Adolescents with Rett syndrome at critical care pathway junctures: Examining clinicians' decision to initiate invasive long-term ventilation.

BACKGROUND: The initiation of invasive long-term ventilation (I-LTV) for an adolescent with Rett Syndrome (RTT) involves many serious bioethical considerations. In moving towards a more inclusive model of patient participation, transparency surrounding the main influencing factors around this decision is important. OBJECTIVE: We aimed to identify the main drivers influencing a clinician's decision to support initiation of I-LTV for an adolescent with RTT. METHOD: We used an anonymous online vignette-based factorial survey. The survey was distributed internationally through eight professional multi-disciplinary organisations to reach clinicians working in paediatrics. RESULTS: We analysed 504 RTT vignettes completed by 246 clinicians using mixed effect regression modelling. The main three significant influencing factors identified were: parental agreement with the decision to support initiation, the family's support network, and proximity to a tertiary care centre. Additional comments from participants focused on family support, and the importance of on-going communication with the family. CONCLUSION: As the rights of those with disabilities improve and participation of adolescents in decision-making becomes more established, effective communications with the family around goals of care and particular sensitivity and reflective practice around methods of consensus building will likely contribute to a positive decision-making process at this difficult time.

Treatment guidelines for rare, early-onset conditions associated with epileptic seizures: a literature review on Rett syndrome and tuberous sclerosis complex.

BACKGROUND: Rett syndrome (RTT) and tuberous sclerosis complex (TSC) are two rare disorders presenting with a range of different epileptic seizures. Seizure management requires careful therapy selection, thereby necessitating development of high-quality treatment guidelines. This targeted literature review (TLR) aimed to characterise country-specific and international treatment guidelines available for pharmacological management of seizures in RTT and TSC. METHODS: A TLR was performed between 25-Jan and 11-Mar 2021. Manual searches of online rare disease and guideline databases, and websites of national heath technology assessment bodies were conducted for the following countries: Australia, Canada, France, Germany, Israel, Italy, Japan, Spain, Switzerland, UK, and US as defined by pre-specified eligibility criteria. Search terms were developed for each condition and translated into local languages where appropriate. Eligible publications were defined as guidelines/guidance reporting pharmacological management of seizures in patients with RTT and TSC. Guideline development methodology, geographical focus, author information and treatment recommendations were extracted from guidelines. An author map was generated using R version 3.5.1 to visualise extent of collaboration between authors. RESULTS: 24 total guidelines were included, of which three and six contained only recommendations for RTT and TSC, respectively (some provided recommendations for ≥ 1 condition). Guideline development processes were poorly described (50% [12 guidelines] had unclear/absent literature review methodologies); reported methodologies were variable, including systematic literature reviews (SLRs)/TLRs and varying levels of expert consultation. Most (83% [20/24]) were country-specific, with guideline authors predominantly publishing in contained national groups; four guidelines were classified as 'International,' linking author groups in the US, UK, Italy and France. High levels of heterogeneity were observed in the availability of treatment recommendations across indications, with 13 and 67 recommendations found for RTT and TSC, respectively. For RTT, all treatment recommendations were positive and sodium valproate had the highest number of positive recommendations (Khwaja, Sahin (2011) Curr Opin Pediatr 23(6):633-9). All TSC treatments (21 medications) received either exclusively negative (National Organization for Rare Disorders (2019)) or positive (Chu-Shore et al. (2010) Epilepsia 51(7):1236-41) recommendations; vigabatrin received the highest number of positive recommendations (Kaur, Christodoulou (2019)). CONCLUSIONS: This review highlights the need for the development of international high-quality and comprehensive consensus-based guidance for the management of seizures with pharmacological therapy in RTT and TSC. TRIAL REGISTRATION: Not applicable.

Therapeutic effects of extracorporeal shock wave therapy on patients with spastic cerebral palsy and Rett syndrome: clinical and ultrasonographic findings.

