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Zhou W, Ye D, Tester DJ, Bains S, Giudicessi JR, Haglund-Turnquist CM, Orland KM, January CT, Eckhardt LL, Maginot KR, Ackerman MJ. Elucidation of ALG10B as a Novel Long-QT Syndrome-Susceptibility Gene. Circ Genom Precis Med 2023; 16:e003726. [PMID: 37071726 PMCID: PMC10844923 DOI: 10.1161/circgen.122.003726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Accepted: 11/04/2022] [Indexed: 02/24/2023]
Abstract
BACKGROUND Long-QT syndrome (LQTS) is characterized by QT prolongation and increased risk for syncope, seizures, and sudden cardiac death. The majority of LQTS stems from pathogenic mutations in KCNQ1, KCNH2, or SCN5A. However, ≈10% of patients with LQTS remain genetically elusive. We utilized genome sequencing to identify a novel LQTS genetic substrate in a multigenerational genotype-negative LQTS pedigree. METHODS Genome sequencing was performed on 5 affected family members. Only rare nonsynonymous variants present in all affected family members were considered. The candidate variant was characterized functionally in patient-derived induced pluripotent stem cell and gene-edited, variant corrected, isogenic control induced pluripotent stem cell-derived cardiomyocytes. RESULTS A missense variant (p.G6S) was identified in ALG10B-encoded α-1,2-glucosyltransferase B protein. ALG10B (alpha-1,2-glucosyltransferase B protein) is a known interacting protein of KCNH2-encoded Kv11.1 (HERG [human Ether-à-go-go-related gene]). Compared with isogenic control, ALG10B-p.G6S induced pluripotent stem cell-derived cardiomyocytes showed (1) decreased protein expression of ALG10B (p.G6S, 0.7±0.18, n=8 versus control, 1.25±0.16, n=9; P<0.05), (2) significant retention of HERG in the endoplasmic reticulum (P<0.0005), and (3) a significantly prolonged action potential duration confirmed by both patch clamp (p.G6S, 531.1±38.3 ms, n=15 versus control, 324.1±21.8 ms, n=13; P<0.001) and multielectrode assay (P<0.0001). Lumacaftor-a compound known to rescue HERG trafficking-shortened the pathologically prolonged action potential duration of ALG10B-p.G6S induced pluripotent stem cell-derived cardiomyocytes by 10.6% (n=31 electrodes; P<0.001). CONCLUSIONS Here, we demonstrate that ALG10B-p.G6S downregulates ALG10B, resulting in defective HERG trafficking and action potential duration prolongation. Therefore, ALG10B is a novel LQTS-susceptibility gene underlying the LQTS phenotype observed in a multigenerational pedigree. ALG10B mutation analysis may be warranted, especially in genotype-negative patients with an LQT2-like phenotype.
