Key result
Genetic testing confirms pathogenic KCNH2 and KCNQ1 variants in 3 Ecuadorian patients with congenital LQTS.
Why the study?
Long QT syndrome is a hereditary cardiac channelopathy associated with delayed ventricular repolarization and an increased risk of life-threatening arrhythmias and sudden cardiac death.
Case Report (n=3)
No
Integrating ECG findings, genetic testing, and ancestry-informed interpretation improves diagnostic accuracy and personalizes management in admixed populations with inherited arrhythmia syndromes like LQTS.
Answers are grounded in this paper and cite their sources.
May aid LQTS diagnosis in admixed populations; extends variant data but leaves broader applicability open.
Long QT syndrome (LQTS) is a hereditary cardiac channelopathy associated with delayed ventricular repolarization and increased risk of life-threatening arrhythmias and sudden cardiac death. We report three Ecuadorian patients with LQTS, each presenting distinct clinical features and carrying pathogenic or likely pathogenic variants in KCNH2 or KCNQ1. Subject A, an 18-year-old woman with exertion-related syncope and a QTc of 520 ms, was diagnosed with LQT2 due to a KCNH2 p.Ala614Val variant. Subject B, a 3-year-old girl with congenital deafness and a QTc of 580 ms, was diagnosed with Jervell and Lange-Nielsen syndrome (JLNS), harboring a homozygous KCNQ1 p.Arg192Cys variant. Subject C, a 44-year-old man with recurrent syncope misdiagnosed as epilepsy and a strong family history of sudden death, was found to carry a KCNH2 p.Val612Met variant and had a QTc of 600 ms. All variants were classified according to ACMG/AMP guidelines and supported by in silico and functional data. Ancestry analysis provided additional genomic context in this admixed population. These cases underscore the clinical utility of integrating ECG findings, genetic testing, and ancestry-informed interpretation to improve diagnostic accuracy and personalize management in patients with inherited arrhythmia syndromes.
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Paz-Cruz et al. (2026) conducted a case report in Admixed Ecuadorian patients with genetically confirmed congenital long QT syndrome including LQT2 and Jervell and Lange-Nielsen syndrome (n=3). Beta-blocker therapy with propranolol and implantable cardioverter-defibrillator (ICD) in one patient was evaluated on Diagnosis confirmation of LQTS via genetic testing and QTc interval prolongation; risk stratification via clinical history and ECG; prevention of sudden cardiac death. Genetic testing identified pathogenic or likely pathogenic KCNH2 and KCNQ1 variants in three Ecuadorian patients with congenital LQTS, each with prolonged QTc intervals (520-600 ms) and clinical features including syncope and hearing loss.
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