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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
Keita Harada, Hidetada Matsuoka, Masumi Inoue
M-type K+ channels contribute to the resting membrane potential in the sympathetic ganglion neurons of various animals, whereas their expression in adrenal medullary (AM) cells has been controversial. The present experiment aims to explore the expression of M channels comprising the KCNQ2 subunit in the rat AM cell and its immortalized cell line PC12 cells at the protein level and how its expression in PC12 cells is regulated. The KCNQ2 isoform was recognized in homogenates of PC12 cells but not the rat adrenal medullae by immunoblotting and KCNQ2-like immunoreactivity (IR) was detected in PC12 cells but not in rat AM cells...
February 27, 2018: Cell and Tissue Research
Ganeko Bernardo-Seisdedos, Eider Nuñez, Carolina Gomis, Covadonga Malo, Álvaro Villarroel, Oscar Millet
The Kv7.2 (KCNQ2) channel is the principal molecular component of the slow voltage-gated, noninactivating K+ M-current, a key controller of neuronal excitability. To investigate the calmodulin (CaM)-mediated Ca2+ gating of the channel, we used NMR spectroscopy to structurally and dynamically describe the association of helices h A and h B of Kv7.2 with CaM, as a function of Ca2+ concentration. The structures of the CaM/Kv7.2-hAB complex at two different calcification states are reported here. In the presence of a basal cytosolic Ca2+ concentration (10-100 nM), only the N-lobe of CaM is Ca2+ -loaded and the complex (representative of the open channel) exhibits collective dynamics on the millisecond time scale toward a low-populated excited state (1...
February 20, 2018: Proceedings of the National Academy of Sciences of the United States of America
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
Paolo Ambrosino, Elena Freri, Barbara Castellotti, Maria Virginia Soldovieri, Ilaria Mosca, Laura Manocchio, Cinzia Gellera, Laura Canafoglia, Silvana Franceschetti, Barbara Salis, Nunzio Iraci, Francesco Miceli, Francesca Ragona, Tiziana Granata, Jacopo C DiFrancesco, Maurizio Taglialatela
Over one hundred mutations in the Kv7.2 (KCNQ2) gene encoding for phosphatidylinositol 4,5-bisphosphate (PIP2)-sensitive voltage-gated K+ channel subunits have been identified in early-onset epilepsies with wide phenotypic variability. By contrast, only few mutations in the closely related Kv7.3 (KCNQ3) gene have been reported, mostly associated with typical benign familial neonatal seizures (BFNS). We herein describe a patient affected by early onset epileptic encephalopathy (EOEE) carrying two Kv7.3 missense mutations (p...
January 30, 2018: Molecular Neurobiology
Luke W Bonham, Daniel S Evans, Yongmei Liu, Steven R Cummings, Kristine Yaffe, Jennifer S Yokoyama
BACKGROUND/RATIONALE: Experimental studies support the role of neurotransmitter genes in dementia risk, but human studies utilizing single variants in candidate genes have had limited success. METHODS: We used the gene-based testing program Versatile Gene-based Association Study to assess whether aggregate variation across 6 neurotransmitter pathways influences risk of cognitive decline in 8159 cognitively normal elderly (≥65 years old) adults from 3 community-based cohorts...
January 1, 2018: American Journal of Alzheimer's Disease and Other Dementias
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
Qi Zeng, Xiaoling Yang, Jing Zhang, Aijie Liu, Zhixian Yang, Xiaoyan Liu, Ye Wu, Xiru Wu, Liping Wei, Yuehua Zhang
Benign familial epilepsies that present themselves in the first year of life include benign familial neonatal epilepsy (BFNE), benign familial neonatal-infantile epilepsy (BFNIE) and benign familial infantile epilepsy (BFIE). We used Sanger sequencing and targeted next-generation sequencing to detect gene mutations in a Chinese cohort of patients with these three disorders. A total of 79 families were collected, including 4 BFNE, 7 BFNIE, and 68 BFIE. Genetic testing led to the identification of gene mutations in 60 families (60 out of 79, 75...
January 2018: Journal of Human Genetics
Laura Ortega-Moreno, Beatriz G Giráldez, Victor Soto-Insuga, Rebeca Losada-Del Pozo, María Rodrigo-Moreno, Cristina Alarcón-Morcillo, Gema Sánchez-Martín, Esther Díaz-Gómez, Rosa Guerrero-López, José M Serratosa
Pediatric epilepsies are a group of disorders with a broad phenotypic spectrum that are associated with great genetic heterogeneity, thus making sequential single-gene testing an impractical basis for diagnostic strategy. The advent of next-generation sequencing has increased the success rate of epilepsy diagnosis, and targeted resequencing using genetic panels is the a most cost-effective choice. We report the results found in a group of 87 patients with epilepsy and developmental delay using targeted next generation sequencing (custom-designed Haloplex panel)...
2017: PloS One
Bernt Popp, Arif B Ekici, Christian T Thiel, Juliane Hoyer, Antje Wiesener, Cornelia Kraus, André Reis, Christiane Zweier
High throughput sequencing has greatly advanced disease gene identification, especially in heterogeneous entities. Despite falling costs this is still an expensive and laborious technique, particularly when studying large cohorts. To address this problem we applied Exome Pool-Seq as an economic and fast screening technology in neurodevelopmental disorders (NDDs). Sequencing of 96 individuals can be performed in eight pools of 12 samples on less than one Illumina sequencer lane. In a pilot study with 96 cases we identified 27 variants, likely or possibly affecting function...
