ATXN3 and Spinocerebellar ataxia type 3: Spinocerebellar ataxia type 3 (SCA3), known as Machado-Joseph disease, is one of nine polyglutamine (polyQ) diseases that occurs due to an abnormal expansion of polyglutamine in exon 10 of the ATXN3 gene (Kawaguchi et al., 1994).