A picture emerged in which malfunctions of the same brain Nav isoform can lead to very different neural pathologies; for instance, Nav1.1 mutations may cause several forms of epilepsy or genetic migraine, but the channel is suspected to also be involved in autism spectrum disorders; similarly, Nav1.2 is correlated with epilepsy and with several forms of autism; finally Nav1.6 when mutated gives rise to epilepsy, whereas when its expression is impaired is correlated with developmental regression or with the most common neurodegenerative diseases such as Alzheimer’s and Parkinson’s. The gene discussed is SCN8A; the disease is Parkinson disease.