CACNA1A and familial or sporadic hemiplegic migraine: Pathogenic variants of the CACNA1A gene result in allelic disorders with a broad clinical spectrum including episodic ataxia type 2 (OMIM: 108500), familial hemiplegic migraine type 1 (OMIM: 141500), spinocerebellar ataxia type 6 (OMIM: 183086) (5, 6), and overlapping features between these conditions in individual patients.