BACKGROUND: Extracorporeal shock wave therapy (ESWT) is reportedly effective for improving spasticity and motor function in children with cerebral palsy (CP). Because late-stage Rett syndrome has a similar presentation, this study aimed to investigate the effects of ESWT on these two diseases. MATERIAL AND METHODS: Patients diagnosed with spastic CP and Rett syndrome received 1500 impulses of ESWT at 4 Hz and 0.1 mJ/mm2, on their spastic legsonce weekly for a total of 12 weeks. Outcomes were assessed before and 4 and 12 weeks after ESWT. Clinical assessments included the Modified Ashworth Scale (MAS), passive range of motion (PROM), and Gross Motor Function Measure 88 (GMFM-88). Ultrasonographic assessments included muscle thickness, acoustic radiation force impulse (ARFI), and strain elastography. RESULTS: Fifteen patients with CP and six with Rett syndrome were enrolled in this study. After ESWT, patients with CP showed significant clinical improvement in the MAS (P = 0.011), ankle PROM (P = 0.002), walking/running/jumping function (P = 0.003), and total function (P < 0.001) of the GMFM-88. The patients with Rett syndrome showed improved MAS scores (P = 0.061) and significantly improved total gross motor function (P = 0.030). Under ARFI, patients with CP demonstrated decreased shear wave speed in the gastrocnemius medial head (P = 0.038). Conversely, patients with Rett syndrome show increased shear-wave speeds after ESWT. CONCLUSION: Our study provides evidence that a weekly course of low-dose ESWT for 12 weeks is beneficial for children with both CP and Rett syndrome, with the clinical effects of reducing spasticity and improving the gross motor function of the lower limbs. The ARFI sonoelastography reveals improvement of muscle stiffness in patients with CP after ESWT, but deteriorated in patients with Rett syndrome. The diverse therapeutic response to ESWT may be caused by the MECP2 mutation in Rett syndrome, having a continuous impact and driving the pathophysiology differently as compared to CP, which is secondary to a static insult. Trial registration IRB 201700462A3. Registered 22March 2017, https://cghhrpms.cgmh.org.tw/HRPMS/Default.aspx .

Adenosinergic System and BDNF Signaling Changes as a Cross-Sectional Feature of RTT: Characterization of Mecp2 Heterozygous Mouse Females.

Rett Syndrome is an X-linked neurodevelopmental disorder (RTT; OMIM#312750) associated to MECP2 mutations. MeCP2 dysfunction is seen as one cause for the deficiencies found in brain-derived neurotrophic factor (BDNF) signaling, since BDNF is one of the genes under MeCP2 jurisdiction. BDNF signaling is also dependent on the proper function of the adenosinergic system. Indeed, both BDNF signaling and the adenosinergic system are altered in Mecp2-null mice (Mecp2-/y), a representative model of severe manifestation of RTT. Considering that symptoms severity largely differs among RTT patients, we set out to investigate the BDNF and ADO signaling modifications in Mecp2 heterozygous female mice (Mecp2+/-) presenting a less severe phenotype. Symptomatic Mecp2+/- mice have lower BDNF levels in the cortex and hippocampus. This is accompanied by a loss of BDNF-induced facilitation of hippocampal long-term potentiation (LTP), which could be restored upon selective activation of adenosine A2A receptors (A2AR). While no differences were observed in the amount of adenosine in the cortex and hippocampus of Mecp2+/- mice compared with healthy littermates, the density of the A1R and A2AR subtype receptors was, respectively, upregulated and downregulated in the hippocampus. Data suggest that significant changes in BDNF and adenosine signaling pathways are present in an RTT model with a milder disease phenotype: Mecp2+/- female animals. These features strengthen the theory that boosting adenosinergic activity may be a valid therapeutic strategy for RTT patients, regardless of their genetic penetrance.

Forniceal deep brain stimulation in a mouse model of Rett syndrome increases neurogenesis and hippocampal memory beyond the treatment period.

