ATP1A3 and Rare pervasive developmental disorder: Paroxysmal episodic symptoms such as transient tonic or flaccid hemiplegia, dystonia, tonic seizures, episodic cerebellar ataxia, and abnormal ocular movements are the most common symptoms in patients with ATP1A3‐related disorders1, 2 (Table 1), except for childhood‐onset schizophrenia or autism spectrum disorders.