CACNA1A and Huntington disease: Currently, nine disorders fall under this category of neurological diseases, including Huntington's disease (HD), spinobulbar muscular atrophy (SBMA), dentatorubral-pallidoluysian atrophy (DRPLA), and spinocerebellar ataxias (SCA1, SCA2, SCA3, SCA6, SCA7, and SCA17) (2–4).