Emerging neuroimaging contribution to the diagnosis and management of the ring chromosome 20 syndrome

Vaudano, Anna Elisabetta; Ruggieri, Andrea; Canevini, Maria Paola; Meletti, Stefano

doi:10.1016/j.yebeh.2015.02.002

Cited by 10 publications

(11 citation statements)

References 74 publications

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“…We converted a linear synV to a ring by design, a process that could eventually enable more precise modeling of ring chromosome disorders if performed in mammalian cells. Circular "ring" chromosomes have been reported in a wide variety of human genetic disorders, including epilepsy (14,15), intellectual delay (15), various dysmorphic features (16), leukemia (17), and microcephaly (18,19). Further, therapies for genetic disorders based on chromosome circularization have been proposed (20).…”

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confidence: 99%

“Perfect” designer chromosome V and behavior of a ring derivative

Xie

Mitchell

et al. 2017

Science

203

151

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INTRODUCTION The Saccharomyces cerevisiae 2.0 project (Sc2.0) aims to modify the yeast genome with a series of densely spaced designer changes. Both a synthetic yeast chromosome arm (synIXR) and the entirely synthetic chromosome (synIII) function with high fitness in yeast. For designer genome synthesis projects, precise engineering of the physical sequence to match the specified design is important for the systematic evaluation of underlying design principles. Yeast can maintain nuclear chromosomes as rings, occurring by chance at repeated sequences, although the cyclized format is unfavorable in meiosis given the possibility of dicentric chromosome formation from meiotic recombination. Here, we describe the de novo synthesis of synthetic yeast chromosome V (synV) in the “Build-A-Genome China” course, perfectly matching the designer sequence and bearing loxPsym sites, distinguishable watermarks, and all the other features of the synthetic genome. We generated a ring synV derivative with user-specified cyclization coordinates and characterized its performance in mitosis and meiosis. RATIONALE Systematic evaluation of underlying Sc2.0 design principles requires that the final assembled synthetic genome perfectly match the designed sequence. Given the size of yeast chromosomes, synthetic chromosome construction is performed iteratively, and new mutations and unpredictable events may occur during synthesis; even a very small number of unintentional nucleotide changes across the genome could have substantial effects on phenotype. Therefore, precisely matching the physical sequence to the designed sequence is crucial for verification of the design principles in genome synthesis. Ring chromosomes can extend those design principles to provide a model for genomic rearrangement, ring chromosome evolution, and human ring chromosome disorders. RESULTS We chemically synthesized, assembled, and incorporated designer chromosome synV (536,024 base pairs) of S. cerevisiae according to Sc2.0 principles, based on the complete nucleotide sequence of native yeast chromosome V (576,874 base pairs). This work was performed as part of the “Build-A-Genome China” course in Tianjin University. We corrected all mutations found—including duplications, substitutions, and indels—in the initial synV strain by using integrative cotransformation of the precise desired changes and by means of a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein 9 (Cas9)–based method. Altogether, 3331 corrected base pairs were required to match to the designed sequence. We generated a strain that exactly matches all designer sequence changes that displays high fitness under a variety of culture conditions. All corrections were verified with whole-genome sequencing; RNA sequencing revealed only minor changes in gene expression—most notably, decreases in expression of genes relocated near synthetic telomeres as a result of design. We constructed a functional circular synV (ring_synV) derivative in yeast by precisely joining both chromosome ends (telomeres) at specified coordinates. The ring chromosome showed restoration of subtelomeric gene expression levels. The ring_synV strain exhibited fitness comparable with that of the linear synV strain, revealed no change in sporulation frequency, but notably reduced spore viability. In meiosis, heterozygous or homozygous diploid ring_wtV and ring_synV chromosomes behaved similarly, exhibiting substantially higher frequency of the formation of zero-spore tetrads, a type that was not seen in the rod chromosome diploids. Rod synV chromosomes went through meiosis with high spore viability, despite no effort having been made to preserve meiotic competency in the design of synV. CONCLUSION The perfect designer-matched synthetic chromosome V provides strategies to edit sequence variants and correct unpredictable events, such as off-target integration of extra copies of synthetic DNA elsewhere in the genome. We also constructed a ring synthetic chromosome derivative and evaluated its fitness and stability in yeast. Both synV and synVI can be circularized and can power yeast cell growth without affecting fitness when gene content is maintained. These fitness and stability phenotypes of the ring synthetic chromosome in yeast provide a model system with which to probe the mechanism of human ring chromosome disorders. Synthesis, cyclization, and characterization of synV . ( A ) Synthetic chromosome V (synV, 536,024 base pairs) was designed in silico from native chromosome V (wtV, 576,874 base pairs), with extensive genotype modification designed to be phenotypically neutral. ( B ) CRISPR/Cas9 strategy for multiplex repair. ( C ) Colonies of wtV, synV, and ring_synV strains.

