1
|
Xiol C, Heredia M, Pascual-Alonso A, Oyarzabal A, Armstrong J. Technological Improvements in the Genetic Diagnosis of Rett Syndrome Spectrum Disorders. Int J Mol Sci 2021; 22:10375. [PMID: 34638716 DOI: 10.3390/ijms221910375] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/17/2021] [Accepted: 09/22/2021] [Indexed: 11/17/2022] Open
Abstract
Rett syndrome (RTT) is a severe neurodevelopmental disorder that constitutes the second most common cause of intellectual disability in females worldwide. In the past few years, the advancements in genetic diagnosis brought by next generation sequencing (NGS), have made it possible to identify more than 90 causative genes for RTT and significantly overlapping phenotypes (RTT spectrum disorders). Therefore, the clinical entity known as RTT is evolving towards a spectrum of overlapping phenotypes with great genetic heterogeneity. Hence, simultaneous multiple gene testing and thorough phenotypic characterization are mandatory to achieve a fast and accurate genetic diagnosis. In this review, we revise the evolution of the diagnostic process of RTT spectrum disorders in the past decades, and we discuss the effectiveness of state-of-the-art genetic testing options, such as clinical exome sequencing and whole exome sequencing. Moreover, we introduce recent technological advancements that will very soon contribute to the increase in diagnostic yield in patients with RTT spectrum disorders. Techniques such as whole genome sequencing, integration of data from several “omics”, and mosaicism assessment will provide the tools for the detection and interpretation of genomic variants that will not only increase the diagnostic yield but also widen knowledge about the pathophysiology of these disorders.
Collapse
|
2
|
Spagnoli C, Fusco C, Pisani F. Rett Syndrome Spectrum in Monogenic Developmental-Epileptic Encephalopathies and Epilepsies: A Review. Genes (Basel) 2021; 12:genes12081157. [PMID: 34440332 PMCID: PMC8394997 DOI: 10.3390/genes12081157] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 07/21/2021] [Accepted: 07/23/2021] [Indexed: 01/22/2023] Open
Abstract
INTRODUCTION Progress in the clinical application of next-generation-sequencing-based techniques has resulted in a dramatic increase in the recognized genetic heterogeneity of the Rett syndrome spectrum (RSS). Our awareness of the considerable overlap with pediatric-onset epilepsies and epileptic/developmental encephalopathies (EE/DE) genes is also growing, and the presence of variable clinical features inside a general frame of commonalities has drawn renewed attention into deep phenotyping. METHODS We decided to review the medical literature on atypical Rett syndrome and "Rett-like" phenotypes, with special emphasis on described cases with pediatric-onset epilepsies and/or EE-DE, evaluating Neul's criteria for Rett syndrome and associated movement disorders and notable stereotypies. RESULTS "Rett-like" features were described in syndromic and non-syndromic monogenic epilepsy- and DE/EE-related genes, in "intellectual disability plus epilepsy"-related genes and in neurodegenerative disorders. Additionally, prominent stereotypies can be observed in monogenic complex neurodevelopmental disorders featuring epilepsy with or without autistic features outside of the RSS. CONCLUSIONS Patients share a complex neurodevelopmental and neurological phenotype (developmental delay, movement disorder) with impaired gait, abnormal tone and hand stereotypies. However, the presence and characteristics of regression and loss of language and functional hand use can differ. Finally, the frequency of additional supportive criteria and their distribution also vary widely.
