Mutations in KCNE genes have been associated with a number of diseases, i.e. cardiac arrhythmia by mutations in KCNE1 (long QT syndrome and Jervell Lange Nielsen Syndrome) [14-17], KCNE2 (long QT syndrome, atrial fibrillation, drug induced ventricular fibrillation) [18-20], KCNE3 (Brugada syndrome) [21] and KCNE5 (atrial fibrillation) [22]; mutations in KCNE3 have also been associated with periodic paralysis and hypo-and hyperkalemic disorders [23]. The gene discussed is KCNE5; the disease is atrial fibrillation.