CACNA1A and autosomal dominant cerebellar ataxia: In the 1990’s, genetic mapping studies in patients with autosomal dominant cerebellar ataxias (ADCAs) identified 7 polyglutamine diseases: SCA type 1 [SCA1], SCA2, SCA3, SCA6, SCA7, SCA17, and dentatorubral-pallidoluysian atrophy [DRPLA] [2].