Furthermore, the atrial arrhythmias seen in rodents may be a poor comparator for human AF due to the differences in ion channel expression between rodents and man (Gussak et al., 2000), the differences in the relative importance of SERCA and NCX in clearing cytosolic calcium (Bassani et al., 1994), and the lack of an extensive t-tubule network in rodents that is found in larger mammals (Richards et al., 2011). The gene discussed is TLX2; the disease is atrial fibrillation.