Intranuclear aggregation of the mutant polyglutamine expanded ATXN3 protein is a neuropathological hallmark of SCA3/MJD linking to neurotoxicity, which is associated with neuronal dysfunction and degeneration (Bichelmeier et al. 2007; Matos et al. 2019; Koeppen 2018). The gene discussed is ATXN3; the disease is Machado-Joseph disease.