Mutations in β1 [21] were associated with AED resistance in animal models, as are some β-subunits [8], such as SCN2B, SCN3B [22] and SCN4B. Mutations in SCN4B have been reported in neuropathologies linked with epilepsy [8], such as sudden unexpected death in epilepsy (SUDEP) and Dravet syndrome [8]. Here, SCN4B is linked to encephalopathy, progressive, early-onset, with brain edema and/or leukoencephalopathy.