Cumulative data suggested a strong link between AF and SCN5A mutations, and the association of loss-of-function mutations in SCN5A with AF has been reported.39 The voltage-gated potassium channel Kv1.5, conducting the ultrarapid delayed rectifier current (IKur), is the main repolarizing current in the atria. The gene discussed is SCN5A; the disease is atrial fibrillation.