A Case Report: Two Young Children with Long QT Syndrome Type-2 Diagnosed by Presymptomatic Genetic Testing

Abstract

Long QT syndromes (LQTSs) can lead to sudden cardiac death, yet these syndromes are often asymptomatic and clinically undetected, despite the prolongation of the QT interval. Currently, when a disease-causing variant is identified in an individual, presymptomatic genetic testing is available and can form part of the recommended cascade testing to identify other family members at risk. We herein report the cases of two daughters who received presymptomatic genetic testing in infancy when the proband mother had been diagnosed with LQTS type 2 (LQT2; c.1171C > T, p.Q391X in KCNH2) after suffering from cardiac arrhythmia at 30 years of age. The daughters had a normal QTc interval, but they carried the same disease-causing variant as their mother. Children with family members who have genetically confirmed LQTS have a high risk of suffering from cardiac events later in life, so genetic testing is required. This poses a complex problem, as guidelines for medical intervention and follow-up systems among asymptomatic children with LQTS have yet to be established. Genetic testing should only be performed after adequate counseling to support children later in life. Individualized long-term genetic counseling is required for both parents and children at stages throughout life.

Keywords

long QT syndrome - presymptomatic genetic testing - genetic counseling - pathogenic variant

Ethical Statement

This study was performed in accordance with the recommendations of the Ethics Review Committee of the Nagasaki University Graduate School of Biomedical Sciences, and the protocol was approved by this committee. All patients gave their written informed consent, except in the case of minors, where written informed consent was obtained from their parents, in accordance with the Declaration of Helsinki.

Publication History

Received: 06 August 2020

Accepted: 26 September 2020

Article published online:
23 November 2020

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