Earlier studies of patient cohorts with a clinical phenotype of AHC mostly reported normal MRIs.39 More recently, however, as the diverse phenotypes associated with ATP1A3 are evolving, several reports of abnormal neuroimaging have also been published including cerebellar atrophy40 and PMG.8, –, 10 Eleven of our patients also had abnormal MRI, most commonly with cerebellar atrophy, in 1 case proven to be progressive. The gene discussed is ATP1A3; the disease is alternating hemiplegia of childhood.