We investigated the genetic causes in patients with prolonged QTc intervals who were negative for pathogenic variants in three major LQTS-related genes (KCNQ1, KCNH2, and SCN5A).
The study included 59 LQT1 and 72 LQT2 patients from the Rochester-based LQTS Registry with corrected QT (QT<sub>c</sub>) prolongation and a history of AD therapy.
Long QT syndrome mutations in the SCN5A gene are associated with an enhanced late sodium current (I<sub>Na,L</sub>) which may lead to pro-arrhythmic action potential prolongation and intracellular calcium dysregulation.
It has been suggested that ∼10%-20% of rare LQTS case-derived variants in the literature may have been published erroneously as LQT1-causative mutations and may be "false positives."
Retrospective review was used to compare demographics, symptomatology, and QT parameters of individuals with p.Asp85Asn-KCNE1 in the absence of other rare/ultra-rare variants in LQTS-susceptibility genes and those who underwent comprehensive LQTS genetic testing.
Catecholaminergic polymorphic ventricular tachycardia (CPVT) has been often misdiagnosed as long QT syndrome (LQTS) type 1 (LQT1), which phenotypically mimics CPVT but has a relatively better prognosis.
We aimed to investigate if a KCNQ1 variant [p.(Pro64_Pro70del)], previously reported as pathogenic, contributes to the long-QT syndrome phenotype, co-segregates with disease or affects KCNQ1 function in vitro.
Our study consisted of 1,923 U.S. subjects from the Rochester-based LQTS Registry with genotype-positive LQT1 (n = 879), LQT2 (n = 807), and LQT3 (n = 237).
Our study consisted of 1,923 U.S. subjects from the Rochester-based LQTS Registry with genotype-positive LQT1 (n = 879), LQT2 (n = 807), and LQT3 (n = 237).
Deletion of QKP1507-1509 amino-acids in SCN5A gene product, the voltage-gated Na<sup>+</sup> channel Nav1.5, has been associated with a large phenotypic spectrum of type 3 long QT syndrome, conduction disorder, dilated cardiomyopathy and high incidence of sudden death.
Complex aberrant splicing in the induced pluripotent stem cell-derived cardiomyocytes from a patient with long QT syndrome carrying KCNQ1-A344Aspl mutation.
We therefore analysed variations in the LQTS-associated genes KCNQ1 (LQT1) and KCNH2 (LQT2) using cardiac blood and myocardial tissue from subjects having died suddenly during MP or NPS use to investigate the relationship between congenital genetic abnormalities and sudden death during illegal drug use.
Among VCG parameters, QTpeak and TwEVs significantly differentiated patients with ecLQTS from controls (P ≤ .01 for each) as well as differentiated KCNQ1-encoded type 1 LQTS (ecLQT1), KCNH2-encoded type 2 LQTS (ecLQT2), and SCN5A-encoded type 3 LQTS (ecLQT3) from controls (P < .01). ecLQT3 was differentiated from controls and ecLQT1 and ecLQT2 by the fourth TwEV (P < .01 for each).