Voltage-gated sodium channels (VGSCs; NaV1.1–NaV1.9) have been proven to be critical in controlling the function of excitable cells, and human genetic evidence shows that aberrant function of these channels causes channelopathies, including epilepsy, arrhythmia, paralytic myotonia, and pain. The gene discussed is SCN11A; the disease is cardiac arrhythmia.