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1.
Int Heart J ; 61(5): 1049-1055, 2020 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-32921676

RESUMO

While a KCND3 V392I mutation uniquely displays a mixed electrophysiological phenotype of Kv4.3, only limited clinical information on the mutation carriers is available. We report two teenage siblings exhibiting both cardiac (early repolarization syndrome and paroxysmal atrial fibrillation) and cerebral phenotypes (epilepsy and intellectual disability), in whom we identified the KCND3 V392I mutation. We propose a link between the KCND3 mutation with a mixed electrophysiological phenotype and cardiocerebral phenotypes, which may be defined as a novel cardiocerebral channelopathy.


Assuntos
Fibrilação Atrial/genética , Canalopatias/genética , Epilepsias Parciais/genética , Deficiência Intelectual/genética , Canais de Potássio Shal/genética , Adolescente , Morte Súbita Cardíaca , Eletrocardiografia , Eletroencefalografia , Feminino , Humanos , Pessoa de Meia-Idade , Mães , Mutação , Linhagem , Irmãos , Síncope/genética , Adulto Jovem
2.
PLoS One ; 15(9): e0239850, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32986766

RESUMO

Massively parallel sequencing (MPS) has revolutionised clinical genetics and research within human genetics by enabling the detection of variants in multiple genes in several samples at the same time. Today, multiple approaches for MPS of DNA are available, including targeted gene sequencing (TGS) panels, whole exome sequencing (WES), and whole genome sequencing (WGS). As MPS is becoming an integrated part of the work in genetic laboratories, it is important to investigate the variant detection performance of the various MPS methods. We compared the results of single nucleotide variant (SNV) detection of three MPS methods: WGS, WES, and HaloPlex target enrichment sequencing (HES) using matched DNA of 10 individuals. The detection performance was investigated in 100 genes associated with cardiomyopathies and channelopathies. The results showed that WGS overall performed better than those of WES and HES. WGS had a more uniform and widespread coverage of the investigated regions compared to WES and HES, which both had a right-skewed coverage distribution and difficulties in covering regions and genes with high GC-content. WGS and WES showed roughly the same high sensitivities for detection of SNVs, whereas HES showed a lower sensitivity due to a higher number of false negative results.


Assuntos
Sequenciamento de Nucleotídeos em Larga Escala/métodos , Polimorfismo de Nucleotídeo Único , Sequenciamento Completo do Exoma/métodos , Alelos , Cardiomiopatias/genética , Canalopatias/genética , Exoma , Genoma Humano , Genótipo , Humanos , Sensibilidade e Especificidade , Análise de Sequência de DNA/métodos
3.
Am J Hum Genet ; 107(2): 278-292, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32707085

RESUMO

Dominantly inherited disorders are not typically considered to be therapeutic candidates for gene augmentation. Here, we utilized induced pluripotent stem cell-derived retinal pigment epithelium (iPSC-RPE) to test the potential of gene augmentation to treat Best disease, a dominant macular dystrophy caused by over 200 missense mutations in BEST1. Gene augmentation in iPSC-RPE fully restored BEST1 calcium-activated chloride channel activity and improved rhodopsin degradation in an iPSC-RPE model of recessive bestrophinopathy as well as in two models of dominant Best disease caused by different mutations in regions encoding ion-binding domains. A third dominant Best disease iPSC-RPE model did not respond to gene augmentation, but showed normalization of BEST1 channel activity following CRISPR-Cas9 editing of the mutant allele. We then subjected all three dominant Best disease iPSC-RPE models to gene editing, which produced premature stop codons specifically within the mutant BEST1 alleles. Single-cell profiling demonstrated no adverse perturbation of retinal pigment epithelium (RPE) transcriptional programs in any model, although off-target analysis detected a silent genomic alteration in one model. These results suggest that gene augmentation is a viable first-line approach for some individuals with dominant Best disease and that non-responders are candidates for alternate approaches such as gene editing. However, testing gene editing strategies for on-target efficiency and off-target events using personalized iPSC-RPE model systems is warranted. In summary, personalized iPSC-RPE models can be used to select among a growing list of gene therapy options to maximize safety and efficacy while minimizing time and cost. Similar scenarios likely exist for other genotypically diverse channelopathies, expanding the therapeutic landscape for affected individuals.


