyped hand movements. In over 95% of typical RTT, a pathogenic variant is found in the methyl‐CPG binding protein 2 gene (MECP2). Here, we describe a young woman with clinically diagnosed typical RTT syndrome who lacked a genetic diagnosis despite 20 years of investigation and multiple rounds of sequencing the MECP2 gene. Recently, additional genetic testing using next‐generation sequencing was completed, which revealed a partial insertion of the BCL11A gene within exon 4 of MECP2, resulting in a small deletion in MECP2, causing likely disruption of MeCP2 function due to a frameshift. This case demonstrates the ever‐changing limitations of genetic testing, as well as the importance of continual pursuit of a diagnosis as technologies improve and are more widely utilized. [ABSTRACT FROM AUTHOR]

Mounting evidence suggests a prominent role for alpha-synuclein (a-syn) in neuronal cell function. Alterations in the levels of cellular a-syn have been hypothesized to play a critical role in the development of Parkinson's disease (PD); however, mechanisms that control expression of the gene for a-syn (SNCA) in cis and trans as well as turnover of a-syn are not well understood. We analyzed whether methyl-CpG binding protein 2 (MeCP2), a protein that specifically binds methylated DNA, thus regulating transcription, binds at predicted binding sites in intron 1 of the SNCA gene and regulates a-syn protein expression. Chromatin immunoprecipitation (ChIP) and electrophoretic mobility-shift assays (EMSA) were used to confirm binding of MeCP2 to regulatory regions of SNCA. Site-specific methylation and introduction of localized mutations by CRISPR/Cas9 were used to investigate the binding properties of MeCP2 in human SK-N-SH neuroblastoma cells. The significance of MeCP2 for SNCA regulation was further investigated by overexpressing MeCP2 and mutated variants of MeCP2 in MeCP2 knockout cells. We found that methylation-dependent binding of MeCP2 at a restricted region of intron 1 of SNCA had a significant impact on the production of a-syn. A single nucleotide substitution near to CpG1 strongly increased the binding of MeCP2 to intron 1 of SNCA and decreased a-syn protein expression by 60%. In contrast, deletion of a single nucleotide closed to CpG2 led to reduced binding of MeCP2 and significantly increased a-syn levels. In accordance, knockout of MeCP2 in SK-N-SH cells resulted in a significant increase in a-syn production, demonstrating that SNCA is a genomic target for MeCP2 regulation. In addition, the expression of two mutated MeCP2 variants found in Rett syndrome (RTT) showed a loss of their ability to reduce a-syn expression. This study demonstrates that methylation of CpGs and binding of MeCP2 to intron 1 of the SNCA gene plays an important role in the control of a-syn expression. In addition, the changes in SNCA regulation found by expression of MeCP2 variants carrying mutations found in RTT patients may be of importance for the elucidation of a new molecular pathway in RTT, a rare neurological disorder caused by mutations in MECP2. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract Loss-of-function mutations in MECP2 are associated to Rett syndrome (RTT), a severe neurodevelopmental disease. Mainly working as a transcriptional regulator, MeCP2 absence leads to gene expression perturbations resulting in deficits of synaptic function and neuronal activity. In addition, RTT patients and mouse models suffer from a complex metabolic syndrome, suggesting that related cellular pathways might contribute to neuropathogenesis. Along this line, autophagy is critical in sustaining developing neuron homeostasis by breaking down dysfunctional proteins, lipids, and organelles. Here, we investigated the autophagic pathway in RTT and found reduced content of autophagic vacuoles in Mecp2 knock-out neurons. This correlates with defective lipidation of LC3B, probably caused by a deficiency of the autophagic membrane lipid phosphatidylethanolamine. The administration of the autophagy inducer trehalose recovers LC3B lipidation, autophagosomes content in knock-out neurons, and ameliorates their morphology, neuronal activity and synaptic ultrastructure. Moreover, we provide evidence for attenuation of motor and exploratory impairment in Mecp2 knock-out mice upon trehalose administration. Overall, our findings open new perspectives for neurodevelopmental disorders therapies based on the concept of autophagy modulation.

