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Welborn MC, Redding G, Evers P, Nicol L, Bauer DF, Iyer RR, Poon S, Hwang S. Pre-op considerations in neuromuscular scoliosis deformity surgery: proceedings of the half day course at the 58th annual meeting of the Scoliosis Research Society. Spine Deform 2024; 12:867-876. [PMID: 38634998 DOI: 10.1007/s43390-024-00865-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Accepted: 03/16/2024] [Indexed: 04/19/2024]
Abstract
Scoliosis is a common complication of neuromuscular disorders. These patients are frequently recalcitrant to nonoperative treatment. When treated surgically, they have the highest risk of complications of all forms of scoliosis. While recent studies have shown an improvement in the rate of complications, they still remain high ranging from 6.3 to 75% depending upon the underlying etiology and the treatment center (Mohamad et al. in J Pediatr Orthop 27:392-397, 2007; McElroy et al. in Spine, 2012; Toll et al. in J Neurosurg Pediatr 22:207-213, 2018; Cognetti et al. in Neurosurg Focus 43:E10, 2017). For those patients who are able to recover from the perioperative period without major complications, several recent studies have shown decreased long-term mortality and improved health-related quality of life in neuromuscular patients who have undergone spine fusion (Bohtz et al. in J Pediatr Orthop 31:668-673, 2011; Ahonen et al. in Neurology 101:e1787-e1792, 2023; Jain et al. in JBJS 98:1821-1828, 2016). It is critically important to optimize patients preoperatively to minimize the risk of post-operative complications and maximize long-term outcomes. In order to do so, one must familiarize themselves with the common complications and their treatment. The most common complications are pulmonary in nature. With reported rates as high as 23-29%, pre-operative optimization should be employed for these patients to minimize the risk of post-operative complications (Sharma et al. in Eur Spine J 22:1230-1249, 2013; Rumalla et al. in J Neurosurg Spine 25:500-508, 2016). The next most common cause of complications are implant related, with 13-23% of patients experiencing an implant-related complication that may require a second procedure (Toll et al. in J Neurosurg Pediatr 22:207-213, 2018; Sharma et al. in Eur Spine J 22:1230-1249, 2013) Therefore optimization of bone quality prior to surgical intervention is important to help minimize the risk of instrumentation failure. Optimization of muscle tone and spasticity may help to decrease the risk of instrumentation complications, but may also contribute to the progression of scoliosis. While only 3% of patients have neurologic complication, significant equipoise remains regarding whether or not patients should undergo prophylactic detethering procedures to minimize those risks (Sharma et al. in Eur Spine J 22:1230-1249, 2013). Although only 1.8% of complications are classified as cardiac related, they can be among the most devastating (Rumalla et al. in J Neurosurg Spine 25:500-508, 2016). Simply understanding the underlying etiology and the potential risks associated with each condition (i.e., conduction abnormalities in a patient with Rett syndrome or cardiomyopathies patients with muscular dystrophy) can be lifesaving. The following article is a summation of the half day course on neuromuscular scoliosis from the 58th annual SRS annual meeting, summarizing the recommendations from some of the world's experts on medical considerations in surgical treatment of neuromuscular scoliosis.
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Affiliation(s)
- Michelle C Welborn
- Shriners Children's Portland, 3101 SW Sam Jackson Park Road, Portland, OR, 97229, USA.
| | - Gregory Redding
- Pulmonary and Sleep Medicine Division, Seattle Children's Hospital, Room O.C. 7.730, 4800 Sand Point Way N E, Seattle, WA, 98105, USA
| | - Patrick Evers
- Doernbecher Children's Hospital, 700 SW Campus Dr, Portland, OR, 97239, USA
| | - Lindsey Nicol
- Shriners Children's Portland, 3101 SW Sam Jackson Park Road, Portland, OR, 97229, USA
- Doernbecher Children's Hospital, 700 SW Campus Dr, Portland, OR, 97239, USA
| | - David F Bauer
- Texas Children's Hospital, 6701 Fannin St., Suite 1230.01, Houston, TX, USA
| | - Rajiv R Iyer
- , 100 N. Mario Capecchi Drive, Suite 3850, Salt Lake City, UT, 84113, USA
| | - Selina Poon
- Shriners Children's Southern California, 909 S. Fair Oaks Ave, Pasadena, CA, 91105, USA
| | - Steven Hwang
- Shriners Children's Philadelphia, 3551 N Broad St., Philadelphia, PA, 19140, USA
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Leoncini S, Boasiako L, Di Lucia S, Beker A, Scandurra V, Vignoli A, Canevini MP, Prato G, Nobili L, Nicotera AG, Di Rosa G, Chiarini MBT, Cutrera R, Grosso S, Lazzeri G, Tongiorgi E, Morano P, Botteghi M, Barducci A, De Felice C. 24-h continuous non-invasive multiparameter home monitoring of vitals in patients with Rett syndrome by an innovative wearable technology: evidence of an overlooked chronic fatigue status. Front Neurol 2024; 15:1388506. [PMID: 38952469 PMCID: PMC11215834 DOI: 10.3389/fneur.2024.1388506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 05/13/2024] [Indexed: 07/03/2024] Open
Abstract
Background Sleep is disturbed in Rett syndrome (RTT), a rare and progressive neurodevelopmental disorder primarily affecting female patients (prevalence 7.1/100,000 female patients) linked to pathogenic variations in the X-linked methyl-CpG-binding protein 2 (MECP2) gene. Autonomic nervous system dysfunction with a predominance of the sympathetic nervous system (SNS) over the parasympathetic nervous system (PSNS) is reported in RTT, along with exercise fatigue and increased sudden death risk. The aim of the present study was to test the feasibility of a continuous 24 h non-invasive home monitoring of the biological vitals (biovitals) by an innovative wearable sensor device in pediatric and adolescent/adult RTT patients. Methods A total of 10 female patients (mean age 18.3 ± 9.4 years, range 4.7-35.5 years) with typical RTT and MECP2 pathogenic variations were enrolled. Clinical severity was assessed by validated scales. Heart rate (HR), respiratory rate (RR), and skin temperature (SkT) were monitored by the YouCare Wearable Medical Device (Accyourate Group SpA, L'Aquila, Italy). The average percentage of maximum HR (HRmax%) was calculated. Heart rate variability (HRV) was expressed by consolidated time-domain and frequency-domain parameters. The HR/LF (low frequency) ratio, indicating SNS activation under dynamic exercise, was calculated. Simultaneous continuous measurement of indoor air quality variables was performed and the patients' contributions to the surrounding water vapor partial pressure [PH2O (pt)] and carbon dioxide [PCO2 (pt)] were indirectly estimated. Results Of the 6,559.79 h of biovital recordings, 5051.03 h (77%) were valid for data interpretation. Sleep and wake hours were 9.0 ± 1.1 h and 14.9 ± 1.1 h, respectively. HRmax % [median: 71.86% (interquartile range 61.03-82%)] and HR/LF [median: 3.75 (interquartile range 3.19-5.05)] were elevated, independent from the wake-sleep cycle. The majority of HRV time- and frequency-domain parameters were significantly higher in the pediatric patients (p ≤ 0.031). The HRV HR/LF ratio was associated with phenotype severity, disease progression, clinical sleep disorder, subclinical hypoxia, and electroencephalographic observations of multifocal epileptic activity and general background slowing. Conclusion Our findings indicate the feasibility of a continuous 24-h non-invasive home monitoring of biovital parameters in RTT. Moreover, for the first time, HRmax% and the HR/LF ratio were identified as potential objective markers of fatigue, illness severity, and disease progression.
