CACNA1A and Huntington disease: The polyQ expansions are fundamental to nine genetic neurological diseases, namely Huntington’s disease (HD), spinocerebellar ataxias (SCAs) (SCA1, SCA2, SCA3, SCA6, SCA7 and SCA17), dentatorubral-pallidoluysian atrophy (DRPLA) and spinobulbar muscular atrophy (SBMA) [1,2,3].