BACKGROUND: Rett syndrome (RTT), caused by mutations in the X-linked gene encoding methyl-CpG binding protein 2 (MeCP2), severely impairs learning and memory. We previously showed that forniceal deep brain stimulation (DBS) stimulates hippocampal neurogenesis with concomitant improvements in hippocampal-dependent learning and memory in a mouse model of RTT. OBJECTIVES: To determine the duration of DBS benefits; characterize DBS effects on hippocampal neurogenesis; and determine whether DBS influences MECP2 genotype and survival of newborn dentate granular cells (DGCs) in RTT mice. METHODS: Chronic DBS was delivered through an electrode implanted in the fimbria-fornix. We tested separate cohorts of mice in contextual and cued fear memory at different time points after DBS. We then examined neurogenesis, DGC apoptosis, and the expression of brain-derived neurotrophic factor (BDNF) and vascular endothelial growth factor (VEGF) after DBS by immunohistochemistry. RESULTS: After two weeks of forniceal DBS, memory improvements lasted between 6 and 9 weeks. Repeating DBS every 6 weeks was sufficient to maintain the improvement. Forniceal DBS stimulated the birth of more MeCP2-positive than MeCP2-negative DGCs and had no effect on DGC survival. It also increased the expression of BDNF but not VEGF in the RTT mouse dentate gyrus. CONCLUSION: Improvements in learning and memory from forniceal DBS in RTT mice extends well beyond the treatment period and can be maintained by repeated DBS. Stimulation of BDNF expression correlates with improvements in hippocampal neurogenesis and memory benefits.

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.

Diet and Nutritional Status of Polish Girls with Rett Syndrome-A Case-Control Study.

(1) Background: Rett syndrome may be considered a disease strongly associated with nutritional disorders that are likely to require special management strategies, extending beyond what is usually required for children with other developmental disorders. The aim of the study was to assess the nutritional status and diet of Polish girls with Rett syndrome. (2) Methods: Each patient (study group = 49, control group = 22) underwent anthropometric measurements, including body weight and height, waist, hip and arm circumference, and skinfold measurement. The assessment of the diet was based on the analysis of 7-day menus and the Food Frequency Questionnaire (FFQ-6). Data were analyzed using Statistica 13.3. (3) Results: The majority of the girls with Rett syndrome were deficient in weight and height, and consumed fewer calories, less protein, dietary fiber, calcium, and iron than the control group. They also drank less fluid. Soft products that were easy to chew and considered to be high in energy value were significantly more common in the menus. (4) Conclusions: Girls with Rett syndrome are characterized by weight deficiencies, poor growth that deteriorates with age, and are at risk of food shortages. Various nutritional intervention strategies should be explored to reduce and, if possible, prevent malnutrition and cachexia in such patients.

Novel MECP2 gene therapy is effective in a multicenter study using two mouse models of Rett syndrome and is safe in non-human primates.

The AAV9 gene therapy vector presented in this study is safe in mice and non-human primates and highly efficacious without causing overexpression toxicity, a major challenge for clinical translation of Rett syndrome gene therapy vectors to date. Our team designed a new truncated methyl-CpG-binding protein 2 (MECP2) promoter allowing widespread expression of MECP2 in mice and non-human primates after a single injection into the cerebrospinal fluid without causing overexpression symptoms up to 18 months after injection. Additionally, this new vector is highly efficacious at lower doses compared with previous constructs as demonstrated in extensive efficacy studies performed by two independent laboratories in two different Rett syndrome mouse models carrying either a knockout or one of the most frequent human mutations of Mecp2. Overall, data from this multicenter study highlight the efficacy and safety of this gene therapy construct, making it a promising candidate for first-in-human studies to treat Rett syndrome.

Rare variants in the MECP2 gene in girls with central precocious puberty: a translational cohort study.

