Given a passage with a context and an answer, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.

Context: 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.', 'We present a child with topiramate-responsive alternating hemiplegia of childhood who was tested for an ATP1A3 gene mutation.', '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.
Answer: 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.
Does identical ATP1A3 mutation cause alternating hemiplegia of childhood and rapid-onset dystonia parkinsonism phenotypes?