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Greiner AM, Mehdi H, Cevan C, Gutmann R, London B. The role of GPD1L, a sodium channel interacting gene, in the pathogenesis of Brugada Syndrome. Front Med (Lausanne) 2024; 10:1159586. [PMID: 38962240 PMCID: PMC11221213 DOI: 10.3389/fmed.2023.1159586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 03/06/2023] [Indexed: 07/05/2024] Open
Abstract
Background Brugada Syndrome (BrS) is an inherited arrhythmia syndrome in which mutations in the cardiac sodium channel SCN5A (NaV1.5) account for approximately 20% of cases. Mutations in sodium channel-modifying genes may account for additional BrS cases, though BrS may be polygenic given common SNPs associated with BrS have been identified. Recent analysis, however, has suggested that SCN5A should be regarded as the sole monogenic cause of BrS. Objective We sought to re-assess the genetic underpinnings of BrS in a large mutligenerational family with a putative mutation in GPD1L that affects surface membrane expression of NaV1.5 in vitro. Methods Fine linkage mapping was performed in the family using the Illumina Global Screening Array. Whole exome sequencing of the proband was performed to identify rare variants and mutations, and Sanger sequencing was used to assay previously-reported risk single nucleotide polymorphsims (SNPs) for BrS. Results Linkage analysis decreased the size of the previously-reported microsatellite linkage region to approximately 3 Mb. GPD1L-A280V was the only coding non-synonymous variation present at less than 1% allele frequency in the proband within the linkage region. No rare non-synonymous variants were present outside the linkage area in affected individuals in genes associated with BrS. Risk SNPs known to predispose to BrS were overrepresented in affected members of the family. Conclusion Together, our data suggest GPD1L-A280V remains the most likely cause of BrS in this large multigenerational family. While care should be taken in interpreting variant pathogenicity given the genetic uncertainty of BrS, our data support inclusion of other putative BrS genes in clinical genetic panels.
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Affiliation(s)
- Alexander M. Greiner
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, United States
- Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA, United States
- University of Iowa Interdisciplinary Graduate Program in Genetics, Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA, United States
| | - Haider Mehdi
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, United States
- Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Chloe Cevan
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Rebecca Gutmann
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Barry London
- Division of Cardiovascular Medicine, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, United States
- Department of Internal Medicine, Abboud Cardiovascular Research Center, University of Iowa Carver College of Medicine, Iowa City, IA, United States
- University of Iowa Interdisciplinary Graduate Program in Genetics, Interdisciplinary Graduate Program in Genetics, University of Iowa, Iowa City, IA, United States
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Muhammad A, Calandranis ME, Li B, Yang T, Blackwell DJ, Harvey ML, Smith JE, Daniel ZA, Chew AE, Capra JA, Matreyek KA, Fowler DM, Roden DM, Glazer AM. High-throughput functional mapping of variants in an arrhythmia gene, KCNE1, reveals novel biology. Genome Med 2024; 16:73. [PMID: 38816749 PMCID: PMC11138074 DOI: 10.1186/s13073-024-01340-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Accepted: 04/26/2024] [Indexed: 06/01/2024] Open
Abstract
BACKGROUND KCNE1 encodes a 129-residue cardiac potassium channel (IKs) subunit. KCNE1 variants are associated with long QT syndrome and atrial fibrillation. However, most variants have insufficient evidence of clinical consequences and thus limited clinical utility. METHODS In this study, we leveraged the power of variant effect mapping, which couples saturation mutagenesis with high-throughput sequencing, to ascertain the function of thousands of protein-coding KCNE1 variants. RESULTS We comprehensively assayed KCNE1 variant cell surface expression (2554/2709 possible single-amino-acid variants) and function (2534 variants). Our study identified 470 loss- or partial loss-of-surface expression and 574 loss- or partial loss-of-function variants. Of the 574 loss- or partial loss-of-function variants, 152 (26.5%) had reduced cell surface expression, indicating that most functionally deleterious variants affect channel gating. Nonsense variants at residues 56-104 generally had WT-like trafficking scores but decreased functional scores, indicating that the latter half of the protein is dispensable for protein trafficking but essential for channel function. 22 of the 30 KCNE1 residues (73%) highly intolerant of variation (with > 70% loss-of-function variants) were in predicted close contact with binding partners KCNQ1 or calmodulin. Our functional assay data were consistent with gold standard electrophysiological data (ρ = - 0.64), population and patient cohorts (32/38 presumed benign or pathogenic variants with consistent scores), and computational predictors (ρ = - 0.62). Our data provide moderate-strength evidence for the American College of Medical Genetics/Association of Molecular Pathology functional criteria for benign and pathogenic variants. CONCLUSIONS Comprehensive variant effect maps of KCNE1 can both provide insight into I Ks channel biology and help reclassify variants of uncertain significance.