Assuntos
Células-Tronco Pluripotentes Induzidas/fisiologia , Degeneração Macular/genética , Mutação/genética , Alelos , Bestrofinas/genética , Cálcio/metabolismo , Linhagem Celular , Canalopatias/genética , Proteínas do Olho/genética , Edição de Genes/métodos , Terapia Genética/métodos , Genótipo , Células HEK293 , Humanos , Epitélio Pigmentado da Retina/fisiologia
4.
Neurol Clin ; 38(3): 481-491, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32703462

RESUMO

Skeletal muscle channelopathies are rare genetic neuromuscular conditions that include the nondystrophic myotonias and periodic paralyses. They cause disabling muscle symptoms and can limit educational potential, work opportunities, socialization, and quality of life. Effective therapy is available, making it essential to recognize and treat this group of disorders. Here, the authors highlight important aspects regarding diagnosis and management using illustrative case reports.


Assuntos
Síndrome de Andersen/diagnóstico , Síndrome de Andersen/genética , Canalopatias/diagnóstico , Canalopatias/genética , Paralisia Periódica Hipopotassêmica/diagnóstico , Paralisia Periódica Hipopotassêmica/genética , Adolescente , Síndrome de Andersen/fisiopatologia , Canalopatias/fisiopatologia , Humanos , Paralisia Periódica Hipopotassêmica/fisiopatologia , Masculino , Músculo Esquelético/fisiopatologia , Mutação/genética , Transtornos Miotônicos/diagnóstico , Transtornos Miotônicos/genética , Transtornos Miotônicos/fisiopatologia , Doenças da Junção Neuromuscular/diagnóstico , Doenças da Junção Neuromuscular/genética , Doenças da Junção Neuromuscular/fisiopatologia
5.
Orphanet J Rare Dis ; 15(1): 157, 2020 06 22.
Artigo em Inglês | MEDLINE | ID: mdl-32571376

RESUMO

Inherited heart disease represent a very heterogenous group of cardiac disorders, characterized by inherited, acquired, and often rare disorders affecting the heart muscle (cardiomyopathies) or the cardiac electrical system (ion channel disease). They are often familial diseases, and are among the leading cause of juvenile sudden death and heart failure. The aim of this paper is to give a perspective on how to run a clinical service during an epidemic or pandemic emergency and to describe the potential COVID-19 associated risks for patients affected by inherited heart diseases.


Assuntos
Betacoronavirus , Cardiomiopatias/complicações , Cardiomiopatias/genética , Canalopatias/complicações , Canalopatias/genética , Infecções por Coronavirus/complicações , Pneumonia Viral/complicações , Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/prevenção & controle , Predisposição Genética para Doença , Humanos , Ambulatório Hospitalar/organização & administração , Pandemias/prevenção & controle , Pneumonia Viral/epidemiologia , Pneumonia Viral/prevenção & controle , Doenças Raras/complicações , Fatores de Risco , Telemedicina/organização & administração
6.
Int J Mol Sci ; 21(7)2020 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-32276507

RESUMO

Myotonia congenita (MC) is a rare disorder characterized by stiffness and weakness of the limb and trunk muscles. Mutations in the SCN4A gene encoding the alpha-subunit of the voltage-gated sodium channel Nav1.4 have been reported to be responsible for sodium channel myotonia (SCM). The Nav1.4 channel is expressed in skeletal muscles, and its related channelopathies affect skeletal muscle excitability, which can manifest as SCM, paramyotonia and periodic paralysis. In this study, the missense mutation p.V445M was identified in two individual families with MC. To determine the functional consequences of having a mutated Nav1.4 channel, whole-cell patch-clamp recording of transfected Chinese hamster ovary cells was performed. Evaluation of the transient Na+ current found that a hyperpolarizing shift occurs at both the activation and inactivation curves with an increase of the window currents in the mutant channels. The Nav1.4 channel's co-expression with the Navß4 peptide can generate resurgent Na+ currents at repolarization following a depolarization. The magnitude of the resurgent currents is higher in the mutant than in the wild-type (WT) channel. Although the decay kinetics are comparable between the mutant and WT channels, the time to the peak of resurgent Na+ currents in the mutant channel is significantly protracted compared with that in the WT channel. These findings suggest that the p.V445M mutation in the Nav1.4 channel results in an increase of both sustained and resurgent Na+ currents, which may contribute to hyperexcitability with repetitive firing and is likely to facilitate recurrent myotonia in SCM patients.