Abstract Introduction Rett syndrome (RTT) is a rare neurodevelopmental disorder with developmental impairments, comorbidities, and abnormal behaviours such as hand stereotypies and emotional features. The Rett Syndrome Behaviour Questionnaire (RSBQ) was developed to describe the behavioural and emotional features of RTT. Little is known how RSBQ scores are associated with genetic and clinical characteristics in RTT. This study investigated relationships between genotype, age, walking, hand function, sleep, and RSBQ total and subscale scores in RTT. Methods This is a cross-sectional analysis of data collected in the Australian Rett Syndrome Database and the International Rett Syndrome Phenotype Database. Parent caregivers completed the RSBQ and Sleep Disturbance Scale for Children [subscales for disorders of initiating and maintaining sleep (DIMS), disorders of excessive somnolence (DOES)], and provided information on age, variant type, functional abilities (mobility, hand function), seizure frequency and gastrointestinal problems. Associations between the RSBQ scores and the independent variables were modelled using linear regression. Results Data were available for 365 individuals with RTT [median (range) age 17.8 (2.9–51.9) years, 2 males]. Compared to adults, 2- to 12-year-old children had higher mean Total, Night-time Behaviour and Fear/Anxiety scores. Compared to individuals with a C-terminal deletion, individuals with the p.Arg255* variant had higher mean Total and Night-time Behaviours scores, whereas the p.Arg294* variant had higher mean Mood scores. Individuals with intermediate mobility and hand function abilities had a higher mean Total score. Total RSBQ and subscale scores were similar across categories for seizures, constipation, and reflux, but were higher with abnormal DIMS and abnormal DOES scores. Conclusion Except for associations with sleep, the RSBQ measures the behavioural phenotype rather than clinical severity in RTT, as traditionally conceptualised in terms of functional abilities and comorbidities. When designing clinical trials, the RSBQ needs to be complemented by other outcome measures to assess specific core functions and associated comorbidities in RTT.

Loss-of-function mutations in MECP2 cause Rett syndrome (RTT), a severe neurological disorder that mainly affects girls. Mutations in MECP2 do occur in males occasionally and typically cause severe encephalopathy and premature lethality. Recently, we identified a missense mutation (c.353G>A, p.Gly118Glu [G118E]), which has never been seen before in MECP2, in a young boy who suffered from progressive motor dysfunction and developmental delay. To determine whether this variant caused the clinical symptoms and study its functional consequences, we established two disease models, including human neurons from patient-derived iPSCs and a knock-in mouse line. G118E mutation partially reduces MeCP2 abundance and its DNA binding, and G118E mice manifest RTT-like symptoms seen in the patient, affirming the pathogenicity of this mutation. Using live-cell and single-molecule imaging, we found that G118E mutation alters MeCP2s chromatin interaction properties in live neurons independently of its effect on protein levels. Here we report the generation and characterization of RTT models of a male hypomorphic variant and reveal new insight into the mechanism by which this pathological mutation affects MeCP2s chromatin dynamics. Our ability to quantify protein dynamics in disease models lays the foundation for harnessing high-resolution single-molecule imaging as the next frontier for developing innovative therapies for RTT and other diseases.

Abstract Understanding clinical features and disease progression of Rett syndrome (RTT) and establishing clinical trial readiness was enhanced by the RTT Natural History Study (NHS). The NHS benefited from two key developments: one, the Orphan Drug Act passed by Congress in 1983 defining criteria for rare disorders in the United States and creating opportunities for pharmaceutical companies to develop products for individuals with rare disorders, and two, the Rare Diseases Act of 2002, which established the National Institutes of Health Office of Rare Diseases and provided research funding. Funding for the RTT and related disorders NHS was obtained in 2003, creating a broad network of experienced clinical investigators across the United States and producing critical results not only for RTT but also for related disorders: CDKL5 deficiency disorder, FOXG1 disorder, and MECP2 duplication syndrome. Longitudinal information from over 1800 participants (more than 1600 diagnosed with RTT) led to multiple reports describing their clinical features and natural progression and identified putative biomarkers and clinical outcome measures. Establishing clinical trial readiness assisted in evaluating the first FDA‐approved medication for RTT in 2023 and continues to provide opportunities to develop potentially life‐altering therapies. The experiences of the RTT NHS journey provide informative guidance for studying other rare neurological disorders. These lessons include positive features of developing productive collaborations focused on improving lives of people and families with RTT and related disorders, as well as lessons learned through retrospective analysis for improving overall conduct of natural history studies in rare disorders.

