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Zachary Niday, Anastasios V Tzingounis
Exome and targeted sequencing have revolutionized clinical diagnosis. This has been particularly striking in epilepsy and neurodevelopmental disorders, for which new genes or new variants of preexisting candidate genes are being continuously identified at increasing rates every year. A surprising finding of these efforts is the recognition that gain of function potassium channel variants are actually associated with certain types of epilepsy, such as malignant migrating partial seizures of infancy or early-onset epileptic encephalopathy...
March 1, 2018: Neuroscientist: a Review Journal Bringing Neurobiology, Neurology and Psychiatry
Ara Ko, Song Ee Youn, Se Hee Kim, Joon Soo Lee, Sangwoo Kim, Jong Rak Choi, Heung Dong Kim, Seung-Tae Lee, Hoon-Chul Kang
OBJECTIVE: We performed targeted gene-panel sequencing for children with developmental and epileptic encephalopathy (DEE) and evaluated the clinical implications of genotype-phenotype correlations. METHODS: We assessed 278 children with DEE using a customized gene panel that included 172 genes, and extensively reviewed their clinical characteristics, including therapeutic efficacy, according to genotype. RESULTS: In 103 (37.1%) of the 278 patients with DEE, 35 different disease-causing monogenic mutations were identified...
February 12, 2018: Epilepsy Research
Marie-Coralie Cornet, Tristan T Sands, Maria Roberta Cilio
Whereas the majority of seizures in neonates are related to acute brain injury, a substantial minority are the first symptom of a neonatal-onset epilepsy, often linked to a pathogenic genetic variant. This defect may disrupt cortical development (e.g., lissencephaly, focal cortical dysplasia), lead to metabolic changes (e.g., pyridoxine-dependent epilepsy, sulfite oxidase deficiency) or lead to cortical dysfunction without metabolic or macroscopic structural changes (e.g., channelopathies, STXBP1). Historically, studies on treatment response and long-term consequences of neonatal seizures have lumped all etiologies together...
January 31, 2018: Seminars in Fetal & Neonatal Medicine
John Hoon Rim, Se Hee Kim, In Sik Hwang, Soon Sung Kwon, Jieun Kim, Hyun Woo Kim, Min Jung Cho, Ara Ko, Song Ee Youn, Jihun Kim, Young Mock Lee, Hee Jung Chung, Joon Soo Lee, Heung Dong Kim, Jong Rak Choi, Seung-Tae Lee, Hoon-Chul Kang
BACKGROUND: We intended to evaluate diagnostic utility of a targeted gene sequencing by using next generation sequencing (NGS) panel in patients with intractable early-onset epilepsy (EOE) and find the efficient analytical step for increasing the diagnosis rate. METHODS: We assessed 74 patients with EOE whose seizures started before 3 years of age using a customized NGS panel that included 172 genes. Single nucleotide variants (SNVs) and exonic and chromosomal copy number variations (CNVs) were intensively examined with our customized pipeline and crosschecked with commercial or pre-built software...
February 1, 2018: BMC Medical Genomics
P Zhou, N He, J-W Zhang, Z-J Lin, J Wang, L-M Yan, H Meng, B Tang, B-M Li, X-R Liu, Y-W Shi, Q-X Zhai, Y-H Yi, W-P Liao
Epileptic encephalopathies are severe epilepsy disorders with strong genetic bases. We performed targeted next-generation sequencing (NGS) in 70 patients with epileptic encephalopathies. The likely pathogenicity of variants in candidate genes was evaluated by American College of Medical Genetics and Genomics (ACMG) scoring taken together with the accepted clinical presentation. Thirty-three candidate variants were detected after population filtration and computational prediction. According to ACMG, 21 candidate variants, including 18 de novo variants, were assessed to be pathogenic/likely pathogenic with clinical concordance...
January 4, 2018: Genes, Brain, and Behavior
Elie Abdelnour, William Gallentine, Marie McDonald, Monisha Sachdev, Yong-Hui Jiang, Mohamad A Mikati
PURPOSE: Gain-of-function mutations in the KCNT1 gene have been reported in a number of drug resistant epilepsy syndromes including Epilepsy of Infancy with Migrating Focal Seizures. Quinidine, a potassium channel blocker, has been proposed as a potential therapeutic agent with only a few patients reported in the literature to have received it. Here we report 3 additional children, with such KCNT1 mutations and refractory seizures, who received quinidine therapy. METHODS: Retrospective chart review of 3 children with KCNT1 mutations, of ages 3 months, 9 years and 13 years old...