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Affiliation(s)
- Silvia Leoncini
- Rett Syndrome Trial Center, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
- Neonatal Intensive Care Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
- U.O.S.A. Programmazione e Ricerca Clinica, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Lidia Boasiako
- Rett Syndrome Trial Center, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
- Neonatal Intensive Care Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Sofia Di Lucia
- Neonatal Intensive Care Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | | | - Valeria Scandurra
- Child Neuropsychiatry Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Aglaia Vignoli
- Childhood and Adolescence Neurology and Psychiatry Unit, ASST GOM Niguarda, Milan, Italy
| | - Maria Paola Canevini
- Epilepsy Center – Sleep Medicine Center, Childhood and Adolescence Neuropsychiatry Unit, ASST Santi Paolo e Carlo, San Paolo Hospital, Milan, Italy
| | - Giulia Prato
- Child Neuropsychiatry Unit, IRCCS Istituto Giannina Gaslini, Genova, Italy
| | - Lino Nobili
- Child Neuropsychiatry Unit, IRCCS Istituto Giannina Gaslini, Genova, Italy
- Department of Neurosciences, Rehabilitation, Ophthalmology, Genetics and Maternal and Child Health (DINOGMI), University of Genova, Genova, Italy
| | | | - Gabriella Di Rosa
- Child Neuropsychiatry Unit, University Hospital “G. Martino”, Messina, Italy
- Department of Biomedical and Dental Sciences and of Morphological and Functional Imaging (BIOMORF), University of Messina, Messina, Italy
| | - Maria Beatrice Testa Chiarini
- Pneumology and Cystic Fibrosis Unit, Academic Department of Pediatrics, Bambino Gesù Children’s Hospital, Rome, Italy
| | - Renato Cutrera
- Pneumology and Cystic Fibrosis Unit, Academic Department of Pediatrics, Bambino Gesù Children’s Hospital, Rome, Italy
| | - Salvatore Grosso
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
- Pediatrics Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
| | - Giacomo Lazzeri
- U.O.S.A. Programmazione e Ricerca Clinica, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
- Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy
| | - Enrico Tongiorgi
- Department of Life Sciences, University of Trieste, Trieste, Italy
| | | | - Matteo Botteghi
- Department of Clinical and Molecular Sciences – Experimental Pathology Research Group, Università Politecnica delle Marche, Ancona, Italy
- Medical Physics Activities Coordination Centre – Alma Mater Studiorum – University of Bologna, Bologna, Italy
| | | | - Claudio De Felice
- Rett Syndrome Trial Center, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
- Neonatal Intensive Care Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
- Pediatrics Unit, University Hospital Azienda Ospedaliera Universitaria Senese, Siena, Italy
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Allison K, Maletic-Savatic M, Pehlivan D. MECP2-related disorders while gene-based therapies are on the horizon. Front Genet 2024; 15:1332469. [PMID: 38410154 PMCID: PMC10895005 DOI: 10.3389/fgene.2024.1332469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 01/23/2024] [Indexed: 02/28/2024] Open
Abstract
The emergence of new genetic tools has led to the discovery of the genetic bases of many intellectual and developmental disabilities. This creates exciting opportunities for research and treatment development, and a few genetic disorders (e.g., spinal muscular atrophy) have recently been treated with gene-based therapies. MECP2 is found on the X chromosome and regulates the transcription of thousands of genes. Loss of MECP2 gene product leads to Rett Syndrome, a disease found primarily in females, and is characterized by developmental regression, motor dysfunction, midline hand stereotypies, autonomic nervous system dysfunction, epilepsy, scoliosis, and autistic-like behavior. Duplication of MECP2 causes MECP2 Duplication Syndrome (MDS). MDS is found mostly in males and presents with developmental delay, hypotonia, autistic features, refractory epilepsy, and recurrent respiratory infections. While these two disorders share several characteristics, their differences (e.g., affected sex, age of onset, genotype/phenotype correlations) are important to distinguish in the light of gene-based therapy because they require opposite solutions. This review explores the clinical features of both disorders and highlights these important clinical differences.
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Affiliation(s)
- Katherine Allison
- Royal College of Surgeons in Ireland, School of Medicine, Dublin, Ireland
| | - Mirjana Maletic-Savatic
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, United States
| | - Davut Pehlivan
- Section of Pediatric Neurology and Developmental Neuroscience, Department of Pediatrics, Baylor College of Medicine, Houston, TX, United States
- Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX, United States
- Blue Bird Circle Rett Center, Texas Children's Hospital, Houston, TX, United States
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Czosek RJ, Baskar S, Mohan S, Anderson JB, Spar DS. Incidence and outcome of arrhythmias and electrical disease in patients with Trisomy 18. Am J Med Genet A 2023; 191:2518-2523. [PMID: 37303261 DOI: 10.1002/ajmg.a.63324] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 05/11/2023] [Accepted: 05/26/2023] [Indexed: 06/13/2023]
Abstract
Patients with Trisomy 18 have a high incidence of cardiac anomalies and are associated with early death. Because of early mortality, electrical system disease and arrhythmia has been difficult to delineate and the incidence remain unknown. We sought to describe the association and clinical outcomes of electrical system disease and cardiac tachy-arrhythmias in patients with Trisomy 18. This was a retrospective, single institutional study. All patients with Trisomy 18 were included in the study. Patient characteristics, congenital heart disease (CHD), conduction system and clinical tachy-arrhythmia data were collected on all patients. Outcomes including cardiac surgical interventions, electrical system interventions and death were collected until the time of study. Patients with tachy-arrhythmias/electrical system involvement were compared to those without to identify potential associated variables. A total of 54 patients with Trisomy 18 were included in analysis. The majority of patients was female and had associated CHD. AV nodal conduction system abnormalities with either first or second degree AV block were common (15%) as was QTc prolongation (37%). Tachy-arrhythmias were common with 22% of patients having at least one form of tachy-arrhythmia and associated with concomitant conduction system disease (p = 0.002). Tachy-arrhythmias were typically treatable with monitoring or medication with eventual resolution without need for procedural intervention. Although early death was common, there were no causes of death associated with tachy-arrhythmia or conduction system disease. In conclusion, patients with Trisomy 18 have a high incidence of conduction system abnormalities and burden of clinical tachy-arrhythmias. Although frequent, electrical system disease did not affect patient outcome or difficultly of care delivery.
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Affiliation(s)
- Richard J Czosek
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, The Heart Institute, Cincinnati, Ohio, USA
- Department of Pediatrics, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - Shankar Baskar
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, The Heart Institute, Cincinnati, Ohio, USA
- Department of Pediatrics, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - Shaun Mohan
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, The Heart Institute, Cincinnati, Ohio, USA
- Department of Pediatrics, University of Kentucky Albert B. Chandler Hospital, Lexington, Kentucky, USA
| | - Jeffrey B Anderson
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, The Heart Institute, Cincinnati, Ohio, USA
- Department of Pediatrics, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
| | - David S Spar
- Department of Pediatrics, Cincinnati Children's Hospital Medical Center, The Heart Institute, Cincinnati, Ohio, USA
- Department of Pediatrics, University of Cincinnati Medical Center, Cincinnati, Ohio, USA
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Vilvarajan S, McDonald M, Douglas L, Newham J, Kirkland R, Tzannes G, Tay D, Christodoulou J, Thompson S, Ellaway C. Multidisciplinary Management of Rett Syndrome: Twenty Years' Experience. Genes (Basel) 2023; 14:1607. [PMID: 37628658 PMCID: PMC10454341 DOI: 10.3390/genes14081607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Revised: 07/31/2023] [Accepted: 08/08/2023] [Indexed: 08/27/2023] Open
Abstract
Over the last 20 years, the understanding and natural history of Rett syndrome has advanced, but to date no cure has emerged, with multidisciplinary management being symptomatic and supportive. This study provides a comprehensive review of the clinical features, comorbidities and multidisciplinary management of a well-characterized cohort of females with classical Rett syndrome. We aim to improve awareness and understanding of Rett syndrome amongst pediatricians, pediatric subspecialists and allied health professionals to enable early diagnosis and a streamlined enrolment approach for future clinical trials. Rett syndrome, a complex X-linked condition, affecting mainly females, is due to pathogenic variants of the MECP2 gene in most affected individuals. The Rett syndrome Multidisciplinary Management clinic at The Children's Hospital at Westmead, Sydney, Australia, was established in 2000. This retrospective analysis of individuals who attended the clinic from 2000 to 2020 was performed to identify the incidence and predicted age of onset of Rett syndrome related comorbidities, disease progression and to review management principles. Data collected included age of Rett syndrome diagnosis, MECP2 genotype, clinical features and medical comorbidities, such as sleep disturbance, seizures, breathing irregularities, scoliosis, mobility, hand stereotypies, hand function, constipation, feeding ability, use of gastrostomy, communication skills, QTc prolongation, anthropometry, and bruxism. Analysis of 103 girls who fulfilled the clinical diagnostic criteria for classical Rett syndrome with a pathogenic variant of the MECP2 gene showed a median age of diagnosis of 3 years. The most frequent MECP2 variant was c.502 C>T.
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Affiliation(s)
| | | | - Lyndal Douglas
- Department of Clinical Genetics, Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
| | - Jessica Newham
- Department of Physiotherapy, Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
| | - Robyn Kirkland
- Department of Occupational Therapy, Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
| | - Gloria Tzannes
- Department of Speech Pathology, Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
| | - Diane Tay
- Department of Dentistry, Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
| | - John Christodoulou
- Discipline of Child and Adolescent Health, The University of Sydney, Sydney, NSW 2006, Australia
- Brain and Mitochondrial Research Group, Murdoch Children’s Research Institute, Melbourne, VIC 3052, Australia
- Department of Pediatrics, University of Melbourne, Melbourne, VIC 3052, Australia
| | - Susan Thompson
- Faculty of Medicine, Sydney University, Sydney, NSW 2006, Australia
- Genetic Metabolic Disorders Service, Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
| | - Carolyn Ellaway
- Faculty of Medicine, Sydney University, Sydney, NSW 2006, Australia
- Discipline of Child and Adolescent Health, The University of Sydney, Sydney, NSW 2006, Australia
- Genetic Metabolic Disorders Service, Children’s Hospital at Westmead, Sydney, NSW 2145, Australia
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Cheng H, Charles I, James AF, Abdala AP, Hancox JC. QT c interval and ventricular action potential prolongation in the Mecp2 Null/+ murine model of Rett syndrome. Physiol Rep 2022; 10:e15437. [PMID: 36200140 PMCID: PMC9535259 DOI: 10.14814/phy2.15437] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/27/2022] [Accepted: 08/06/2022] [Indexed: 06/16/2023] Open
Abstract
Rett Syndrome (RTT) is a congenital, X-chromosome-linked developmental disorder characterized by developmental delay, dysautonomia, and breathing irregularities. RTT is also associated with sudden death and QT intervals are prolonged in some RTT patients. Most individuals with RTT have mutations in the MECP2 gene. Whilst there is some evidence for QT prolongation in mouse models of RTT, there is comparatively little information on how loss of Mecp2 function affects ventricular action potentials (APs) and, to-date, none on ventricular APs from female RTT mice. Accordingly, the present study was conducted to determine ECG and ventricular AP characteristics of Mecp2Null/+ female mice. ECG recordings from 12-13 month old female Mecp2Null/+ mice showed prolonged rate corrected QT (QTc) intervals compared to wild-type (WT) controls. Although Mecp2Null/+ animals exhibited longer periods of apnoea than did controls, no correlation between apnoea length and QTc interval was observed. Action potentials (APs) from Mecp2Null/+ myocytes had longer APD90 values than those from WT myocytes and showed augmented triangulation. Application of the investigational INa,Late inhibitor GS-6615 (eleclazine; 10 μM) reduced both APD90 and AP triangulation in Mecp2Null/+ and WT myocytes. These results constitute the first direct demonstration of delayed repolarization in Mecp2Null/+ myocytes and provide further evidence that GS-6615 may have potential as an intervention against QT prolongation in RTT.