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Affiliation(s)
- Wei Zhou
- Departments of Cardiovascular Medicine (Division of Heart
Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric
Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland
Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - Dan Ye
- Departments of Cardiovascular Medicine (Division of Heart
Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric
Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland
Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - David J. Tester
- Departments of Cardiovascular Medicine (Division of Heart
Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric
Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland
Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - Sahej Bains
- Departments of Cardiovascular Medicine (Division of Heart
Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric
Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland
Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - John R. Giudicessi
- Departments of Cardiovascular Medicine (Division of Heart
Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric
Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland
Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
- Departments of Cardiovascular Medicine
(Clinician-Investigator Training Program), Mayo Clinic, Rochester, MN
| | - Carla M. Haglund-Turnquist
- Departments of Cardiovascular Medicine (Division of Heart
Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric
Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland
Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - Kate M. Orland
- Department of Medicine, Division of Cardiovascular
Medicine, Cellular and Molecular Arrhythmia Research Program and Inherited
Arrhythmia Clinic, University of Wisconsin-Madison, Madison, WI
| | - Craig T. January
- Department of Medicine, Division of Cardiovascular
Medicine, Cellular and Molecular Arrhythmia Research Program and Inherited
Arrhythmia Clinic, University of Wisconsin-Madison, Madison, WI
| | - Lee L. Eckhardt
- Department of Medicine, Division of Cardiovascular
Medicine, Cellular and Molecular Arrhythmia Research Program and Inherited
Arrhythmia Clinic, University of Wisconsin-Madison, Madison, WI
| | - Kathleen R. Maginot
- Department of Pediatrics, University of Wisconsin School of
Medicine and Public Health, Madison, WI
| | - Michael J. Ackerman
- Departments of Cardiovascular Medicine (Division of Heart
Rhythm Services), Pediatric and Adolescent Medicine (Division of Pediatric
Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland
Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
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Tobert KE, Tester DJ, Zhou W, Haglund-Turnquist CM, Giudicessi JR, Ackerman MJ. Genome Sequencing in a Genetically Elusive Multi-Generational Long QT Syndrome Pedigree Identifies a Novel LQT2-Causative Deeply Intronic KCNH2 Variant. Heart Rhythm 2022; 19:998-1007. [PMID: 35144019 DOI: 10.1016/j.hrthm.2022.02.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 01/31/2022] [Accepted: 02/01/2022] [Indexed: 12/13/2022]
Abstract
BACKGROUND Most of long QT syndrome (LQTS) stems from pathogenic variants in KCNQ1, KCNH2, or SCN5A. However, ∼10-20% of LQTS index cases remain genotype-negative. OBJECTIVE Here, we identified and characterized functionally a novel LQTS genetic substrate in a multi-generational, "genotype-negative" LQTS pedigree. METHODS The patient was a 40-year-old female with a history of syncope, seizures, ventricular fibrillation, and a family history of LQTS and sudden death. Commercial genetic testing of all LQTS-causative genes was negative. Genome sequencing was performed on 6 affected family members. Patient-specific and CRISPR/Cas9 "gene-corrected" isogenic control induced pluripotent stem cell-derived cardiomyocytes (iPSC-CMs) were generated. RESULTS No ultra-rare, nonsynonymous heterozygous variants co-segregated among the 6 LQTS phenotype-positive individuals. Instead, a deep intronic KCNH2 variant (c.3331-316G>T) was present in all affected individuals. RT-PCR analysis of patient-specific iPSC-CM-derived RNA revealed that c.3331-316G>T creates a novel 89 base-pair exon that results in a frame-shift variant (p.S1112Pfs*171). The action potential duration (APD90) was significantly longer in p.S1112Pfs*171-iPSC-CMs (602.4 ± 12.2 ms, n=70) compared to isogenic control iPSC-CMs (425.7 ± 9.3 ms, n=61, p<0.0001). Further, the field potential duration (FPD) was significantly longer in p.S1112Pfs*171-iPSC-CMs (358.9 ± 7.7 ms, n=65) compared to isogenic control iPSC-CMs (282.2 ± 10.8 ms, n=51, p<0.0001). CONCLUSIONS A novel deep intronic KCNH2 variant was identified in a multi-generational, genetically elusive LQTS pedigree. The iPSC-CMs establish that the variant is the monogenetic cause for this family's LQTS. Deep intronic variants within the two most common LQTS-susceptibility genes should be considered in patients with seemingly, genetically elusive LQTS.
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Affiliation(s)
- Kathryn E Tobert
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - David J Tester
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - Wei Zhou
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - Carla M Haglund-Turnquist
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN
| | - John R Giudicessi
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN; Departments of Cardiovascular Medicine (Clinician-Investigator Training Program), Mayo Clinic, Rochester, MN
| | - Michael J Ackerman
- Departments of Cardiovascular Medicine (Division of Heart Rhythm Services, Windland Smith Rice Genetic Heart Rhythm Clinic), Pediatric and Adolescent Medicine (Division of Pediatric Cardiology), and Molecular Pharmacology & Experimental Therapeutics (Windland Smith Rice Sudden Death Genomics Laboratory), Mayo Clinic, Rochester, MN.
