ATXN3 and Spinocerebellar ataxia type 3: Immunohistochemical staining for human ataxin-3 in the brain of 18-week-old mice revealed the presence of ataxin-3-positive aggregates within various regions of the MJD mouse brain, including the pons, medulla oblongata and deep cerebellar nuclei (DCN) (Fig. 5A).