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Affiliation(s)
- Hongwei Cheng
- School of Physiology, Pharmacology and NeuroscienceUniversity WalkBristolUK
| | - Ian Charles
- School of Physiology, Pharmacology and NeuroscienceUniversity WalkBristolUK
| | - Andrew F. James
- School of Physiology, Pharmacology and NeuroscienceUniversity WalkBristolUK
| | - Ana P. Abdala
- School of Physiology, Pharmacology and NeuroscienceUniversity WalkBristolUK
| | - Jules C. Hancox
- School of Physiology, Pharmacology and NeuroscienceUniversity WalkBristolUK
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Delayed Ventricular Repolarization and Sodium Channel Current Modification in a Mouse Model of Rett Syndrome. Int J Mol Sci 2022; 23:ijms23105735. [PMID: 35628543 PMCID: PMC9147596 DOI: 10.3390/ijms23105735] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Revised: 05/13/2022] [Accepted: 05/17/2022] [Indexed: 02/01/2023] Open
Abstract
Rett syndrome (RTT) is a severe developmental disorder that is strongly linked to mutations in the MECP2 gene. RTT has been associated with sudden unexplained death and ECG QT interval prolongation. There are mixed reports regarding QT prolongation in mouse models of RTT, with some evidence that loss of Mecp2 function enhances cardiac late Na current, INa,Late. The present study was undertaken in order to investigate both ECG and ventricular AP characteristics in the Mecp2Null/Y male murine RTT model and to interrogate both fast INa and INa,Late in myocytes from the model. ECG recordings from 8-10-week-old Mecp2Null/Y male mice revealed prolongation of the QT and rate corrected QT (QTc) intervals and QRS widening compared to wild-type (WT) controls. Action potentials (APs) from Mecp2Null/Y myocytes exhibited longer APD75 and APD90 values, increased triangulation and instability. INa,Late was also significantly larger in Mecp2Null/Y than WT myocytes and was insensitive to the Nav1.8 inhibitor A-803467. Selective recordings of fast INa revealed a decrease in peak current amplitude without significant voltage shifts in activation or inactivation V0.5. Fast INa 'window current' was reduced in RTT myocytes; small but significant alterations of inactivation and reactivation time-courses were detected. Effects of two INa,Late inhibitors, ranolazine and GS-6615 (eleclazine), were investigated. Treatment with 30 µM ranolazine produced similar levels of inhibition of INa,Late in WT and Mecp2Null/Y myocytes, but produced ventricular AP prolongation not abbreviation. In contrast, 10 µM GS-6615 both inhibited INa,Late and shortened ventricular AP duration. The observed changes in INa and INa,Late can account for the corresponding ECG changes in this RTT model. GS-6615 merits further investigation as a potential treatment for QT prolongation in RTT.
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Ramirez JM, Karlen-Amarante M, Wang JDJ, Huff A, Burgraff N. Breathing disturbances in Rett syndrome. HANDBOOK OF CLINICAL NEUROLOGY 2022; 189:139-151. [PMID: 36031301 PMCID: PMC10029146 DOI: 10.1016/b978-0-323-91532-8.00018-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Rett Syndrome is an X-linked neurological disorder characterized by behavioral and neurological regression, seizures, motor deficits, and dysautonomia. A particularly prominent presentation includes breathing abnormalities characterized by breathing irregularities, hyperventilation, repetitive breathholding during wakefulness, obstructive and central apneas during sleep, and abnormal responses to hypoxia and hypercapnia. The condition and pathology of the respiratory system is further complicated by dysfunctions of breathing-motor coordination, which is reflected in dysphagia. The discovery of the X-linked mutations in the MECP2 gene has transformed our understanding of the cellular and molecular mechanisms that are at the root of various clinical phenotypes. However, the genotype-phenotype relationship is complicated by various factors which include not only X-inactivation but also consequences of the intermittent hypoxia and oxidative stress associated with the breathing abnormalities.
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Affiliation(s)
- Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States; Department of Neurological Surgery, University of Washington School of Medicine, Seattle, WA, United States.
| | - Marlusa Karlen-Amarante
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Jia-Der Ju Wang
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Alyssa Huff
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
| | - Nicholas Burgraff
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, WA, United States
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Abstract
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.
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Affiliation(s)
- Emilie Borloz
- Aix Marseille Univ, INSERM, MMG, U1251, Faculté de médecine Timone, 13385, Marseille, France
| | - Laurent Villard
- Aix Marseille Univ, INSERM, MMG, U1251, Faculté de médecine Timone, 13385, Marseille, France
| | - Jean-Christophe Roux
- Aix Marseille Univ, INSERM, MMG, U1251, Faculté de médecine Timone, 13385, Marseille, France
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Pecorelli A, Cordone V, Schiavone ML, Caffarelli C, Cervellati C, Cerbone G, Gonnelli S, Hayek J, Valacchi G. Altered Bone Status in Rett Syndrome. Life (Basel) 2021; 11:life11060521. [PMID: 34205017 PMCID: PMC8230033 DOI: 10.3390/life11060521] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 05/31/2021] [Accepted: 06/02/2021] [Indexed: 11/24/2022] Open
Abstract
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.
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Affiliation(s)
- Alessandra Pecorelli
- Animal Science Department, Plants for Human Health Institute, North Carolina State University, Kannapolis, NC 28081, USA;
- Correspondence: (A.P.); (G.V.)
| | - Valeria Cordone
- Department of Neuroscience and Rehabilitation, University of Ferrara, 44121 Ferrara, Italy;
| | - Maria Lucia Schiavone
- Animal Science Department, Plants for Human Health Institute, North Carolina State University, Kannapolis, NC 28081, USA;
| | - Carla Caffarelli
- Department of Medicine, Surgery and Neuroscience, University of Siena, Policlinico Le Scotte, 53100 Siena, Italy; (C.C.); (S.G.)
| | - Carlo Cervellati
- Department of Translational Medicine and for Romagna, University of Ferrara, 44121 Ferrara, Italy;
| | - Gaetana Cerbone
- Division of Medical Genetics, “S.G. Moscati” Hospital, 74100 Avellino, Italy;
| | - Stefano Gonnelli
- Department of Medicine, Surgery and Neuroscience, University of Siena, Policlinico Le Scotte, 53100 Siena, Italy; (C.C.); (S.G.)
| | - Joussef Hayek
- Toscana Life Sciences Foundation, 53100 Siena, Italy;
| | - Giuseppe Valacchi
- Animal Science Department, Plants for Human Health Institute, North Carolina State University, Kannapolis, NC 28081, USA;
- Department of Neuroscience and Rehabilitation, University of Ferrara, 44121 Ferrara, Italy;
- Department of Food and Nutrition, Kyung Hee University, Seoul 02447, Korea
- Correspondence: (A.P.); (G.V.)
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11
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Cicaloni V, Pecorelli A, Cordone V, Tinti L, Rossi M, Hayek J, Salvini L, Tinti C, Valacchi G. A proteomics approach to further highlight the altered inflammatory condition in Rett syndrome. Arch Biochem Biophys 2020; 696:108660. [PMID: 33159892 DOI: 10.1016/j.abb.2020.108660] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Revised: 10/24/2020] [Accepted: 10/28/2020] [Indexed: 12/12/2022]
Abstract
Rett syndrome (RTT) is a progressive neurodevelopmental disorder caused by mutations in the X-linked MECP2 gene. RTT patients show multisystem disturbances associated with perturbed redox homeostasis and inflammation, which appear as possible key factors in RTT pathogenesis. In this study, using primary dermal fibroblasts from control and RTT subjects, we performed a proteomic analysis that, together with data mining approaches, allowed us to carry out a comprehensive characterization of RTT cellular proteome. Functional and pathway enrichment analyses showed that differentially expressed proteins in RTT were mainly enriched in biological processes related to immune/inflammatory responses. Overall, by using proteomic data mining as supportive approach, our results provide a detailed insight into the molecular pathways involved in RTT immune dysfunction that, causing tissue and organ damage, can increase the vulnerability of affected patients to unknown endogenous factors or infections.
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Affiliation(s)
- Vittoria Cicaloni
- Toscana Life Science Foundation, Via Fiorentina 1, 53100, Siena, Italy
| | - Alessandra Pecorelli
- Plants for Human Health Institute, Animal Science Dept., NC Research Campus, NC State University, 600 Laureate Way, Kannapolis, NC, 28081, USA
| | - Valeria Cordone
- Department of Biomedical and Specialist Surgical Sciences, University of Ferrara, Ferrara, Italy
| | - Laura Tinti
- Toscana Life Science Foundation, Via Fiorentina 1, 53100, Siena, Italy
| | - Marco Rossi
- Toscana Life Science Foundation, Via Fiorentina 1, 53100, Siena, Italy
| | - Joussef Hayek
- Toscana Life Science Foundation, Via Fiorentina 1, 53100, Siena, Italy
| | - Laura Salvini
- Toscana Life Science Foundation, Via Fiorentina 1, 53100, Siena, Italy
| | - Cristina Tinti
- Toscana Life Science Foundation, Via Fiorentina 1, 53100, Siena, Italy
| | - Giuseppe Valacchi
- Plants for Human Health Institute, Animal Science Dept., NC Research Campus, NC State University, 600 Laureate Way, Kannapolis, NC, 28081, USA; Department of Biomedical and Specialist Surgical Sciences, University of Ferrara, Ferrara, Italy; Kyung Hee University, Department of Food and Nutrition, Seoul, South Korea.
