SCN5A and Prolonged QT interval: SCN5A pathogenic variations are thought to have variable expressivity and can cause variable phenotypes, including Brugada syndrome, long QT syndrome, and cardiac conduction disease, depending on the type of mutation and patient factors.19–21SCN5A channelopathies are unlikely to respond to endocardial ablation in the long term and often require epicardial intervention or other alternative therapies.22,23