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Parravicini S, Pasca L, Zanaboni MP, Varesio C, Rognone E, Totaro M, Gana S, Rossi E, De Giorgis V. Electroclinical Improvement in a Patient with Ring Chromosome 20 Syndrome Treated with Zonisamide: A Case Report. J Pediatr Genet 2023; 12:219-223. [PMID: 37575645 PMCID: PMC10421690 DOI: 10.1055/s-0041-1726281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 02/06/2021] [Indexed: 10/21/2022]
Abstract
Ring chromosome 20 or r(20) syndrome is a rare chromosomal disorder, mainly characterized by childhood-onset drug-resistant epilepsy with typical electroencephalographic findings, followed by mild to severe cognitive-behavioral decline. Recent studies support a possible role of the dopaminergic system in the epileptogenesis of this syndrome. We report the case of a 13-year-old female with mosaic r(20) who showed typical disease onset and evolution and a remarkable electroclinical improvement with zonisamide. Epilepsy related to r(20) is often medically intractable. When valproate and lamotrigine are not effective, zonisamide could be further investigated as a therapeutic option, since it acts as antifocal and it has a potential role in the prevention of dopamine depletion.
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Affiliation(s)
- Stefano Parravicini
- Department of Child Neurology and Psychiatry, IRCSS Mondino Foundation, European Reference Network for Rare and Complex Epilepsies, EpiCARE, Pavia, Italy
- Brain and Behaviour Department, University of Pavia, Pavia, Italy
| | - Ludovica Pasca
- Department of Child Neurology and Psychiatry, IRCSS Mondino Foundation, European Reference Network for Rare and Complex Epilepsies, EpiCARE, Pavia, Italy
- Brain and Behaviour Department, University of Pavia, Pavia, Italy
| | - Martina Paola Zanaboni
- Department of Child Neurology and Psychiatry, IRCSS Mondino Foundation, European Reference Network for Rare and Complex Epilepsies, EpiCARE, Pavia, Italy
| | - Costanza Varesio
- Department of Child Neurology and Psychiatry, IRCSS Mondino Foundation, European Reference Network for Rare and Complex Epilepsies, EpiCARE, Pavia, Italy
- Brain and Behaviour Department, University of Pavia, Pavia, Italy
| | - Elisa Rognone
- Department of Neuroradiology, IRCSS Mondino Foundation, Pavia, Italy
| | - Martina Totaro
- Department of Child Neurology and Psychiatry, IRCSS Mondino Foundation, European Reference Network for Rare and Complex Epilepsies, EpiCARE, Pavia, Italy
- Brain and Behaviour Department, University of Pavia, Pavia, Italy
| | - Simone Gana
- Medical Genetics, IRCCS Mondino Foundation, Pavia, Italy
| | - Elena Rossi
- Medical Genetics, IRCCS Mondino Foundation, Pavia, Italy
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
| | - Valentina De Giorgis
- Department of Child Neurology and Psychiatry, IRCSS Mondino Foundation, European Reference Network for Rare and Complex Epilepsies, EpiCARE, Pavia, Italy
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Status Epilepticus in Chromosomal Disorders Associated with Epilepsy: A Systematic Review. Genes (Basel) 2023; 14:genes14020299. [PMID: 36833226 PMCID: PMC9956098 DOI: 10.3390/genes14020299] [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: 12/29/2022] [Revised: 01/17/2023] [Accepted: 01/19/2023] [Indexed: 01/24/2023] Open
Abstract
Status Epilepticus (SE) is a neurological emergency resulting from the failure of mechanisms of seizure termination or from the initiation of mechanisms that lead to prolonged seizures. The International League Against Epilepsy (ILAE) identified 13 chromosomal disorders associated with epilepsy (CDAE); data regarding SE occurrence in these patients is lacking. A systematic scoping review was conducted to outline current literature evidence about clinical features, treatments, and outcomes of SE in pediatric and adult patients with CDAE. A total of 373 studies were identified with the initial search; 65 of these were selected and regarded as SE in Angelman Syndrome (AS, n = 20), Ring 20 Syndrome (R20, n = 24), and other syndromes (n = 21). Non-convulsive status epilepticus (NCSE) is frequently observed in AS and R20. No specific, targeted therapies for SE in CDAE are available to date; anecdotal reports about SE treatment are described in the text, as well as various brief- and long-term outcomes. Further evidence is needed to precisely portray the clinical features, treatment options, and outcomes of SE in these patients.
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Ling J, Yeung WL, Hon KL, Lo IFM, Luk HM, Fung CW, Leung AKC. Successful Treatment of Drug-Resistant Seizures Secondary to Ring 20 Mosaicism with Perampanel as an Add-On Antiepileptic Drug. Case Rep Pediatr 2022; 2022:7414628. [PMID: 35664544 PMCID: PMC9162848 DOI: 10.1155/2022/7414628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 04/21/2022] [Indexed: 11/27/2022] Open
Abstract
We report a girl with drug-resistant seizures, progressive behavioral changes, and cognitive decline. Investigations showed abnormal EEG with frequent high-voltage bifrontotemporal sharp and slow waves, especially during sleep. Seizures were difficult to control, despite the usage of various antiepileptic drugs. Perampanel as an add-on antiepileptic drug appeared efficacious. Due to the recognizable pattern of seizures and EEG findings, a karyotype study was performed which revealed 46 chromosomes with a ring 20 chromosome mosaicism. Ring 20 chromosome is associated with drug-resistant refractory seizures, cognitive decline, and behavioral problems. This case highlights the difficulty and challenge faced in managing drug-resistant refractory seizures associated with ring 20 chromosome. While ring 20 chromosome is often underdiagnosed, one should have a high index of awareness and suspicion of such rare epilepsy syndrome, so that an early diagnosis can be made.