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12
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Gomathi M, Padmapriya S, Balachandar V. Drug Studies on Rett Syndrome: From Bench to Bedside. J Autism Dev Disord 2020; 50:2740-2764. [PMID: 32016693 DOI: 10.1007/s10803-020-04381-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Drug studies on Rett syndrome (RTT) have drastically increased over the past few decades. This review aims to provide master data on bench-to-bedside drug studies involving RTT. A comprehensive literature review was performed by searching in PUBMED, MEDLINE and Google Scholar, international, national and regional clinical trial registries and pharmaceutical companies using the keywords "Rett syndrome treatment and/or drug or compound or molecule". Seventy drugs were investigated in non-clinical (N = 65 animal/cell line-based studies; N = 5 iPSC-based study) and clinical trials (N = 34) for ameliorating the symptoms of RTT. Though there is good progress in both clinical and non-clinical studies, none of these drugs entered phase III/IV for being launched as a therapeutic agent for RTT.
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Affiliation(s)
- Mohan Gomathi
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore, Tamil Nadu, 641046, India
| | | | - Vellingiri Balachandar
- Human Molecular Genetics and Stem Cell Laboratory, Department of Human Genetics and Molecular Biology, Bharathiar University, Coimbatore, Tamil Nadu, 641046, India.
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13
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Johnson CM, Cui N, Xing H, Wu Y, Jiang C. The antitussive cloperastine improves breathing abnormalities in a Rett Syndrome mouse model by blocking presynaptic GIRK channels and enhancing GABA release. Neuropharmacology 2020; 176:108214. [PMID: 32622786 DOI: 10.1016/j.neuropharm.2020.108214] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 06/12/2020] [Accepted: 06/14/2020] [Indexed: 12/21/2022]
Abstract
Rett Syndrome (RTT) is an X-linked neurodevelopmental disorder caused mainly by mutations in the MECP2 gene. One of the major RTT features is breathing dysfunction characterized by periodic hypo- and hyperventilation. The breathing disorders are associated with increased brainstem neuronal excitability, which can be alleviated with GABA agonists. Since neuronal hypoexcitability occurs in the forebrain of RTT models, it is necessary to find pharmacological agents with a relative preference to brainstem neurons. Here we show evidence for the improvement of breathing disorders of Mecp2-disrupted mice with the brainstem-acting drug cloperastine (CPS) and its likely neuronal targets. CPS is an over-the-counter cough medicine that has an inhibitory effect on brainstem neuronal networks. In Mecp2-disrupted mice, CPS (30 mg/kg, i.p.) decreased the occurrence of apneas/h and breath frequency variation. GIRK currents expressed in HEK cells were inhibited by CPS with IC50 1 μM. Whole-cell patch clamp recordings in locus coeruleus (LC) and dorsal tegmental nucleus (DTN) neurons revealed an overall inhibitory effect of CPS (10 μM) on neuronal firing activity. Such an effect was reversed by the GABAA receptor antagonist bicuculline (20 μM). Voltage clamp studies showed that CPS increased GABAergic sIPSCs in LC cells, which was blocked by the GABAB receptor antagonist phaclofen. Functional GABAergic connections of DTN neurons with LC cells were shown. These results suggest that CPS improves breathing dysfunction in Mecp2-null mice by blocking GIRK channels in synaptic terminals and enhancing GABA release.
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Affiliation(s)
- Christopher M Johnson
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA, 30303, USA
| | - Ningren Cui
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA, 30303, USA
| | - Hao Xing
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA, 30303, USA
| | - Yang Wu
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA, 30303, USA
| | - Chun Jiang
- Department of Biology, Georgia State University, 100 Piedmont Avenue, Atlanta, GA, 30303, USA.
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14
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Clark BC, Kopp A, Morey W, Djukic A. Serial follow-up of corrected QT interval in Rett syndrome. Dev Med Child Neurol 2020; 62:833-836. [PMID: 31797351 DOI: 10.1111/dmcn.14419] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 10/24/2019] [Indexed: 01/14/2023]
Abstract
AIM To identify factors associated with baseline prolonged corrected QT (QTc) and higher risk of QTc prolongation during follow-up in patients with Rett syndrome (RTT). METHOD A retrospective review of patients receiving an electrocardiogram (ECG) between June 2012 and June 2018 was performed. Age, methyl-CpG binding protein 2 gene (MECP2) mutation, RTT Severity Scale (RSSS) score, breathing abnormalities, seizure frequency, medications, and ECG parameters were collected. Prolonged QTc was defined as greater than or equal to 460ms. Comparisons at baseline and during follow-up were made. RESULTS In total, 129 unique patients (all female) had 349 ECGs. At baseline, 12 (9.3%) had a prolonged QTc (median 474ms, interquartile range 470-486ms) and were more likely to have moderate/severe breathing abnormalities (66.7% vs 24.8%; p=0.005) and take selective serotonin reuptake inhibitors (SSRIs) (41.7% vs 15.4%; p=0.04). There was no difference in age, RSSS score, seizures, or mutation. Twenty-six developed prolonged QTc during a median follow-up of 1 year 7 months (interquartile range 0-3y 6mo). QTc prolongation was associated with p.(Thr158Met) mutation versus the remaining six common mutations (hazard ratio 4.1, 95% confidence interval 1.4-12.0; p=0.01) but not with age, RSSS score, seizures, breathing abnormalities, or SSRIs. INTERPRETATION Breathing abnormalities and SSRIs were associated with baseline QTc prolongation and those with p.(Thr158Met) mutation were more likely to develop prolonged QTc over time. Identification of patients with prolonged QTc warrants increased clinical monitoring. WHAT THIS PAPER ADDS Breathing abnormalities and selective serotonin reuptake inhibitors are associated with prolonged baseline corrected QT (QTc). Development of QTc prolongation is associated with the p.(Thr158Met) mutation.
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Affiliation(s)
- Bradley C Clark
- Division of Cardiology, Children's Hospital at Montefiore, Bronx, NY, USA.,Department of Pediatrics, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Adam Kopp
- Albert Einstein College of Medicine, Bronx, NY, USA
| | - Wenzhu Morey
- Department of Epidemiology and Population Health, Albert Einstein College of Medicine, Bronx, NY, USA
| | - Aleksandra Djukic
- Albert Einstein College of Medicine, Bronx, NY, USA.,Rett Syndrome Center, Division of Neurology, Children's Hospital at Montefiore, Bronx, NY, USA
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15
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Singh J, Lanzarini E, Santosh P. Autonomic dysfunction and sudden death in patients with Rett syndrome: a systematic review. J Psychiatry Neurosci 2020; 45:150-181. [PMID: 31702122 PMCID: PMC7828978 DOI: 10.1503/jpn.190033] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Rett syndrome (RTT), a debilitating neuropsychiatric disorder that begins in early childhood, is characterized by impairments in the autonomic nervous system that can lead to sudden unexpected death. This study explores the mechanisms of autonomic dysfunction to identify potential risk factors for sudden death in patients with RTT. METHODS Following the Reporting Items for Systematic Review and Meta-Analyses (PRISMA) criteria, we undertook comprehensive systematic reviews using the PubMed, Scopus, Cochrane, PsycINFO, Embase and Web of Science databases. RESULTS We identified and critically appraised 39 articles for autonomic dysfunction and 5 for sudden death that satisfied the eligibility criteria. Following thematic analysis, we identified 7 themes: breathing irregularities, abnormal spontaneous brainstem activations, heart rate variability metrics, QTc changes, vagal imbalance, fluctuation in peptides and serotonergic neurotransmission. We grouped these 7 themes into 3 final themes: (A) brainstem modulation of breathing, (B) electrical instability of the cardiovascular system and (C) neurochemical changes contributing to autonomic decline. We described key evidence relating to each theme and identified important areas that could improve the clinical management of patients with RTT. LIMITATIONS The heterogeneity of the methods used to assess autonomic function increased the difficulty of making inferences from the different studies. CONCLUSION This study identified the important mediators of autonomic dysfunction and sudden death in patients with RTT. We proposed brainstem mechanisms and emphasized risk factors that increase brainstem vulnerability. We discussed clinical management to reduce sudden death and future directions for this vulnerable population.