BACKGROUND: Identification of genetic causes of central precocious puberty have revealed epigenetic mechanisms as regulators of human pubertal timing. MECP2, an X-linked gene, encodes a chromatin-associated protein with a role in gene transcription. MECP2 loss-of-function mutations usually cause Rett syndrome, a severe neurodevelopmental disorder. Early pubertal development has been shown in several patients with Rett syndrome. The aim of this study was to explore whether MECP2 variants are associated with an idiopathic central precocious puberty phenotype. METHODS: In this translational cohort study, participants were recruited from seven tertiary centres from five countries (Brazil, Spain, France, the USA, and the UK). Patients with idiopathic central precocious puberty were investigated for rare potentially damaging variants in the MECP2 gene, to assess whether MECP2 might contribute to the cause of central precocious puberty. Inclusion criteria were the development of progressive pubertal signs (Tanner stage 2) before the age of 8 years in girls and 9 years in boys and basal or GnRH-stimulated LH pubertal concentrations. Exclusion criteria were the diagnosis of peripheral precocious puberty and the presence of any recognised cause of central precocious puberty (CNS lesions, known monogenic causes, genetic syndromes, or early exposure to sex steroids). All patients included were followed up at the outpatient clinics of participating academic centres. We used high-throughput sequencing in 133 patients and Sanger sequencing of MECP2 in an additional 271 patients. Hypothalamic expression of Mecp2 and colocalisation with GnRH neurons were determined in mice to show expression of Mecp2 in key nuclei related to pubertal timing regulation. FINDINGS: Between Jun 15, 2020, and Jun 15, 2022, 404 patients with idiopathic central precocious puberty (383 [95%] girls and 21 [5%] boys; 261 [65%] sporadic cases and 143 [35%] familial cases from 134 unrelated families) were enrolled and assessed. We identified three rare heterozygous likely damaging coding variants in MECP2 in five girls: a de novo missense variant (Arg97Cys) in two monozygotic twin sisters with central precocious puberty and microcephaly; a de novo missense variant (Ser176Arg) in one girl with sporadic central precocious puberty, obesity, and autism; and an insertion (Ala6_Ala8dup) in two unrelated girls with sporadic central precocious puberty. Additionally, we identified one rare heterozygous 3'UTR MECP2 insertion (36_37insT) in two unrelated girls with sporadic central precocious puberty. None of them manifested Rett syndrome. Mecp2 protein colocalised with GnRH expression in hypothalamic nuclei responsible for GnRH regulation in mice. INTERPRETATION: We identified rare MECP2 variants in girls with central precocious puberty, with or without mild neurodevelopmental abnormalities. MECP2 might have a role in the hypothalamic control of human pubertal timing, adding to the evidence of involvement of epigenetic and genetic mechanisms in this crucial biological process. FUNDING: Fundação de Amparo à Pesquisa do Estado de São Paulo, Conselho Nacional de Desenvolvimento Científico e Tecnológico, and the Wellcome Trust.

Exploring gastrointestinal health in MECP2 duplication syndrome.

BACKGROUND: MECP2 duplication syndrome (MDS) is a rare neurogenetic syndrome caused by duplications of MECP2 at the Xq28 region. Although constipation and gastrointestinal reflux are reported in MDS, a comprehensive characterization of gastrointestinal health has not been fully explored. METHODS: We conducted a parent survey to explore the characteristics of gastrointestinal health in individuals with MDS using a secure online registry and compared differences in gastrointestinal symptoms between individuals with MDS and those with Rett syndrome (RTT). KEY RESULTS: One hundred six surveys were analyzed. Symptoms commonly associated with constipation occurred in 72% to 89% of MDS individuals. Eleven percent of MDS individuals underwent surgery for complications associated with constipation. We observed a bimodal distribution for gastroesophageal reflux disease (GERD) and gastrostomy feeding, with higher prevalence in 0-3 and >12-year-old MDS individuals. Constipation and GERD were significantly more common, and gas bloating was significantly less common in MDS than in RTT. Biliary tract disease requiring surgery was an unrecognized problem in 5% of MDS individuals. We determined that gastrointestinal problems in MDS individuals contribute to caretaker burden. CONCLUSION AND INFERENCES: Our study is the first in-depth investigation that characterizes gastrointestinal health in MDS and enumerates differences in gastrointestinal symptoms between MDS and RTT. Strategies to reduce gastrointestinal symptoms will alleviate caregiver burden in MDS. Further studies are needed to examine the mechanisms that cause gastrointestinal problems in MDS.

Photodynamic therapy for intergluteal warts in a child affected by Rett syndrome.