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Affiliation(s)
- Janet Ling
- The Hong Kong Children's Hospital, Kowloon Bay, Hong Kong
| | - Wai Lan Yeung
- The Hong Kong Children's Hospital, Kowloon Bay, Hong Kong
| | - Kam Lun Hon
- The Hong Kong Children's Hospital, Kowloon Bay, Hong Kong
| | - Ivan F. M. Lo
- Clinical Genetic Service, Department of Health, HKSAR, Kowloon Bay, Hong Kong
| | - Ho-Ming Luk
- Clinical Genetics Service Unit, Hong Kong Children's Hospital, Ngau Tau Kok, Hong Kong
| | | | - Alexander K. C. Leung
- Department of Pediatrics, The University of Calgary, Alberta Children's Hospital, Calgary, Alberta, Canada
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Peron A, Catusi I, Recalcati MP, Calzari L, Larizza L, Vignoli A, Canevini MP. Ring Chromosome 20 Syndrome: Genetics, Clinical Characteristics, and Overlapping Phenotypes. Front Neurol 2020; 11:613035. [PMID: 33363513 PMCID: PMC7753021 DOI: 10.3389/fneur.2020.613035] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Accepted: 11/09/2020] [Indexed: 12/15/2022] Open
Abstract
Ring chromosome 20 [r(20)] syndrome is a rare condition characterized by a non-supernumerary ring chromosome 20 replacing a normal chromosome 20. It is commonly seen in a mosaic state and is diagnosed by means of karyotyping. r(20) syndrome is characterized by a recognizable epileptic phenotype with typical EEG pattern, intellectual disability manifesting after seizure onset in otherwise normally developing children, and behavioral changes. Despite the distinctive phenotype, many patients still lack a diagnosis-especially in the genomic era-and the pathomechanisms of ring formation are poorly understood. In this review we address the genetic and clinical aspects of r(20) syndrome, and discuss differential diagnoses and overlapping phenotypes, providing the reader with useful tools for clinical and laboratory practice. We also discuss the current issues in understanding the mechanisms through which ring 20 chromosome causes the typical manifestations, and present unpublished data about methylation studies. Ultimately, we explore future perspectives of r(20) research. Our intended audience is clinical and laboratory geneticists, child and adult neurologists, and genetic counselors.
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Affiliation(s)
- Angela Peron
- Human Pathology and Medical Genetics, ASST Santi Paolo e Carlo, San Paolo Hospital, Milan, Italy.,Child Neuropsychiatry Unit - Epilepsy Center, Department of Health Sciences, ASST Santi Paolo e Carlo, San Paolo Hospital, Università Degli Studi di Milano, Milan, Italy.,Division of Medical Genetics, Department of Pediatrics, University of Utah School of Medicine, Salt Lake City, UT, United States
| | - Ilaria Catusi
- Laboratory of Cytogenetics and Molecular Genetics, Istituto Auxologico Italiano IRCCS-Istituto di Ricovero e Cura a Carattere Scientifico, Cusano Milanino, Milan, Italy
| | - Maria Paola Recalcati
- Laboratory of Cytogenetics and Molecular Genetics, Istituto Auxologico Italiano IRCCS-Istituto di Ricovero e Cura a Carattere Scientifico, Cusano Milanino, Milan, Italy
| | - Luciano Calzari
- Bioinformatics and Statistical Genomics Unit, Istituto Auxologico Italiano IRCCS-Istituto di Ricovero e Cura a Carattere Scientifico, Cusano Milanino, Milan, Italy
| | - Lidia Larizza
- Laboratory of Cytogenetics and Molecular Genetics, Istituto Auxologico Italiano IRCCS-Istituto di Ricovero e Cura a Carattere Scientifico, Cusano Milanino, Milan, Italy
| | - Aglaia Vignoli
- Child Neuropsychiatry Unit - Epilepsy Center, Department of Health Sciences, ASST Santi Paolo e Carlo, San Paolo Hospital, Università Degli Studi di Milano, Milan, Italy
| | - Maria Paola Canevini
- Child Neuropsychiatry Unit - Epilepsy Center, Department of Health Sciences, ASST Santi Paolo e Carlo, San Paolo Hospital, Università Degli Studi di Milano, Milan, Italy
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Budisteanu M, Jurca C, Papuc SM, Focsa I, Riga D, Riga S, Jurca A, Arghir A. Treatment of Epilepsy Associated with Common Chromosomal Developmental Diseases. Open Life Sci 2020; 15:21-29. [PMID: 33987468 PMCID: PMC8114617 DOI: 10.1515/biol-2020-0003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 10/22/2019] [Indexed: 11/15/2022] Open
Abstract
Chromosomal diseases are heterogeneous conditions with complex phenotypes, which include also epileptic seizures. Each chromosomal syndrome has a range of specific characteristics regarding the type of seizures, EEG findings and specific response to antiepileptic drugs, significant in the context of the respective genetic etiology. Therefore, it is very important to know these particularities, in order to avoid an exacerbation of seizures or some side effects. In this paper we will present a review of the epileptic seizures and antiepileptic treatment in some of the most common chromosomal syndromes.
