HCN4 and atrial fibrillation: Distinct laboratories, including ours, have demonstrated that PITX2 potentially regulates AF through modulation of multiple genes implicated in AF; KCNN3 [140,145,147]; TBX5 [148,149,150]; HCN4 [145,151]; KCNJ2 [104,152]; CAV-1 [145,147]; KCNQ1 [151,153]; ZFHX3; SYNE2; Il6R [147]; ENPEP [154].