Assuntos
Mutação de Sentido Incorreto , Miotonia Congênita/genética , Miotonia Congênita/fisiopatologia , Canal de Sódio Disparado por Voltagem NAV1.4/fisiologia , Sequência de Aminoácidos , Animais , Grupo com Ancestrais do Continente Asiático , Células CHO , Canalopatias/genética , Canalopatias/metabolismo , Canalopatias/fisiopatologia , Cricetulus , Feminino , Humanos , Masculino , Miotonia Congênita/metabolismo , Canal de Sódio Disparado por Voltagem NAV1.4/química , Canal de Sódio Disparado por Voltagem NAV1.4/genética , Canal de Sódio Disparado por Voltagem NAV1.4/metabolismo , Técnicas de Patch-Clamp , Linhagem
7.
Hum Genet ; 139(9): 1161-1172, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32318853

RESUMO

Stillbirth after 20 weeks gestation happens in 1 in 200 pregnancies and occurs more commonly than neonatal loss and sudden infant death syndrome (SIDs) combined. The stillbirth rate is several times greater in low as opposed to high-resource countries. However, among high-resource countries, although a lower overall stillbirth rate exists, there has been little change for several decades. Molecular genetic technologies are emerging as important contributors to our understanding of stillbirth. Initially, genetic etiologies included alterations in chromosome number or structure such as aneuploidy and microduplications and deletions. More recently, next-generation sequencing analysis in two genetic conditions, Smith Lemli Optiz Syndrome (SLOs) and the channelopathy disorders (such as long QT syndrome (LQTS)) provide examples into the association of pathogenic gene variants with stillbirth. Although these specific conditions individually account for only a small number of stillbirths, investigating these disorders provides a new and innovative approach for further understanding genetic contributors to adverse pregnancy outcomes. Our knowledge of the role of genetic disease as an etiology for stillbirth is elementary. Genomic interrogation of maternal-fetal genotypes, gene-gene, and genotype-environment interaction is lacking in stillbirth research. At the DNA sequence level, further investigation of variants of unknown significance is an opportunity for exploration of biologic pathways of importance to pregnancy loss. This review concentrates on SLO as an example of a single gene disorder with a high carrier but low affected liveborn proband rate. The channelopathy disorders are included as initial examples of genetic conditions with variable presentation including an association with sudden infant death syndrome. Highlighted are the challenges when numerous genes and variants are involved, and the task of assigning pathogenicity. The advantages and limitations of genetic evaluations are presented and avenues for further research considered.


Assuntos
Canalopatias/genética , Aberrações Cromossômicas/estatística & dados numéricos , Síndrome de Smith-Lemli-Opitz/genética , Natimorto/epidemiologia , Natimorto/genética , Feminino , Idade Gestacional , Humanos , Recém-Nascido , Gravidez , Sequenciamento Completo do Exoma
8.
Lancet Child Adolesc Health ; 4(7): 536-547, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32142633

RESUMO

Voltage-gated sodium channels are essential for excitability of skeletal muscle fibres and neurons. An increasing number of disabling or fatal paediatric neurological disorders linked to mutations of voltage-gated sodium channel genes are recognised. Muscle phenotypes include episodic paralysis, myotonia, neonatal hypotonia, respiratory compromise, laryngospasm or stridor, congenital myasthenia, and myopathy. Evidence suggests a possible link between sodium channel dysfunction and sudden infant death. Increasingly recognised phenotypes of brain sodium channelopathies include several epilepsy disorders and complex encephalopathies. Together, these early-onset muscle and brain phenotypes have a substantial morbidity and a considerable mortality. Important advances in understanding the pathophysiological mechanisms underlying these channelopathies have helped to identify effective targeted therapies. The availability of effective treatments underlines the importance of increasing clinical awareness and the need to achieve a precise genetic diagnosis. In this Review, we describe the expanded range of phenotypes of muscle and brain sodium channelopathies and the underlying knowledge regarding mechanisms of sodium channel dysfunction. We also outline a diagnostic approach and review the available treatment options.


Assuntos
Encefalopatias/diagnóstico , Encefalopatias/genética , Canalopatias/diagnóstico , Canalopatias/genética , Doenças Musculares/diagnóstico , Doenças Musculares/genética , Canais de Sódio Disparados por Voltagem/genética , Transtorno do Espectro Autista/genética , Encefalopatias/terapia , Canalopatias/terapia , Morte Súbita/etiologia , Testes Genéticos , Humanos , Deficiência Intelectual/genética , Doenças Musculares/terapia , Prognóstico
9.
Eur J Paediatr Neurol ; 24: 123-128, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31889633

RESUMO

Voltage-gated sodium channels (VGSCs) play a crucial role in generation of action potentials. Pathogenic variants in the five human brain expressed VGSC genes, SCN1A, SCN2A, SCN3A, SCN8A and SCN1B have been associated with a spectrum of epilepsy phenotypes and neurodevelopmental disorders. In the last decade, next generation sequencing techniques have revolutionized the way we diagnose these channelopathies, which is paving the way towards precision medicine. Knowing the functional effect (Loss-of-function versus Gain-of-function) of a variant is not only important for understanding the underlying pathophysiology, but it is particularly crucial to orient therapeutic decisions. Here we provide a review of the literature dealing with treatment options in epilepsy-related sodium channelopathies, including the current and emerging medications.


