CACNA1A. CACNA1A is a large gene with a long history. Its first gene-disease association was with spinocerebellar ataxia type 6 (SCA6), an adult-onset progressive neurological disorder. Next, it was found to be associated with episodic ataxia and familial hemiplegic migraine. It took several more years before it was also found to be associated with epilepsy, developmental delay, and a more severe form of hemiplegic migraine. Here is a blog post on the range of neurological disorders associated with CACNA1A and the mechanism driving it.