Interestingly, mutations in a number of ion channel genes such as KCNQ1, KCND3 (Kv4.3), CACNB2,12, and CACNA2D4 have now been associated with AF (Chen et al., 2003; Weeke et al., 2014; Huang et al., 2017). The gene discussed is KCND3; the disease is atrial fibrillation.