Atrial Fibrillation, Familial, 4, also known as atfb4, is related to long qt syndrome 6 and long qt syndrome. An important gene associated with Atrial Fibrillation, Familial, 4 is KCNE2 (Potassium Voltage-Gated Channel Subfamily E Regulatory Subunit 2). Affiliated tissues include heart and heart-atrium, and related phenotypes are atrial fibrillation and premature atrial contractions