SCA3 is a neurological disease where cerebellar degeneration is clearly and robustly demonstrated, ADHD and ASD are neuropsychiatric disorders that have been associated with cerebellar abnormalities, but the extent of cerebellar involvement is not as pronounced as in the case of SCA3 (Riva et al., 2013; Wan et al., 2020; Duan et al., 2021; Stezin et al., 2021). This evidence concerns the gene ATXN3 and attention deficit-hyperactivity disorder.