CACNA1A and dentatorubral-pallidoluysian atrophy: These include Huntington disease, X-linked spinobulbar muscular atrophy (SBMA, Kennedy disease) and the spinocerebellar ataxias SCA1, SCA2, SCA3 (also known as Machado-Joseph disease), SCA6, SCA7 and SCA17 as well as dentatorubral pallidoluysian atrophy (DRPLA).