ATP1A3 and Pes cavus: Mutations in the ATP1A3 gene are associated with three related rare neurological disorders, Rapid-onset Dystonia-Parkinsonism (RDP) (de Carvalho Aguiar et al., 2004), Alternating Hemiplegia of Childhood (AHC) (Heinzen et al., 2012; Rosewich et al., 2012), and recently, Cerebellar ataxia, Areflexia, Pes cavus, Optic atrophy, and Sensorineural hearing loss (CAPOS) syndrome (Demos et al., 2014).