ATP1A3 and alternating hemiplegia of childhood: Heterozygous missense and de novo mutations in the Na+/K+-ATPase alpha3 subunit (ATP1A3) can cause either rapid-onset dystonia-parkinsonism (DYT12) (44), or alternating hemiplegia of childhood (AHC), a severe neurodevelopmental syndrome characterized by hemiplegic episodes and neurological complaints (45), respectively.