Autosomal dominant mutations in ATP1A3 were first shown to cause Rapid-onset Dystonia Parkinsonism (RDP, de Carvalho Aguiar et al., 2004), and later two other neurological syndromes, Alternating Hemiplegia of Childhood (AHC, Heinzen et al., 2012; Rosewich et al., 2012) and CAPOS (cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss, Demos et al., 2014). This evidence concerns the gene ATP1A3 and alternating hemiplegia of childhood.