This drug is used for the treatment of Lambert-Eaton myasthenic syndrome with an acceptable profile of safety and tolerability, although epileptic seizures and arrhythmias are experienced in response to 3,4-diaminopyridine as a result of the widespread expression of type-A potassium channel Kv4.3 in excitable cells [55]. The gene discussed is KCNA4; the disease is Lambert-Eaton myasthenic syndrome.