Collapse
Affiliation(s)
- Carlotta Spagnoli
- Child Neurology Unit, AUSL-IRCCS di Reggio Emilia, 42123 Reggio Emilia, Italy;
- Correspondence:
| | - Carlo Fusco
- Child Neurology Unit, AUSL-IRCCS di Reggio Emilia, 42123 Reggio Emilia, Italy;
| | - Francesco Pisani
- Child Neuropsychiatry Unit, University-Hospital of Parma, 43123 Parma, Italy;
| |
Collapse
|
3
|
Wang J, Zhang Q, Chen Y, Yu S, Wu X, Bao X. Rett and Rett-like syndrome: Expanding the genetic spectrum to KIF1A and GRIN1 gene. Mol Genet Genomic Med 2019; 7:e968. [PMID: 31512412 PMCID: PMC6825848 DOI: 10.1002/mgg3.968] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 01/03/2019] [Accepted: 08/09/2019] [Indexed: 12/19/2022] Open
Abstract
Background This study aimed to investigate the new genetic etiologies of Rett syndrome (RTT) or Rett‐like phenotypes. Methods Targeted next‐generation sequencing (NGS) was performed on 44 Chinese patients with RTT or Rett‐like phenotypes, in whom genetic analysis of MECP2, CDKL5, and FOXG1 was negative. Results The detection rate was 31.8% (14/44). A de novo pathogenic variant (c.275_276ins AA, p. Cys92*) of KIF1A was identified in a girl with all core features of typical RTT. A patient with atypical RTT was detected having de novo GRIN1 pathogenic variant (c.2337C > A, p. Val793Phe). Additionally, compound heterozygous pathogenic variants of PPT1 gene were detected in a girl, who initially displayed typical RTT features, but progressed into neuronal ceroid lipofuscinoses (NCL) afterwards. Pathogenic variants in KCNQ2, MEF2C, WDR45, TCF4, IQSEC2, and SDHA were also found in our cohort. Conclusions It is the first time that pathogenic variants of GRIN1 and KIF1A were linked to RTT and Rett‐like profiles. Our findings expanded the genetic heterogeneity of Chinese RTT or Rett‐like patients, and also suggest that some patients with genetic metabolic disease such as NCL, might displayed Rett features initially, and clinical follow‐up is essential for the diagnosis.
Collapse
Affiliation(s)
- 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
| | - Shujie Yu
- Department of Neurology, Harbin Children's Hospital, Harbin, China
| | - Xiru Wu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xinhua Bao
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| |
Collapse
|
4
|
Vidal S, Xiol C, Pascual-Alonso A, O'Callaghan M, Pineda M, Armstrong J. Genetic Landscape of Rett Syndrome Spectrum: Improvements and Challenges. Int J Mol Sci 2019; 20:ijms20163925. [PMID: 31409060 PMCID: PMC6719047 DOI: 10.3390/ijms20163925] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/08/2019] [Accepted: 08/10/2019] [Indexed: 02/06/2023] Open
Abstract
Rett syndrome (RTT) is an early-onset neurodevelopmental disorder that primarily affects females, resulting in severe cognitive and physical disabilities, and is one of the most prevalent causes of intellectual disability in females. More than fifty years after the first publication on Rett syndrome, and almost two decades since the first report linking RTT to the MECP2 gene, the research community's effort is focused on obtaining a better understanding of the genetics and the complex biology of RTT and Rett-like phenotypes without MECP2 mutations. Herein, we review the current molecular genetic studies, which investigate the genetic causes of RTT or Rett-like phenotypes which overlap with other genetic disorders and document the swift evolution of the techniques and methodologies employed. This review also underlines the clinical and genetic heterogeneity of the Rett syndrome spectrum and provides an overview of the RTT-related genes described to date, many of which are involved in epigenetic gene regulation, neurotransmitter action or RNA transcription/translation. Finally, it discusses the importance of including both phenotypic and genetic diagnosis to provide proper genetic counselling from a patient's perspective and the appropriate treatment.
Collapse
Affiliation(s)
- Silvia Vidal
- Sant Joan de Déu Research Foundation, 08950 Barcelona, Spain
- Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, 08950 Barcelona, Spain
| | - Clara Xiol
- Sant Joan de Déu Research Foundation, 08950 Barcelona, Spain
- Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, 08950 Barcelona, Spain
| | - Ainhoa Pascual-Alonso
- Sant Joan de Déu Research Foundation, 08950 Barcelona, Spain
- Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, 08950 Barcelona, Spain
| | - M O'Callaghan
- Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, 08950 Barcelona, Spain
- Neurology Service, Hospital Sant Joan de Déu, 08950 Barcelona, Spain
- CIBER-ER (Biomedical Network Research Center for Rare Diseases), Institute of Health Carlos III (ISCIII), 28029 Madrid, Spain
| | - Mercè Pineda
- Sant Joan de Déu Research Foundation, 08950 Barcelona, Spain
| | - Judith Armstrong
- Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, 08950 Barcelona, Spain.
