[Long QT syndrome in children: analysis of the Lyon series]

Area of Science:

• Pediatric Cardiology
• Molecular Genetics
• Clinical Electrophysiology

Context:

• Congenital long QT syndrome (LQTS) is a rare but severe pediatric cardiac disorder.
• Diagnosis traditionally relies on clinical and electrocardiographical criteria.
• Molecular genetics has identified specific genes linked to LQTS.

Purpose:

• To retrospectively analyze genotype-phenotype correlations in pediatric LQTS patients.
• To evaluate the role and limitations of genetic testing in diagnosing LQTS.
• To assess the relationship between genotype, symptoms, and cardiac events.

Summary:

• A retrospective study analyzed 23 pediatric LQTS patients (<21 years) with an average 2-year follow-up.
• Genotyping revealed mutations in implicated genes (e.g., SCN5A, KCNE2), with two deaths linked to specific mutations.
• Symptomatic patients showed longer QT/QTc intervals, though not significantly different; LQT3 and double mutations correlated with increased cardiac arrest risk.
• Notably, three patients had no identified mutation but still experienced severe cardiac events, highlighting diagnostic limitations.

Impact:

• This study underscores the importance of integrating genetic analysis with clinical and ECG findings for accurate LQTS diagnosis.
• It emphasizes that genetic testing alone may not capture all cases, necessitating a comprehensive diagnostic approach.
• Findings contribute to understanding genotype-specific severity and guiding risk stratification in pediatric LQTS.