Question category: Cardiology
An 20 year old student is brought to A and E following a collapse in an a night club. There was no suspicion of illicit drug use. He has had 3 collapse episodes previously. He had regained consciousness after a few minutes. There is nil of note on examination with BP and HR within normal parameters. However, an ECG shows a QT interval of 0.56. Which ion channel is likely to be defective and have caused these signs and symptoms?