[Mutations in the heart's pacemaker channels--a new cause of sick sinus node syndrome and long-QT syndrome].

The sinus node hyperpolarization-activated If current generated by the cardiac pacemaker channels HCN2 and HCN4 determines the autonomous beating of the heart. Cardiac arrhythmias, like long-QT syndrome, are often caused by irregularities of the heart action potential generated by mutations in cardiac ion channel genes. Mutations in the HCN4 gene have been associated with sick sinus syndrome and long-QT syndrome. The identification of cardiac arrhythmia disease-associated genes makes possible new therapeutic strategies based on gene-specific drug treatment and gene therapy.