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Affiliation(s)
- Jatinder Singh
- From the Department of Child and Adolescent Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK (Singh, Santosh); the Centre for Interventional Paediatric Psychopharmacology and Rare Diseases, South London, and Maudsley NHS Foundation Trust, London, UK (Singh, Lanzarini, Santosh); and the Child and Adolescent Neuropsychiatry Unit, S. Orsola-Malpighi Hospital, University of Bologna, Via Massarenti 9, 40138, Bologna, Italy (Lanzarini)
| | - Evamaria Lanzarini
- From the Department of Child and Adolescent Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK (Singh, Santosh); the Centre for Interventional Paediatric Psychopharmacology and Rare Diseases, South London, and Maudsley NHS Foundation Trust, London, UK (Singh, Lanzarini, Santosh); and the Child and Adolescent Neuropsychiatry Unit, S. Orsola-Malpighi Hospital, University of Bologna, Via Massarenti 9, 40138, Bologna, Italy (Lanzarini)
| | - Paramala Santosh
- From the Department of Child and Adolescent Psychiatry, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, London, UK (Singh, Santosh); the Centre for Interventional Paediatric Psychopharmacology and Rare Diseases, South London, and Maudsley NHS Foundation Trust, London, UK (Singh, Lanzarini, Santosh); and the Child and Adolescent Neuropsychiatry Unit, S. Orsola-Malpighi Hospital, University of Bologna, Via Massarenti 9, 40138, Bologna, Italy (Lanzarini)
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16
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Carroll MS, Ramirez JM, Weese-Mayer DE. Diurnal variation in autonomic regulation among patients with genotyped Rett syndrome. J Med Genet 2020; 57:786-793. [PMID: 32156713 DOI: 10.1136/jmedgenet-2019-106601] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 01/07/2020] [Accepted: 02/05/2020] [Indexed: 01/03/2023]
Abstract
BACKGROUND Rett syndrome is a severe neurological disorder with a range of disabling autonomic and respiratory symptoms and resulting predominantly from variants in the methyl-CpG binding protein 2 gene on the long arm of the X-chromosome. As basic research begins to suggest potential treatments, sensitive measures of the dynamic phenotype are needed to evaluate the results of these research efforts. Here we test the hypothesis that the physiological fingerprint of Rett syndrome in a naturalistic environment differs from that of controls, and differs among genotypes within Rett syndrome. METHODS A comprehensive array of heart rate variability, cardiorespiratory coupling and cardiac repolarisation measures were evaluated from an existing database of overnight and daytime inhome ambulatory recordings in 47 cases and matched controls. RESULTS Differences between girls with Rett syndrome and matched controls were apparent in a range of autonomic measures, and suggest a shift towards sympathetic activation and/or parasympathetic inactivation. Daily temporal trends analysed in the context of circadian rhythms reveal alterations in amplitude and phase of diurnal patterns of autonomic balance. Further analysis by genotype class confirms a graded presentation of the Rett syndrome phenotype such that patients with early truncating mutations were most different from controls, while late truncating and missense mutations were least different from controls. CONCLUSIONS Comprehensive autonomic measures from extensive inhome physiological measurements can detect subtle variations in the phenotype of girls with Rett syndrome, suggesting these techniques are suitable for guiding novel therapies.
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Affiliation(s)
- Michael Sean Carroll
- Data Analytics and Reporting, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA .,Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.,Division of Autonomic Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
| | - Jan-Marino Ramirez
- Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA.,Department of Neurological Surgery, University of Washington, Seattle, Washington, USA
| | - Debra E Weese-Mayer
- Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.,Division of Autonomic Medicine, Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, Illinois, USA
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17
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Potent hERG channel inhibition by sarizotan, an investigative treatment for Rett Syndrome. J Mol Cell Cardiol 2019; 135:22-30. [PMID: 31362019 PMCID: PMC6856717 DOI: 10.1016/j.yjmcc.2019.07.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2019] [Accepted: 07/26/2019] [Indexed: 12/31/2022]
Abstract
Rett Syndrome (RTT) is an X-linked neurodevelopmental disorder associated with respiratory abnormalities and, in up to ~40% of patients, with prolongation of the cardiac QTc interval. QTc prolongation calls for cautious use of drugs with a propensity to inhibit hERG channels. The STARS trial has been undertaken to investigate the efficacy of sarizotan, a 5-HT1A receptor agonist, at correcting RTT respiratory abnormalities. The present study investigated whether sarizotan inhibits hERG potassium channels and prolongs ventricular repolarization. Whole-cell patch-clamp measurements were made at 37 °C from hERG-expressing HEK293 cells. Docking analysis was conducted using a recent cryo-EM structure of hERG. Sarizotan was a potent inhibitor of hERG current (IhERG; IC50 of 183 nM) and of native ventricular IKr from guinea-pig ventricular myocytes. 100 nM and 1 μM sarizotan prolonged ventricular action potential (AP) duration (APD90) by 14.1 ± 3.3% (n = 6) and 29.8 ± 3.1% (n = 5) respectively and promoted AP triangulation. High affinity IhERG inhibition by sarizotan was contingent upon channel gating and intact inactivation. Mutagenesis experiments and docking analysis implicated F557, S624 and Y652 residues in sarizotan binding, with weaker contribution from F656. In conclusion, sarizotan inhibits IKr/IhERG, accessing key binding residues on channel gating. This action and consequent ventricular AP prolongation occur at concentrations relevant to those proposed to treat breathing dysrhythmia in RTT. Sarizotan should only be used in RTT patients with careful evaluation of risk factors for QTc prolongation.
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18
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Faundez V, Wynne M, Crocker A, Tarquinio D. Molecular Systems Biology of Neurodevelopmental Disorders, Rett Syndrome as an Archetype. Front Integr Neurosci 2019; 13:30. [PMID: 31379529 PMCID: PMC6650571 DOI: 10.3389/fnint.2019.00030] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 07/02/2019] [Indexed: 12/17/2022] Open
Abstract
Neurodevelopmental disorders represent a challenging biological and medical problem due to their genetic and phenotypic complexity. In many cases, we lack the comprehensive understanding of disease mechanisms necessary for targeted therapeutic development. One key component that could improve both mechanistic understanding and clinical trial design is reliable molecular biomarkers. Presently, no objective biological markers exist to evaluate most neurodevelopmental disorders. Here, we discuss how systems biology and "omic" approaches can address the mechanistic and biomarker limitations in these afflictions. We present heuristic principles for testing the potential of systems biology to identify mechanisms and biomarkers of disease in the example of Rett syndrome, a neurodevelopmental disorder caused by a well-defined monogenic defect in methyl-CpG-binding protein 2 (MECP2). We propose that such an approach can not only aid in monitoring clinical disease severity but also provide a measure of target engagement in clinical trials. By deepening our understanding of the "big picture" of systems biology, this approach could even help generate hypotheses for drug development programs, hopefully resulting in new treatments for these devastating conditions.
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Affiliation(s)
- Victor Faundez
- Department of Cell Biology, Emory University, Atlanta, GA, United States
| | - Meghan Wynne
- Department of Cell Biology, Emory University, Atlanta, GA, United States
| | - Amanda Crocker
- Program in Neuroscience, Middlebury College, Middlebury, VT, United States
| | - Daniel Tarquinio
- Rare Neurological Diseases (Private Research Institution), Atlanta, GA, United States
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19
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Crosson J, Srivastava S, Bibat GM, Gupta S, Kantipuly A, Smith-Hicks C, Myers SM, Sanyal A, Yenokyan G, Brenner J, Naidu SR. Evaluation of QTc in Rett syndrome: Correlation with age, severity, and genotype. Am J Med Genet A 2017; 173:1495-1501. [PMID: 28394409 DOI: 10.1002/ajmg.a.38191] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Revised: 01/26/2017] [Accepted: 02/01/2017] [Indexed: 11/10/2022]
Abstract
Rett syndrome (RTT) is caused by MECP2 mutations, resulting in various neurological symptoms. Prolonged corrected QT interval (QTc) is also reported and is a speculated cause of sudden death in RTT. The purpose of this study was to correlate QTc in RTT patients with age, clinical severity, and genotype. 100 RTT patients (98 females, 2 males) with MECP2 mutations underwent baseline neurological evaluation (KKI-RTT Severity Scale) and QTc measurement (standard 12 lead electrocardiogram) as part of our prospective natural history study. Mean QTc of the cohort was 422.6 msec, which did not exceed the normal values for age. 7/100 patients (7%) had QTc prolongation (>450 msec). There was a trend for increasing QTc with age and clinical severity (P = 0.09). No patients with R106C, R106W, R133C, R168*, R270*, R294*, R306C, R306H, and R306P mutations demonstrated QTc prolongation. There was a relatively high proportion of QTc prolongation in patients with R255* mutations (2/8, 25%) and large deletions (1/4, 25%). The overall presence of QTc prolongation did not correlate with mutation category (P = 0.52). Our findings demonstrate that in RTT, the prevalence of QTc prolongation is lower than previously reported. Hence, all RTT patients warrant baseline ECG; if QTc is prolonged, then cardiac followup is warranted. If initial QTc is normal, then annual ECGs, particularly in younger patients, may not be necessary. However, larger sample sizes are needed to solidify the association between QTc and age and clinical severity. The biological and clinical significance of mild QTc prolongation above the normative data remains undetermined.