Assuntos
Canalopatias/tratamento farmacológico , Canalopatias/genética , Epilepsia/tratamento farmacológico , Epilepsia/genética , Canais de Sódio Disparados por Voltagem/genética , Humanos
10.
J Med Genet ; 57(1): 1-10, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31217264

RESUMO

T-type channels are low-voltage-activated calcium channels that contribute to a variety of cellular and physiological functions, including neuronal excitability, hormone and neurotransmitter release as well as developmental aspects. Several human conditions including epilepsy, autism spectrum disorders, schizophrenia, motor neuron disorders and aldosteronism have been traced to variations in genes encoding T-type channels. In this short review, we present the genetics of T-type channels with an emphasis on structure-function relationships and associated channelopathies.


Assuntos
Canais de Cálcio/genética , Canalopatias/metabolismo , Animais , Canalopatias/genética , Humanos , Mutação
11.
Curr Med Sci ; 39(6): 863-873, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31845216

RESUMO

Voltage-gated sodium (Nav) channels are critical players in the generation and propagation of action potentials by triggering membrane depolarization. Mutations in Nav channels are associated with a variety of channelopathies, which makes them relevant targets for pharmaceutical intervention. So far, the cryoelectron microscopic structure of the human Nav1.2, Nav1.4, and Nav1.7 has been reported, which sheds light on the molecular basis of functional mechanism of Nav channels and provides a path toward structure-based drug discovery. In this review, we focus on the recent advances in the structure, molecular mechanism and modulation of Nav channels, and state updated sodium channel blockers for the treatment of pathophysiology disorders and briefly discuss where the blockers may be developed in the future.


Assuntos
Canalopatias/genética , Mutação , Bloqueadores dos Canais de Sódio/química , Canais de Sódio Disparados por Voltagem/metabolismo , Potenciais de Ação , Canalopatias/tratamento farmacológico , Microscopia Crioeletrônica , Desenho de Fármacos , Humanos , Modelos Moleculares , Conformação Proteica , Bloqueadores dos Canais de Sódio/farmacologia , Bloqueadores dos Canais de Sódio/uso terapêutico , Relação Estrutura-Atividade , Canais de Sódio Disparados por Voltagem/química , Canais de Sódio Disparados por Voltagem/genética
12.
BMC Bioinformatics ; 20(1): 565, 2019 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-31718537

RESUMO

BACKGROUND: Biologically data-driven networks have become powerful analytical tools that handle massive, heterogeneous datasets generated from biomedical fields. Protein-protein interaction networks can identify the most relevant structures directly tied to biological functions. Functional enrichments can then be performed based on these structural aspects of gene relationships for the study of channelopathies. Channelopathies refer to a complex group of disorders resulting from dysfunctional ion channels with distinct polygenic manifestations. This study presents a semi-automatic workflow using protein-protein interaction networks that can identify the most relevant genes and their biological processes and pathways in channelopathies to better understand their etiopathogenesis. In addition, the clinical manifestations that are strongly associated with these genes are also identified as the most characteristic in this complex group of diseases. RESULTS: In particular, a set of nine representative disease-related genes was detected, these being the most significant genes in relation to their roles in channelopathies. In this way we attested the implication of some voltage-gated sodium (SCN1A, SCN2A, SCN4A, SCN4B, SCN5A, SCN9A) and potassium (KCNQ2, KCNH2) channels in cardiovascular diseases, epilepsies, febrile seizures, headache disorders, neuromuscular, neurodegenerative diseases or neurobehavioral manifestations. We also revealed the role of Ankyrin-G (ANK3) in the neurodegenerative and neurobehavioral disorders as well as the implication of these genes in other systems, such as the immunological or endocrine systems. CONCLUSIONS: This research provides a systems biology approach to extract information from interaction networks of gene expression. We show how large-scale computational integration of heterogeneous datasets, PPI network analyses, functional databases and published literature may support the detection and assessment of possible potential therapeutic targets in the disease. Applying our workflow makes it feasible to spot the most relevant genes and unknown relationships in channelopathies and shows its potential as a first-step approach to identify both genes and functional interactions in clinical-knowledge scenarios of target diseases. METHODS: An initial gene pool is previously defined by searching general databases under a specific semantic framework. From the resulting interaction network, a subset of genes are identified as the most relevant through the workflow that includes centrality measures and other filtering and enrichment databases.