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Affiliation(s)
- Magdalena Budisteanu
- Prof. Dr. Alexandru Obregia” Clinical Hospital of Psychiatry, BucharestRomania
- ”Victor Babes“ National Institute of Pathology, BucharestRomania
- ”Titu Maiorescu” University – Faculty of Medicine, BucharestRomania
| | - Claudia Jurca
- University of Oradea, Faculty of Medicine and Pharmacy, Preclinical Department, OradeaRomania
| | | | - Ina Focsa
- ”Carol Davila” University of Pharmacy and Medicine, BucharestRomania
| | - Dan Riga
- Prof. Dr. Alexandru Obregia” Clinical Hospital of Psychiatry, BucharestRomania
| | - Sorin Riga
- Prof. Dr. Alexandru Obregia” Clinical Hospital of Psychiatry, BucharestRomania
| | - Alexandru Jurca
- University of Oradea, Faculty of Medicine and Pharmacy, Preclinical Department, OradeaRomania
| | - Aurora Arghir
- ”Victor Babes“ National Institute of Pathology, BucharestRomania
- ”Carol Davila” University of Pharmacy and Medicine, BucharestRomania
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Corrêa T, Venâncio AC, Galera MF, Riegel M. Candidate Genes Associated with Delayed Neuropsychomotor Development and Seizures in a Patient with Ring Chromosome 20. Case Rep Genet 2020; 2020:5957415. [PMID: 32082653 PMCID: PMC6995492 DOI: 10.1155/2020/5957415] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2019] [Accepted: 12/17/2019] [Indexed: 11/25/2022] Open
Abstract
Ring chromosome 20 (r20) is characterized by intellectual impairment, behavioral disorders, and refractory epilepsy. We report a patient presenting nonmosaic ring chromosome 20 followed by duplication and deletion in 20q13.33 with seizures, delayed neuropsychomotor development and language, mild hypotonia, low weight gain, and cognitive deficit. Chromosomal microarray analysis (CMA) enabled us to restrict a chromosomal segment and thus integrate clinical and molecular data with systems biology. With this approach, we were able to identify candidate genes that may help to explain the consequences of deletions in 20q13.33. In our analysis, we observed five hubs (ARFGAP1, HELZ2, COL9A3, PTK6, and EEF1A2), seven bottlenecks (CHRNA4, ARFRP1, GID8, COL9A3, PTK6, ZBTB46, and SRMS), and two H-B nodes (PTK6 and COL9A3). The candidate genes may play an important role in the developmental delay and seizures observed in r20 patients. Gene ontology included microtubule-based movement, nucleosome assembly, DNA repair, and cholinergic synaptic transmission. Defects in these bioprocesses are associated with the development of neurological diseases, intellectual disability, neuropathies, and seizures. Therefore, in this study, we can explore molecular cytogenetic data, identify proteins through network analysis of protein-protein interactions, and identify new candidate genes associated with the main clinical findings in patients with 20q13.33 deletions.
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Affiliation(s)
- Thiago Corrêa
- Genetics Department, Post-Graduate Program in Genetics and Molecular Biology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
| | - Amanda Cristina Venâncio
- Post-Graduate Program in Health Sciences, Universidade Federal do Mato Grosso (UFMT), Cuiabá, MT, Brazil
| | - Marcial Francis Galera
- Department of Pediatrics, Universidade Federal do Mato Grosso (UFMT), Cuiabá, MT, Brazil
| | - Mariluce Riegel
- Genetics Department, Post-Graduate Program in Genetics and Molecular Biology, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS, Brazil
- Medical Genetics Service, Hospital de Clínicas, Porto Alegre, RS, Brazil
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Inal A, Chaumette B, Soleimani M, Guerrot A, Goldenberg A, Lebas A, Gerardin P, Ferrafiat V. Lithium improved behavioral and epileptic symptoms in an adolescent with ring chromosome 20 and bipolar disorder not otherwise specified. Clin Case Rep 2018; 6:2234-2239. [PMID: 30455928 PMCID: PMC6230629 DOI: 10.1002/ccr3.1796] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Revised: 07/29/2018] [Accepted: 08/12/2018] [Indexed: 01/16/2023] Open
Abstract
We present a case of ring chromosome 20 syndrome in a twelve-year-old girl, with resistant epileptic disease and severe behavioral impairment that both drastically improved after a lithium challenge. If replicated, this could support the use of lithium as a safe treatment in the management of this severe phenotype.
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Affiliation(s)
- Adlane Inal
- URHEAChild and Adolescent Psychiatry Intensive Care UnitCentre Hospitalier du RouvraySottevile les RouenFrance
| | - Boris Chaumette
- Department of Neurology and NeurosurgeryMcGill UniversityMontrealCanada
| | - Maryam Soleimani
- URHEAChild and Adolescent Psychiatry Intensive Care UnitCentre Hospitalier du RouvraySottevile les RouenFrance
- Department of Clinical GeneticsRouen University HospitalRouenFrance
- Department of Child and Adolescent PsychiatryRouen University HospitalRouenFrance
| | | | - Alice Goldenberg
- Department of Clinical GeneticsRouen University HospitalRouenFrance
| | - Axel Lebas
- Department of NeurophysiologyRouen University HospitalRouenFrance
| | - Priscille Gerardin
- Department of Child and Adolescent PsychiatryRouen University HospitalRouenFrance
| | - Vladimir Ferrafiat
- URHEAChild and Adolescent Psychiatry Intensive Care UnitCentre Hospitalier du RouvraySottevile les RouenFrance
- Department of Child and Adolescent PsychiatryRouen University HospitalRouenFrance
- Centre Compétent Maladies Rares à Expression PsychiatriqueRouen University HospitalRouenFrance
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A survey of undetected, clinically relevant chromosome abnormalities when replacing postnatal karyotyping by Whole Genome Sequencing. Eur J Med Genet 2018; 62:103543. [PMID: 30248410 DOI: 10.1016/j.ejmg.2018.09.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 07/30/2018] [Accepted: 09/18/2018] [Indexed: 11/21/2022]
Abstract
Whole genome sequencing (WGS) holds the potential to identify pathogenic gene mutations, copy number variation, uniparental disomy and structural rearrangements in a single genetic test. With its high diagnostic yield and decreasing costs, the question arises whether WGS can serve as a single test for all referrals to diagnostic genome laboratories ("one test fits all"). Here, we provide an estimate for the proportion of clinically relevant aberrations identified by light microscopy in postnatal referrals that would go undetected by WGS. To this end, we compiled the clinically relevant abnormal findings for each of the different referral categories in our laboratory during the period 2006-2015. We assumed that WGS would be performed on 300-500 bp DNA fragments with 150-bp paired sequence reads, and that the mean genome coverage is 30x, corresponding to current practice. For the detection of chromosomal mosaicism we set minimum thresholds of 10% for monosomy and 20% for trisomy. Based on the literature we assumed that balanced Robertsonian translocations and ∼9% of other, balanced chromosome rearrangements would not be detectable because of breakpoints in sequences of repetitive DNA. Based on our analysis of all 14,957 referrals, including 1455 abnormal cases, we show that at least 8.1% of these abnormalities would escape detection (corresponding to 0.79% of all referrals). The highest rate occurs in referrals of premature ovarian failure, as 73.3% of abnormalities would not be identified because of the frequent occurrence of low-level sex chromosome mosaicism. Among referrals of recurrent miscarriage, 25.6% of abnormalities would go undetected, mainly because of a high proportion of balanced Robertsonian translocations. In referrals of mental retardation (with or without multiple congenital anomalies) the abnormality would be missed in only 0.35% of referrals. These include cases without imbalances of unique DNA sequences but of clinical relevance, as for example, r(20) epilepsy syndrome. The expected shift to large-scale implementation of WGS ("one test fits most") as initial genetic test will be beneficial to patients and their families, since a cause for the clinical phenotype can be identified in more cases by a single genetic test at an early phase in the diagnostic process. However, a niche for genome analysis by light microscopy will remain. For example, in referrals of newborns with a suspicion of Down syndrome, karyotyping is not only a cost-effective method for providing a quick diagnosis, but also discriminates between trisomy 21 and a Robertsonian translocation involving chromosome 21. Thus, when replacing karyotyping by WGS, one must be aware of the rates and spectra of undetected abnormalities. In addition, it is equally important that requirements for cytogenetic follow-up studies are recognized.
