ATP1A3 and dystonia 12: Heterozygous variants in ATP1A3 cause rapid-onset dystonia parkinsonism (RDP, OMIM # 128235)2, alternating hemiplegia of childhood (AHC, OMIM # 614820)4, cerebellar ataxia, areflexia, pes cavus, optic atrophy, sensorineural hearing loss (CAPOS) syndrome (OMIM # 601338), and polymicrogyria5,6.