Assuntos
Canalopatias/genética , Estudos de Associação Genética , Predisposição Genética para Doença , Anotação de Sequência Molecular , Mapas de Interação de Proteínas , Bases de Dados Genéticas , Redes Reguladoras de Genes , Humanos
13.
BMC Neurol ; 19(1): 246, 2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31640633

RESUMO

BACKGROUND: To describe a patient with sleep alleviated episodic ataxia type 2 with a novel CACNA1A pathogenic variant and provide a possible link to sleep responsive migraine. CASE PRESENTATION: A 26-year-old woman with recurrent attacks of dizziness, nausea, vomiting, ataxia and dysarthria presented for a possible diagnosis of vestibular migraine. Unique to her attacks was if she could fall asleep for as little as 15 min the spells would subside. If however she remained awake the attacks would continue unabated. A presumed diagnosis of episodic ataxia type 2 was made and she became attack free on acetazolamide without recurrence. Genetic testing demonstrated a novel pathogenic variant in CACNA1A on chromosome 19. This pathogenic variant has not been previously reported in the literature and is suggested to truncate the CACNA1A polypeptide by introducing a premature stop codon. CONCLUSION: A case of episodic ataxia type 2 with a novel pathogenic variant in CACNA1A is described. Interestingly, the patient's symptoms would completely alleviate with sleep which suggests a sleep modulated channelopathy. The mechanisms by which sleep could potentially alter this pathogenic variant are hypothesized. A potential link to sleep alleviated migraine is suggested. Further study of this novel pathogenic variant may help us understand not only how sleep can modulate episodic ataxia type 2, but also migraine.


Assuntos
Ataxia/genética , Canais de Cálcio/genética , Sono , Acetazolamida/uso terapêutico , Adulto , Ataxia/complicações , Ataxia/tratamento farmacológico , Inibidores da Anidrase Carbônica/uso terapêutico , Canalopatias/genética , Códon sem Sentido , Feminino , Humanos , Transtornos de Enxaqueca/genética , Linhagem
14.
Forensic Sci Int Genet ; 42: 203-212, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31376648

RESUMO

Drug-induced arrhythmia is an adverse drug reaction that can be potentially fatal since it is mostly related to drug-induced QT prolongation, a known risk factor for Torsade de Pointes and sudden cardiac death (SCD). Several risk factors have been described in association to these drug-induced events, such as preexistent cardiac disease and genetic variation. Our objective was to study the genetic susceptibility in pharmacodynamic and pharmacokinetic pathways underlying suspected drug-induced arrhythmias and sudden unexplained deaths in 32 patients. The genetic component in the pharmacodynamic pathway was studied by analysing 96 genes associated with higher risk of SCD through massive parallel sequencing. Pharmacokinetic-mediated genetic susceptibility was investigated by studying the genes encoding cytochrome P450 enzymes using medium-throughput genotyping. Pharmacodynamic analysis showed three probably pathogenic variants and 45 variants of uncertain significance in 28 patients, several of them previously described in relation to mild or late onset cardiomyopathies. These results suggest that genetic variants in cardiomyopathy genes, in addition to those related with channelopathies, could be relevant to drug-induced cardiotoxicity and contribute to the arrhythmogenic phenotype. Pharmacokinetic analysis showed three patients that could have an altered metabolism of the drugs they received involving CYP2C19 and/or CYP2D6, probably contributing to the arrhythmogenic phenotype. The study of genetic variants in both pharmacodynamic and pharmacokinetic pathways may be a useful strategy to understand the multifactorial mechanism of drug-induced events in both clinical practice and forensic field. However, it is necessary to comprehensively study and evaluate the contribution of the genetic susceptibility to drug-induced cardiotoxicity.