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Gago-Veiga AB, Toledano R, García-Morales I, Pérez-Jiménez MA, Bernar J, Gil-Nagel A. Specificity of electroclinical features in the diagnosis of ring chromosome 20. Epilepsy Behav 2018; 80:215-220. [PMID: 29414555 DOI: 10.1016/j.yebeh.2017.12.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 12/01/2017] [Accepted: 12/01/2017] [Indexed: 10/18/2022]
Abstract
BACKGROUND Ring chromosome 20 (R20) syndrome is a chromosomal disorder characterized mainly by drug-resistant frontal lobe seizures, recurrent nonconvulsive status epilepticus (NCSE), and typical EEG features. The aim of this study was to investigate if this triad is common and specific to all patients with R20. METHODS In this cross-sectional study (from 2000 to 2011), we selected patients who fulfilled at least two out of three criteria: drug-resistant frontal lobe seizures, recurrent NCSE, and characteristic electroencephalography (EEG) features. In all patients, diagnosis was based on karyotype analysis of at least 100 metaphases. RESULTS We identified 36 patients who met at least two of the selected criteria: six patients (16.7%) with R20 and 30 (83.3%) without R20 (non-R20). All patients with R20 met all three criteria. Eleven (36.7%) patients without R20, however, also displayed the full triad. In 19 patients without R20 (63.3%), one of the three clinical features was missing: frontal lobe seizures were not resistant to antiepileptic drugs (AED) in four (13.3%), recurrent NCSE was missing in six (20%), and nine (30%) patients did not have typical EEG features. Based on this data, specificity was 63.3%, positive predictive value was 35.3%, and sensitivity and negative predictive values were 100%. Additionally, a review of all publications describing the R20 phenotype revealed that 81.98% of patients with R20 display the full electroclinical triad. CONCLUSIONS In our study, all patients with R20 displayed the three electroclinical characteristics. This is in line with previous reports (presenting high sensitivity and negative predictive value). However, these features can also be observed in other epilepsies and are not specific to R20. Our findings suggest that in the presence of the full triad of symptoms, karyotype analysis focused on chromosome 20 should be conducted.
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Affiliation(s)
- A B Gago-Veiga
- Epilepsy Unit, Department of Neurology, Hospital Universitario de La Princesa, Diego de León 62, 28006 Madrid, Spain
| | - R Toledano
- Epilepsy Program, Department of Neurology, Hospital Ruber International, La Masó 38, 28034 Madrid, Spain
| | - I García-Morales
- Epilepsy Program, Department of Neurology, Hospital Ruber International, La Masó 38, 28034 Madrid, Spain
| | - M A Pérez-Jiménez
- Epilepsy Monitoring Unit, Clinical Neurophysiology Department, Niño Jesús Pediatric University Hospital, Menendez Pelayo 65, 28009 Madrid, Spain
| | - J Bernar
- Department of Genetics, Hospital Ruber International, La Masó 38, 28034 Madrid, Spain
| | - A Gil-Nagel
- Epilepsy Program, Department of Neurology, Hospital Ruber International, La Masó 38, 28034 Madrid, Spain.
