Spinocerebellar ataxia type 3 (SCA3), also known as Machado–Joseph disease, is an autosomal dominant disorder due to CAG repeat in the ATXN3 gene that leads to cerebellar ataxia, pyramidal signs, dystonia, peripheral neuropathy, and progressive external ophthalmoplegia, although the clinical heterogeneity is the hallmark of this entity (70, 71). The gene discussed is ATXN3; the disease is Spinocerebellar ataxia type 3.