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Wen Y, Wang J, Zhang Q, Chen Y, Wu X, Bao X. MECP2 mutation spectrum and its clinical characteristics in a Chinese cohort. Clin Genet 2020; 98:240-250. [PMID: 32472557 DOI: 10.1111/cge.13790] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2019] [Revised: 05/24/2020] [Accepted: 05/25/2020] [Indexed: 01/08/2023]
Abstract
The dysfunction of methyl-CpG-binding protein 2 (MeCP2) is associated with several neurological disorders, of which Rett syndrome (RTT) is the most prominent. This study focused on a Chinese patient cohort with MECP2 mutations, and analyzed the characteristics of these mutations and their clinical manifestations. In total, 666 patients were identified with 126 different MECP2 mutations, including 22 novel mutations. Over 80% of patients carried an MECP2 mutation on exon 4. Nonsense and missense mutations were the most commonly reported types. Missense mutations were mainly located on methyl-CpG-binding domain (MBD), and nonsense mutations predominantly occurred on transcription repression domain (TRD) and inter domain. The predilection site of large deletion was exon 3 and/or exon 4. Patients with p.R133C, p.R294*, p.R306C, and C-terminal domain (CTD) deletions were less severely affected. Significant differences were found in ambulation ability, hand function, and language among different mutation groups. Three female patients with MECP2 mutations (1 with p.R306P and 2 with p.R309W) only presented with intellectual disability/developmental delay (ID/DD), and no obvious RTT symptoms were reported. Eight male individuals with MECP2 mutations were also identified in this study, including 2 diagnosed with typical RTT, 3 with atypical RTT and 3 with ID/DD.
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Affiliation(s)
- Yongxin Wen
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Jiaping Wang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Qingping Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Yan Chen
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xiru Wu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xinhua Bao
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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Clarke AJ, Abdala Sheikh AP. A perspective on "cure" for Rett syndrome. Orphanet J Rare Dis 2018; 13:44. [PMID: 29609636 PMCID: PMC5879810 DOI: 10.1186/s13023-018-0786-6] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 03/16/2018] [Indexed: 01/08/2023] Open
Abstract
The reversal of the Rett syndrome disease process in the Mecp2 mouse model of Guy et al. (2007) has motivated families and researchers to work on this condition. The reversibility in adult mice suggests that there is potentially much to be gained from rational treatments applied to patients of any age. However, it may be difficult to strike the right balance between enthusiasm on the one hand and realism on the other. One effect of this has been a fragmentation of the "Rett syndrome community" with some groups giving priority to work aimed at a cure while fewer resources are devoted to medical or therapy-based interventions to enhance the quality of life of affected patients or provide support for their families.Several possible therapeutic approaches are under development that, it is claimed and hoped, may lead to a "cure" for patients with Rett syndrome. While all have a rationale, there are potential obstacles to each being both safe and effective. Furthermore, any strategy that succeeded in restoring normal levels of MECP2 gene expression throughout the brain carries potential pitfalls, so that it will be of crucial importance to introduce any clinical trials of such therapies with great care.Expectations of families for a radical, rational treatment should not be inflated beyond a cautious optimism. This is particularly because affected patients with us now may not be able to reap the full benefits of a "cure". Thus, interventions aimed at enhancing the quality of life of affected patients should not be forgone and their importance should not be minimised.
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Affiliation(s)
- Angus John Clarke
- Institute of Medical Genetics, Division of Cancer & Genetics, School of Medicine, Cardiff University, Cardiff, Wales, UK
- Institute of Medical Genetics, University Hospital of Wales, Heath Park, Cardiff, CF14 4XN Wales, UK
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Zhang Q, Zhao Y, Bao X, Luo J, Zhang X, Li J, Wei L, Wu X. Familial cases and male cases with MECP2 mutations. Am J Med Genet B Neuropsychiatr Genet 2017; 174:451-457. [PMID: 28394482 PMCID: PMC5485058 DOI: 10.1002/ajmg.b.32534] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2016] [Accepted: 02/06/2017] [Indexed: 12/03/2022]
Abstract
This is the first report of Chinese familial cases with Rett syndrome (RTT) or X-linked mental retardation (XLMR). RTT is a neurodevelopmental disorder that almost exclusively affects females. Most RTT cases are sporadic. We have studied eight cases with MECP2 mutations in six Chinese families, including three females and five males with RTT or XLMR. All shared identical MECP2 mutations with their mothers. The three females fulfilled the diagnostic criteria for RTT, while the five males were XLMR. A random X-chromosome inactive (XCI) pattern was seen in all the three female patients and two mothers while a skewed XCI in the rest four mothers. The clinical manifestations and pathogenic gene spectrum between male and female patients were different. The different MECP2 mutations and different XCI pattern may be the determinants of the phenotypic heterogeneity between the family members.
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Affiliation(s)
- Qingping Zhang
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Ying Zhao
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Xinhua Bao
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Jinjun Luo
- Departments of Neurology and PharmacologyLewis Katz School of Medicine at Temple UniversityPhiladelphiaPennsylvania
| | - Xiaoying Zhang
- Department of PediatricsPeking University First HospitalBeijingChina
| | - Jiarui Li
- State Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking University, Center for BioinformaticsBeijingChina
| | - Liping Wei
- State Key Laboratory of Protein and Plant Gene ResearchSchool of Life SciencesPeking University, Center for BioinformaticsBeijingChina
| | - Xiru Wu
- Department of PediatricsPeking University First HospitalBeijingChina
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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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Yuan L, Wu S, Xu H, Xiao J, Yang Z, Xia H, Liu A, Hu P, Lu A, Chen Y, Xu F, Deng H. Identification of a novel PHEX mutation in a Chinese family with X-linked hypophosphatemic rickets using exome sequencing. Biol Chem 2015; 396:27-33. [PMID: 25060345 DOI: 10.1515/hsz-2014-0187] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 07/20/2014] [Indexed: 01/23/2023]
Abstract
Abstract
Familial hypophosphatemic rickets (HR), the most common inherited form of rickets, is a group of inherited renal phosphate wasting disorders characterized by growth retardation, rickets with bone deformities, osteomalacia, poor dental development, and hypophosphatemia. The purpose of this study was to identify the genetic defect responsible for familial HR in a four-generation Chinese Han pedigree by exome sequencing and Sanger sequencing. Clinical features include skeletal deformities, teeth abnormalities, hearing impairments and variable serum phosphate level in patients of this family. A novel deletion mutation, c.1553delT (p.F518Sfs*4), was identified in the X-linked phosphate regulating endopeptidase homolog gene (PHEX). The mutation is predicted to result in prematurely truncated and loss-of-function PHEX protein. Our data suggest that exome sequencing is a powerful tool to discover mutation(s) in HR, a disorder with genetic and clinical heterogeneity. The findings may also provide new insights into the cause and diagnosis of HR, and have implications for genetic counseling and clinical management.
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