According to the literature published to date, cognitive dysfunction in polyglutamine ataxias is prominent in SCA1, SCA2, SCA3, SCA6, SCA7, SCA17, and dentatorubral-pallidoluysian atrophy (DRPLA), which are caused by expanded CAG repeats in the coding exons (Schöls et al., 2004; Gatchel and Zoghbi, 2005; Lindsay and Storey, 2017; Giocondo and Curcio, 2018). The gene discussed is ATXN2; the disease is Dentatorubral pallidoluysian atrophy.