November 20, 2017: European Journal of Human Genetics: EJHG
X Yang, G Pan, W H Li, L M Zhang, B B Wu, H J Wang, P Zhang, S Z Zhou
Objective: To summarize the gene mutation of early onset epileptic spasm with unknown reason. Method: In this prospective study, data of patients with early onset epileptic spasm with unknown reason were collected from neurological department of Children's Hospital of Fudan University between March 2016 and December 2016. Patients with known disorders such as infection, metabolic, structural, immunological problems and known genetic mutations were excluded. Patients with genetic disease that can be diagnosed by clinical manifestations and phenotypic characteristics were also excluded...
November 2, 2017: Zhonghua Er Ke za Zhi. Chinese Journal of Pediatrics
Jennifer Ling, Ferhat Erol, Jianguo G Gu
Sensitivity to cooling temperatures often becomes heightened in orofacial regions leading to orofacial cold allodynia/hyperalgesia after chronic trigeminal nerve injury. KCNQ2 channels are involved in controlling excitability of primary afferent neurons and thereby regulate sensory functions under both physiological and pathological conditions. In the present study, we sought to determine whether KCNQ2 channels in trigeminal nerves are involved in regulating orofacial operant behavioral responses to cooling stimulation...
January 18, 2018: Neuroscience Letters
Radhika Dhamija, Howard P Goodkin, Russell Bailey, Chelsea Chambers, J Nicholas Brenton
The differential diagnosis of fever-induced movement disorders in childhood is broad. Whole exome sequencing has yielded new insights into those cases with a suspected genetic basis. We report the case of an 8-year-old boy with a history of neonatal seizures who presented with near-continuous hyperkinetic movements of his limbs during a febrile illness. Initial diagnostic testing did not explain his abnormalities; however, given the suspicion for a channelopathy, whole exome sequencing was performed and it demonstrated a de novo pathogenic heterozygous variant in KCNQ2...
December 2017: Journal of Child Neurology
Robin Y Kim, Stephan A Pless, Harley T Kurata
Retigabine (RTG) is a first-in-class antiepileptic drug that suppresses neuronal excitability through the activation of voltage-gated KCNQ2-5 potassium channels. Retigabine binds to the pore-forming domain, causing a hyperpolarizing shift in the voltage dependence of channel activation. To elucidate how the retigabine binding site is coupled to changes in voltage sensing, we used voltage-clamp fluorometry to track conformational changes of the KCNQ3 voltage-sensing domains (VSDs) in response to voltage, retigabine, and PIP2...
November 7, 2017: Proceedings of the National Academy of Sciences of the United States of America
Jérôme Devaux, Sandra Dhifallah, Michela De Maria, Geoffrey Stuart-Lopez, Hélène Becq, Mathieu Milh, Florence Molinari, Laurent Aniksztejn
OBJECTIVE: Kv7 channels mediate the voltage-gated M-type potassium current. Reduction of M current due to KCNQ2 mutations causes early onset epileptic encephalopathies (EOEEs). Mutations in STXBP1 encoding the syntaxin binding protein 1 can produce a phenotype similar to that of KCNQ2 mutations, suggesting a possible link between STXBP1 and Kv7 channels. These channels are known to be modulated by syntaxin-1A (Syn-1A) that binds to the C-terminal domain of the Kv7.2 subunit and strongly inhibits M current...
December 2017: Epilepsia
Qiansen Zhang, Huaiyu Yang
Lipids and membrane proteins are the main components of cell membranes. Lipid-protein interactions are dynamic because these interactions typically occur on shallow protein surface clefts. Molecular dynamics (MD) simulations provide a tool for studying the dynamics of these interactions. Here, we describe the interactions of phosphatidylinositol-4,5-bisphosphate (PIP2) with both the open and closed states of a KCNQ2 channel. Through these methods, we show that a lipid can migrate between different binding sites in a protein and this migration modulates protein functions...
2018: Methods in Molecular Biology
Kameryn M Butler, Cristina da Silva, John J Alexander, Madhuri Hegde, Andrew Escayg
BACKGROUND: The contribution of genetic factors to epilepsy has long been recognized and has been estimated to play a role in 70% to 80% of cases. Identification of a pathogenic variant can help families to better cope with the disorder, allows for genetic counseling to determine recurrence risk, and in some cases, can directly influence treatment options. In this study, we determined the diagnostic yield of a clinical gene panel applied to an unselected cohort of epilepsy patients. METHODS: Variant reports from 339 clinically referred epilepsy patients screened using a 110-gene panel were retrospectively reviewed...
December 2017: Pediatric Neurology
Ana Vilan, José Mendes Ribeiro, Pasquale Striano, Sarah Weckhuysen, Lauren C Weeke, Eva Brilstra, Linda S de Vries, Maria Roberta Cilio
BACKGROUND: Recurrent and prolonged seizures are harmful for the developing brain, emphasizing the importance of early seizure recognition and effective therapy. Amplitude-integrated electroencephalography (aEEG) has become a valuable tool to diagnose epileptic seizures, and, in parallel, genetic etiologies are increasingly being recognized, changing the paradigm of the workup and management of neonatal seizures. OBJECTIVE: To report the ictal aEEG pattern in neonates with KCNQ2-related epilepsy...
2017: Neonatology
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