CACNA1C and Timothy syndrome: The first TS-associated mutation identified in CACNA1C was p.G406R in the alternatively spliced exon 8a of CACNA1C. Functional characterization of p.G406R revealed a marked reduction in voltage-dependent inactivation (VDI); the consequent increase in Ca2+ influx prolongs the cardiac action potential, and thus the QT interval, and can generate early afterdepolarizations capable of triggering life-threatening arrhythmias [3]–[5].