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Tester DJ, Bombei HM, Fitzgerald KK, Giudicessi JR, Pitel BA, Thorland EC, Russell BG, Hamrick SK, Kim CSJ, Haglund-Turnquist CM, Johnsrude CL, Atkins DL, Ochoa Nunez LA, Law I, Temple J, Ackerman MJ. Identification of a Novel Homozygous Multi-Exon Duplication in RYR2 Among Children With Exertion-Related Unexplained Sudden Deaths in the Amish Community. JAMA Cardiol 2021; 5:13-18. [PMID: 31913406 DOI: 10.1001/jamacardio.2019.5400] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Importance The exome molecular autopsy may elucidate a pathogenic substrate for sudden unexplained death. Objective To investigate the underlying cause of multiple sudden deaths in young individuals and sudden cardiac arrests that occurred in 2 large Amish families. Design, Setting, and Participants Two large extended Amish families with multiple sudden deaths in young individuals and sudden cardiac arrests were included in the study. A recessive inheritance pattern was suggested based on an extended family history of sudden deaths in young individuals and sudden cardiac arrests, despite unaffected parents. A family with exercise-associated sudden deaths in young individuals occurring in 4 siblings was referred for postmortem genetic testing using an exome molecular autopsy. Copy number variant (CNV) analysis was performed on exome data using PatternCNV. Chromosomal microarray validated the CNV identified. The nucleotide break points of the CNV were determined by mate-pair sequencing. Samples were collected for this study between November 2004 and June 2019. Main Outcomes and Measures The identification of an underlying genetic cause for sudden deaths in young individuals and sudden cardiac arrests consistent with the recessive inheritance pattern observed in the families. Results A homozygous duplication, involving approximately 26 000 base pairs of intergenic sequence, RYR2's 5'UTR/promoter region, and exons 1 through 4 of RYR2, was identified in all 4 siblings of a family. Multiple distantly related relatives experiencing exertion-related sudden cardiac arrest also had the identical RYR2 homozygous duplication. A second, unrelated family with multiple exertion-related sudden deaths and sudden cardiac arrests in young individuals, with the same homozygous duplication, was identified. Several living, homozygous duplication-positive symptomatic patients from both families had nondiagnostic cardiologic testing, with only occasional ventricular ectopy occurring during exercise stress tests. Conclusions and Relevance In this analysis, we identified a novel, highly penetrant, homozygous multiexon duplication in RYR2 among Amish youths with exertion-related sudden death and sudden cardiac arrest but without an overt phenotype that is distinct from RYR2-mediated catecholaminergic polymorphic ventricular tachycardia. Considering that no cardiac tests reliably identify at-risk individuals and given the high rate of consanguinity in Amish families, identification of unaffected heterozygous carriers may provide potentially lifesaving premarital counseling and reproductive planning.
