Specificity of electroclinical features in the diagnosis of ring chromosome 20

Gago-Veiga, Ana Beatriz; Toledano, Rafael; García‐Morales, Irene; Pérez-Jiménez, M.A.; Bernar, J; Gil-Nagel, Anthony

doi:10.1016/j.yebeh.2017.12.001

Cited by 12 publications

(23 citation statements)

References 31 publications

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“…The clinical semiology during NCSE consists of altered state of vigilance, staring, loss of emotional facial expression, reduced spontaneous motor activity and speech production, with a slow response to questions. Associated motor symptoms, such as myoclonus, tonic posturing, oral automatisms, and frightened facial expression have been reported (66,68). Frequent NCSE episodes in this syndrome might be related to the deregulation of the system(s) involved in seizure initiation and termination.…”

Section: ) Nocturnal Seizures (Hyperkinetic or Hypermotor Seizures)mentioning

confidence: 92%

“…Despite the rarity of these patients, the evaluation of r(20) individuals using prolonged video-EEG monitoring may allow shortening of the diagnostic odyssey in many, thanks to the recordings of the typical electro-clinical patterns (68).…”

Section: Diagnosismentioning

confidence: 99%

“…Gago-Veiga et al (68) observed that all the patients with a confirmed cytogenetic diagnosis of r (20) syndrome had a triad of signs and symptoms (drug-resistant frontal lobe seizures, recurrent NCSE, and typical EEG), giving this electro-clinical triad a high sensitivity and negative predictive value (100%).…”

Section: Epileptic Syndromesmentioning

confidence: 99%

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Ring Chromosome 20 Syndrome: Genetics, Clinical Characteristics, and Overlapping Phenotypes

et al. 2020

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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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Section: ) Nocturnal Seizures (Hyperkinetic or Hypermotor Seizures)mentioning

confidence: 92%

Section: Diagnosismentioning

confidence: 99%

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Ring Chromosome 20 Syndrome: Genetics, Clinical Characteristics, and Overlapping Phenotypes

et al. 2020

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“…The relation between phenotype severity and the level of mosaicism remains debated. 2 Epilepsy represents the main clinical feature of this syndrome and it is characterized by a typical electroclinical triad, 3,4 represented by refractory seizures with frontal lobe semiology, recurrent nonconvulsive status epilepticus (NCSE), and characteristic electroencephalographic (EEG) alterations. Seizures are mainly focal with impaired awareness and nocturnal tonic or hyperkinetic.…”

Section: Introductionmentioning

confidence: 99%

Electroclinical Improvement in a Patient with Ring Chromosome 20 Syndrome Treated with Zonisamide: A Case Report

et al. 2021

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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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“…Classically, R20 is characterised by a triad of signs: mild to moderate intellectual disability, behavioural changes and epilepsy (for a review see Genton et al, 2019). Recently, the primary features of R20 have been described as the following three electroclinical characteristics: refractory frontal lobe seizures, recurrent non‐convulsive status epilepticus (NCSE) and typical EEG findings including long‐lasting, high‐voltage slow waves or frequent trains of theta waves in the frontotemporal areas (Gago‐Veiga et al, 2018). However, detailed cytogenetic and epileptic mechanisms and clinical features of R20 are still unknown.…”

mentioning

confidence: 99%

Praxis‐induced reflex seizures in two Japanese cases with ring chromosome 20 syndrome

Yamagishi

Goto

Osaka

et al. 2020

Epileptic Disorders

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Ring chromosome 20 syndrome is an epileptic and neurodevelopmental encephalopathy that occurs in children, characterised by a triad of refractory frontal lobe seizures, recurrent non‐convulsive status epilepticus and frontal lobe‐dominant paroxysmal discharges. However, details of other clinical features associated with ring chromosome 20 syndrome remain unknown. Here, we report two patients with ring chromosome 20 syndrome who had praxis‐induced reflex seizures. Case 1 was an 11‐year‐old girl who presented with seizures triggered by specific activities such as mental and written calculations, writing, decision‐making, recall, sudden changes in routine or ambient temperature and bathing. During calculations, left frontal lobe‐dominant, 3‐Hz slow‐wave bursts were observed on EEG. Lacosamide effectively suppressed her tonic seizures. Case 2 was a six‐year‐old boy who presented with seizures triggered by specific activities such as calculations, recall and bathing. During calculations, frontal lobe‐dominant, 3‐Hz spike and slow‐wave bursts were observed on EEG. Although his epilepsy was refractory, gabapentin reduced the frequency of focal seizures. In both cases, the hyperexcitability in the frontal lobe may have spread to the motor cortex and precipitated praxis‐induced seizures. Therefore, in addition to the known characteristic triad, praxis‐induced reflex seizures may also be a feature of ring chromosome 20 syndrome.

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Specificity of electroclinical features in the diagnosis of ring chromosome 20

Cited by 12 publications

References 31 publications

Ring Chromosome 20 Syndrome: Genetics, Clinical Characteristics, and Overlapping Phenotypes

Ring Chromosome 20 Syndrome: Genetics, Clinical Characteristics, and Overlapping Phenotypes

Electroclinical Improvement in a Patient with Ring Chromosome 20 Syndrome Treated with Zonisamide: A Case Report

Praxis‐induced reflex seizures in two Japanese cases with ring chromosome 20 syndrome

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