Assuntos
Arritmias Cardíacas/etiologia , Morte Súbita/etiologia , Predisposição Genética para Doença , Variantes Farmacogenômicos , Adolescente , Adulto , Canalopatias/genética , Criança , Citocromo P-450 CYP2C19/genética , Citocromo P-450 CYP2C9/genética , Citocromo P-450 CYP2D6/genética , Citocromo P-450 CYP3A/genética , Canal de Potássio ERG1/genética , Feminino , Variação Genética , Genótipo , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Síndrome do QT Longo , Masculino , Pessoa de Meia-Idade , Testes Farmacogenômicos , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Adulto Jovem
15.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 36(8): 809-812, 2019 Aug 10.
Artigo em Chinês | MEDLINE | ID: mdl-31400134

RESUMO

OBJECTIVE: To explore the clinical features of a Chinese pedigree affected with skeletal muscle sodium channelopathies due to variation of SCN4A gene. METHODS: Potential variation of the 24 exons of the SCN4A gene was screened using PCR and Sanger sequencing. RESULTS: Four family members were affected with the disease in an autosomal dominant inheritance pattern. Three patients had normekalemic periodic paralysis, while 1 showed paramyotonia congenita. Genetic analysis detected a missense variation c.2078T>C (p.Ile693Thr) in exon 13 of the SCN4A gene in the proband and other 3 affected relatives. CONCLUSION: Normokalemic periodic paralysis and paramyotonia congenita can occur in different family members with skeletal muscle sodium channelopathies due to c.2078T>C(p.Ile693Thr) variation of SCN4A gene.


Assuntos
Canalopatias/genética , Músculo Esquelético/fisiopatologia , Canal de Sódio Disparado por Voltagem NAV1.4/genética , Humanos , Mutação , Linhagem
16.
Int J Mol Sci ; 20(10)2019 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-31137773

RESUMO

Ion channels and transporters play essential roles in excitable cells including cardiac, skeletal and smooth muscle cells, neurons, and endocrine cells. In pancreatic beta-cells, for example, potassium KATP channels link the metabolic signals generated inside the cell to changes in the beta-cell membrane potential, and ultimately regulate insulin secretion. Mutations in the genes encoding some ion transporter and channel proteins lead to disorders of glucose homeostasis (hyperinsulinaemic hypoglycaemia and different forms of diabetes mellitus). Pancreatic KATP, Non-KATP, and some calcium channelopathies and MCT1 transporter defects can lead to various forms of hyperinsulinaemic hypoglycaemia (HH). Mutations in the genes encoding the pancreatic KATP channels can also lead to different types of diabetes (including neonatal diabetes mellitus (NDM) and Maturity Onset Diabetes of the Young, MODY), and defects in the solute carrier family 2 member 2 (SLC2A2) leads to diabetes mellitus as part of the Fanconi-Bickel syndrome. Variants or polymorphisms in some ion channel genes and transporters have been reported in association with type 2 diabetes mellitus.


Assuntos
Canalopatias/metabolismo , Transtornos do Metabolismo de Glucose/metabolismo , Canais Iônicos/metabolismo , Bombas de Íon/metabolismo , Animais , Canalopatias/genética , Transtornos do Metabolismo de Glucose/genética , Humanos , Canais Iônicos/genética , Bombas de Íon/genética
17.
Rev. esp. cardiol. (Ed. impr.) ; 72(4): 324-332, abr. 2019. ilus, tab, graf
Artigo em Espanhol | IBECS | ID: ibc-187898

RESUMO

Introducción y objetivos: En 4 miembros de una familia española se identificó una mutación en los canales cardiacos Nav1.5 (p.R1644H) descrita ya y relacionada con el síndrome de QT largo con anterioridad. Sin embargo, solo 1 de los portadores presentaba el intervalo QT prolongado. En los otros 3 individuos se identificó una nueva mutación con cambio de sentido en los canales cardiacos Cav1.2 (p.S1961N). En este trabajo se analizaron las características funcionales de los canales p.S1961N Cav1.2 para averiguar si dicha mutación regula la expresividad del síndrome de QT largo en esta familia. Métodos: La corriente de calcio tipo L (ICaL) se registró mediante la técnica de patch-clamp en células de ovario de hámster chino transfectadas transitoriamente con los canales cardiacos humanos en su forma nativa o mutada. Resultados: La expresión de canales p.S1961N disminuye significativamente la densidad de la ICaL. Al sustituir el ion calcio por bario para suprimir la inactivación dependiente del calcio de los canales Cav1.2, se demostró que la mutación acelera significativamente la inactivación dependiente del voltaje de los canales Cav1.2 y disminuye la constante de tiempo de inactivación. Como consecuencia, la carga total que atraviesa los canales p.S1961N Cav1.2 disminuye significativamente. Los efectos que las mutaciones p.S1961N Cav1.2 y p.R1644H Nav1.5, por separado o en combinación, producen sobre las características de los potenciales de acción (PA) se simularon mediante un modelo matemático de PA ventriculares humanos. Los resultados demuestran que la mutación p.S1961N Cav1.2 abrevia la duración del PA y suprime la prolongación inducida por la mutación p.R1644H de los canales Nav1.5. Conclusiones: La mutación p.S1961N en los canales Cav1.2 disminuye la ICaL, un efecto que podría abreviar la duración de los PA ventriculares humanos. La presencia de esta mutación que disminuye la función de los canales Cav1.2 compensa funcionalmente los efectos producidos por la mutación de los canales Nav1.5 que aumenta su función y prolonga la duración de los PA