Genital warts (GWs) are the most common sexually transmitted infections worldwide, caused by the human papillomavirus (HPV). The increasing prevalence of GWs in children has renewed the interest in therapeutic management which still presents a unique challenge, being influenced by many variables including size, quantity, and location of warts, as well as the presence of comorbidities. Conventional photodynamic therapy (C-PDT) has already shown encouraging results in the treatment of viral warts in adult patients, but its use is still not standardized in the pediatric population. On this topic, we report our experience with C-PDT in a difficult-to-treat area like the perianal region in a 12-year-old girl affected by Rett syndrome, an X-linked dominant neurological disorder, with a 10-month history of florid genital condylomatosis. After the third session of C-PDT, complete clearance of the lesions was achieved. Our case is paradigmatic of the potentiality of PDT to treat difficult lesions in difficult patients. Despite being expensive and time-consuming, this procedure has been demonstrated to be safe and well-tolerated. Lastly, the therapy is also well accepted by parents, due to its minimal invasiveness and the few side effects, compared to the other therapeutic options.

Early Complications After Posterior Spinal Fusion in Patients With Rett Syndrome.

BACKGROUND: Neuromuscular scoliosis in Rett syndrome (RS) is common, progressive, and often requires posterior spinal fusion (PSF). While PSF is associated with improved overall outcomes, there is a paucity of information describing complications. We aimed to report the postoperative complications, readmissions, and reoperations for patients with RS undergoing PSF. METHODS: Female pediatric patients with RS treated by PSF with segmental instrumentation, with or without concurrent pelvis fixation, during January 2012 to August 2022 were included. Preoperative patient characteristics, intraoperative data (estimated blood loss, cell saver, packed red blood cells transfused), postoperative complications according to the Modified Clavien-Dindo-Sink classification within 90 days, unplanned readmissions within 30 days, and unplanned reoperations within 90 days were recorded. RESULTS: A total of 25 females were included. The mean (SD) age at surgery was 12.9 (1.8) years and the mean follow-up of 38.6 (24.9) months. The mean preoperative major coronal curve was 79 degrees (23 degrees) which decreased to 32 degrees (15 degrees) by the last follow-up ( P <0.001). The median estimated blood loss was 600 mL and length of stay was 7 days. There were 81 total postoperative complications (3.2 complications/patient). Eight (32%) had grade IVa complications (disseminated intravascular coagulopathy, hypotensive shock, respiratory failure, chronic urosepsis). Five (20%) patients experienced seizures, 48% had pulmonary complications, and 56% had gastrointestinal complications. There were 3 readmissions (12%) within 30 days for pneumonia and 2 (8%) reoperations (an incision and drainage and C2-T2 fusion for significant kyphosis) within 90 days. One patient also had their fusion extended to the pelvis 1 year later. There were more nonambulatory patients in the group fused to the pelvis, but otherwise no differences between those fused and unfused to the pelvis. CONCLUSIONS: This is the largest review of early postoperative complications for patients with RS who underwent PSF. PSF effectively reduced the major coronal curve, but surgeons and families should be aware of a high postoperative seizure and respiratory complication rate, as well as 8% having reoperations within 90 days and 12% being readmitted within 30 days. LEVEL OF EVIDENCE: Level IV-therapeutic study.

Involvement of Mitochondrial Dysfunction in FOXG1 Syndrome.

FOXG1 (Forkhead box g1) syndrome is a neurodevelopmental disorder caused by a defective transcription factor, FOXG1, important for normal brain development and function. As FOXG1 syndrome and mitochondrial disorders have shared symptoms and FOXG1 regulates mitochondrial function, we investigated whether defective FOXG1 leads to mitochondrial dysfunction in five individuals with FOXG1 variants compared to controls (n = 6). We observed a significant decrease in mitochondrial content and adenosine triphosphate (ATP) levels and morphological changes in mitochondrial network in the fibroblasts of affected individuals, indicating involvement of mitochondrial dysfunction in FOXG1 syndrome pathogenesis. Further investigations are warranted to elucidate how FOXG1 deficiency impairs mitochondrial homeostasis.

MiR-422a promotes adipogenesis via MeCP2 downregulation in human bone marrow mesenchymal stem cells.