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Affiliation(s)
- Ayesha Muhammad
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, 1235 Medical Research Building IV, 2215B Garland Avenue, Nashville, TN, 37232, USA
- Medical Scientist Training Program, Vanderbilt University, Nashville, TN, 37232, USA
| | - Maria E Calandranis
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Bian Li
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Regeneron Pharmaceuticals Inc., Tarrytown, NY, USA
| | - Tao Yang
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Daniel J Blackwell
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - M Lorena Harvey
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Jeremy E Smith
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Zerubabell A Daniel
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Ashli E Chew
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - John A Capra
- Bakar Computational Health Sciences Institute and Department of Epidemiology and Biostatistics, University of California, San Francisco, CA, 94143, USA
| | - Kenneth A Matreyek
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA
| | - Douglas M Fowler
- Department of Genome Sciences, University of Washington, Seattle, WA, 98195, USA
| | - Dan M Roden
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, 1235 Medical Research Building IV, 2215B Garland Avenue, Nashville, TN, 37232, USA
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
- Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, 37232, USA
| | - Andrew M Glazer
- Vanderbilt Genetics Institute, Vanderbilt University Medical Center, 1235 Medical Research Building IV, 2215B Garland Avenue, Nashville, TN, 37232, USA.
- Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, 37232, USA.
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Lopez-Medina AI, Chahal CAA, Luzum JA. The genetics of drug-induced QT prolongation: evaluating the evidence for pharmacodynamic variants. Pharmacogenomics 2022; 23:543-557. [PMID: 35698903 DOI: 10.2217/pgs-2022-0027] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Drug-induced long QT syndrome (diLQTS) is an adverse effect of many commonly prescribed drugs, and it can increase the risk for lethal ventricular arrhythmias. Genetic variants in pharmacodynamic genes have been associated with diLQTS, but the strength of the evidence for each of those variants has not yet been evaluated. Therefore, the purpose of this review was to evaluate the strength of the evidence for pharmacodynamic genetic variants associated with diLQTS using a novel, semiquantitative scoring system modified from the approach used for congenital LQTS. KCNE1-D85N and KCNE2-T8A had definitive and strong evidence for diLQTS, respectively. The high level of evidence for these variants supports current consideration as risk factors for patients that will be prescribed a QT-prolonging drug.
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Affiliation(s)
- Ana I Lopez-Medina
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI 48109, USA
| | - Choudhary Anwar A Chahal
- Division of Cardiovascular Medicine, Hospital of the University of Pennsylvania, Philadelphia, PA 19104, USA.,Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN 55905, USA.,Barts Heart Centre, St. Bartholomew's Hospital, West Smithfield, London, EC1A 7BE, UK.,WellSpan Health, Lancaster, PA 17607, USA
| | - Jasmine A Luzum
- Department of Clinical Pharmacy, University of Michigan College of Pharmacy, Ann Arbor, MI 48109, USA
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Roden DM. A current understanding of drug-induced QT prolongation and its implications for anticancer therapy. Cardiovasc Res 2020; 115:895-903. [PMID: 30689740 DOI: 10.1093/cvr/cvz013] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/18/2018] [Accepted: 01/16/2019] [Indexed: 01/08/2023] Open
Abstract
The QT interval, a global index of ventricular repolarization, varies among individuals and is influenced by diverse physiologic and pathophysiologic stimuli such as gender, age, heart rate, electrolyte concentrations, concomitant cardiac disease, and other diseases such as diabetes. Many drugs produce a small but reproducible effect on QT interval but in rare instances this is exaggerated and marked QT prolongation can provoke the polymorphic ventricular tachycardia 'torsades de pointes', which can cause syncope or sudden cardiac death. The generally accepted common mechanism whereby drugs prolong QT is block of a key repolarizing potassium current in heart, IKr, generated by expression of KCNH2, also known as HERG. Thus, evaluation of the potential that a new drug entity may cause torsades de pointes has relied on exposure of normal volunteers or patients to drug at usual and high concentrations, and on assessment of IKr block in vitro. More recent work, focusing on anticancer drugs with QT prolonging liability, is defining new pathways whereby drugs can prolong QT. Notably, the in vitro effects of some tyrosine kinase inhibitors to prolong cardiac action potentials (the cellular correlate of QT) can be rescued by intracellular phosphatidylinositol 3,4,5-trisphosphate, the downstream effector of phosphoinositide 3-kinase. This finding supports a role for inhibition of this enzyme, either directly or by inhibition of upstream kinases, to prolong QT through mechanisms that are being worked out, but include enhanced inward 'late' sodium current during the plateau of the action potential. The definition of non-IKr-dependent pathways to QT prolongation will be important for assessing risk, not only with anticancer therapies but also with other QT prolonging drugs and for generating a refined understanding how variable activity of intracellular signalling systems can modulate QT and associated arrhythmia risk.
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Affiliation(s)
- Dan M Roden
- Department of Medicine, Vanderbilt University Medical Center, 2215B Garland Avenue, Room 1285B, Nashville, TN, USA.,Department of Pharmacology, Vanderbilt University Medical Center, 2215B Garland Avenue, Room 1285B, Nashville, TN, USA.,Department of Biomedical Informatics, Vanderbilt University Medical Center, 2215B Garland Avenue, Room 1285B, Nashville, TN, USA
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