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Affiliation(s)
- Jane Crosson
- Division of Pediatric Cardiology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | | | - Genila M Bibat
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland.,Department of Pediatrics, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Siddharth Gupta
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland
| | - Aditi Kantipuly
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland
| | - Constance Smith-Hicks
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland.,Department of Pediatrics, Johns Hopkins School of Medicine, Baltimore, Maryland.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Scott M Myers
- Autism & Developmental Institute, Geisinger Health System, Lewisburg, Pennsylvania
| | - Abanti Sanyal
- Johns Hopkins Biostatistics Center, Department of Biostatistics, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland
| | - Gayane Yenokyan
- Johns Hopkins Biostatistics Center, Department of Biostatistics, Johns Hopkins University Bloomberg School of Public Health, Baltimore, Maryland
| | - Joel Brenner
- Division of Pediatric Cardiology, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Sakkubai R Naidu
- Department of Neurogenetics, Kennedy Krieger Institute, Baltimore, Maryland.,Department of Pediatrics, Johns Hopkins School of Medicine, Baltimore, Maryland.,Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, Maryland
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20
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Herrera JA, Ward CS, Wehrens XH, Neul JL. Methyl-CpG binding-protein 2 function in cholinergic neurons mediates cardiac arrhythmogenesis. Hum Mol Genet 2016; 25:4983-4995. [PMID: 28159985 PMCID: PMC6078594 DOI: 10.1093/hmg/ddw326] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Revised: 09/20/2016] [Accepted: 09/21/2016] [Indexed: 01/22/2023] Open
Abstract
Sudden unexpected death occurs in one quarter of deaths in Rett Syndrome (RTT), a neurodevelopmental disorder caused by mutations in Methyl-CpG-binding protein 2 (MECP2). People with RTT show a variety of autonomic nervous system (ANS) abnormalities and mouse models show similar problems including QTc interval prolongation and hypothermia. To explore the role of cardiac problems in sudden death in RTT, we characterized cardiac rhythm in mice lacking Mecp2 function. Male and female mutant mice exhibited spontaneous cardiac rhythm abnormalities including bradycardic events, sinus pauses, atrioventricular block, premature ventricular contractions, non-sustained ventricular arrhythmias, and increased heart rate variability. Death was associated with spontaneous cardiac arrhythmias and complete conduction block. Atropine treatment reduced cardiac arrhythmias in mutant mice, implicating overactive parasympathetic tone. To explore the role of MeCP2 within the parasympathetic neurons, we selectively removed MeCP2 function from cholinergic neurons (MeCP2 ChAT KO), which recapitulated the cardiac rhythm abnormalities, hypothermia, and early death seen in RTT male mice. Conversely, restoring MeCP2 only in cholinergic neurons rescued these phenotypes. Thus, MeCP2 in cholinergic neurons is necessary and sufficient for autonomic cardiac control, thermoregulation, and survival, and targeting the overactive parasympathetic system may be a useful therapeutic strategy to prevent sudden unexpected death in RTT.
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Affiliation(s)
- José A. Herrera
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX, USA
- Jan and Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX, USA
| | - Christopher S. Ward
- Jan and Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX, USA
| | - Xander H.T. Wehrens
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX, USA
- Cardiovascular Research Institute
- Departments of Medicine
- Molecular Physiology and Biophysics
- Pediatrics, Baylor College of Medicine, Houston, TX, USA
| | - Jeffrey L. Neul
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX, USA
- Jan and Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, TX, USA
- Molecular Physiology and Biophysics
- Neuroscience
- Human and Molecular Genetics
- Pediatrics, Baylor College of Medicine, Houston, TX, USA
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21
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Som A, Baidya DK, Arora MK, Maitra S, Gupta S. Rett syndrome: a concern for the anesthesiologists. J Clin Anesth 2016; 31:247-8. [PMID: 27185720 DOI: 10.1016/j.jclinane.2016.01.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 01/11/2016] [Indexed: 10/21/2022]
Affiliation(s)
- Anirban Som
- Department of Anaesthesiology, Pain Medicine & Critical Care, All India Institute of Medical Sciences, New Delhi, India
| | - Dalim K Baidya
- Department of Anaesthesiology, Pain Medicine & Critical Care, All India Institute of Medical Sciences, New Delhi, India
| | - Mahesh K Arora
- Department of Anaesthesiology, Pain Medicine & Critical Care, All India Institute of Medical Sciences, New Delhi, India
| | - Souvik Maitra
- Department of Anaesthesiology, Pain Medicine & Critical Care, All India Institute of Medical Sciences, New Delhi, India.
| | - Stuti Gupta
- Department of Anaesthesiology, Pain Medicine & Critical Care, All India Institute of Medical Sciences, New Delhi, India
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Tarquinio DC, Hou W, Neul JL, Kaufmann WE, Glaze DG, Motil KJ, Skinner SA, Lee HS, Percy AK. The Changing Face of Survival in Rett Syndrome and MECP2-Related Disorders. Pediatr Neurol 2015; 53:402-11. [PMID: 26278631 PMCID: PMC4609589 DOI: 10.1016/j.pediatrneurol.2015.06.003] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2015] [Revised: 06/04/2015] [Accepted: 06/05/2015] [Indexed: 10/23/2022]
Abstract
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.
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Affiliation(s)
| | - Wei Hou
- Stony Brook University Medical Center, Stony Brook, NY
| | - Jeffrey L. Neul
- Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | | | - Daniel G. Glaze
- Department of Pediatrics, Baylor College of Medicine, Houston, TX
| | | | | | - Hye-Seung Lee
- Pediatrics Epidemiology Center, University of South Florida, Tampa, FL
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Herrera JA, Ward CS, Pitcher MR, Percy AK, Skinner S, Kaufmann WE, Glaze DG, Wehrens XHT, Neul JL. Treatment of cardiac arrhythmias in a mouse model of Rett syndrome with Na+-channel-blocking antiepileptic drugs. Dis Model Mech 2015; 8:363-71. [PMID: 25713300 PMCID: PMC4381335 DOI: 10.1242/dmm.020131] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 02/12/2015] [Indexed: 12/11/2022] Open
Abstract
One quarter of deaths associated with Rett syndrome (RTT), an X-linked neurodevelopmental disorder, are sudden and unexpected. RTT is associated with prolonged QTc interval (LQT), and LQT-associated cardiac arrhythmias are a potential cause of unexpected death. The standard of care for LQT in RTT is treatment with β-adrenergic antagonists; however, recent work indicates that acute treatment of mice with RTT with a β-antagonist, propranolol, does not prevent lethal arrhythmias. In contrast, acute treatment with the Na+ channel blocker phenytoin prevented arrhythmias. Chronic dosing of propranolol may be required for efficacy; therefore, we tested the efficacy of chronic treatment with either propranolol or phenytoin on RTT mice. Phenytoin completely abolished arrhythmias, whereas propranolol showed no benefit. Surprisingly, phenytoin also normalized weight and activity, but worsened breathing patterns. To explore the role of Na+ channel blockers on QT in people with RTT, we performed a retrospective analysis of QT status before and after Na+ channel blocker antiepileptic therapies. Individuals with RTT and LQT significantly improved their QT interval status after being started on Na+ channel blocker antiepileptic therapies. Thus, Na+ channel blockers should be considered for the clinical management of LQT in individuals with RTT.
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Affiliation(s)
- José A Herrera
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA. Jan and Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Christopher S Ward
- Jan and Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Meagan R Pitcher
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA. Jan and Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA
| | - Alan K Percy
- Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Walter E Kaufmann
- Department of Neurology, Boston Children's Hospital, Boston, MA 02115, USA
| | - Daniel G Glaze
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Xander H T Wehrens
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA. Cardiovascular Research Institute, Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jeffrey L Neul
- Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA. Jan and Duncan Neurological Research Institute, Texas Children's Hospital, Houston, TX, USA. Department of Pediatrics, University of Alabama at Birmingham, Birmingham, AL, USA. Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA. Cardiovascular Research Institute, Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA.
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Abstract
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.
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26
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McCauley MD, Wang T, Mike E, Herrera J, Beavers DL, Huang TW, Ward CS, Skinner S, Percy AK, Glaze DG, Wehrens XHT, Neul JL. Pathogenesis of lethal cardiac arrhythmias in Mecp2 mutant mice: implication for therapy in Rett syndrome. Sci Transl Med 2012; 3:113ra125. [PMID: 22174313 DOI: 10.1126/scitranslmed.3002982] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Rett syndrome is a neurodevelopmental disorder typically caused by mutations in methyl-CpG-binding protein 2 (MECP2) in which 26% of deaths are sudden and of unknown cause. To explore the hypothesis that these deaths may be due to cardiac dysfunction, we characterized the electrocardiograms in 379 people with Rett syndrome and found that 18.5% show prolongation of the corrected QT interval (QTc), an indication of a repolarization abnormality that can predispose to the development of an unstable fatal cardiac rhythm. Male mice lacking MeCP2 function, Mecp2(Null/Y), also have prolonged QTc and show increased susceptibility to induced ventricular tachycardia. Female heterozygous null mice, Mecp2(Null/+), show an age-dependent prolongation of QTc associated with ventricular tachycardia and cardiac-related death. Genetic deletion of MeCP2 function in only the nervous system was sufficient to cause long QTc and ventricular tachycardia, implicating neuronally mediated changes to cardiac electrical conduction as a potential cause of ventricular tachycardia in Rett syndrome. The standard therapy for prolonged QTc in Rett syndrome, β-adrenergic receptor blockers, did not prevent ventricular tachycardia in Mecp2(Null/Y) mice. To determine whether an alternative therapy would be more appropriate, we characterized cardiomyocytes from Mecp2(Null/Y) mice and found increased persistent sodium current, which was normalized when cells were treated with the sodium channel-blocking anti-seizure drug phenytoin. Treatment with phenytoin reduced both QTc and sustained ventricular tachycardia in Mecp2(Null/Y) mice. These results demonstrate that cardiac abnormalities in Rett syndrome are secondary to abnormal nervous system control, which leads to increased persistent sodium current. Our findings suggest that treatment in people with Rett syndrome would be more effective if it targeted the increased persistent sodium current to prevent lethal cardiac arrhythmias.