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confidence: 99%

“Perfect” designer chromosome V and behavior of a ring derivative

Xie

Mitchell

et al. 2017

Science

203

151

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“…7 Epilepsy in r(20) syndrome is often drug-resistant, and only several patients achieved seizure control with multiple antiepileptic drugs in previous reports. 2 The EEG of patient revealed characteristic NCSE (Figure 1A), and she underwent a variety of antiepileptic drugs but the seizures could not be controlled. A diagnosis of r(20) syndrome was suspected based on her characteristic EEG alterations, recurrent NCSE, refractory epilepsy, and normal brain MRI, and karyotyping confirmed this diagnosis.…”

Section: Discussionmentioning

confidence: 99%

Adult‐onset frequent non‐convulsive status epilepticus in a patient with ring chromosome 20 syndrome

Liu

Omote

Ikegami

et al. 2020

Neurology & Clinical Neurosc

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Ring chromosome 20 [r(20)] syndrome is a rare chromosomal disorder and a cause of refractory epilepsy. Since the first description of r(20) syndrome from 1972, over 100 cases have been reported, but it is still difficult to diagnose due to the absence of significant diagnostic dysmorphic features and delayed cytogenetic analysis after seizure onset. 1 Most patients in reported cases were associated with refractory epilepsy, mild-to-moderate cognitive impairment, and/or behavioral problems. 2 Herein, we report a 31-year-old woman with r(20) syndrome who presented intractable seizures and non-convulsive status epilepticus (NCSE) from 30 years old, without mental deterioration.

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“…However, the effects of IEDs on cognitive networks were not often explored until recently. Following pioneering work relating IED-correlated decreases in Default Mode Network activity in temporal lobe epilepsy (84) and generalized epilepsy (85), recent works have shown the possible impact of interictal activity on several ICNs in focal epilepsy in adults (33, 36, 45), focal epilepsy in children (22), children with idiopathic focal epilepsy [Benign Epilepsy with Centro-temporal Spikes (BECTS)] (53, 55, 86), epileptic encephalopathy (56–59), as well as generalized epilepsies (61, 64), including Childhood Absence Epilepsy (CAE) (87), and even reflex epilepsies (60). The majority of recent EEG-fMRI studies who evaluate the interaction between interictal discharges, ICNs, and their relationship to neuropsychological outcome have been in BECTS patients; these studies found a negative correlation between cognitive functioning and Functional Connectivity (FC).…”

Section: Methodsmentioning

confidence: 99%

“…CAE patients also have widespread GSWD-related decreases found in DMN, DAN, central executive, and salience networks (87). Also, in ring chromosome 20 syndrome, which is a rare and severe form of generalized epilepsy, increases in slow wave rhythm were related to decreases in activity of the DMN and Dorsal Attention Network (DAN) (64). However, the clinical meaning of this slow-wave activity, and whether it supplies transient or long-term effects on cognition, is still under debate.…”

Section: Methodsmentioning

confidence: 99%

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The Role of EEG-fMRI in Studying Cognitive Network Alterations in Epilepsy

Shamshiri¹,

Sheybani

Vulliémoz

2019

Front. Neurol.

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Brain functions do not arise from isolated brain regions, but from interactions in widespread networks necessary for both normal and pathological conditions. These Intrinsic Connectivity Networks (ICNs) support cognitive processes such as language, memory, or executive functions, but can be disrupted by epileptic activity. Simultaneous EEG-fMRI can help explore the hemodynamic changes associated with focal or generalized epileptic discharges, thus providing information about both transient and non-transient impairment of cognitive networks related to spatio-temporal overlap with epileptic activity. In the following review, we discuss the importance of interictal discharges and their impact on cognition in different epilepsy syndromes. We explore the cognitive impact of interictal activity in both animal models and human connectivity networks in order to confirm that this effect could have a possible clinical impact for prescribing medication and characterizing post-surgical outcome. Future work is needed to further investigate electrophysiological changes, such as amplitude/latency of single evoked responses or spontaneous epileptic activity in either scalp or intracranial EEG and determine its relative change in hemodynamic response with subsequent network modifications.

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Emerging neuroimaging contribution to the diagnosis and management of the ring chromosome 20 syndrome

Cited by 10 publications

References 74 publications

“Perfect” designer chromosome V and behavior of a ring derivative

“Perfect” designer chromosome V and behavior of a ring derivative

Adult‐onset frequent non‐convulsive status epilepticus in a patient with ring chromosome 20 syndrome

The Role of EEG-fMRI in Studying Cognitive Network Alterations in Epilepsy

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