ATXN3 and Machado-Joseph disease: Ataxin-3 is responsible for the neurodegenerative disorder Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (Paulson, 2012), which is the most common dominantly inherited ataxia and a member of the polyglutamine disease family (Kawaguchi et al., 1994; Matos et al., 2011).