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Affiliation(s)
- Mark D McCauley
- Department of Molecular Physiology and Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
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27
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Alvarez-Saavedra M, Carrasco L, Sura-Trueba S, Demarchi Aiello V, Walz K, Neto JX, Young JI. Elevated expression of MeCP2 in cardiac and skeletal tissues is detrimental for normal development. Hum Mol Genet 2010; 19:2177-90. [PMID: 20203171 DOI: 10.1093/hmg/ddq096] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
MeCP2 plays a critical role in interpreting epigenetic signatures that command chromatin conformation and regulation of gene transcription. In spite of MeCP2's ubiquitous expression, its functions have always been considered in the context of brain physiology. In this study, we demonstrate that alterations of the normal pattern of expression of MeCP2 in cardiac and skeletal tissues are detrimental for normal development. Overexpression of MeCP2 in the mouse heart leads to embryonic lethality with cardiac septum hypertrophy and dysregulated expression of MeCP2 in skeletal tissue produces severe malformations. We further show that MeCP2's expression in the heart is developmentally regulated; further suggesting that it plays a key role in regulating transcriptional programs in non-neural tissues.
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Weese-Mayer DE, Lieske SP, Boothby CM, Kenny AS, Bennett HL, Silvestri JM, Ramirez JM. Autonomic nervous system dysregulation: breathing and heart rate perturbation during wakefulness in young girls with Rett syndrome. Pediatr Res 2006; 60:443-9. [PMID: 16940240 DOI: 10.1203/01.pdr.0000238302.84552.d0] [Citation(s) in RCA: 131] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This study characterizes cardiorespiratory dysregulation in young girls with MECP2 mutation-confirmed Rett syndrome (RS). Respiratory inductance plethysmography of chest/abdomen and ECG was obtained during daytime wakefulness in 47 girls with MECP2 mutation-confirmed RS and 47 age-, gender-, and ethnicity-matched controls (ages 2-7 y). An in-home breath-to-breath and beat-to-beat characterization was conducted and revealed that breathing was more irregular, with an increased breathing frequency, mean airflow, and heart rate in RS versus controls. There was a decreased correlation between normal breathing and heart rate variability, and an exaggerated increase in heart rate response to breathholds in RS versus controls. We conclude that girls with RS have cardiorespiratory dysregulation during breathholds as well as during "normal" breaths and during breaths before and subsequent to breathholds. This dysregulation may offer insight into the mechanisms that render girls with RS more vulnerable to sudden death.
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Affiliation(s)
- Debra E Weese-Mayer
- Pediatric Respiratory Medicine, Rush University Medical Center, Chicago, Illinois 60612, USA.
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29
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Abstract
The scope of pediatric autonomic disorders is not well recognized. The goal of this review is to increase awareness of the expanding spectrum of pediatric autonomic disorders by providing an overview of the autonomic nervous system, including the roles of its various components and its pervasive influence, as well as its intimate relationship with sensory function. To illustrate further the breadth and complexities of autonomic dysfunction, some pediatric disorders are described, concentrating on those that present at birth or appear in early childhood.
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Affiliation(s)
- Felicia B Axelrod
- Dysautonomia Treatment and Evaluation Center, Department of Pediatrics and Neurology, New York University School of Medicine, 530 First Ave, Suite 9Q, New York, New York 10016, USA.
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Abstract
Rett syndrome (RS) is a neurodevelopmental disease,1 affecting approximately 1 in 10 000-15 000 females. Clinical severity of RS may vary with increasing age, following a four stage model.
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Affiliation(s)
- M Acampa
- Section of Internal Medicine, Department of Clinical Medicine and Immunological Sciences, University of Siena, Siena, Italy.
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31
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Weaving LS, Ellaway CJ, Gécz J, Christodoulou J. Rett syndrome: clinical review and genetic update. J Med Genet 2006; 42:1-7. [PMID: 15635068 PMCID: PMC1735910 DOI: 10.1136/jmg.2004.027730] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Rett syndrome (RS) is a severe neurodevelopmental disorder that contributes significantly to severe intellectual disability in females worldwide. It is caused by mutations in MECP2 in the majority of cases, but a proportion of atypical cases may result from mutations in CDKL5, particularly the early onset seizure variant. The relationship between MECP2 and CDKL5, and whether they cause RS through the same or different mechanisms is unknown, but is worthy of investigation. Mutations in MECP2 appear to give a growth disadvantage to both neuronal and lymphoblast cells, often resulting in skewing of X inactivation that may contribute to the large degree of phenotypic variation. MeCP2 was originally thought to be a global transcriptional repressor, but recent evidence suggests that it may have a role in regulating neuronal activity dependent expression of specific genes such as Hairy2a in Xenopus and Bdnf in mouse and rat.
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Affiliation(s)
- L S Weaving
- Program in Developmental Biology, the Hospital for Sick Children, Toronto, Canada
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Guideri F, Acampa M, Hayek Y, Zappella M. Effects of acetyl-L-carnitine on cardiac dysautonomia in Rett syndrome: prevention of sudden death? Pediatr Cardiol 2005; 26:574-7. [PMID: 16235010 DOI: 10.1007/s00246-005-0784-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
There is a higher incidence of sudden death in patients with Rett syndrome than individuals in the general population. Previous studies have implicated cardiac dysautonomia and a long QT interval as causative factors. Because carnitine plays a critical role in cellular metabolism and may have beneficial effects on cardiac and nerve function, we investigated the effects of long-term treatment with acetyl-L-carnitine on heart rate variability and electrocardiographic abnormalities in 10 girls with Rett syndrome and compared the results with 12 control patients (girls with Rett syndrome who were not treated). The age range of the subjects was 2-21 years. The study design called for the evaluation of heart rate variability, corrected QT interval, and QTc dispersion. In the 10 Rett girls treated with acetyl-L-carnitine, a significant increase in heart rate variability was observed. To explain these results, we hypothesize that acetyl-L-carnitine has a neurotrophic action on the cardiac autonomic nervous system. This effect may reduce the risk of sudden death in patients with this syndrome.
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Affiliation(s)
- F Guideri
- Department of Internal Medicine and Immunological Sciences, Section of Clinical Immunology, University of Siena, Viale Bracci, Siena 53100, Italy.
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33
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Abstract
Rett syndrome is a neurodevelopmental disorder that in most cases is consequent to a mutation in the MECP2 gene. The central nervous system is the primary organ system involved in Rett syndrome. Neurophysiologic evaluations provide information concerning the developmental aspects of Rett syndrome and the character and extent of involvement of the central, peripheral, and autonomic nervous system pathways. Evoked potentials typically demonstrate intactness of peripheral auditory and visual pathways and suggest dysfunction of central or "higher" cortical pathways. Somatosensory evoked potentials can be characterized by "giant" responses, suggesting cortical hyperexcitability. Cortical hyperexcitability is further suggested by the findings of the electroencephalogram (EEG), which are primarily characterized by a loss of expected developmental features; the appearance of focal, multifocal, and generalized epileptiform abnormalities; and the occurrence of rhythmic slow (theta) activity, primarily in the frontal-central regions. Epileptic seizures are reported to occur frequently in Rett syndrome. However, many events presumed to be seizures have no EEG correlate during video-EEG monitoring. Impairment of the autonomic nervous system in Rett syndrome is suggested by an increased incidence of long Q-T intervals during electrocardiographic recordings and diminished heart rate variability. Autonomic nervous system dysfunction can contribute to the increased incidence of sudden unexpected death in Rett syndrome.
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Affiliation(s)
- Daniel G Glaze
- Department of Pediatrics, Baylor College of Medicine, Houston, TX 77030, USA.
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Lotan M, Isakov E, Merrick J. Improving functional skills and physical fitness in children with Rett syndrome. JOURNAL OF INTELLECTUAL DISABILITY RESEARCH : JIDR 2004; 48:730-735. [PMID: 15494062 DOI: 10.1111/j.1365-2788.2003.00589.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
BACKGROUND To investigate the feasibility of a physical exercise programme with treadmill for persons with Rett syndrome (RS) in order to promote fitness and health. METHODS A daily training programme on a treadmill was designed for four females with RS over a period of 2 months with tests performed in three intervals, at time 1, 2 and 3, 2 months apart with intervention taking place between tests 2 and 3. Participants were four girls with RS aged 8.5-11 years (mean: 10 years) attending the educational facility Beit Issie Shapiro, Raanana, Israel, all with independent mobility and with typical characteristics of RS stage III. The training took place at the educational facility, on a 1400 model treadmill (Trimline, capable of very low speeds < 0.5 k/h), with very long side rails. Special low side rails were adapted to the treadmill in order to fit the height of the children and velcro straps were added to assist in safely placing the hands. Pulse was monitored constantly during exercise by an A3 polar pulse belt. Pulse measurements at rest during training were considered as evaluators of aerobic physical condition. Functional measurement was based on a scale specially established for the present study. The scale was a 31-item motor-functioning tool that measures the ability of participants to knee walk and knee stand, to get up to a standing position, duration of walking different paths, and to go up and down stairs and slopes. RESULTS The study showed that physical fitness of the children at the end of the training programme had improved considerably (P < 0.05). Tests showed that general functional abilities had improved considerably (P < 0.0001). Although all items of the functional ability measure showed impressive positive change, some of the 31 items on it showed statistically significant improvement (knee walking, going up and down stairs and speed of walking for 25 m. Pearson correlation showed high linkage (r = -0.76) between functional improvement and change in physical fitness. CONCLUSIONS Physical fitness programme executed on a daily basis is capable of improving functional ability of children with RS. Nonprofessional personnel can execute such a programme under supervision of a qualified physical therapist.