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Dynamic functional disturbances of brain network in seizure-related cognitive outcomes. Epilepsy Res 2018; 140:15-21. [DOI: 10.1016/j.eplepsyres.2017.12.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 11/13/2017] [Accepted: 12/02/2017] [Indexed: 11/23/2022]
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Vignoli A, Bisulli F, Darra F, Mastrangelo M, Barba C, Giordano L, Turner K, Zambrelli E, Chiesa V, Bova S, Fiocchi I, Peron A, Naldi I, Milito G, Licchetta L, Tinuper P, Guerrini R, Dalla Bernardina B, Canevini MP. Epilepsy in ring chromosome 20 syndrome. Epilepsy Res 2016; 128:83-93. [PMID: 27816898 DOI: 10.1016/j.eplepsyres.2016.10.004] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 09/29/2016] [Accepted: 10/22/2016] [Indexed: 11/26/2022]
Abstract
OBJECTIVE Ring chromosome 20 syndrome is characterized by severe, drug resistant childhood onset epilepsy, often accompanied by cognitive impairment. We characterized the electro-clinical phenotype and the long-term course of epilepsy in a large series. METHODS We reviewed the electro-clinical phenotype of 25 patients (aged 8-59 years), and assessed the relationship between epilepsy severity and clinical and/or genetic variables. We also searched for reports of patients diagnosed with r(20) syndrome in the literature, included those whose clinical information was sufficiently accurate, and compared their clinical features with the ones of our patients. RESULTS Epilepsy exhibited an age dependent course. When seizure onset occurred in childhood (21 patients), terrifying hallucinations associated with focal motor seizures, often sleep-related (8 patients), or dyscognitive seizures (13 patients), were prominent features, often evolving into epileptic encephalopathy associated with non-convulsive status epilepticus (11 patients). In the long-term, progressive stabilization of drug resistant epilepsy associated with non-convulsive status epilepticus, focal seizures with motor and autonomic features, and eyelid myoclonia were noticed. Epilepsy onset in adolescence (3 patients) was accompanied by a milder developmental course, dyscognitive seizures and non-convulsive status epilepticus, and no cognitive decline. Only three older patients became seizure free (>5 years) We found statistically significant correlations between age at epilepsy onset and cognitive level. Although in the study cohort the relationship between r(20) ratio, age at epilepsy onset and cognitive level was non-statistically significant, it reached significance evaluating the larger cohort of patients previously published. SIGNIFICANCE In ring(20) syndrome, epilepsy has an age dependent course and a worse outcome when age at seizure onset is earlier. The r(20) ratio and severity of cognitive impairment appear to be directly related to each other and inversely correlated with the age at epilepsy onset.
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Affiliation(s)
- Aglaia Vignoli
- Epilepsy Center, San Paolo Hospital, Milano, Italy; Department of Health Sciences, University of Milan, Milano, Italy.
| | - Francesca Bisulli
- IRCCS Istituto delle Scienze Neurologiche di Bologna and Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Francesca Darra
- Department of Life and Reproduction Sciences, University of Verona, Verona, Italy
| | | | - Carmen Barba
- Pediatric Neurology, A. Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Lucio Giordano
- Child Neuropsychiatric Division, Spedali Civili, Brescia, Italy
| | | | | | | | - Stefania Bova
- Pediatric Neurology, V. Buzzi Hospital, ICP, Milan, Italy
| | | | - Angela Peron
- Epilepsy Center, San Paolo Hospital, Milano, Italy; Department of Health Sciences, University of Milan, Milano, Italy
| | - Ilaria Naldi
- IRCCS Istituto delle Scienze Neurologiche di Bologna and Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Giuseppe Milito
- Child Neuropsychiatric Division, Spedali Civili, Brescia, Italy
| | - Laura Licchetta
- IRCCS Istituto delle Scienze Neurologiche di Bologna and Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Paolo Tinuper
- IRCCS Istituto delle Scienze Neurologiche di Bologna and Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Renzo Guerrini
- Pediatric Neurology, A. Meyer Children's Hospital, University of Florence, Florence, Italy
| | | | - Maria Paola Canevini
- Epilepsy Center, San Paolo Hospital, Milano, Italy; Department of Health Sciences, University of Milan, Milano, Italy
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12
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Vaudano AE, Ruggieri A, Vignoli A, Canevini MP, Meletti S. Emerging neuroimaging contribution to the diagnosis and management of the ring chromosome 20 syndrome. Epilepsy Behav 2015; 45:155-63. [PMID: 25843339 DOI: 10.1016/j.yebeh.2015.02.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2014] [Revised: 01/28/2015] [Accepted: 02/01/2015] [Indexed: 01/13/2023]
Abstract
Ring chromosome 20 [r(20)] syndrome is an underdiagnosed chromosomal anomaly characterized by severe epilepsy, behavioral problems, and mild-to-moderate cognitive deficits. Since the cognitive and behavioral decline follows seizure onset, this syndrome has been proposed as an epileptic encephalopathy (EE). The recent overwhelming development of advanced neuroimaging techniques has opened a new era in the investigation of the brain networks subserving the EEs. In particular, functional neuroimaging tools are well suited to show alterations related to epileptiform discharges at the network level and to build hypotheses about the mechanisms underlying the cognitive disruption observed in these conditions. This paper reviews the brain circuits and their disruption as revealed by functional neuroimaging studies in patients with [r(20)] syndrome. It discusses the clinical consequences of the neuroimaging findings on the management of patients with [r(20)] syndrome, including their impact to an earlier diagnosis of this disorder. Based on the available lines of evidences, [r(20)] syndrome is characterized by interictal and ictal dysfunctions within basal ganglia-prefrontal lobe networks and by long-lasting effects of the peculiar theta-delta rhythm, which represents an EEG marker of the syndrome on integrated brain networks that subserve cognitive functions.
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Affiliation(s)
- Anna Elisabetta Vaudano
- Department of Biomedical, Metabolic, and Neural Science, University of Modena and Reggio Emilia, Modena, Italy; N.O.C.S.A.E. Hospital, ASL Modena, Italy
| | - Andrea Ruggieri
- Department of Biomedical, Metabolic, and Neural Science, University of Modena and Reggio Emilia, Modena, Italy
| | - Aglaia Vignoli
- Department of Health Sciences, Epilepsy Centre, San Paolo Hospital, University of Milan, Italy
| | - Maria Paola Canevini
- Department of Health Sciences, Epilepsy Centre, San Paolo Hospital, University of Milan, Italy
| | - Stefano Meletti
- Department of Biomedical, Metabolic, and Neural Science, University of Modena and Reggio Emilia, Modena, Italy; N.O.C.S.A.E. Hospital, ASL Modena, Italy.
