A genome-wide association study points to mutations in the human gene ATP1A3 as causative in alternating hemiplegia of childhood (AHC). The authors state that distinct mutations in same gene has been implicated in rapid-onset dystonia-parkinsonism.
Heinzen EL, Swoboda KJ, Hitomi Y, Gurrieri F, Nicole S, et al. De novo mutations in ATP1A3 cause alternating hemiplegia of childhood. Nat Genet. 2012 Jul 29. doi:10.1038/ng.2358. PubMed PMID: 22842232.
The fly ortholog of ATP1A3 appears to be ATPalpha (FBgn0002921) (DIOPT score = 8, indicating that 8 of 9 published ortholog prediction algorithms/tools predict this human-fly gene relationship).
As annotated in FlyBase, researchers have isolated a large number of mutations in ATPalpha and mutant phenotypes include lethality, the 'bang sensitive' phenotype, hypoactivity, paralysis and neurophysiological defects. Presumably these existing fly models could be used to study AHC.