Methyl-CpG binding protein 2 (MeCP2) is a ubiquitous transcriptional regulator. The study of this protein has been mainly focused on the central nervous system because alterations of its expression are associated with neurological disorders such as Rett syndrome. However, young patients with Rett syndrome also suffer from osteoporosis, suggesting a role of MeCP2 in the differentiation of human bone marrow mesenchymal stromal cells (hBMSCs), the precursors of osteoblasts and adipocytes. Here, we report an in vitro downregulation of MeCP2 in hBMSCs undergoing adipogenic differentiation (AD) and in adipocytes of human and rat bone marrow tissue samples. This modulation does not depend on MeCP2 DNA methylation nor on mRNA levels but on differentially expressed miRNAs during AD. MiRNA profiling revealed that miR-422a and miR-483-5p are upregulated in hBMSC-derived adipocytes compared to their precursors. MiR-483-5p, but not miR-422a, is also up-regulated in hBMSC-derived osteoblasts, suggesting a specific role of the latter in the adipogenic process. Experimental modulation of intracellular levels of miR-422a and miR-483-5p affected MeCP2 expression through direct interaction with its 3' UTR elements, and the adipogenic process. Accordingly, the knockdown of MeCP2 in hBMSCs through MeCP2-targeting shRNA lentiviral vectors increased the levels of adipogenesis-related genes. Finally, since adipocytes released a higher amount of miR-422a in culture medium compared to hBMSCs we analyzed the levels of circulating miR-422a in patients with osteoporosis-a condition characterized by increased marrow adiposity-demonstrating that its levels are negatively correlated with T- and Z-scores. Overall, our findings suggest that miR-422a has a role in hBMSC adipogenesis by downregulating MeCP2 and its circulating levels are associated with bone mass loss in primary osteoporosis.

Multiplex epigenome editing of MECP2 to rescue Rett syndrome neurons.

Rett syndrome (RTT) is an X-linked neurodevelopmental disorder caused by loss-of-function heterozygous mutations of methyl CpG-binding protein 2 (MECP2) on the X chromosome in young females. Reactivation of the silent wild-type MECP2 allele from the inactive X chromosome (Xi) represents a promising therapeutic opportunity for female patients with RTT. Here, we applied a multiplex epigenome editing approach to reactivate MECP2 from Xi in RTT human embryonic stem cells (hESCs) and derived neurons. Demethylation of the MECP2 promoter by dCas9-Tet1 with target single-guide RNA reactivated MECP2 from Xi in RTT hESCs without detectable off-target effects at the transcriptional level. Neurons derived from methylation-edited RTT hESCs maintained MECP2 reactivation and reversed the smaller soma size and electrophysiological abnormalities, two hallmarks of RTT. In RTT neurons, insulation of the methylation-edited MECP2 locus by dCpf1-CTCF (a catalytically dead Cpf1 fused with CCCTC-binding factor) with target CRISPR RNA enhanced MECP2 reactivation and rescued RTT-related neuronal defects, providing a proof-of-concept study for epigenome editing to treat RTT and potentially other dominant X-linked diseases.

Scoliosis in RETT Syndrome: A National Referral Centre Experience.

STUDY DESIGN: This was a retrospective case series. OBJECTIVE: The objective of this study was to discuss the treatment challenges in scoliosis patients with Rett syndrome (RTT) in a national referral centre for RTT. We describe structural characteristics of curves, age of onset, genetic mutation, ambulation status, and treatment through RTT progression. Based on this unique experience, we aimed to suggest guidelines for scoliosis treatment in RTT patients. SUMMARY OF BACKGROUND DATA: RTT is a neurodevelopmental disorder associated with a mutation in the methyl-CpG binding protein 2 (MECP2) gene, primarily in females with significant features of growth failure, gastrointestinal and pulmonary dysfunction, ataxia, seizures, and intellectual disability. Scoliosis is the most common orthopedic manifestation of RTT and is present in 64%-75% of patients. No clear guidelines for scoliosis treatment in RTT are available, and typically patients are treated according to guidelines of another neuromuscular scoliosis. METHODS: Clinical and radiographic data were gathered, including MECP2 mutation type, scoliosis characteristics, preoperative treatment, surgical treatment, functional status, and postoperative follow-up. RESULTS: Our cohort included 102 patients with RTT. They were 36 who presented with scoliosis; 18 were treated surgically. C-curve was found in 17 patients and S-type in 19. Scoliosis treatment onset was 8.76 years in the C-type group and 13.88 years in the S-type group. The average curve at the time of surgery was 52.42 degrees. The average time until surgery was 2.44 years. Seventeen patients underwent posterior spinal fusion, and 1 patient underwent posterior spinal fusion+anterior spinal fusion with an average correction of 40 degrees. The most common mutation was R255X nucleotide (30% of cases). The most severe curves had mutations R168X and R270X nucleotides. CONCLUSIONS: We advise early monitoring for patients with RTT and scoliosis due to early and rapid progression. Common mutations found were R255X, R168X, R270X, and T158M. We recommend surgical treatment in every curve above 45 degrees, independently of age.