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Falsaperla R, Striano P, Parisi P, Lubrano R, Mahmood F, Pavone P, Vitaliti G. Usefulness of video-EEG in the paediatric emergency department. Expert Rev Neurother 2014; 14:769-785. [PMID: 24917085 DOI: 10.1586/14737175.2014.923757] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
Over the past two decades the EEG has technically improved from the use of analog to digital machines and more recently to video-EEG systems. Despite these advances, recording a technically acceptable EEG in an electrically hostile environment such as the emergency department (ED) remains a challenge, particularly with infants or young children. In 1996, a meeting of French experts established a set of guidelines for performing an EEG in the ED based on a review of the available literature. The authors highlighted the most suitable indications for an emergency EEG including clinical suspicion of cerebral death, convulsive and myoclonic status epilepticus, focal or generalized relapsing convulsive seizures as well as follow-up of known convulsive patients. They further recommended emergency EEG in the presence of doubt regarding the epileptic nature of the presentation as well as during the initiation or modification of sedation following brain injury. Subsequently, proposals for expanding the use of EEG in emergency patients have been advocated including trauma, vascular and anoxic-ischemic injury due to cardiorespiratory arrest, postinfective encephalopathy and nonconvulsive status epilepticus. The aim of this review is to show the diagnostic importance of video-EEG, as well as highlighting the predictive prognostic factors for positive and negative outcomes, when utilized in the pediatric ED for seizures as well as other neurological presentations.
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Affiliation(s)
- Raffaele Falsaperla
- Pediatric Acute and Emergency Operative Unit and Department, Policlinico-Vittorio Emanuele University Hospital, University of Catania, Via Plebiscito 628, 95124 Catania, Italy
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14
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Vaudano AE, Ruggieri A, Vignoli A, Avanzini P, Benuzzi F, Gessaroli G, Nichelli PF, Darra F, Cantalupo G, Mastrangelo M, Dalla Bernardina B, Canevini MP, Meletti S. Epilepsy-related brain networks in ring chromosome 20 syndrome: an EEG-fMRI study. Epilepsia 2014; 55:403-13. [PMID: 24483620 DOI: 10.1111/epi.12539] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/19/2013] [Indexed: 11/25/2022]
Abstract
OBJECTIVE To identify the brain networks that are involved in the different electroencephalography (EEG) abnormalities in patients with ring chromosome 20 [r(20)] syndrome. We hypothesize the existence of both distinctive and common brain circuits for the paroxysmal high voltage sharp waves (hSWs), the seizures, and the slow-wave 3-7 Hz rhythm that characterize this condition. METHODS Thirteen patients with [r(20)] syndrome were studied by means of EEG simultaneously recorded with functional magnetic resonance imaging (EEG-fMRI). EEG traces were reviewed in order to detect the pathologic interictal (hSWs) and ictal activities; the 3-7 Hz theta-delta power was derived using a fast Fourier transform. A group-level analysis was performed for each type of EEG abnormality separately using a fixed-effect model and a conjunction analysis. Finally, a second-level random-effect model was applied considering together the different EEG abnormalities, without distinction between hSW, seizures, or theta-delta rhythms. RESULTS Subcontinuous theta-delta rhythm was recorded in seven patients, seizures in two, and hSWs in three patients. The main results are the following: (1) the slow-wave rhythm was related to blood oxygen level-dependent (BOLD) increases in the premotor, sensory-motor, and temporoparietal cortex, and to BOLD decrements involving the default mode (DMN) and the dorsal attention networks (DANs); (2) the ictal-related BOLD changes showed an early involvement of the prefrontal lobe; (3) increases in BOLD signal over the basal ganglia, either for interictal and ictal activities, were observed; (4) a common pattern of positive BOLD changes in the bilateral perisylvian regions was found across the different EEG abnormalities. SIGNIFICANCE The BOLD increment in the perisylvian network and the decrease of the DMN and DAN could be the expression of the [r(20)] syndrome-related cognitive and behavioral deficits. The observed BOLD patterns are similar to the ones detected in other epileptic encephalopathies, suggesting that different epileptic disorders characterized by neurobehavioral regression are associated with dysfunction in similar brain networks. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here.
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Affiliation(s)
- Anna Elisabetta Vaudano
- Department of Biomedical Sciences, Metabolic, and Neuroscience, NOCSAE Hospital, University of Modena and Reggio Emilia, Modena, Italy
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15
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Avanzini P, Vaudano AE, Vignoli A, Ruggieri A, Benuzzi F, Darra F, Mastrangelo M, Dalla Bernardina B, Nichelli PF, Canevini MP, Meletti S. Low frequency mu-like activity characterizes cortical rhythms in epilepsy due to ring chromosome 20. Clin Neurophysiol 2013; 125:239-49. [PMID: 23968845 DOI: 10.1016/j.clinph.2013.07.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 05/22/2013] [Accepted: 07/24/2013] [Indexed: 12/22/2022]
Abstract
OBJECTIVES To evaluate the spectral and spatial features of the cortical rhythms in patients affected by ring chromosome 20 - [r(20)]-syndrome. METHODS Twelve patients with [r(20)] syndrome were studied. As controls we enrolled 12 patients with idiopathic generalized epilepsy (IGE) and 12 healthy volunteers (HV). Blind source separation, spectral analyses and source reconstruction were applied in all cases in order to identify reliable spatio-temporal patterns of cortical activity. RESULTS A theta-delta EEG rhythm was identified in [r(20)] patients, with spectral peak ranging between 3 and 7Hz and whose generators mapped over the sensory-motor cortices. A second peak laying at a frequency about double with respect to the first one was present in 6 cases. Analogue methodological approach in HV and IGE groups failed to show similar findings. CONCLUSIONS EEG of [r(20)] patients reveals the existence of a highly reproducible EEG pattern arising from the sensory-motor system. SIGNIFICANCE The recognition of this peculiar EEG pattern could help the diagnostic work-up. Additionally, our findings supports the existence of a parallelism between this EEG trait and the physiological "mu" rhythm which is generate by the sensory-motor system. Such link suggests a sensory-motor system dysfunction in [r(20)] patients.
