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A novel three base-pair deletion in domain two of the cardiac sodium channel causes Brugada syndrome. J Electrocardiol 2018; 51:667-673. [PMID: 29997009 DOI: 10.1016/j.jelectrocard.2018.03.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 03/12/2018] [Accepted: 03/21/2018] [Indexed: 11/21/2022]
Abstract
INTRODUCTION Mutations within SCN5A are found in a significant proportion (15-30%) of Brugada syndrome (BrS) cases and impair sodium transport across excitable cardiac cells that mediate ventricular contractions. Genetic testing offers a means to clinically assess and manage affected individuals and their family members. METHODS AND RESULTS The proband at age 44 years old exhibited a syncopal event during exercise, and presented later with a spontaneous type-I BrS pattern on 12‑lead resting electrocardiogram (ECG). Mutational analysis performed across all SCN5A exons revealed a unique three base-pair deletion p.M741_T742delinsI (c.2223_2225delGAC), in a heterozygous state in the proband and 2 siblings. This mutation was not seen in a cohort of 105 ethnicity-matched controls or in public genome databases. Patch clamp electrophysiology study conducted in TSA201 cells showed an abolishment of sodium current (INa). The proband, and several relatives, also harboured a known SCN5A variant, p.R1193Q (c.3578G>A). CONCLUSION Our study has demonstrated the deleterious effect of a novel SCN5A mutation p.M741_T742delinsI (c.2223_2225delGAC). The findings highlight the complex effects of gender and age in phenotype manifestation. It also offers insights into improving the long-term management of BrS, and the utility of cascade genetic screening for risk stratification.
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Pablo Flórez J, García D, Valverde I, Rubín J, Pérez D, González-Vasserot M, Reguero J, María de la Hera J, Avanzas P, Gómez J, Coto E, Morís C, Calvo D. Role of syncope in predicting adverse outcomes in patients with suspected Brugada syndrome undergoing standardized flecainide testing. Europace 2017; 20:f64-f71. [DOI: 10.1093/europace/eux315] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2017] [Accepted: 09/11/2017] [Indexed: 11/14/2022] Open
Affiliation(s)
- Juan Pablo Flórez
- Department of Cadiology, Hospital Universitario Central de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
| | - Daniel García
- Department of Cadiology, Hospital Universitario Central de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
| | - Irene Valverde
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Department of Cadiology, Hospital de Cabueñes, C/Los Prados, 395, 33394 Gijón, Asturias, Spain
| | - José Rubín
- Department of Cadiology, Hospital Universitario Central de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
| | - Diego Pérez
- Department of Cadiology, Hospital Universitario Central de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
| | - Mar González-Vasserot
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Department of Cadiology, Hospital de Cabueñes, C/Los Prados, 395, 33394 Gijón, Asturias, Spain
| | - Julián Reguero
- Department of Cadiology, Hospital Universitario Central de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
| | - Jesús María de la Hera
- Department of Cadiology, Hospital Universitario Central de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
| | - Pablo Avanzas
- Department of Cadiology, Hospital Universitario Central de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
| | - Juan Gómez
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Department of Molecular Genetics, Hospital Universitario Central de Asturias, C/Avd. de Roma, s/n, 33006 Oviedo, Spain
| | - Eliecer Coto
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Department of Molecular Genetics, Hospital Universitario Central de Asturias, C/Avd. de Roma, s/n, 33006 Oviedo, Spain
| | - César Morís
- Department of Cadiology, Hospital Universitario Central de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
| | - David Calvo
- Department of Cadiology, Hospital Universitario Central de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
- Instituto de Investigación Sanitaria del Principado de Asturias, C/Avd de Roma, s/n, 33006 Oviedo, Spain
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Calvo D, Rubín JM, Pérez D, Gómez J, Flórez JP, Avanzas P, García-Ruíz JM, de la Hera JM, Reguero J, Coto E, Morís C. Time-dependent responses to provocative testing with flecainide in the diagnosis of Brugada syndrome. Heart Rhythm 2014; 12:350-7. [PMID: 25460174 DOI: 10.1016/j.hrthm.2014.10.036] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Indexed: 11/28/2022]
Abstract
BACKGROUND Time-dependent variability of electrocardiogram (ECG) in patients with Brugada syndrome could affect the interpretation of provocative testing. OBJECTIVE The aim of this study was to characterize ECG changes during and after flecainide infusion. METHODS We studied 59 consecutive patients. The ECG was continuously analyzed during the first 30 minutes of provocative testing, and a single ECG was recorded 60 minutes later. We analyzed CYP2D6 and CYP3A5 variants affecting flecainide metabolism and performed blinded measurements at lead II. RESULTS At baseline, ECG patterns were classified as follows: type II in 31 patients (53%), type III in 15 (25%), and normal ECG in 13 (22%). Because of induction of type I ECG, the percentage of responders progressively increased with longer recording time periods (6.8% in 10 minutes vs 11.9% in 20-30 minutes vs 18.6% in 90 minutes; P < .01). Four patients displayed a late response, which was evidenced 90 minutes after the initiation of provocative testing. QRS width differentially increased between responders and nonresponders (P < .01), with a maximum QRS width of 110 ms during the first 30 minutes being effective for identifying possible late responders (sensitivity 100%; specificity 85.6%; positive predictive value 88%; negative predictive value 100%). The incidence of CYP2D6 variants was lower in late responders than in early or delayed responders (0% vs 75% vs 100%; P = .04), while a homogeneous distribution of CYP3A5*3/*3 was observed in our population. CONCLUSION Response to flecainide exhibits time-dependent variability of ECG patterns and intervals. Longer periods of ECG recording increase the recognition probability of type I ECG.
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Affiliation(s)
| | | | | | - Juan Gómez
- Department of Molecular Genetics, Hospital Universitario Central de Asturias, Oviedo, Spain; Red de Investigación Renal (REDINREN), Hospital Universitario Central de Asturias, Oviedo, Spain
| | | | - Pablo Avanzas
- Cardiology Department, Hospital Universitario Central de Asturias, Oviedo, Spain
| | | | - Jesús María de la Hera
- Red de Investigación Renal (REDINREN), Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Julián Reguero
- Cardiology Department, Hospital Universitario Central de Asturias, Oviedo, Spain
| | - Eliecer Coto
- Department of Molecular Genetics, Hospital Universitario Central de Asturias, Oviedo, Spain; Red de Investigación Renal (REDINREN), Hospital Universitario Central de Asturias, Oviedo, Spain
| | - César Morís
- Cardiology Department, Hospital Universitario Central de Asturias, Oviedo, Spain
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