ATP1A3 and cerebellar ataxia: Ataxia has appeared with ATP1A3 mutations in a syndrome with cerebellar ataxia, areflexia, pes cavus, optic nerve atrophy, and sensorimotor deafness (CAPOS) [12], and in pediatric cases where febrile episodes resulted in relapsing ataxia combined variably with symptoms shared with RDP and/or AHC [13–16], including one patient with an ataxia episode as an adult [15].