Few arrhythmogenic mutations in CACNA1C, which encodes the pore-forming α1C subunit of the CaV1.2 L-type Ca2+ channel have been reported in long QT syndrome (LQTS), an inherited or acquired arrhythmia characterized by an abnormally long electrocardiographic QT interval, which reflects an underlying prolonged ventricular cardiomyocyte action potential caused by the specific biophysical consequences of the underlying mutation. Here, CACNA1C is linked to familial long QT syndrome.