Abstract Background Defective mitochondria and aberrant brain mitochondrial bioenergetics are consistent features in syndromic intellectual disability disorders, such as Rett syndrome (RTT), a rare neurologic disorder that severely affects mainly females carrying mutations in the X-linked MECP2 gene. A pool of CB1 cannabinoid receptors (CB1R), the primary receptor subtype of the endocannabinoid system in the brain, is located on brain mitochondrial membranes (mtCB1R), where it can locally regulate energy production, synaptic transmission and memory abilities through the inhibition of the intra-mitochondrial protein kinase A (mtPKA). In the present study, we asked whether an overactive mtCB1R-mtPKA signaling might underlie the brain mitochondrial alterations in RTT and whether its modulation by systemic administration of the CB1R inverse agonist rimonabant might improve bioenergetics and cognitive defects in mice modeling RTT. Methods Rimonabant (0.3 mg/kg/day, intraperitoneal injections) was administered daily to symptomatic female mice carrying a truncating mutation of the Mecp2 gene and its effects on brain mitochondria functionality, systemic oxidative status, and memory function were assessed. Results mtCB1R is overexpressed in the RTT mouse brain. Subchronic treatment with rimonabant normalizes mtCB1R expression in RTT mouse brains, boosts mtPKA signaling, and restores the defective brain mitochondrial bioenergetics, abnormal peripheral redox homeostasis, and impaired cognitive abilities in RTT mice. Limitations The lack of selectivity of the rimonabant treatment towards mtCB1R does not allow us to exclude that the beneficial effects exerted by the treatment in the RTT mouse model may be ascribed more broadly to the modulation of CB1R activity and distribution among intracellular compartments, rather than to a selective effect on mtCB1R-mediated signaling. The low sample size of few experiments is a further limitation that has been addressed replicating the main findings under different experimental conditions. Conclusions The present data identify mtCB1R overexpression as a novel molecular alteration in the RTT mouse brain that may underlie defective brain mitochondrial bioenergetics and cognitive dysfunction.

Abstract Studies on MECP2 function and its implications in Rett Syndrome (RTT) have traditionally centered on neurons. Here, using human embryonic stem cell (hESC) lines, we modeled MECP2 loss-of-function to explore its effects on astrocyte (AST) development and dysfunction in the brain. Ultrastructural analysis of RTT hESC-derived cerebral organoids revealed significantly smaller mitochondria compared to controls (CTRs), particularly pronounced in glia versus neurons. Employing a multiomics approach, we observed increased gene expression and accessibility of a subset of nuclear-encoded mitochondrial genes upon mutation of MECP2 in ASTs compared to neurons. Analysis of hESC-derived ASTs showed reduced mitochondrial respiration and altered key proteins in the tricarboxylic acid cycle and electron transport chain in RTT versus CTRs. Additionally, RTT ASTs exhibited increased cytosolic amino acids under basal conditions, which were depleted upon increased energy demands. Notably, mitochondria isolated from RTT ASTs exhibited increased reactive oxygen species and influenced neuronal activity when transferred to cortical neurons. These findings underscore MECP2 mutation's differential impact on mitochondrial and metabolic pathways in ASTs versus neurons, suggesting that dysfunctional AST mitochondria may contribute to RTT pathophysiology by affecting neuronal health.

Objective Summarize the clinical and genetic characteristics of atypical Rett syndrome and developmental epileptic encephalopathy caused by IQSEC2 gene variation. Methods and Results From May 2020 to April 2022, Anhui Provincial Children's Hospital diagnosed and treated 4 children with atypical Rett syndrome and developmental epileptic encephalopathy caused by IQSEC2 gene variation, including 2 males and 2 females were a pair of identical twins. They all had comprehensive developmental delay before onset. At the age of 2 years, all cases gradually exhibited clinical manifestations of atypical Rett syndrome, such as frequent clapping, biting, sleep disorders (increased sleep or difficulty falling asleep), and grinding teeth, followed by developmental regression and seizures. The initial age of epilepsy was from 2 years and 2 months to 2 years and 10 months. All cases started with generalized tonic-clonic seizure, with epileptic spasm occurring between 2 and 11 months of course. Case 2, Case 3 and Case 4 were also accompanied by focal seizures. Four cases with VEEG background of 4-6 Hz θ wave, the VEEG during the interictal phase was a broad multifocal sharp slow complex wave. In Case 2, Case 3 and Case 4,MRI was abnormal, mainly with increased depth of cerebral hemispheric sulcus and gyrus. The whole exome sequencing suggested pathogenicity and possible pathogenic variations in the IQSEC2 gene, Case 1 and Case 2 were frameshift mutations of c. 608dup (p. Gln204Profs*35), while Case 3 and Case 4 were nonsense mutations of c.2231C > A (p.Ser744Ter) and c.2521C > T (p.Gln841Ter), respectively. The four mutation sites have not been reported domestically or internationally. All cases received treatment with multiple antiepileptic seizure medicine. The last follow-up age was from 4 years and 3 months to 6 years and 3 months. All cases were unable to walk alone and had no active language. There were no seizures in Case 1 for 3 years, occasional seizures in Case 2 and Case 4, and frequent seizures in Case 3. Conclusions IQSEC2 gene variation can manifest as atypical Rett syndrome, which can be accompanied by refractory epileptic spasms. Both males and females have severe phenotypes, and the severity of clinical phenotypes at the same mutation site varies. Our report enriches the variation spectrum and clinical phenotype spectrum of the IQSEC2 gene, expands the genetic spectrum of Rett syndrome and developmental epileptic encephalopathy, and provides value for the clinical diagnosis, treatment and subsequent research of this disease.