A progressive complex neurodevelopmental condition caused by variants in the CACNA1A gene. Phenotypic onset (usually) occurs around age 1 and most often includes intellectual disability but can also include epileptic encephalopathy, benign paroxysmal torticollis of infancy and paroxysmal tonic upgaze psychomotor delay, learning difficulties, absence epilepsy, episodic ataxia, and hemiplegic migraines.