TBX5 and atrial fibrillation: Several cardiac-specific transcription factors, such as paired-like homeodomain transcription factor 2 (PITX2) and T-Box transcription factor 5 (TBX5), have been shown to be involved in the regulation of ion channel genes and play a role in AF, with decreasing PITX2 level shortening atrial effective refractory period [34,35].