In 1995, Mark Keating and colleagues identified two genes responsible for congenital long QT syndrome, a cause of sudden cardiac death. Perturbations in the ion channels that orchestrate the beating heart were central to the disorder. This revelation provided a molecular model for the study of ventricular arrhythmias and enabled further dissection of the genetic defects underlying subtleties in the cardiac phenotype. Soon, these discoveries will be further translated to clinical medicine, with the expected release of one of the first comprehensive clinical genetic tests in cardiology.