February 2018: Seizure: the Journal of the British Epilepsy Association
Amy McTague, Umesh Nair, Sony Malhotra, Esther Meyer, Natalie Trump, Elena V Gazina, Apostolos Papandreou, Adeline Ngoh, Sally Ackermann, Gautam Ambegaonkar, Richard Appleton, Archana Desurkar, Christin Eltze, Rachel Kneen, Ajith V Kumar, Karine Lascelles, Tara Montgomery, Venkateswaran Ramesh, Rajib Samanta, Richard H Scott, Jeen Tan, William Whitehouse, Annapurna Poduri, Ingrid E Scheffer, W K Kling Chong, J Helen Cross, Maya Topf, Steven Petrou, Manju A Kurian
OBJECTIVE: To characterize the phenotypic spectrum, molecular genetic findings, and functional consequences of pathogenic variants in early-onset KCNT1 epilepsy. METHODS: We identified a cohort of 31 patients with epilepsy of infancy with migrating focal seizures (EIMFS) and screened for variants in KCNT1 using direct Sanger sequencing, a multiple-gene next-generation sequencing panel, and whole-exome sequencing. Additional patients with non-EIMFS early-onset epilepsy in whom we identified KCNT1 variants on local diagnostic multiple gene panel testing were also included...
January 2, 2018: Neurology
Saul A Mullen, Patrick W Carney, Annie Roten, Michael Ching, Paul A Lightfoot, Leonid Churilov, Umesh Nair, Melody Li, Samuel F Berkovic, Steven Petrou, Ingrid E Scheffer
OBJECTIVE: To evaluate quinidine as a precision therapy for severe epilepsy due to gain of function mutations in the potassium channel gene KCNT1 . METHODS: A single-center, inpatient, order-randomized, blinded, placebo-controlled, crossover trial of oral quinidine included 6 patients with severe autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) due to KCNT1 mutation. Order was block randomized and blinded. Four-day treatment blocks were used with a 2-day washout between...
January 2, 2018: Neurology
Xiaolin Zhu, Raghavendra Padmanabhan, Brett Copeland, Joshua Bridgers, Zhong Ren, Sitharthan Kamalakaran, Ailbhe O'Driscoll-Collins, Samuel F Berkovic, Ingrid E Scheffer, Annapurna Poduri, Davide Mei, Renzo Guerrini, Daniel H Lowenstein, Andrew S Allen, Erin L Heinzen, David B Goldstein
Trio exome sequencing has been successful in identifying genes with de novo mutations (DNMs) causing epileptic encephalopathy (EE) and other neurodevelopmental disorders. Here, we evaluate how well a case-control collapsing analysis recovers genes causing dominant forms of EE originally implicated by DNM analysis. We performed a genome-wide search for an enrichment of "qualifying variants" in protein-coding genes in 488 unrelated cases compared to 12,151 unrelated controls. These "qualifying variants" were selected to be extremely rare variants predicted to functionally impact the protein to enrich for likely pathogenic variants...
November 2017: PLoS Genetics
Fiona M Baumer, Maureen Sheehan
No abstract text is available yet for this article.
November 21, 2017: Neurology
Priyanka Madaan, Prashant Jauhari, Aparajita Gupta, Biswaroop Chakrabarty, Sheffali Gulati
Epilepsy of infancy with migrating focal seizures {a.k.a malignant migrating partial seizures of infancy (MMPSI)} is an uncommon epileptic encephalopathy with a poor prognosis. Migrating focal seizures with autonomic features, developmental stagnation and refractoriness to treatment are its key features. It is caused by genetic defects in various ion channels, most common being sodium activated potassium channel (KCNT1), found in up to 50% of cases. With advent of genetic diagnosis and precision medicine, many targeted therapies have been identified...
March 2018: Brain & Development
Yuki Kawasaki, Ichiro Kuki, Eiji Ehara, Yosuke Murakami, Shin Okazaki, Hisashi Kawawaki, Munetsugu Hara, Yoriko Watanabe, Shintaro Kishimoto, Kenji Suda, Hirotomo Saitsu, Naomichi Matsumoto
KCNT1 mutations are gain-of-function mutations in potassium channels resulting in severe infantile epilepsy. Herein we describe 3 infants with malignant migrating partial seizures with KCNT1 mutations accompanied by massive systemic to pulmonary collateral arteries with life-threatening hemoptysis and heart failure.
December 2017: Journal of Pediatrics
Sushmitha Gururaj, Katherine M Evely, Kerri D Pryce, Jun Li, Jun Qu, Arin Bhattacharjee
The sodium-activated potassium (KNa ) channel Kcnt1 (Slack) is abundantly expressed in nociceptor (pain-sensing) neurons of the dorsal root ganglion (DRG), where they transmit the large outward conductance I KNa and arbitrate membrane excitability. Slack channel expression at the DRG membrane is necessary for their characteristic firing accommodation during maintained stimulation, and reduced membrane channel density causes hyperexcitability. We have previously shown that in a pro-inflammatory state, a decrease in membrane channel expression leading to reduced Slack-mediated I KNa expression underlies DRG neuronal sensitization...