Introduction and objectives: A known long QT syndrome-related mutation in Nav1.5 cardiac channels (p.R1644H) was found in 4 members of a Spanish family but only 1 of them showed prolongation of the QT interval. In the other 3 relatives, a novel missense mutation in Cav1.2 cardiac channels was found (p.S1961N). Here, we functionally analyzed p.S1961N Cav1.2 channels to elucidate whether this mutation regulates the expressivity of the long QT syndrome phenotype in this family. Methods: L-type calcium current (ICaL) recordings were performed by using the whole-cell patch-clamp technique in Chinese hamster ovary cells transiently transfected with native and/or p.S1961N Cav1.2 channels. Results: Expression of p.S1961N channels significantly decreased ICaL density. Using Ba as a charge carrier to suppress the Ca-dependent inactivation of Cav1.2 channels, we demonstrated that the mutation significantly accelerates the voltage-dependent inactivation of Cav1.2 channels decreasing the inactivation time constant. As a consequence, the total charge flowing through p.S1961N Cav1.2 channels significantly decreased. The effects of the p.S1961N Cav1.2 and p.R1644H Nav1.5 mutations alone or their combination on the action potential (AP) morphology were simulated using a validated model of the human ventricular AP. The p.S1961N Cav1.2 mutation shortens the AP duration and abrogates the prolongation induced by p.R1644H Nav1.5 channels. Conclusions: The p.S1961N mutation in Cav1.2 channels decreased the ICaL, an effect which might shorten ventricular AP. The presence of the loss-of-function Cav1.2 mutation could functionally compensate the prolonging effects produced by the Nav1.5 gain-of-function mutation


Assuntos
Humanos , Masculino , Feminino , Adolescente , Adulto , Pessoa de Meia-Idade , Síndrome do QT Longo/genética , Heterozigoto , Transfecção/métodos , Mutagênese/genética , Canalopatias/genética , Canal de Sódio Disparado por Voltagem NAV1.1/genética , Canal de Sódio Disparado por Voltagem NAV1.5/genética , Doenças Genéticas Inatas , Mutação/genética , Eletrocardiografia/estatística & dados numéricos , Testes Genéticos/métodos , Técnicas de Patch-Clamp/métodos , Morte Súbita Cardíaca
18.
Forensic Sci Int ; 298: 80-87, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30878466

RESUMO

BACKGROUND: Genetic variation in ion channel genes ('channelopathies') are often associated with inherited arrhythmias and sudden death. Genetic testing ('molecular autopsies') of channelopathy genes can be used to assist in determining the likely causes of sudden unexpected death. However, different in silico approaches can yield conflicting pathogenicity predictions and assessing their impact on ion channel function can assist in this regard. METHODS AND RESULTS: We performed genetic testing of cases of sudden expected death in the New York City metropolitan area and found four rare or novel variants in ABCC9, which codes for the regulatory SUR2 subunit of KATP channels. All were missense variants, causing amino acid changes in the protein. Three of the variants (A355S, M941V, and K1379Q) were in cases of infants less than six-months old and one (H1305Y) was in an adult. The predicted pathogenicities of the variants were conflicting. We have introduced these variants into a human SUR2A cDNA, which we coexpressed with the Kir6.2 pore-forming subunit in HEK-293 cells and subjected to patch clamp and biochemical assays. Each of the four variants led to gain-of-function phenotypes. The A355S and M941V variants increased in the overall patch current. The sensitivity of the KATP channels to inhibitory 'cytosolic' ATP was repressed for the M941V, H1305Y and K1379Q variants. None of the variants had any effect on the unitary KATP channel current or the surface expression of KATP channels, as determined with biotinylation assays, suggesting that all of the variants led to an enhanced open state. CONCLUSIONS: All four variants caused a gain-of-function phenotype. Given the expression of SUR2-containing KATP channels in the heart and specialized cardiac conduction, vascular smooth muscle and respiratory neurons, it is conceivable that electrical silencing of these cells may contribute to the vulnerability element, which is a component of the triple risk model of sudden explained death in infants. The gain-of-function phenotype of these ABCC9 variants should be considered when assessing their potential pathogenicity.


