KCNH7 and atrial fibrillation: While various potassium (KCNJ3, KCNJ5), calcium (CACNA1C), or sodium (SCN5A) channel genes show a decrease in expression in cardiomyocytes in AF, other components such as HCN2 (K/Na hyperpolarization-activated cyclic nucleotide-gated channel 2) or KCNH7 (Kv11.3) are increased [22].