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Affiliation(s)
- David J Tester
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
| | - Hannah M Bombei
- Stead Family Children's Hospital, Division of Pediatric Cardiology, University of Iowa, Iowa City
| | - Kristi K Fitzgerald
- Nemours Cardiac Center, Alfred I. duPont Hospital for Children, Wilmington, Delaware
| | - John R Giudicessi
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
| | - Beth A Pitel
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.,Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Erik C Thorland
- Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, Minnesota.,Genomics Laboratory, Mayo Clinic, Rochester, Minnesota
| | - Barbara G Russell
- Division of Pediatric Cardiology, University of Louisville, Louisville, Kentucky
| | - Samantha K Hamrick
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
| | - C S John Kim
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
| | - Carla M Haglund-Turnquist
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
| | | | - Dianne L Atkins
- Stead Family Children's Hospital, Division of Pediatric Cardiology, University of Iowa, Iowa City
| | - Luis A Ochoa Nunez
- Stead Family Children's Hospital, Division of Pediatric Cardiology, University of Iowa, Iowa City
| | - Ian Law
- Stead Family Children's Hospital, Division of Pediatric Cardiology, University of Iowa, Iowa City
| | - Joel Temple
- Nemours Cardiac Center, Alfred I. duPont Hospital for Children, Wilmington, Delaware
| | - Michael J Ackerman
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic, Rochester, Minnesota.,Division of Heart Rhythm Services, Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota.,Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota
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Tester DJ, Kim CSJ, Hamrick SK, Ye D, O'Hare BJ, Bombei HM, Fitzgerald KK, Haglund-Turnquist CM, Atkins DL, Nunez LAO, Law I, Temple J, Ackerman MJ. Molecular characterization of the calcium release channel deficiency syndrome. JCI Insight 2020; 5:135952. [PMID: 32663189 PMCID: PMC7455073 DOI: 10.1172/jci.insight.135952] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 07/01/2020] [Indexed: 11/26/2022] Open
Abstract
We identified a potentially novel homozygous duplication involving the promoter region and exons 1–4 of the gene encoding type 2 cardiac ryanodine receptor (RYR2) that is responsible for highly penetrant, exertion-related sudden deaths/cardiac arrests in the Amish community without an overt phenotype to suggest RYR2-mediated catecholaminergic polymorphic ventricular tachycardia (CPVT). Homozygous RYR2 duplication (RYR2-DUP) induced pluripotent stem cell cardiomyocytes (iPSC-CMs) were generated from 2 unrelated patients. There was no difference in baseline Ca2+ handling measurements between WT-iPSC-CM and RYR2-DUP-iPSC-CM lines. However, compared with WT-iPSC-CMs, both patient lines demonstrated a dramatic reduction in caffeine-stimulated and isoproterenol-stimulated (ISO-stimulated) Ca2+ transient amplitude, suggesting RyR2 loss of function. There was a greater than 50% reduction in RYR2 transcript/RyR2 protein expression in both patient iPSC-CMs compared with WT. Delayed afterdepolarization was observed in the RYR2-DUP-iPSC-CMs but not in the WT-iPSC-CMs. Compared with WT-iPSC-CMs, there was significantly elevated arrhythmic activity in the RYR2-DUP-iPSC-CMs in response to ISO. Nadolol, propranolol, and flecainide reduced erratic activity by 8.5-fold, 6.8-fold, and 2.4-fold, respectively, from ISO challenge. Unlike the gain-of-function mechanism observed in RYR2-mediated CPVT, the homozygous multiexon duplication precipitated a dramatic reduction in RYR2 transcription and RyR2 protein translation, a loss of function in calcium handling, and a calcium-induced calcium release apparatus that is insensitive to catecholamines and caffeine. Molecular and functional characterization of the calcium release channel deficiency syndrome in patient-specific induced pluripotent stem cell-cardiomyocytes.
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Affiliation(s)
- David J Tester
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - C S John Kim
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Samantha K Hamrick
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Dan Ye
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Bailey J O'Hare
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Hannah M Bombei
- Division of Cardiology, University of Iowa Stead Family Children's Hospital, Iowa City, Iowa, USA
| | - Kristi K Fitzgerald
- Nemours Cardiac Center, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware, USA
| | - Carla M Haglund-Turnquist
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
| | - Dianne L Atkins
- Division of Cardiology, University of Iowa Stead Family Children's Hospital, Iowa City, Iowa, USA
| | - Luis A Ochoa Nunez
- Division of Cardiology, University of Iowa Stead Family Children's Hospital, Iowa City, Iowa, USA
| | - Ian Law
- Division of Cardiology, University of Iowa Stead Family Children's Hospital, Iowa City, Iowa, USA
| | - Joel Temple
- Nemours Cardiac Center, Nemours/Alfred I. duPont Hospital for Children, Wilmington, Delaware, USA
| | - Michael J Ackerman
- Windland Smith Rice Sudden Death Genomics Laboratory, Department of Molecular Pharmacology and Experimental Therapeutics; Division of Heart Rhythm Services, Department of Cardiovascular Medicine; and Division of Pediatric Cardiology, Department of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, Minnesota, USA
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