Identical ATP1A3 Mutation Causes Alternating Hemiplegia of Childhood and Rapid-Onset Dystonia Parkinsonism Phenotypes

Abstract Background Alternating hemiplegia of childhood and rapid-onset dystonia parkinsonism are two separate movement disorders with different dominant mutations in the same sodium-potassium transporter ATPase subunit gene, ATP1A3. Patient We present a child with topiramate-responsive alternating hemiplegia of childhood who was tested for an ATP1A3 gene mutation. Results Gene sequencing revealed an identical ATP1A3 mutation as in three typical adult-onset rapid-onset dystonia parkinsonism cases but never previously described in an alternating hemiplegia of childhood case. Conclusion The discordance of these phenotypes suggests that there are other undiscovered environmental, genetic, or epigenetic factors influencing the development of alternating hemiplegia of childhood or rapid-onset dystonia parkinsonism.