ATP1A3 and alternating hemiplegia of childhood: Positional mutations 274, 583, 867, and 923 lead to both RDP and AHC, suggesting different pathomechanisms.4,5 The E818K mutation underlies all reported cases of CAPOS/CAOS, including an AHC-CAPOS overlap syndrome.6 We report a family with features of all 3 ATP1A3-spectrum disorders.