Inherited cardiac arrhythmia syndromes have received a lot of attention in recent years, particularly the molecular genetic basis, which has been unraveled to a great extent in the past years. Disease entities have been subdivided based on their causal gene defect, which, indeed, has been shown to impact on disease expression, clinical characteristics, prognosis and treatment. This particularly holds for the long QT syndrome. Studies in other, more recently described, disease entities, such as Brugada syndrome, catecholaminergic polymorphic ventricular arrhythmias and the short QT syndrome, are ongoing. For some of them the heterogenetic nature has just very recently been established. For these reasons, genetic testing has been introduced to clinical practice in several countries, which enables timely treatment of affected individuals and reassurance of those not inheriting the causal gene defect. Presymptomatic testing, however, is not without drawbacks. Psychosocial studies are needed in this field and should be promoted. It is likely that this development will further increase the knowledge of the (patho-) physiology of these disease entities, but also of more common arrhythmia syndromes.