ATXN3 and cerebellar ataxia: Machado-Joseph disease, also known as spinocerebellar ataxia type 3 (SCA3/MJD), is anautosomal dominant spinocerebellar ataxia caused by an expanded CAG repeat (longerthan 51 triplets) at ATXN3 gene, giving rise to an expandedpolyglutamine (polyQ) at ataxin-3 protein (Saute andJardim, 2015).