title: Exome Sequencing Identifies a Novel LMNA Splice-Site Mutation and Multigenic Heterozygosity of Potential Modifiers in a Family with Sick Sinus Syndrome, Dilated Cardiomyopathy, and Sudden Cardiac Death.
abstract: The goals are to understand the primary genetic mechanisms that cause Sick Sinus Syndrome and to identify potential modifiers that may result in intrafamilial variability within a multigenerational family. The proband is a 63-year-old male with a family history of individuals (>10) with sinus node dysfunction, ventricular arrhythmia, cardiomyopathy, heart failure, and sudden death. We used exome sequencing of a single individual to identify a novel LMNA mutation and demonstrated the importance of Sanger validation and family studies when evaluating candidates. After initial single-gene studies were negative, we conducted exome sequencing for the proband which produced 9 gigabases of sequencing data. Bioinformatics analysis showed 94% of the reads mapped to the reference and identified 128,563 unique variants with 108,795 (85%) located in 16,319 genes of 19,056 target genes. We discovered multiple variants in known arrhythmia, cardiomyopathy, or ion channel associated genes that may serve as potential modifiers in disease expression. To identify candidate mutations, we focused on ~2,000 variants located in 237 genes of 283 known arrhythmia, cardiomyopathy, or ion channel associated genes. We filtered the candidates to 41 variants in 33 genes using zygosity, protein impact, database searches, and clinical association. Only 21 of 41 (51%) variants were validated by Sanger sequencing. We selected nine confirmed variants with minor allele frequencies <1% for family studies. The results identified LMNA c.357-2A>G, a novel heterozygous splice-site mutation as the primary mutation with rare or novel variants in HCN4, MYBPC3, PKP4, TMPO, TTN, DMPK and KCNJ10 as potential modifiers and a mechanism consistent with haploinsufficiency.
authors.affiliation: UC Irvine Cardiogenomics Program, Department of Pediatrics, Division of Genetics & Genomics and Department of Biological Sciences, University of California Irvine, Irvine, California, United States of America.
authors.forename: Michael V
authors.initials: MV
authors.lastname: Zaragoza
authors.affiliation: UC Irvine Cardiogenomics Program, Department of Pediatrics, Division of Genetics & Genomics and Department of Biological Sciences, University of California Irvine, Irvine, California, United States of America.
authors.forename: Lianna
authors.initials: L
authors.lastname: Fung
authors.affiliation: UC Irvine Cardiogenomics Program, Department of Pediatrics, Division of Genetics & Genomics and Department of Biological Sciences, University of California Irvine, Irvine, California, United States of America.
authors.forename: Ember
authors.initials: E
authors.lastname: Jensen
authors.affiliation: UC Irvine Cardiogenomics Program, Department of Pediatrics, Division of Genetics & Genomics and Department of Biological Sciences, University of California Irvine, Irvine, California, United States of America.
authors.forename: Frances
authors.initials: F
authors.lastname: Oh
authors.affiliation: UC Irvine Cardiogenomics Program, Department of Pediatrics, Division of Genetics & Genomics and Department of Biological Sciences, University of California Irvine, Irvine, California, United States of America.
authors.forename: Katherine
authors.initials: K
authors.lastname: Cung
authors.affiliation: Department of Biomedical Engineering and The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California Irvine, Irvine, California, United States of America.
authors.forename: Linda A
authors.initials: LA
authors.lastname: McCarthy
authors.affiliation: UC Irvine Cardiogenomics Program, Department of Pediatrics, Division of Genetics & Genomics and Department of Biological Sciences, University of California Irvine, Irvine, California, United States of America.
authors.forename: Christine K
authors.initials: CK
authors.lastname: Tran
authors.affiliation: UC Irvine Cardiogenomics Program, Department of Pediatrics, Division of Genetics & Genomics and Department of Biological Sciences, University of California Irvine, Irvine, California, United States of America.
authors.forename: Van
authors.initials: V
authors.lastname: Hoang
authors.affiliation: UC Irvine Cardiogenomics Program, Department of Pediatrics, Division of Genetics & Genomics and Department of Biological Sciences, University of California Irvine, Irvine, California, United States of America.
authors.forename: Simin A
authors.initials: SA
authors.lastname: Hakim
authors.affiliation: Department of Biomedical Engineering and The Edwards Lifesciences Center for Advanced Cardiovascular Technology, University of California Irvine, Irvine, California, United States of America.
authors.forename: Anna
authors.initials: A
authors.lastname: Grosberg
mesh_terms: D000328:Adult; D000483:Alleles; D015415:Biomarkers; D002311:Cardiomyopathy, Dilated / Q000175:diagnosis / Q000235:genetics*; D004252:DNA Mutational Analysis; D016757:Death, Sudden, Cardiac / Q000209:etiology*; D059472:Exome; D005260:Female; D020869:Gene Expression Profiling; D005787:Gene Frequency; D056726:Genetic Association Studies; D018740:Genetic Heterogeneity; D020022:Genetic Predisposition to Disease; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D034904:Lamin Type A / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D022821:RNA Splice Sites; D015203:Reproducibility of Results; D017422:Sequence Analysis, DNA; D012804:Sick Sinus Syndrome / Q000175:diagnosis / Q000235:genetics*
chemical_list: D015415:Biomarkers; C494847:LMNA protein, human; D034904:Lamin Type A; D022821:RNA Splice Sites