KCND3 and Familial paroxysmal ataxia: Therefore, their dysfunction can cause various neurological disorders, such as episodic ataxia (KCNA1/Kv1.1), epilepsy and epileptic disorders (KCNA2/Kv1.2, KCNB1/Kv2.1, KCNC1/Kv3.1, KCNQ2/Kv7.2, and KCNQ3/Kv7.3) [2], and cardiac disorders with arrhythmias, such as atrial fibrillation, long QT syndrome (KCNQ1/Kv7.1 and KCNH2/Kv11.1) [3], and Brugada syndrome (KCND3/Kv4.3) [4].