Author + information
- Received December 8, 2017
- Revision received March 13, 2018
- Accepted April 12, 2018
- Published online June 25, 2018.
- Priyanka Garg, PhDa,
- Angelos Oikonomopoulos, PhDa,
- Haodong Chen, PhDa,
- Yingxin Li, PhDa,
- Chi Keung Lam, PhDa,
- Karim Sallam, MDa,
- Marco Perez, MDa,b,
- Robert L. Lux, PhDc,
- Michael C. Sanguinetti, PhDc,d and
- Joseph C. Wu, MD, PhDa,∗ (, )@StanfordCVI
- aStanford Cardiovascular Institute and Department of Medicine, Division of Cardiology, Stanford University, Stanford, California
- bCenter for Inherited Cardiovascular Disease, Division of Cardiovascular Medicine, Stanford University, Stanford, California
- cNora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah
- dDivision of Cardiovascular Medicine, Department of Internal Medicine, University of Utah, Salt Lake City, Utah
- ↵∗Address for correspondence:
Dr. Joseph C. Wu, Lorry I. Lokey Stem Cell Research Building, 265 Campus Drive, Room G1120, Stanford, California 94305-5111.
Background The long QT syndrome (LQTS) is an arrhythmogenic disorder of QT interval prolongation that predisposes patients to life-threatening ventricular arrhythmias such as Torsades de pointes and sudden cardiac death. Clinical genetic testing has emerged as the standard of care to identify genetic variants in patients suspected of having LQTS. However, these results are often confounded by the discovery of variants of uncertain significance (VUS), for which there is insufficient evidence of pathogenicity.
Objectives The purpose of this study was to demonstrate that genome editing of patient-specific induced pluripotent stem cells (iPSCs) can be a valuable approach to delineate the pathogenicity of VUS in cardiac channelopathy.
Methods Peripheral blood mononuclear cells were isolated from a carrier with a novel missense variant (T983I) in the KCNH2 (LQT2) gene and an unrelated healthy control subject. iPSCs were generated using an integration-free Sendai virus and differentiated to iPSC-derived cardiomyocytes (CMs).
Results Whole-cell patch clamp recordings revealed significant prolongation of the action potential duration (APD) and reduced rapidly activating delayed rectifier K+ current (IKr) density in VUS iPSC-CMs compared with healthy control iPSC-CMs. ICA-105574, a potent IKr activator, enhanced IKr magnitude and restored normal action potential duration in VUS iPSC-CMs. Notably, VUS iPSC-CMs exhibited greater propensity to proarrhythmia than healthy control cells in response to high-risk torsadogenic drugs (dofetilide, ibutilide, and azimilide), suggesting a compromised repolarization reserve. Finally, the selective correction of the causal variant in iPSC-CMs using CRISPR/Cas9 gene editing (isogenic control) normalized the aberrant cellular phenotype, whereas the introduction of the homozygous variant in healthy control cells recapitulated hallmark features of the LQTS disorder.
Conclusions The results suggest that the KCNH2T983I VUS may be classified as potentially pathogenic.
- genome editing
- induced pluripotent stem cells
- long QT syndrome
- variant of uncertain significance
Funding support was received from the National Institutes of Health (NIH) through grants T32 EB009035 (to Dr. Garg) and NIH R01 HL113006, NIH R01 HL128170, R01 HL14131, R01 HL130020, and American Heart Association 17MERIT33610009 (to Dr. Wu). All authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received December 8, 2017.
- Revision received March 13, 2018.
- Accepted April 12, 2018.
- 2018 American College of Cardiology Foundation
This article requires a subscription or purchase to view the full text. If you are a subscriber or member, click Login or the Subscribe link (top menu above) to access this article.