Final answer:
QT syndrome is caused by mutations in potassium channels, affecting the heart's electrical activity and potentially leading to irregular heartbeats.
Step-by-step explanation:
The channelopathy known as QT syndrome is a result of mutation in potassium channels. Specifically, this condition affects the heart's electrical activity by altering the way potassium channels function during the cardiac action potential. These potassium channels are essential for repolarizing the myocardium after each heartbeat, and mutations can lead to prolonged repolarization, which is observed as a lengthened QT interval on an electrocardiogram (ECG). This can increase the risk of an irregular heartbeat, or arrhythmias, which can be life-threatening.