ATP1A3 and hereditary optic atrophy: Sodium pump dysfunction is associated with a range of disorders, with three neurological diseases linked to missense mutations in the ATP1A3 gene encoding the α3 subunit: alternating hemiplegia of childhood (Heinzen et al., 2012), rapid-onset dystonia parkinsonism (de Carvalho Aguiar et al., 2004), and CAPOS syndrome (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss) (Demos et al., 2014).