KCNA1 and episodic ataxia type 1: Diagnosis is primarily based on clinical findings and molecular genetic testing of KCNA1, and these investigations in several affected families have broadened the clinical spectrum of EA1 to now include phenotypes with delay in motor development, choreoathetosis, cognitive dysfunction, transient postural abnormalities in infancy, shortening of the Achilles tendon in children and epileptic seizures (Zuberi et al., 1999; Demos et al., 2009; D'Adamo et al., 2012, 2013; Pessia et al., 2012).