Both loss-of-function and gain-of-function mutations in KCNA5 have been identified in patients with AF (Olson et al., 2006; Yang et al., 2009, 2010; Christophersen et al., 2013; Hayashi et al., 2015; Tian et al., 2015). This evidence concerns the gene KCNA5 and atrial fibrillation.