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Affiliation(s)
- Pietro Avanzini
- Department of Biomedical Sciences, Metabolism and Neuroscience, University of Modena and Reggio Emilia, NOCSE Hospital, Modena, Italy; Department di Neuroscience, University of Parma, Parma, Italy
| | - Anna Elisabetta Vaudano
- Department of Biomedical Sciences, Metabolism and Neuroscience, University of Modena and Reggio Emilia, NOCSE Hospital, Modena, Italy
| | - Aglaia Vignoli
- Epilepsy Centre, San Paolo Hospital, Health Science Department, University of Milano, Italy
| | - Andrea Ruggieri
- Department of Biomedical Sciences, Metabolism and Neuroscience, University of Modena and Reggio Emilia, NOCSE Hospital, Modena, Italy
| | - Francesca Benuzzi
- Department of Biomedical Sciences, Metabolism and Neuroscience, University of Modena and Reggio Emilia, NOCSE Hospital, Modena, Italy
| | - Francesca Darra
- Department of Life and Reproduction Sciences, University of Verona, Verona, Italy
| | | | | | - Paolo Frigio Nichelli
- Department of Biomedical Sciences, Metabolism and Neuroscience, University of Modena and Reggio Emilia, NOCSE Hospital, Modena, Italy
| | - Maria Paola Canevini
- Epilepsy Centre, San Paolo Hospital, Health Science Department, University of Milano, Italy; Department of Medicine, Surgery and Dentistry, Faculty of Medicine and Surgery, University of Milano, Milano, Italy
| | - Stefano Meletti
- Department of Biomedical Sciences, Metabolism and Neuroscience, University of Modena and Reggio Emilia, NOCSE Hospital, Modena, Italy.
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Gahr M, Kerling F, Ludolph A, Plener P. Cognitive impairment and abnormal behaviour related to ring chromosome 20 aberration. J Autism Dev Disord 2012; 42:1146-8. [PMID: 21858587 DOI: 10.1007/s10803-011-1346-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Meletti S, Vignoli A, Benuzzi F, Avanzini P, Ruggieri A, Pugnaghi M, Nichelli P, Canevini MP. Ictal involvement of the nigrostriatal system in subtle seizures of ring chromosome 20 epilepsy. Epilepsia 2012; 53:e156-60. [PMID: 22738216 DOI: 10.1111/j.1528-1167.2012.03568.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Studies in animal models and patients with epilepsy have suggested that basal ganglia circuits may control epileptic seizures and that striatal dopaminergic transmission may play a role in seizure modulation and interruption. Chromosome 20 [r(20)] syndrome is a well-defined chromosomal disorder characterized by epilepsy, mild-to-moderate mental retardation, and lack of recognizable dysmorphic features. Epilepsy is often the most important clinical manifestation of the syndrome, with prolonged episodes of nonconvulsive status epilepticus suggesting dysfunction in the seizure control system. We present the ictal blood oxygen level-dependent (BOLD) changes in brief seizures recorded by means of electroencephalography-functional magnetic resonance imaging (EEG-fMRI) coregistration in a patient with [r(20)] syndrome. We observed ictal BOLD increments in a cortical-subcortical network involving substantia nigrastriatum and frontal cortex. At present, this is the first functional neuroimaging evidence of the involvement of the nigrostriatal system during ictal EEG discharges in [r(20)] syndrome supporting a role of the basal ganglia circuits in human epileptic seizures.
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Affiliation(s)
- Stefano Meletti
- Department of Neuroscience, NOCSAE Hospital, University of Modena e Reggio Emilia, Modena, Italy.
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Elens I, Vanrykel K, De Waele L, Jansen K, Segeren M, Van Paesschen W, Ceulemans B, Boel M, Frijns JP, Buyse G, Lagae L. Ring chromosome 20 syndrome: electroclinical description of six patients and review of the literature. Epilepsy Behav 2012; 23:409-14. [PMID: 22424860 DOI: 10.1016/j.yebeh.2012.02.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Revised: 02/06/2012] [Accepted: 02/07/2012] [Indexed: 12/20/2022]
Abstract
BACKGROUND Ring chromosome 20 syndrome is a rare chromosomal disorder. METHODS In six patients, we focused on the presenting epileptic phenotype, the behavioral and mental problems and the relationship between the ratio of mosaicism and the age at onset of the epilepsy. RESULTS All patients presented with pharmacoresistant frontal lobe complex partial seizures. The earliest onset of epilepsy was seen in patients without mosaicism. There were three patients out of six with behavioral disturbances before the onset of seizures. All patients had mild to moderate cognitive impairment. Electroencephalogram recordings showed rhythmic theta waves with frontal predominance and non-convulsive status epilepticus (NCSE). CONCLUSIONS The ring chromosome 20 syndrome is characterized by childhood-onset refractory epilepsy continuing throughout adult life, mental disability, and behavioral disturbances which can originate before seizure onset. Ictal EEG reveals a unique pattern. Our findings indicate a possible link between the percentage of affected cells and the age of epilepsy onset.
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Affiliation(s)
- Iris Elens
- Department of Paediatric Neurology, University Hospital Leuven, Belgium
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20
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New association between ring chromosome 20 syndrome and hypomelanosis of Ito. Pediatr Neurol 2011; 45:341-3. [PMID: 22000318 DOI: 10.1016/j.pediatrneurol.2011.08.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/09/2011] [Accepted: 08/08/2011] [Indexed: 11/22/2022]
Abstract
Hypomelanosis of Ito is an uncommon neuroectodermal disease associated with a wide range of cytogenetic abnormalities. Ring chromosome 20 is a rare chromosomal disorder characterized by severe, refractory epilepsy, cognitive delay, and unspecific dysmorphic traits. An association between the hypomelanosis of Ito and ring chromosome 20 syndrome was never reported peviously. We describe a young girl who has ring chromosome 20 and who also has clinical symptoms of hypomelanosis of Ito. After her diagnosis of epilepsy, she was submitted to neurologic and genetic testing, a skin biopsy, and repeated neuropsychologic examinations. Karyotyping revealed a 46 XX, r(20) with mosaicism in 34% of peripheral blood lymphocytes and 8% of skin fibroblasts. A severe, progressive cognitive deterioration was evident. The epilepsy was refractory to antiepileptic drugs, in apparent contrast with the evidence that both telomeric regions were preserved. The percentage of mosaicism seems unrelated to the severity of the clinical phenotype.