Assuntos
Morte Súbita/etiologia , Mutação de Sentido Incorreto , Receptores Sulfonilureia/genética , Adulto , Canalopatias/genética , DNA Complementar , Feminino , Mutação com Ganho de Função , Células HEK293 , Humanos , Lactente , Canais KATP/genética , Masculino , Cidade de Nova Iorque , Técnicas de Patch-Clamp , Fenótipo
19.
Seizure ; 67: 11-14, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30849713

RESUMO

PURPOSE: Ryanodine receptor 2 (RYR2) mutation is well-established in the aetiology of an inherited cardiac disorder known as catecholaminergic polymorphic ventricular tachycardia (CPVT). The RYR2 receptor is expressed in cardiomyocytes, and also in the hippocampus. The RYR2 mutation has not been reported as a potential cause of adult-onset genetic generalised epilepsy (GGE). METHOD: Case report. RESULTS: A 32-year-old right-handed female presented with three unprovoked generalised seizures over twelve years. Electroencephalogram showed epileptiform activity which coincided with normal electrocardiogram recording. Her brother survived a cardiac arrest in his 20's and was diagnosed with CPVT and found to be heterozygous for a novel mutation in the RYR2 gene at chromosome 1q43, c.229 G > A p.(Ala77Thr). The patient inherited the same missense variant, predicted to be damaging by numerous in silico analytic tools. This mutation affects the N-terminal domain of the RYR2 receptor which plays a role in channel activation. However, the patient had repeatedly normal cardiac investigations including normal exercise stress tests. CONCLUSION: We propose that the RYR2 mutation is a potentially novel neurocardiac calcium channelopathy that may manifest with either CPVT or GGE depending on selective involvement of RYR2 receptors expressed in the heart or in the brain. RYR2 mutant mice have demonstrated spontaneous EEG-positive seizures independent of cardiac arrhythmia. Whole exome sequencing analyses have identified RYR2 as a candidate gene in GGE. This case is a reminder for careful assessment of episodes of transient loss of consciousness in an individual with CPVT, so as to not mistake possible neurogenic seizure for cardiogenic syncope, carrying obvious implications for treatment.


Assuntos
Canalopatias/diagnóstico , Canalopatias/genética , Epilepsia Generalizada/diagnóstico , Epilepsia Generalizada/genética , Mutação , Canal de Liberação de Cálcio do Receptor de Rianodina/genética , Adulto , Arritmias Cardíacas/diagnóstico , Arritmias Cardíacas/genética , Diagnóstico Diferencial , Feminino , Humanos
20.
Sci Transl Med ; 11(485)2019 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-30918116

RESUMO

Connexins and pannexins are two protein families that play an important role in cellular communication. Pannexin 1 (PANX1), one of the members of pannexin family, is a channel protein. It is glycosylated and forms three species, GLY0, GLY1, and GLY2. Here, we describe four independent families in which mutations in PANX1 cause familial or sporadic female infertility via a phenotype that we term "oocyte death." The mutations, which are associated with oocyte death, alter the PANX1 glycosylation pattern, influence the subcellular localization of PANX1 in cultured cells, and result in aberrant PANX1 channel activity, ATP release in oocytes, and mutant PANX1 GLY1. Overexpression of a patient-derived mutation in mice causes infertility, recapitulating the human oocyte death phenotype. Our findings demonstrate the critical role of PANX1 in human oocyte development, provide a genetic explanation for a subtype of infertility, and suggest a potential target for therapeutic intervention for this disease.


Assuntos
Canalopatias/genética , Canalopatias/patologia , Conexinas/genética , Infertilidade Feminina/genética , Infertilidade Feminina/patologia , Mutação , Proteínas do Tecido Nervoso/genética , Oócitos/metabolismo , Oócitos/patologia , Trifosfato de Adenosina/metabolismo , Adulto , Animais , Morte Celular/genética , Células Cultivadas , Canalopatias/metabolismo , Conexinas/metabolismo , Feminino , Fertilização In Vitro , Glicosilação , Humanos , Infertilidade Feminina/metabolismo , Masculino , Camundongos Mutantes , Camundongos Transgênicos , Proteínas do Tecido Nervoso/metabolismo , Linhagem , Fenótipo , Pesquisa Médica Translacional
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