Congenital long QT syndrome (LQTS) is an inherited cardiac arrhythmia syndrome characterized
by a prolonged QT interval on the electrocardiogram.
1
Long QT syndrome type 3 (LQT3) is caused by gain-of-function variants in the SCN5A-encoded
α-subunit of the voltage-gated cardiac sodium (Na+) channel Nav1.5. LQT3-linked SCN5A variants typically interfere with fast inactivation
of the channel, which causes increased sustained inward Na+ current (INa) and prolongation of the cardiac action potential.
2
In addition, some variants such as p.D1790G can prolong the ventricular action potential
in the absence of an LQT3 variant-induced sustained Na+ current.
3
Regardless of the biophysical mechanism, the abnormal Na+ influx can lead to early afterdepolarizations, which in turn cause triggered activity
and the development of potentially fatal “torsades de pointes (TdP)-like” polymorphic
ventricular tachycardia.To read this article in full you will need to make a payment
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References
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Article info
Publication history
Published online: February 15, 2023
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This work was supported by National Institutes of Health (NIH) Grants R01-HL089598, R01-HL147108, R01-HL153350, and R01-HL160992 to Dr Wehrens; Baylor College of Medicine Medical Scientist Training Program T32-GM136611 Mr Oliver M. Moore and Ms Lauren E. Dorn; and NIH Grant F30-HL156669 to Mr Oliver M. Moore. Disclosures: Dr Wehrens is a co-founder of Elex Biotech, LLC, a start-up company developing RyR2 modifying drugs for heart disease; and is a consultant to Pfizer and Rocket Pharmaceuticals. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
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- Functional characterization and identification of a therapeutic for a novel SCN5A-F1760C variant causing type 3 long QT syndrome refractory to all guideline-directed therapiesHeart Rhythm
- PreviewPathogenic variants in the SCN5A-encoded Nav1.5 sodium channel cause type 3 long QT syndrome (LQT3). We present the case of an infant with severe LQT3 who was refractory to multiple pharmacologic therapies as well as bilateral stellate ganglionectomy. The patient’s novel variant, p.F1760C-SCN5A, involves a critical residue of the Nav1.5’s local anesthetic binding domain.
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