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The evolving electroclinical syndrome of "epilepsy with ring chromosome 20". Seizure 2011; 21:92-7. [PMID: 22000954 DOI: 10.1016/j.seizure.2011.09.009] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2011] [Revised: 09/25/2011] [Accepted: 09/26/2011] [Indexed: 11/20/2022] Open
Abstract
PURPOSE Ring chromosome 20 {r(20)}--manifests as a refractory epilepsy syndrome with complex partial seizures (CPS), nocturnal frontal lobe seizures and non-convulsive status epilepticus (NCSE) in the majority of cases. r20 lacks a specific phenotypic expression or dysmorphic features. Psychomotor development may be normal, making the diagnosis difficult unless there is a high index of suspicion. This description of further cases is intended to improve recognition of this syndrome. METHODS Karyotyping for r20 was done in patients presenting with cryptogenic refractory epilepsy suggestive of r20 from August 2008 to September 2010. We identified three patients with r20 associated with refractory epilepsy. All were investigated with long-term video EEG. Their unique electro clinical features; epilepsy syndrome and outcome are discussed and compared to the available literature. RESULTS Karyotyping revealed ring 20 in 6-40% of lymphocytes. All manifested with seizures beginning at 2-10years of age. All had CPS; two had NCSE and one a seizure disorder resembling Lennox-Gastaut syndrome. The interictal EEG showed epileptiform abnormalities predominantly over the frontotemporal regions. Two patients had NCSE with generalized, frontally dominant theta and spike and wave discharges. None had facial dysmorphism or imaging abnormalities. They remained resistant to antiepileptic drugs. CONCLUSIONS The use of routine karyotyping can easily pick up r(20); this information is especially useful in resource-poor countries. We have evolved an algorithm stating the indications to attempt r(20) karyotyping in a given patient in the light of the results of the present study and the existing literature.
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Villéga F, Ngayap H, Espil-Taris C, Husson M, Rooryck-Thambo C, Arveiler B, Lacombe D, Pédespan JM. [Polymorphic expression of epilepsy and cognitive impairment in ring chromosome 20 syndrome]. Arch Pediatr 2011; 18:394-6. [PMID: 21397468 DOI: 10.1016/j.arcped.2010.12.025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2009] [Revised: 07/01/2010] [Accepted: 12/29/2010] [Indexed: 10/18/2022]
Abstract
Ring chromosome 20 syndrome combines epilepsy with varying levels of mental retardation, behavioral disorders, and malformations. Epilepsy is generally serious, with frequent drug resistance. The pathophysiology of seizures remains unclear. Rearrangements of two epilepsy genes, CHRNA4 and KCNQ2, have been raised as the cause. We report the observation of one child, with a telomeric deletion 20p13, with no epileptic symptoms. Preservation of CHRNA4 and KCNQ2 gene activity could explain this distinctive feature.
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Affiliation(s)
- F Villéga
- Unité de neuropédiatrie, département de pédiatrie, hôpital des Enfants-Pellegrin, CHU de Bordeaux, place Amélie-Raba-Léon, 33076 Bordeaux cedex, France.
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Giardino D, Vignoli A, Ballarati L, Recalcati MP, Russo S, Camporeale N, Marchi M, Finelli P, Accorsi P, Giordano L, La Briola F, Chiesa V, Canevini MP, Larizza L. Genetic investigations on 8 patients affected by ring 20 chromosome syndrome. BMC MEDICAL GENETICS 2010; 11:146. [PMID: 20939888 PMCID: PMC2967536 DOI: 10.1186/1471-2350-11-146] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Accepted: 10/12/2010] [Indexed: 12/23/2022]
Abstract
Background Mosaic Chromosome 20 ring [r(20)] is a chromosomal disorder associated with a rare syndrome characterized by a typical seizure phenotype, a particular electroclinical pattern, cognitive impairment, behavioural problems and absence of a consistent pattern of dysmorphology. The pathogenic mechanism underlying seizures disorders in r(20) syndrome is still unknown. We performed a detailed clinical and genetic study on 8 patients with r(20) chromosome, aimed at detecting the genetic mechanism underlying r(20) syndrome. Methods We submitted 8 subjects with a previous diagnosis of ring 20 chromosome mosaicism to a clinical re-evaluation, followed by cytogenetic, FISH, array-CGH and molecular analyses. The genetic study was also extended to their available parents. Results FISH and array-CGH experiments indicate that cryptic deletions on chromosome 20 are not the cause of the r(20) chromosome associated disease. Moreover, no evidence of chromosome 20 uniparental disomy was found. Analysis of FISH signals given by variant in size alphoid tandem repeats probes on the normal chromosome 20 and the r(20) chromosome in the mosaic carriers suggests that the r(20) chromosome is the same chromosome not circularized in the "normal" cell line. Conclusions Higher percentages of r(20) chromosome cells were observed to be related with precocious age at seizure onset and with resistance to antiepileptic drug treatment. Behavioural problems also seem to be associated with higher percentages of r(20) chromosome cells. Our results suggest that an epigenetic mechanism perturbing the expression of genes close to the telomeric regions, rather than deletion of genes located at the distal 20p and/or 20q regions, may underlie the manifestation of r(20) syndrome.
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Affiliation(s)
- Daniela Giardino
- Laboratorio di Citogenetica Medica e Genetica Molecolare, IRCCS Istituto Auxologico Italiano Milan, Italy.
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