- CIBER-ER (Biomedical Network Research Center for Rare Diseases), Institute of Health Carlos III (ISCIII), 28029 Madrid, Spain.
- Molecular and Genetics Medicine Section, Hospital Sant Joan de Déu, 08950 Barcelona, Spain.
| |
Collapse
|
5
|
Vidal S, Brandi N, Pacheco P, Maynou J, Fernandez G, Xiol C, Pascual-Alonso A, Pineda M, Armstrong J, Garcia-Cazorla À, del Carmen Serrano Munuera M, García SC, Troncoso M, Fariña G, García Peñas JJ, Fournier BG, León SR, Guitart M, Baena N, de Nanclares GP, Oci IO, Gutiérrez-Delicado E, Abarrategui B, Barroso E, Santos-Simarro F, Lapunzina P, García FJ, Acedo JM, García A, Martinez MA, Martínez-Bermejo A. The most recurrent monogenic disorders that overlap with the phenotype of Rett syndrome. Eur J Paediatr Neurol 2019; 23:609-620. [PMID: 31105003 DOI: 10.1016/j.ejpn.2019.04.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/12/2019] [Accepted: 04/28/2019] [Indexed: 12/30/2022]
Abstract
Rett syndrome (RTT) is an early-onset neurodevelopmental disorder that is caused by mutations in the MECP2 gene; however, defects in other genes (CDKL5 and FOXG1) can lead to presentations that resemble classic RTT, although they are not completely identical. Here, we attempted to identify other monogenic disorders that share features of RTT. A total of 437 patients with a clinical diagnosis of RTT-like were studied; in 242 patients, a custom panel with 17 genes related to an RTT-like phenotype was run via a HaloPlex-Target-Enrichment-System. In the remaining 195 patients, a commercial TruSight-One-Sequencing-Panel was analysed. A total of 40 patients with clinical features of RTT had variants which affect gene function in six genes associated with other monogenic disorders. Twelve patients had variants in STXBP1, nine in TCF4, six in SCN2A, five in KCNQ2, four in MEF2C and four in SYNGAP1. Genetic studies using next generation sequencing (NGS) allowed us to study a larger number of genes associated with RTT-like simultaneously, providing a genetic diagnosis for a wider group of patients. These new findings provide the clinician with more information and clues that could help in the prevention of future symptoms or in pharmacologic therapy.
Collapse
Affiliation(s)
- S Vidal
- Sant Joan de Déu Research Foundation, Barcelona, Spain; Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, Barcelona, Spain
| | - N Brandi
- School of Medicine, Universitat de Barcelona, Barcelona, Spain
| | - P Pacheco
- Molecular and Genetics Medicine Section, Hospital Sant Joan de Déu, Barcelona, Spain
| | - J Maynou
- Molecular and Genetics Medicine Section, Hospital Sant Joan de Déu, Barcelona, Spain; Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, Barcelona, Spain
| | - G Fernandez
- Molecular and Genetics Medicine Section, Hospital Sant Joan de Déu, Barcelona, Spain; Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, Barcelona, Spain
| | - C Xiol
- Sant Joan de Déu Research Foundation, Barcelona, Spain; Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, Barcelona, Spain
| | - A Pascual-Alonso
- Sant Joan de Déu Research Foundation, Barcelona, Spain; Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, Barcelona, Spain
| | - M Pineda
- Sant Joan de Déu Research Foundation, Barcelona, Spain
| | | | - J Armstrong
- Molecular and Genetics Medicine Section, Hospital Sant Joan de Déu, Barcelona, Spain; Institut de Recerca Pediàtrica Hospital Sant Joan de Déu, Barcelona, Spain; CIBER-ER (Biomedical Network Research Center for Rare Diseases), Institute of Health Carlos III (ISCIII), Madrid, Spain.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|