These mechanisms have been described to be impacted by PolyQ protein expression: for example, chaperones and/or proteasome components have been detected in protein aggregates associated with HD, SCA1, SCA3 and SBMA, in cell models101–103, animal models104,105 and patient brain samples106,107; autophagy has been described to be impaired in animal models of SCA1 and SBMA (refs.108,109), and in patients of HD, SCA3, SCA7 (refs. 110,111,112). The gene discussed is ATXN7; the disease is Huntington disease.