title: Genetic Analysis of Arrhythmogenic Diseases in the Era of NGS: The Complexity of Clinical Decision-Making in Brugada Syndrome.
abstract: BACKGROUND
  The use of next-generation sequencing enables a rapid analysis of many genes associated with sudden cardiac death in diseases like Brugada Syndrome. Genetic variation is identified and associated with 30-35% of cases of Brugada Syndrome, with nearly 20-25% attributable to variants in SCN5A, meaning many cases remain undiagnosed genetically. To evaluate the role of genetic variants in arrhythmogenic diseases and the utility of next-generation sequencing, we applied this technology to resequence 28 main genes associated with arrhythmogenic disorders.
  
  
  METHODS
  A cohort of 45 clinically diagnosed Brugada Syndrome patients classified as SCN5A-negative was analyzed using next generation sequencing. Twenty-eight genes were resequenced: AKAP9, ANK2, CACNA1C, CACNB2, CASQ2, CAV3, DSC2, DSG2, DSP, GPD1L, HCN4, JUP, KCNE1, KCNE2, KCNE3, KCNH2, KCNJ2, KCNJ5, KCNQ1, NOS1AP, PKP2, RYR2, SCN1B, SCN3B, SCN4B, SCN5A, SNTA1, and TMEM43. A total of 85 clinically evaluated relatives were also genetically analyzed to ascertain familial segregation.
  
  
  CONCLUSIONS
  Twenty-two patients carried 30 rare genetic variants in 12 genes, only 4 of which were previously associated with Brugada Syndrome. Neither insertion/deletion nor copy number variation were detected. We identified genetic variants in novel candidate genes potentially associated to Brugada Syndrome. These include: 4 genetic variations in AKAP9 including a de novo genetic variation in 3 positive cases; 5 genetic variations in ANK2 detected in 4 cases; variations in KCNJ2 together with CASQ2 in 1 case; genetic variations in RYR2, including a de novo genetic variation and desmosomal proteins encoding genes including DSG2, DSP and JUP, detected in 3 of the cases. Larger gene panels or whole exome sequencing should be considered to identify novel genes associated to Brugada Syndrome. However, application of approaches such as whole exome sequencing would difficult the interpretation for clinical purposes due to the large amount of data generated. The identification of these genetic variants opens new perspectives on the implications of genetic background in the arrhythmogenic substrate for research purposes.
  
  
  CONCLUSIONS
  As a paradigm for other arrhythmogenic diseases and for unexplained sudden death, our data show that clinical genetic diagnosis is justified in a family perspective for confirmation of genetic causality. In the era of personalized medicine using high-throughput tools, clinical decision-making is increasingly complex.
authors.affiliation: Cardiovascular Genetics Center, IdIBGi-Universitat de Girona, Girona, Spain.
authors.forename: Catarina
authors.initials: C
authors.lastname: Allegue
authors.affiliation: Cardiovascular Genetics Center, IdIBGi-Universitat de Girona, Girona, Spain.
authors.forename: Mònica
authors.initials: M
authors.lastname: Coll
authors.affiliation: Cardiovascular Genetics Center, IdIBGi-Universitat de Girona, Girona, Spain.
authors.forename: Jesus
authors.initials: J
authors.lastname: Mates
authors.affiliation: Cardiovascular Genetics Center, IdIBGi-Universitat de Girona, Girona, Spain.
authors.forename: Oscar
authors.initials: O
authors.lastname: Campuzano
authors.affiliation: Cardiovascular Genetics Center, IdIBGi-Universitat de Girona, Girona, Spain.
authors.forename: Anna
authors.initials: A
authors.lastname: Iglesias
authors.affiliation: Grupo Medicina Xenómica, Instituto de Investigación Sanitaria de Santiago de Compostela, Santiago de Compostela, Spain; Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Sobrino
authors.affiliation: Grupo Medicina Xenómica, Instituto de Investigación Sanitaria de Santiago de Compostela, Santiago de Compostela, Spain; Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain.
authors.forename: Maria
authors.initials: M
authors.lastname: Brion
authors.affiliation: Grupo Medicina Xenómica, Instituto de Investigación Sanitaria de Santiago de Compostela, Santiago de Compostela, Spain; Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Amigo
authors.affiliation: Grupo Medicina Xenómica, Instituto de Investigación Sanitaria de Santiago de Compostela, Santiago de Compostela, Spain; Fundación Pública Galega de Medicina Xenómica, SERGAS, Santiago de Compostela, Spain; Center of Excellence in Genomic Medicine Research (CEGMR), King Abdulaziz University, Jeddah, Saudi Arabia.
authors.forename: Angel
authors.initials: A
authors.lastname: Carracedo
authors.affiliation: Heart Rhythm Management Center, UZ Brussel-VUB, Brussels, Belgium.
authors.forename: Pedro
authors.initials: P
authors.lastname: Brugada
authors.affiliation: Cardiology Unit, Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Brugada
authors.affiliation: Cardiovascular Genetics Center, IdIBGi-Universitat de Girona, Girona, Spain.
authors.forename: Ramon
authors.initials: R
authors.lastname: Brugada
mesh_terms: D054758:A Kinase Anchor Proteins / Q000235:genetics; D000328:Adult; D017487:Ankyrins / Q000235:genetics; D001145:Arrhythmias, Cardiac / Q000235:genetics; D053840:Brugada Syndrome / Q000175:diagnosis* / Q000235:genetics*; D002155:Calsequestrin / Q000235:genetics; D000066491:Clinical Decision-Making; D015331:Cohort Studies; D003598:Cytoskeletal Proteins / Q000235:genetics; D016757:Death, Sudden, Cardiac; D051301:Desmoglein 2 / Q000235:genetics; D051180:Desmoplakins / Q000235:genetics; D005260:Female; D005820:Genetic Testing; D014644:Genetic Variation; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D008297:Male; D008875:Middle Aged; D062554:NAV1.5 Voltage-Gated Sodium Channel / Q000235:genetics; D010375:Pedigree; D019683:Penetrance; D024661:Potassium Channels, Inwardly Rectifying / Q000235:genetics; D012189:Retrospective Studies; D019837:Ryanodine Receptor Calcium Release Channel / Q000235:genetics; D017422:Sequence Analysis, DNA; D051185:gamma Catenin
chemical_list: D054758:A Kinase Anchor Proteins; C119719:AKAP9 protein, human; C498994:ANK2 protein, human; D017487:Ankyrins; C443109:CASQ2 protein, human; D002155:Calsequestrin; D003598:Cytoskeletal Proteins; C495314:DSG2 protein, human; C495294:DSP protein, human; D051301:Desmoglein 2; D051180:Desmoplakins; C495292:JUP protein, human; C489457:KCNJ2 protein, human; D062554:NAV1.5 Voltage-Gated Sodium Channel; D024661:Potassium Channels, Inwardly Rectifying; D019837:Ryanodine Receptor Calcium Release Channel; C568320:SCN5A protein, human; D051185:gamma Catenin