ATP1A3 and Areflexia: Pathogenic mutants in the ATP1A3 gene, encoding the α3 isoform, can lead to ATP1A3-related neurological disorders such as alternating hemiplegia of childhood (AHC), rapid-onset dystonia-parkinsonism (RDP), and cerebellar ataxia, areflexia, pes cavus, optic atrophy, and sensorineural hearing loss (CAPOS) syndrome (Sharawat et al., 2020).