In SCA2 patients, this expansion is found in the exon 1 of the gene ATXN2, with a number of CAG repeats above 31 (that can go up to 200), while the healthy individuals usually possess between 13 and 31 repetitions (Magaña et al., 2013). The gene discussed is ATXN2; the disease is spinocerebellar ataxia type 2.