A Novel SCN5A Mutation Found in a Familial Case of Long QT Syndrome Complicated by Severe Left Ventricular Dysfunction

doi:10.1016/j.cjca.2016.10.010

Canadian Journal of Cardiology

Volume 33, Issue 4, April 2017, Pages 554.e5-554.e7

https://doi.org/10.1016/j.cjca.2016.10.010 Get rights and content

Abstract

A 16-year-old boy with long QT syndrome type 3 (LQT3) was admitted for decompensated heart failure resulting from dilated cardiomyopathy (DCM). His brother was also diagnosed with LQT3 and DCM. A comprehensive genetic analysis identified a novel SCN5A missense mutation—p.Q371E—in these 2 affected living family members. It might be important to suspect the coexistence of DCM and LQT3 (which is rare according to previous articles) in cases with this novel SCN5A missense mutation.

Résumé

Un jeune homme de 16 ans atteint du syndrome du QT long de type 3 a été hospitalisé à la suite d’une insuffisance cardiaque décompensée résultant d’une cardiomyopathie dilatée. Son frère avait également reçu un diagnostic de syndrome du QT long de type 3 et de cardiomyopathie dilatée. Une analyse génétique détaillée a permis de repérer une nouvelle mutation faux sens – p.Q371E – du gène SCN5A chez ces deux frères. Il se pourrait donc qu’il soit important de soupçonner la coexistence d’une cardiomyopathie dilatée et d’un syndrome du QT long de type 3 (chose rare selon les articles précédents) dans le cas où cette nouvelle mutation faux sens du gène SCN5A est décelée.

Section snippets

Case Report

The proband (Fig. 1, subject III-3) is a 16-year-old boy. He was initially diagnosed with prolonged QT at the age of 12 years, and LQT3 was confirmed later after genetic analysis (Schwartz score = 4). Although his left ventricular (LV) function at the initial assessment was normal, LV systolic dysfunction deteriorated over time. At the age of 16 years, he was transferred to our hospital because of decompensated heart failure. On admission, his electrocardiogram showed QT prolongation (

Disclosures

The authors have no conflicts of interest to disclose.

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There are more references available in the full text version of this article.

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Citation Excerpt :
Left atrial enlargement is the most common finding and is associated with prolonged QTc and CEs. These changes may stem from underlying contraction abnormalities caused by ion channel dysfunction, structurally normal heart on echocardiography [18], DCM was observed in missense mutation-p.Q371E [19]. Exercise stress testing: Takahashi et al. [20] investigated QT dynamics during exercise testing in LQT3.
Congenital long QT syndrome type 3 (LQT3) is the third in frequency compared to the 15 forms known currently of congenital long QT syndrome (LQTS). Cardiac events are less frequent in LQT3 when compared with LQT1 and LQT2, but more likely to be lethal; the likelihood of dying during a cardiac event is 20% in families with an LQT3 mutation and 4% with either an LQT1 or an LQT2 mutation. LQT3 is consequence of mutation of gene SCN5A which codes for the Nav1.5 Na⁺ channel α-subunit and electrocardiographically characterized by a tendency to bradycardia related to age, prolonged QT/QTc interval (mean QTc value 478 ± 52 ms), accentuated QT dispersion consequence of prolonged ST segment, late onset of T wave and frequent prominent U wave because of longer repolarization of the M cell across left ventricular wall.
Arrhythmic Phenotypes Are a Defining Feature of Dilated Cardiomyopathy-Associated SCN5A Variants: A Systematic Review
2022, Circulation: Genomic and Precision Medicine
SCN5A variants: Association with cardiac disorders
2018, Frontiers in Physiology

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Case ReportA Novel SCN5A Mutation Found in a Familial Case of Long QT Syndrome Complicated by Severe Left Ventricular Dysfunction

Abstract

Résumé

Section snippets

Case Report

Disclosures

Cell

J Am Coll Cardiol

Case Report
A Novel SCN5A Mutation Found in a Familial Case of Long QT Syndrome Complicated by Severe Left Ventricular Dysfunction