Dentatorubral-pallidoluysian atrophy is specific subtype of SCA caused by an expansion of the CAG trinucleotide repeat in the atrophin-1 (ATN1) gene; the number of repeats ranges from 3 to 36 in healthy individuals to 49 to 88 copies in DRPLA patients (Schols et al., 2004; Durr, 2010). The gene discussed is ATN1; the disease is autosomal dominant cerebellar ataxia.