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.
Keywords: ATP1A3; alternating hemiplegia of childhood; genetics; movement disorder; rapid-onset dystonia parkinsonism; topiramate.
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