Genetic variant in the SCN5A gene, which encodes the alpha subunit of the cardiac sodium channel protein Nav1.5, is well known as a cause of various inherited arrhythmic syndromes, including long QT syndrome type 3, Brugada syndrome (BrS), paroxysmal ventricular fibrillation, progressive familial heart block, AF, and sick sinus syndrome [38,39,40]. The gene discussed is SCN5A; the disease is long QT syndrome 3.