CACNA1A and Huntington disease: SCA2 is caused by a CAG triplet repeat expansion in the ATXN2 gene and, therefore, belongs to the group of CAG triplet repeat disorders like SCA1, SCA3, SCA6, SCA7, SCA17, Huntington’s Disease (HD), Dentatorubral pallidoluysian atrophy (DRPLA), and Spinal and bulbar muscle atrophy (SBMA) [9, 10].