The Efficacy of a Human-Ready miniMECP2 Gene Therapy in a Pre-Clinical Model of Rett Syndrome.

Inactivating mutations and the duplication of methyl-CpG binding protein 2 (MeCP2), respectively, mediate Rett syndrome (RTT) and MECP2 duplication syndrome. These disorders underscore the conceptual dose-dependent risk posed by MECP2 gene therapy for mosaic RTT patients. Recently, a miRNA-Responsive Autoregulatory Element (miRARE) mitigated the dose-dependent toxicity posed by self-complementary adeno-associated viral vector serotype 9 (AAV9) miniMECP2 gene therapy (scAAV9/miniMECP2-myc) in mice. Here, we report an efficacy assessment for the human-ready version of this regulated gene therapy (TSHA-102) in male Mecp2-/y knockout (KO) mice after intracerebroventricular (ICV) administration at postnatal day 2 (P2) and after intrathecal (IT) administration at P7, P14 (±immunosuppression), and P28 (±immunosuppression). We also report qPCR studies on KO mice treated at P7-P35; protein analyses in KO mice treated at P38; and a survival safety study in female adult Mecp2-/+ mice. In KO mice, TSHA-102 improved respiration, weight, and survival across multiple doses and treatment ages. TSHA-102 significantly improved the front average stance and swing times relative to the front average stride time after P14 administration of the highest dose for that treatment age. Viral genomic DNA and miniMECP2 mRNA were present in the CNS. MiniMeCP2 protein expression was higher in the KO spinal cord compared to the brain. In female mice, TSHA-102 permitted survivals that were similar to those of vehicle-treated controls. In all, these pivotal data helped to support the regulatory approval to initiate a clinical trial for TSHA-102 in RTT patients (clinical trial identifier number NCT05606614).

KW-2449 and VPA exert therapeutic effects on human neurons and cerebral organoids derived from MECP2-null hESCs.

BACKGROUND: Rett syndrome (RTT), mainly caused by mutations in methyl-CpG binding protein 2 (MECP2), is one of the most prevalent neurodevelopmental disorders in girls. However, the underlying mechanism of MECP2 remains largely unknown and currently there is no effective treatment available for RTT. METHODS: We generated MECP2-KO human embryonic stem cells (hESCs), and differentiated them into neurons and cerebral organoids to investigate phenotypes of MECP2 loss-of-function, potential therapeutic agents, and the underlying mechanism by transcriptome sequencing. RESULTS: We found that MECP2 deletion caused reduced number of hESCs-derived neurons and simplified dendritic morphology. Moreover, MECP2-KO cortical organoids exhibited fewer neural progenitor cells and neurons at day 60. Electrophysiological recordings showed that MECP2 deletion altered synaptic activity in organoids. Transcriptome analysis of organoids identified many genes in the PI3K-AKT pathway downregulated following MECP2 deletion. Treatment with either KW-2449 or VPA, small molecules for the activation of PI3K-AKT signaling pathway, alleviated neuronal deficits and transcriptome changes in MECP2-KO human neuronal models. CONCLUSIONS: These findings suggest that KW-2449 and VPA might be promising drugs for RTT treatment.