A large European cohort study of 155 individuals with a clinical diagnosis of AHC conducted in 2010 reached the conclusion that AHC is a nonprogressive disease.41 However, recent publications dispute this at least for some patients with an AHC phenotype.38,42 Little long-term data have been published for patients with other ATP1A3-related phenotypes. Here, ATP1A3 is linked to alternating hemiplegia of childhood.