November 24, 2017: Journal of Biological Chemistry
Sonia Hasan, Ameera Balobaid, Alessandro Grottesi, Omar Dabbagh, Marta Cenciarini, Rifaat Rawashdeh, Afaf Al-Sagheir, Cecilia Bove, Lara Macchioni, Mauro Pessia, Mohammed Al-Owain, Maria Cristina D'Adamo
A 2-yr-old boy presented profound developmental delay, failure to thrive, ataxia, hypotonia, and tonic-clonic seizures that caused the death of the patient. Targeted and whole exome sequencing revealed two heterozygous missense variants: a novel mutation in the KCNJ10 gene that encodes for the inward-rectifying K + channel Kir4.1 and another previously characterized mutation in KCNT1 that encodes for the Na + -activated K + channel known as Slo2.2 or SLACK. The objectives of this study were to perform the clinical and genetic characterization of the proband and his family and to examine the functional consequence of the Kir4...
October 1, 2017: Journal of Neurophysiology
Norman Delanty, Gianpiero Cavallleri
Traditional antiepileptic drug development approaches have yielded many important clinically valuable anti-epileptic drugs. However, the screening of promising compounds has been naturally agnostic to epilepsy etiology in individual human patients. Now, genomic medicine is changing the way we view human disease. International collaborations are unraveling the many molecular genetic causes of the epilepsies, including the early onset epileptic encephalopathies, and some of the familial focal epilepsies. Further advances in precision diagnostics will be facilitated by ongoing large collaborations and the wider availability of whole exome and whole genome sequencing in clinical practice...
July 2017: Neurochemical Research
T Saito, A Ishii, K Sugai, M Sasaki, S Hirose
Epilepsy of infancy with migrating focal seizures (EIMFS) is an infantile epileptic encephalopathy characterized by refractory seizures, severe psychomotor delay, and multiple moving epileptic discharges. The genetic etiology of EIMFS is relatively homogeneous with the majority of causative mutations found in KCNT1. Currently, gene panel or whole-exome sequencing is used for testing. To verify the pathogenicity of a variant, co-segregation of the variant and the disorder in a pedigree is important; hence, de novo mutations that are judged to be deleterious may be considered pathogenic because the patients are isolated...
May 6, 2017: Clinical Genetics
Katherine M Evely, Kerri D Pryce, Arin Bhattacharjee
Sodium-activated potassium (KNa) channels contribute to firing frequency adaptation and slow after hyperpolarization. The KCNT1 gene (also known as SLACK) encodes a KNa subunit that is expressed throughout the central and peripheral nervous systems. Missense mutations of the SLACK C-terminus have been reported in several patients with rare forms of early onset epilepsy and in some cases severely delayed myelination. To date, such mutations identified in patients with autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE), epilepsy of infancy with migrating focal seizures (EIMFS) and Ohtahara syndrome (OS) have been reported to be gain-of-function mutations (Villa and Combi, 2016)...
May 20, 2017: Neuroscience
Joseph D Symonds, Sameer M Zuberi, Michael R Johnson
PURPOSE OF REVIEW: Epilepsy genetics is shifting from the academic pursuit of gene discovery to a clinical discipline based on molecular diagnosis and stratified medicine. We consider the latest developments in epilepsy genetics and review how gene discovery in epilepsy is influencing the clinical classification of epilepsy and informing new therapeutic approaches and drug discovery. RECENT FINDINGS: Recent studies highlighting the importance of mutation in GABA receptors, NMDA receptors, potassium channels, G-protein coupled receptors, mammalian target of rapamycin pathway and chromatin remodeling are discussed...
April 2017: Current Opinion in Neurology
Yalan Zhang, Weiming Ni, Arthur L Horwich, Leonard K Kaczmarek
Mutations that alter levels of Slack (KCNT1) Na(+)-activated K(+) current produce devastating effects on neuronal development and neuronal function. We now find that Slack currents are rapidly suppressed by oligomers of mutant human Cu/Zn superoxide dismutase 1 (SOD1), which are associated with motor neuron toxicity in an inherited form of amyotrophic lateral sclerosis (ALS). We recorded from bag cell neurons of Aplysia californica, a model system to study neuronal excitability. We found that injection of fluorescent wild-type SOD1 (wt SOD1YFP) or monomeric mutant G85R SOD1YFP had no effect on net ionic currents measured under voltage clamp...
February 22, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
N Hansen, G Widman, E Hattingen, C E Elger, W S Kunz
No abstract text is available yet for this article.
February 2017: Seizure: the Journal of the British Epilepsy Association
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