 Mutation D76N in the KCNE1 protein can lead to long QT syndrome due to structural changes in the KvLQT1/KCNE1 complex, and people with these mutations are advised to avoid triggers of cardiac arrhythmia and prolonged QT intervals, such as stress or strenuous exercise.While loss-of-function mutations in KCNE1 cause Long QT syndrome, gain-of-function KCNE1 mutations are associated with early-onset atrial fibrillation.A common KCNE1 polymorphism, S38G, is associated with altered predisposition to lone atrial fibrillation and postoperative atrial fibrillation.