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Affiliation(s)
- M Lotan
- Zvi Quittman Residential Center, The Millie Shime Campus, Elwyn Jerusalem, Israel
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35
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Colvin L, Fyfe S, Leonard S, Schiavello T, Ellaway C, De Klerk N, Christodoulou J, Msall M, Leonard H. Describing the phenotype in Rett syndrome using a population database. Arch Dis Child 2003; 88:38-43. [PMID: 12495959 PMCID: PMC1719276 DOI: 10.1136/adc.88.1.38] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Mutations in the MECP2 gene have been recently identified as the cause of Rett syndrome, prompting research into genotype-phenotype relations. However, despite these genetic advances there has been little descriptive epidemiology of the full range of phenotypes. AIMS To describe the variation in phenotype in Rett syndrome using four different scales, by means of a population database. METHODS Using multiple sources of ascertainment including the Australian Paediatric Surveillance Unit, the development of an Australian cohort of Rett syndrome cases born since 1976 has provided the first genetically characterised population based study of Rett syndrome. Follow up questionnaires were administered in 2000 to families and used to provide responses for items in four different severity scales. RESULTS A total of 199 verified cases of Rett syndrome were reported between January 1993 and July 2000; 152 families provided information for the follow up study. The mean score using the Kerr scale was 22.9 (SD 4.8) and ranged from 20.5 in those under 7 years to 24.2 in those over 17 years. The mean Percy score was 24.9 (SD 6.6) and also increased with age group from 23.0 to 26.9. The mean Pineda score was 16.3 (SD 4.5) and did not differ by age group. The mean WeeFIM was 29.0 (SD 11.9), indicating extreme dependence, and ranged from 18 to 75. CONCLUSION We have expanded on the descriptive epidemiology of Rett syndrome and shown different patterns according to the severity scale selected. Although all affected children are severely functionally dependent, it is still possible to identify some variation in ability, even in children with identified MECP2 mutations.
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Affiliation(s)
- L Colvin
- Centre for Child Health Research, The University of Western Australia, Telethon Institute for Child Health Research, Perth, Western Australia
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36
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Glaze DG. Neurophysiology of Rett syndrome. MENTAL RETARDATION AND DEVELOPMENTAL DISABILITIES RESEARCH REVIEWS 2002; 8:66-71. [PMID: 12112729 DOI: 10.1002/mrdd.10024] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Neurophysiological evaluations have been widely applied in the study of Rett syndrome (RS) to provide information concerning the developmental aspects of RS; the character and extent of involvement of the central, peripheral, and autonomic nervous system pathways; and evaluation of the clinical symptomatology of RS. The electroencephalogram (EEG) is invariably abnormal and shows characteristic, though not diagnostic, changes: loss of expected developmental features; the appearance of focal, multifocal, and generalized epileptiform abnormalities; and the occurrence of rhythmic slow (theta) activity primarily in the frontal-central regions. Epileptic seizures are reported to occur frequently in RS, and partial and generalized seizures may be experienced by RS girls. However, many events presumed to be seizures have no EEG correlate during video-EEG monitoring, suggesting the possibility of a nonepileptic mechanism. Such monitoring may be necessary to determine appropriate use of antiepileptic drugs. Evoked potentials typically demonstrate intact peripheral auditory and visual pathways and suggest dysfunction of central or "higher" cortical pathways. Somatosensory-evoked potentials may be characterized by "giant" responses, suggesting cortical hyperexcitability. An increased incidence of long QT intervals during electrocardiographic recordings and diminished heart-rate variability, suggesting impairment of the autonomic nervous system, are described in RS. With the discovery of the genetic basis of RS, neurophysiological studies will provide parameters for phenotype-genotype correlations and characterization of animal models.
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Affiliation(s)
- Daniel G Glaze
- Departments of Pediatrics and Neurology, Baylor College of Medicine, Houston, Texas 77030, USA.
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37
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Armstrong DD. Neuropathology of Rett syndrome. MENTAL RETARDATION AND DEVELOPMENTAL DISABILITIES RESEARCH REVIEWS 2002; 8:72-6. [PMID: 12112730 DOI: 10.1002/mrdd.10027] [Citation(s) in RCA: 84] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Rett Syndrome is unlike any other pediatric neurologic disease, and its clinical-pathologic correlation can not be defined with standard histology techniques. Based on hypotheses suggested by careful clinical observations, the nervous system of the Rett child has been explored utilizing morphometry, golgi preparations, computerized tomography, magnetic resonance imaging, chemistry, immunocytochemistry, autoradiography, and molecular biologic techniques. From these many perspectives we conclude that Rett syndrome is not a typical degenerative disorder, storage disorder, nor the result of gross malformation, infectious or neoplastic processes. There remain regions of the brain that have not been studied in detail but the available data suggest that the neuropathology of Rett syndrome can be summarized as follows: the Rett brain is small for the age and the height of the patient; it does not become progressively smaller over three to four decades; it has small dendritic trees in pyramidal neurons of layers III and V in selected lobes (frontal, motor, and temporal); it has small neurons with an increased neuronal packing density; it has an immature expression of microtubular protein-2 and cyclooxygenase; it exhibits a changing pattern of neurotransmitter receptors with an apparent reduction in many neurotransmitters, possibly contributing to some symptomatology. A mutation in Mecp2 causes this unique disorder of brain development. Neuronal mosaicism for normal and mutated Mecp2 produces a consistent phenotype in the classic female patient and a small brain with some preserved islands of function, but with an inability to support hand use and speech. This paper summarizes our current observations about neuropathology of Rett syndrome. MRDD Research Reviews 2002;8:72-76.
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38
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Guideri F, Acampa M, DiPerri T, Zappella M, Hayek Y. Progressive cardiac dysautonomia observed in patients affected by classic Rett syndrome and not in the preserved speech variant. J Child Neurol 2001; 16:370-3. [PMID: 11392524 DOI: 10.1177/088307380101600512] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Incidence of sudden death in Rett syndrome is greater than that of the general population, and cardiac electrical instability is a prime suspect cause. The objective of the present study was the evaluation of heart rate variability, a marker of autonomic activity, in females affected by classic Rett syndrome and atypical variants for a possible explanation of the higher risk for sudden death observed in these subjects. Our study showed that girls with classic Rett syndrome had significantly lower heart rate variability and longer corrected QT intervals than in atypical Rett syndrome and age-matched healthy girls. Reduction of heart rate variability progresses with age and with the clinical stage of the syndrome. These results suggest the possible role of the progressive cardiac dysfunction in the sudden death associated with Rett syndrome.
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Affiliation(s)
- F Guideri
- Department of Internal Medicine, University of Siena, Italy.
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39
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Abstract
The Rett syndrome (RS) is a peculiar, sporadic, atrophic disorder, almost entirely confined to females. After the first six months of life there is developmental slowing with reduced communication and head growth for about one year. This is followed by a rapid destructive stage with severe dementia and loss of hand skills (with frequent hand wringing), apraxia and ataxia, autistic features and irregular breathing with hyperventilation. Seizures often supervene. Subsequently there is some stabilization in a pseudo-stationary stage during the preschool to school years, associated with more emotional contact but also abnormalities of the autonomic and skeletal systems. After the age of 15-20 years, a late motor deterioration occurs with dystonia and frequent spasticity but seizures become milder. RS has generally been considered an X-linked disorder in which affected females represent a new mutation, with male lethality. Linkage studies suggested a critical region at Xq28. In 1999, mutations in the gene MECP2 encoding X-linked methyl cytosine-binding protein 2 (MeCP2) were found in a proportion of Rett girls. This protein can bind methylated DNA. Analyses are leading to much further investigation of mutants and their effects on genes. Neuropathological and electrophysiological studies of RS are described. Description of neurometabolic factors includes reduced levels of dopamine, serotonin, noradrenaline and choline acetyltransferase (ChAT) in brain, also estimation of nerve growth factors, endorphin, substance P, glutamate and other amino acids and their receptor levels. The results of neuroimaging are surveyed, including volumetric magnetic resonance imaging (MRI) and positron emission tomography (PET).
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Affiliation(s)
- H G Dunn
- Division of Neurology, British Columbia's Children's Hospital, Vancouver, BC, Canada
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40
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Abstract
The recent identification of mutations in the gene methyl-Cpg-binding protein-2 (MECP2) in girls with Rett syndrome (RS) has firmly established the molecular genetic basis of this unique, X-linked, dominant disorder and provides a dramatic conclusion to an intensive, decade-long search. This finding has ramifications far beyond establishing the gene for RS. Recent data indicate that the clinical phenotypes for MECP2 mutations range from mild disability in the mother of a girl with RS to rapidly progressive encephalopathy in her brother. Further, the pathobiology of MECP2 could be a prototype for other disorders of neurodevelopment. MECP2 encodes a methyl-CpG-binding protein (MeCP2), which is critical for transcriptional silencing of an as yet unknown number and type of genes responsible for the pathobiology of RS. As such, this discovery opens up completely new vistas as to fundamental neurobiologic processes, to disease mechanisms in the neurodevelopmental disabilities, and to potential new therapeutic strategies for RS and related disorders.
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Affiliation(s)
- A K Percy
- Department of Pediatrics, University of Alabama at Birmingham, School of Medicine, 35233-1711, USA.
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